FROM: Kristine Pelt and Jeff Coburn, RTI International

TO: Brenda Shine, EPA/OAQPS/SPPD

FOR: Docket ID No. EPA-HQ-OAR-2010-0682

DATE: January 22, 2014

SUBJECT: Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

1. Purpose

This memorandum documents the technology review for wastewater collection and treatment 

operations. It reviews control alternatives and estimates the costs and environmental impacts for 

the alternatives identified.

2. Legislative Background

The Clean Air Act (CAA) requires the EPA to review promulgated standards periodically to 

ensure that national emissions standards for hazardous air pollutants (NESHAP) reflect advances 

in emissions reduction technology. Specifically, section 112(d)(6) of the CAA states that “[t]he 

Administrator shall review, and revise as necessary (taking into account developments in 

practices, processes, and control technologies), emission standards promulgated under this 

section no less often than every 8 years.” This memorandum documents the technology review 

for wastewater collection and treatment operations at petroleum refineries subject to 40 CFR 

part 63, subpart CC (also known as “Refinery MACT 1”).

3. Introduction

Industrial wastewater collection and treatment operations range from simple pre-treatment 

operations that discharge to publicly owned treatment works (POTW) to full-scale on-site 

treatment systems. Indirect dischargers, or those facilities that discharge wastewater to a POTW, 

typically collect, store and pretreat the wastewater prior to discharge to a POTW. The receiving 

POTW further treats the wastewater to a level acceptable for discharge to a receiving body of 

water. Facilities with on-site full-scale wastewater treatment operations consist of collection, 

storage and treatment units that treat wastewater to a level that is acceptable for discharge to a 

receiving body or for re-use in the process.

Wastewater collection includes components such as drains, manholes, trenches, junction boxes, 

sumps, lift stations and sewer lines. Drains are the first component of the collection system and 

typically channel wastewater to the process sewer line, although drains can route wastewater to 

sumps, trenches or ditches. Manholes are access points to the sewer line that allow for 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

2

inspection, maintenance, and cleaning of sewer lines. Junction boxes combine wastewater from 

multiple sewer lines together for transport to the treatment system.

Treatment systems are divided into three categories: primary, secondary, or tertiary, depending 

on the design, operation, and application of the wastewater treatment system. In primary 

treatment systems, physical operations remove floatable and settleable solids and oil. Typical 

primary treatment operations include equalization basins and oil-water separators. In secondary 

treatment systems such as biological treatment units or steam strippers, biological, separation and 

chemical processes remove most of the organic matter in the wastewater. In tertiary treatment 

systems, further treatment or filtering of wastewater is done to “polish” the wastewater for 

discharge to a receiving body of water or reuse in a process.

Wastewater can be stored at any point in the wastewater collection and treatment system. 

However, wastewater storage tanks usually collect and store wastewater at the entrance to or exit 

from a wastewater treatment unit. Treatment of wastewater does not occur in wastewater storage 

tanks. Examples of wastewater storage tanks include steam stripper feed, bottoms and overheads 

tanks and tanks used to store wastewater removed from sludge.

There are currently many federal regulations that have been written to minimize air emissions 

from industrial wastewater collection and treatment operations, including NESHAP and new 

source performance standards (NSPS). Although most of these regulations are fairly consistent 

in the control technologies required for industrial wastewater collection and treatment operations, 

there are significant differences in what is included as wastewater and what triggers the need for 

control. One of the purposes of this technology review is to identify any new or improved 

technology, monitoring technique or work practice that has not been identified and implemented 

in an existing regulation for the control of emissions from wastewater collection and treatment.

4. Description of Emission Releases

Volatile organic compounds (VOC) are emitted into the air from wastewater collection, 

treatment and storage systems that are uncovered or open to the atmosphere through 

volatilization of organic compounds at the liquid surface. Emissions occur by diffusive or 

convective means, or both. Diffusion occurs when organic concentrations at the water surface 

are much higher than ambient concentrations. The organics volatilize, or diffuse into the air, in 

an attempt to reach equilibrium between aqueous and vapor phases. Convection occurs when air 

flows over the water surface, sweeping organic vapors from the water surface into the air. The 

rate of volatilization is related directly to the speed of the air flow over the water surface (EPA, 

1998a).

Other factors that can affect the rate of volatilization include wastewater surface area in the unit; 

temperature of the wastewater; turbulence in the unit; wastewater retention time in the unit; the 

depth of the wastewater in the unit; the concentration of organic compounds in the wastewater 

and their physical properties, such as volatility and diffusivity in water; and the presence of a 

mechanism that inhibits or competes with volatilization, such as an oil film or biodegradation 

(EPA, 1998a).
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

3

Emissions can also occur from covered tanks as a result of temperature or pressure changes when 

the vapor in the head space of the tank expands and is expelled through a vent or opening in the 

tank. Emissions from covered tanks also occur when the liquid level in the tank increases which 

displaces vapors from within the tank head space through a vent or opening in the tank.

Emissions from Collection Systems

Emission sources within a wastewater collection system differ among facilities, but they 

generally include drains, manholes, trenches, lift stations, sumps, and/or junction boxes. As 

water flows through the components of the collection system or in sewer lines directly below 

these components, emissions may occur by volatilization of organic compounds at any water/air 

interface. Emission modeling of wastewater collection systems suggests that a large portion of 

the emissions from wastewater can occur in the collection phase if the system is complex (i.e., 

has many components) and open to the atmosphere. Emissions from these wastewater collection 

systems are essentially fugitive emissions and can occur across a wide area of the facility.

Wastewater is introduced into wastewater collection systems through drains and these drains are 

usually connected directly to sewer lines. Drains may be dedicated to a single piece of 

equipment (i.e., a pump) or may serve several sources. Drains are the most numerous 

component in the collection system and some refineries can have in excess of 3,000 drains (EPA, 

1985). Emissions from drains are generally controlled using a water seal that prevents the direct 

diffusion or flow of gases from the sewer line to the atmosphere. It can be difficult to determine 

if a drain seal is working properly, and insufficient water levels in a drain seal can allow VOC to 

be emitted from the drain into the atmosphere.

Junction boxes receive flow from multiple sewer lines. Junction boxes are square or rectangular 

and are sized based on the combined flow rate of the sewers tied into the junction box. 

Generally, the flow rate from the junction box is controlled by the liquid level in the junction 

box. Some junction boxes have water seals at the entrance and exit to prevent emissions from 

the junction box vent by isolating the junction box from the rest of the drain system. Emissions 

occur from a junction box when the junction box is uncovered or is covered and vented to the 

atmosphere without the presence of water seals. If the water levels in the junction box seals are 

inadequate, emissions may also occur.

Trenches and sumps are also used at facilities to collect and transport wastewater. Trenches are 

typically open to the atmosphere and covered with grates. Trenches can be located in a process 

area to receive wastewater directly from a process and wastewater from process equipment pad 

runoff due to spills or cleanup; trenches can also be used to transport wastewater from one 

process area to another or from one treatment unit to another. Sumps are typically used to 

equalize flow from several trenches before treatment and can also receive flow from process 

sewers. Sumps are also typically open to the atmosphere.

Lift stations are usually the last collection component before treatment. Lift stations are similar 

to junction boxes in that they receive wastewater from multiple sewers; however, lift stations are 

typically larger than junction boxes. Wastewater is typically pumped from a lift station to 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

4

treatment or can be transported hydraulically to treatment. Emissions occur from lift stations 

when the lift station is uncovered or is covered and vented to the atmosphere.

Emissions from Wastewater Storage Tanks

Wastewater storage tanks usually collect and store wastewater at the entrance to or exit from a 

wastewater treatment unit. Storage tanks are typically quiescent. In cases where these tanks are 

uncovered, emissions occur through volatilization of organic compounds at the liquid surface 

through diffusion and convection as described above. If the tank has a fixed-roof cover vented to 

the atmosphere, emissions occur as standing and working losses. Standing loss, also known as 

breathing loss, is the expulsion of vapor from a tank through vapor expansion and contraction, 

which are the results of changes in temperature and barometric pressure. This loss occurs 

without any liquid level change in the tank (EPA, 2006).

The combined loss from filling and emptying is called working loss. Evaporation during filling 

operations is a result of an increase in the liquid level in the tank. As the liquid level increases, 

the pressure inside the tank exceeds the relief pressure and vapors are expelled from the tank. 

Evaporative loss during emptying occurs when air drawn into the tank during liquid removal 

becomes saturated with organic vapor and expands, thus exceeding the capacity of the vapor 

space (EPA, 2006).

Emissions from Treatment Systems

The overall objectives of wastewater treatment at refineries are to: (1) equalize flow and 

pollutant load by buffering flow surges in large tanks, (2) separate free and emulsified oils and 

solids from the wastewater by oil-water separators and flotation unit operations (e.g., dissolved 

air flotation (DAF) or induced air flotation (IAF)), and (3) remove organic matter in the 

wastewater through destruction or biodegradation.

Wastewater treatment tanks (primary treatment) are upstream of removal or destruction systems 

(e.g., steam strippers, biological treatment). Equalization tanks, oil-water separators, clarifiers, 

and flotation units (DAF units or IAF units) are examples of wastewater treatment tanks. 

Emissions from these tanks are similar to the emissions from wastewater storage tanks. 

Emissions from open top tanks occur through diffusion and convection and emissions from 

covered tanks vented to the atmosphere occur as standing and working losses. However, the rate 

of volatilization in these tanks can be greater than from storage tanks if the tank is mixed or 

sparged (DAFs and IAFs) or in the case of oil-water separators, the rate of volatilization may be 

less due to the oil layer.

The most common secondary treatment method used at petroleum refineries is biological 

treatment (EPA, 2004). Biological waste treatment usually is accomplished by aeration in open 

basins with mechanical surface aerators or with a diffused air system. Mechanical surface 

aerators float on the water surface and rapidly mix the water. Aeration of the water is 

accomplished through splashing. Diffused air systems, on the other hand, aerate the water by 

bubbling oxygen through the water from the bottom of the tank or device (EPA, 1998a).
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

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The rate of emissions of organic compounds from biotreatment depends on competing 

mechanisms. Multiple fate and transport mechanisms are often involved in the ultimate removal 

of a specific compound. Specifically, biodegradation, volatilization, adsorption, hydrolysis, and 

photo degradation are common mechanisms in wastewater treatment that may compete against 

each other. Emissions from biological treatment operations are also dependent on how well the 

unit is designed and operated. Biological systems often exhibit an operational lag phase when 

there is a significant shift in influent concentration or flows, which can cause a shift in the 

dominant removal mechanism across the system.

Units that remove organics from wastewater through destruction are enclosed units and 

emissions would originate from a stack (e.g., steam strippers). Emissions from destructive units 

are also dependent on how well the unit is designed and operated.

5. Identification of Control Technologies

Collection Systems

The available technologies for collection systems include: 1) covering or enclosing all openings 

in the drain system and routing all vents to a control device; or 2) using water seals (applicable 

primarily for drains and junction boxes) to prevent releases from these components.

The effectiveness of water seals is dependent on how well the water seals are maintained. If the 

liquid level in the water seal is low or there is no water present in the seal, the control efficiency 

of the water seal is greatly reduced. Monitoring the seal using EPA Method 21 (an organic vapor 

analyzer) can be used to determine if emissions are being released from the water seal, 

suggesting an insufficient seal. More frequent monitoring of the seal will ensure that the water 

seal is properly maintained (or that an insufficient seal is corrected in a timely manner). As such, 

the monitoring frequency is expected to impact the overall control efficiency of a water seal

control system.

Covering openings and routing vents to a control device and using water seals are control 

technologies that were available during the development of Refinery MACT 1. No new 

technologies were identified for the control of emissions from wastewater collection systems.

Wastewater Storage and Treatment Tanks

No new technologies for the control of emissions from tanks were identified. The available 

technologies for the control of emissions from tanks includes equipping the tank with a fixed 

cover, equipping the tank with a fixed roof cover and routing the vent to a control device, or 

equipping the tank with a floating roof.

Treatment Technology

The most common treatment technology used at refineries for the removal of organics from

wastewater is biological treatment. Steam strippers are also used at refineries for the removal of 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

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organics from wastewater. A review of other technologies that can be used for the removal or 

destruction of organics from wastewater revealed no new readily available technologies. A list

of the technologies that were reviewed and a summary of the information collected are provided 

in Table 1.

Table 1. Summary of Treatment Technologies

Technology Summary of Information

Activated Carbon Adsorption Activated carbon follows treatment in a biological system because carbon 

usage would be prohibitively high if used as primary treatment. The 

capacity of the carbon to adsorb compounds at a given inlet concentration 

varies widely by compound.

Activated Sludge Activated sludge treatment involves a continuous biological treatment 

system utilizing a suspension of aerobic biological growths in wastewater. 

In an activated sludge process, the wastewater enters an aeration tank 

where the microorganisms and organic compounds are mixed together. 

Diffused air or surface aerators are used to keep the process aerobic and 

to maintain the solids in suspension in the wastewater. A significant portion 

of biological sludge generated in the unit is recovered in a clarifier and 

recycled back to the influent of the aeration tank to maintain a high 

concentration of suspended microorganisms.

Activated Sludge Treatment 

with Powdered Activated 

Carbon

Biological treatment and carbon absorption occur in a single treatment 

tank. Carbon absorption occurs on a powdered activated carbon that is 

recycled with the sludge but a continuous makeup of activated carbon is 

required.

Air Stripping Air stripping is used to separate VOC from contaminated water and heating 

is required to strip less volatile compounds. Air stripping only provides 

phase separation while destruction is achieved in biotreatment. Air 

stripping also requires destruction of the separated organics, usually using 

a carbon adsorber or combustion device. High concentration systems 

require a large amount of air which becomes cost prohibitive. Air stripping 

is more applicable to water with dilute concentrations such as contaminated 

groundwater.

Chemical Oxidation A chemical reaction occurs between organics and an oxidant. Chemical 

oxidation is a cost effective and viable remediation technology for VOC and 

petroleum based contaminants in soil, groundwater, and sediments (i.e., 

low concentrations). Chemical oxidation is not commonly used in refinery 

wastewater treatment plants but is sometimes used as a tertiary treatment 

step. The capital and operating cost is high at high concentrations. 

Applicability depends on the reactivity of the compound.

Ion Exchange Adsorption Ion exchange adsorption is used for inorganic compound removal, 

exchange, or recovery.

Liquid-liquid Extraction Liquid-liquid extraction is used for compounds distributed between two

immiscible liquids, water and an organic liquid. Further treatment is 

required to destroy organics.

(continued)
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

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Table 1. Summary of Treatment Technologies (continued)

Technology Summary of Information

Liquid Phase Carbon 

Adsorption

Liquid phase carbon adsorption is used to treat contaminated groundwater. 

It is effective on low concentration streams at any flow rate and effective on 

high concentration streams at low flow rates (1 gallon per minute). 

Streams with oil and grease may foul the carbon. Costs are high if used as 

primary treatment of high concentration streams. 

Membrane Separation Membrane separation is used for gaseous streams with dilute 

concentrations of VOC.

Sequencing Batch Reactor A sequencing batch reactor involves aeration, sedimentation, and 

clarification in a single unit. This technology is uncommon and has limited 

application in wastewater treatment at petroleum refineries.

Steam Stripping Steam stripping is a continuous distillation process that uses steam to 

remove hydrocarbons from wastewater. A high concentration organic 

vapor stream leaves the top of the column and a relatively organic-free 

water stream from the bottom of the tower can be recycled back to the 

process. The overhead vapor stream requires treatment in a unit such as a 

condenser or combustion unit.

Trickling Filter The biological material is attached to a filter to which wastewater comes in 

contact. Microorganisms are attached to a filter rather than being 

suspended in the wastewater. This technology is usually used as a 

polishing step.

Vapor Phase Carbon 

Adsorption

Adsorption is a mass-transfer operation involving interaction between 

gaseous components and solid-phase components. The gas phase 

(adsorbate) is captured on the solid-phase (adsorbent) surface by physical 

or chemical adsorption mechanisms. The most common industrial 

adsorption systems use activated carbon as the adsorbent. 

Biological Removal

Biological treatment is the most widely used wastewater treatment technology for removal of 

dissolved organic compounds in the oil refining industry (EPA, 2004). Biological treatment 

processes can handle a wide range of flows and concentrations. The two primary classes of 

biological treatment units are suspended-growth and attached-growth systems. Suspendedgrowth systems maintain the biomass (flocs) in suspension by mechanical or aeration devices 

where biodegradation occurs. Examples of suspended-growth systems include activated sludge, 

aerated lagoons, sequencing batch reactors, and membrane bioreactors. Attached-growth 

systems establish biofilms on fixed surfaces where biochemical reactions occur. Examples of 

attached-growth systems include trickling filters and rotating biological contactors. Regardless 

of the type of biological treatment used, the biochemical reactions are generally the same, with 

the oxidation of organic compounds and ammonia forming new cells, carbon dioxide, and water

(RTI, 2011a).

An activated sludge process is the most effective of all biological treatment systems available. 

As stated above, activated sludge is a continuous suspension of aerobic biological growths in 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

8

wastewater. In an activated sludge process, the wastewater enters an aeration tank where the 

microorganisms and organic compounds are mixed together. Air is injected into the mixture to 

keep the process aerobic and to maintain the solids in suspension in the wastewater.

To maintain the health of the microorganisms and ensure adequate biologically mediated 

oxidation of the organic compounds and ammonia, oxygen must be introduced into the system. 

There are two basic methods for aerating wastewater: (1) introducing air or pure oxygen into the 

wastewater through diffusers or other devices, and (2) agitating the water to increase surface area 

and promote the gaseous exchange with the atmosphere. However, the mechanisms that increase 

dissolved oxygen concentration in the water also increase the emission rate of organic 

constituents through increased volatilization. The volatilization rate can be affected by the 

wastewater surface area, turbulence, and temperature; hydraulic retention; water depth; 

concentration and physical properties of the organic constituents (e.g., volatility, diffusivity, 

inhibitory mechanisms); and atmospheric conditions.

Steam stripping

Steam stripping is a continuous distillation process that uses steam to remove hydrocarbons from 

wastewater. Compounds with boiling points less than water and compounds with low solubility 

in water are easily removed. Higher temperatures in steam stripping versus air stripping allow 

the removal of heavier, more soluble organics that are not strippable using air. A high 

concentration organic vapor stream leaves the top of the column and a relatively organic-free 

water stream from the bottom of the tower can be recycled back to the process. The overhead 

vapor stream requires treatment in a unit such as a condenser or combustion unit.

Steam stripping is most applicable to treating wastewaters with organic compounds that are 

highly volatile and have a low solubility in water. Organic compounds that have low volatility 

tend to volatilize less readily and thus are not easily stripped out of the wastewater by the steam. 

Similarly, organic compounds that are very soluble in water tend to remain in the wastewater and 

also are not easily stripped out by steam.

Oil, grease, solids content and pH of a wastewater stream also affect the applicability of steam 

stripping to a particular wastewater. High levels of oil, grease, and solids can cause operating 

problems for steam strippers. High or low pH may prove to be corrosive to equipment. 

However, these problems can usually be circumvented by design or wastewater preconditioning 

techniques (EPA, 1992).

6. Model Development

For this analysis, we developed seven model facilities, each with different VOC loading rates to 

the wastewater collection and treatment plant. We also developed a model process drainage area 

and series of wastewater treatment processes that are similar for each of the different-sized

model facilities. We initially used refinery capacity information from the Energy Information 

Administration (EIA) to develop the three model facilities representing the 20th, 50th and 

80th percentile crude distillation capacities (EIA, 2009); we then developed several additional 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

9

small model facilities (with capacities below the 20th percentile facility and between the 20th and 

50th percentile facilities) to capture a series of volatile organic wastewater loading rates. Each 

model facility was assigned refinery processing units typical of refineries of that size (EIA, 

2009). In general, the larger model refineries are more complex (i.e., have more upgrading 

process units) than the small model refineries. Once processes were assigned to each model 

facility, we then used refinery process-specific wastewater generation rates and benzene and 

organic HAP concentrations from the EPA’s Locating and Estimating Air Emissions from 

Sources of Benzene (EPA, 1998b) to estimate the total flow rate and flow-weighted average 

benzene concentration and organic HAP concentration for each of the model facilities. We 

assumed that the total organic concentration was 5 times the total HAP concentration (i.e., that 

organic HAP was 20 percent of the total organic load) based on data received in response to the 

Petroleum Refinery Information Collection Request (ICR) (EPA, 2011). Finally, we assumed 

that 75 percent of the total organic load would be VOC detectable using EPA Method 25D. The 

parameters for the seven model facilities are shown in Table 2.

Table 2. Model Facility Flow Rates and Concentrations

Model 

Facility

Model 

Capacity 

(bbl/day)a

Flow Rate 

(MGD)a

Organic HAP 

Concentration 

(ppmw)a

Method 25D 

VOC 

Concentration 

(ppmw)a

Benzene 

Concentration 

(ppmw)a

VOC Load at 

Generation 

(Mg/yr)a

1 7,000 0.029 111 415 17.2 16.6

2 10,000 0.080 124 464 22.1 51.2

3 20,000 0.81 37 139 5.94 156

4A 50,000 1.95 39 146 6.30 394

4B 60,000 1.95 68 254 5.56 686

5 80,000 2.75 65 244 6.81 927

6 215,000 9.26 64 241 5.64 3,086

a

 bbl/day = barrels per day; MGD = million gallons per day; ppmw = parts per million by weight; Mg/yr = Megagrams 

per year.

Our model wastewater collection and treatment system included individual drain system 

components, an oil-water separator, an air flotation unit, an equalization tank, and a biological 

treatment process. The wastewater collection and treatment system model was based on 

information obtained from the EPA’s AP-42 (EPA, 1998a), VOC Emissions from Petroleum

Refinery Wastewater Systems – Background Information for Proposed Standards (“NSPS QQQ 

BID”) (EPA, 1985), and the Emissions Estimation Protocol for Petroleum Refineries (RTI, 

2011a). For the collection system, we assumed that each wastewater stream would travel 

through or under four drains, a manhole, a junction box, a sump, and a lift station. The oil-water 

separator, equalization tank, and air flotation unit are referred to as treatment tanks.
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Operations at Petroleum Refineries

January 22, 2014

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Toxic Release Inventory (TRI) data from the year 2000 indicates that every refinery that was a 

direct discharger in that year had some type of biological treatment unit (EPA, 2004). In some 

control options, our model included a steam stripper for selected wastewater streams located 

upstream of the treatment tanks and a biological treatment process downstream of the treatment 

tanks.

We used four surrogate compounds (benzene, phenol, naphthalene, and 1,2-dichloroethane) to 

represent the broad range of compounds that are present in wastewater. These compounds were 

chosen based on their Henry’s Law constant and their biodegradation rates. Phenol has a low 

Henry’s Law constant and a high biodegradation rate, meaning it does not readily volatilize from 

water and is easily biodegraded. The Henry’s Law constant for 1,2-dichloroethane is high and 

the biodegradation constant is low meaning it will readily volatilize from water and is not easily 

biodegraded. The Henry’s Law constant for benzene is high and the biodegradation constant is 

moderate meaning it will readily volatilize from water, but it will also readily biodegrade. The 

volatility of naphthalene is between that for phenol and 1,2-dichloroethane; like benzene, 

naphthalene is moderately biodegradable, but it also has a fairly large octanol-water partition 

coefficient, indicating that naphthalene will tend to remain in the oil or organic layer in an 

organic separation unit (like a decanter or oil-water separator).

For the model plant configuration used, control costs included adding fixed roofs to three 

treatment tanks, adding a carbon adsorption system control device for one treatment tank and 

additional piping to vent the other two treatment tanks to the new control device. Additional 

modeling would be needed to address industry-specific considerations and pollutants; however, 

we anticipate that the cost effectiveness of the various control options and applicability 

thresholds presented for the model wastewater treatment system (and range of chemical 

compounds in the wastewater) would be representative of the cost effectiveness of these control 

options for most refinery plant wastewater treatment systems.

7. Emissions Estimates

The VOC loading rates determined for the model plants (see Table 2) were equally divided 

between the three more volatile surrogates: benzene, naphthalene, and 1,2-dichloroethane. 

Phenol, which was a surrogate for non-volatile components (organics not detected well using 

EPA Method 25D), was assumed to be present at concentrations equal to the loading rate for one 

of the three individual volatile surrogates. We estimated total VOC emissions for each of the 

model facilities considering the entire wastewater collection and treatment system. We did 

evaluate certain control requirements individually, but we found that, while wastewater 

collection system controls appeared to be cost effective at very low VOC loads when considering 

only the drain system, drain controls without subsequent wastewater treatment tank controls 

merely suppressed the emissions until the wastewater treatment tanks, and they did not lead to 

significant emission reductions considering the system as a whole. Therefore, due to the 

interrelationship of the emissions between various components of the wastewater collection and 

treatment systems, emissions were estimated from the system as a whole and not from each 

component of the system independently. Inlet concentrations to a component were adjusted to 

account for emissions from any upstream component; therefore, emissions or emission 
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Operations at Petroleum Refineries

January 22, 2014

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reductions were not accounted for more than once. For example, the inlet concentration to the 

second uncontrolled drain in the drain system accounted for the emissions from the first 

uncontrolled drain and emissions from the entire collection system were used to adjust the inlet 

mass loading to the oil-water separator, and so on. Control options that were modeled included:

1. Control of the drain system components only;

2. Control of the drain system components and equipping oil-water separators, DAF units, 

and equalization tanks with fixed roofs; and allowing use of open biological treatment 

processes meeting minimal performance requirements;

3. Control of the drain system components; equipping oil-water separators, DAF units, and 

equalization tanks with fixed roofs that vent to a control device; and allowing use of open 

biological treatment processes meeting minimal performance requirements;

4. Control of the drain system components; equipping oil-water separators, DAF units, and 

equalization tanks with fixed roofs that vent to a control device; and allowing use of open 

biological treatment processes meeting specific fraction biodegraded (fbio) performance 

requirements;

5. Control of the drain system components; equipping oil-water separators, DAF units, and 

equalization tanks with fixed roofs that vent to a control device; and steam stripping 

wastewater streams with VOC concentrations exceeding 750 parts per million by weight 

(ppmw) prior to using an open biological treatment processes meeting minimal 

performance requirements; and

6. Control of the drain system components; equipping oil-water separators, DAF units, and 

equalization tanks with fixed roofs that vent to a control device; and steam stripping 

wastewater streams with VOC concentrations exceeding 375 ppmw prior to using an 

open biological treatment processes meeting minimal performance requirements.

We also considered requirements to upgrade an open biological treatment process that currently 

only meets minimal performance requirements to a unit that is well-mixed and achieves a 

destruction efficiency of at least 98 percent. However, this alternative was inferior to the steam 

stripping option in terms of both costs and emission reductions. A detailed description of the 

emissions estimates for each of the components in the wastewater collection and treatment 

system is provided below.

Emissions from Collection Systems

Emissions from the model collection systems were estimated using the Refinery Wastewater 

Emission Tool (RWET) (RTI, 2011b). RWET is available on the EPA website and is a tool 

developed as part of the Emission Estimation Protocol for Petroleum Refineries (RTI, 2011a). 

Our model collection system assumed that each stream would flow through or under four drains, 

a junction box, a manhole, a sump, and a lift station. The uncontrolled collection system also 

included 20 meters (65 feet) of open trench. Larger, more complex refineries will have more 

drains, sumps, and junction boxes than smaller refineries, generally because a larger refinery has 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

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more process units and collection points. However, RWET models a “drainage area,” which 

identifies the collection system components that an individual wastewater stream typically 

encounters. A drainage area is fairly consistent for a given process wastewater, so two model 

drainage areas (one controlled and one uncontrolled) can be used to estimate the emissions from 

the collection system. Larger facilities will simply have more model drainage areas than smaller

facilities.

Emissions from the model drainage areas were estimated considering each of the collection 

system components using the predicted fraction emitted (fe) from RWET, which is compound 

and component specific. RWET estimates emissions from controlled collection system 

components assuming a 95 percent control efficiency of the component’s uncontrolled 

emissions. Drains and junction boxes can be controlled using water seals, and well-maintained 

water seals can achieve a VOC reduction efficiency of 95 percent (EPA, 1990). Manholes, 

sumps, trenches, and lift stations are controlled by covering or enclosing openings and routing 

vented emissions to a control device. Control devices typically achieve a control or destruction 

efficiency of at least 95 percent.

Table 3 summarizes the model drainage areas and the aggregate fraction emitted for the four 

surrogate compounds. The emissions for a model plant were determined based on the loading 

rate of the surrogate compound times the applicable fraction emitted presented in Table 3.
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

13

Table 3. Summary of RWET Inputs and Outputs for the Model Drainage Areas

Parameter/Description

Value for 

Uncontrolled 

Model Drainage 

Area

Value for 

Controlled Model 

Drainage Area

Inputs 

Number of uncontrolled drains 4 0

Number of sealed drains 0 4

Linear meters of open trench 20 0

Number of uncontrolled manholes 1 0

Number of sealed manholes 0 1

Number of uncontrolled junction boxes 1 0

Number of controlled junction boxes 0 1

Number of uncontrolled lift stations 1 0

Number of controlled lift stations 0 1

Number of uncontrolled sumps 1 0

Number of controlled sumps 0 0

Outputs

Fraction emitted for benzene surrogate 0.783 0.0311

Fraction emitted for naphthalene surrogate 0.610 0.0208

Fraction emitted for phenol surrogate 0.001 5.5E-5

Fraction emitted for 1,2-dichloroethane surrogate 0.696 0.0253

Emissions from Treatment Tanks

Treatment tanks that were part of our model plant included an oil-water separator followed by an 

equalization tank followed by an air flotation unit. Emissions from these units were estimated 

using RWET for uncovered oil-water separators, uncovered equalization tanks, and uncovered 

DAF units, respectively. Specific design inputs needed for RWET for these treatment tanks are 

dependent on flow rate to the unit and are shown in Table 4. Values for temperature, pressure, 

and wind speed were equal to 25 degrees Celsius, 1.0 atmosphere, and 4.47 meters per second. 

Power to the aerators in the equalization tank was calculated using the equation the equation 

below (EPA, 1998a).

3 ft

1000

0.75 hp Power = ×

The number of aerators needed in the equalization tank was calculated using the equation below 

(EPA, 1998a).
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014 

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75

Power Aerators =

Table 4. Summary of RWET Inputs for Treatment Tanks

Model Facility: 

Flow Rated

Total APIa

Surface 

Area (m2)

d

Total DAFb

Surface 

Areac (m2)

d

DAFb

Depthc

(m)

d

DAFb Air 

Flowc

(m3/s)

d

Equal Tank 

Surface 

Areac (m2)

d

Equal Tank 

Depthc (m)

d

1: 0.00127 m3/s 1.7 0.91 3 4.5×10-6 22 5 

2: 0.0035 m3/s 4.57 2.52 3 1.24×10-5 61 5

3: 0.035 m3/s 45.8 25.2 3 0.000124 605 5

4A: 0.0858 m3/s 112 61.8 3 0.000305 1484 5

4B: 0.0858 m3/s 112 61.8 3 0.000305 1484 5 

5: 0.121 m3/s 158 87.2 3 0.000430 2090 5 

6: 0.406 m3/s 531 292 3 0.00144 7015 5 

a

 American Petroleum Institute (API) separator or oil-water separator (API, 1990). b

 DAF or air flotation unit.

c

 Metcalf & Eddy, Inc., 2003. d

 m3/s = cubic meters per second; m2 = square meters; m = meters.

Other inputs needed for RWET are the wastewater flow rate and compound concentration. The 

flow rate inputs were those determined for the seven model facilities (converted from millions of 

gallons per day (MGD) to cubic meters per second (m3

/s)), and we assumed that there was no 

flow loss in the collection system. Concentration inputs were determined both for a controlled 

collection system and an uncontrolled collection system using RWET. RWET was also used to 

calculate the losses from the wastewater treatment tanks; the outlet concentration of the oil-water 

separator was used as the inlet concentration to the air flotation unit and the outlet concentration 

from the air flotation unit was used as the inlet concentration of the equalization tank. 

RWET calculates emissions from open top (uncontrolled) treatment tanks, but it does not model 

emissions from a fixed roof tank. It is assumed that the treatment tanks operate with a 

continuous inlet and outlet flow rate so they maintain a fairly constant liquid level (minimal 

working losses). A control efficiency of approximately 80 percent was expected when adding a 

fixed roof to a wastewater treatment tank based on available literature (77 percent efficiency 

DAFs with fixed roof, 85 percent oil-water separators with fixed roof (EPA, 1985)). To model 

the effect of a fixed roof tank, the overall mass transfer coefficient calculated for the open 

treatment tank was adjusted downward so that the emissions of the “fixed-roof controlled” 

treatment tanks were approximately 20 percent of the emissions from the open treatment tanks. 

When the overall mass transfer coefficient decreased, the modeled pollutant concentration within 

the tank increased, so that emission reductions were not linearly correlated with the overall mass 
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Operations at Petroleum Refineries

January 22, 2014

15

transfer coefficient. We found that an adjustment factor of 0.02 on the overall mass transfer 

coefficient yielded emissions approximately 20 percent of the uncontrolled case; therefore, to 

estimate the impact of the fixed roof tank, we multiplied the uncontrolled overall mass transfer 

coefficient by 0.02, and used this adjusted value to estimate the emissions (and outlet 

concentrations) from each treatment tank.

We also used this overall mass transfer coefficient adjustment factor when modeling the control 

option of equipping treatment tanks with fixed roofs vented to a control device (i.e., we assumed 

no forced draft convection or sweep gas was needed for the control device). The emissions 

losses from the tanks and the effluent concentrations were not impacted by the addition of a 

control device on the tank. The control device was assumed to achieve a 95 percent reduction in 

the VOC emissions that would have otherwise been emitted from the covered treatment tank 

vent.

Emissions from Biological Treatment Processes and Steam Strippers

Emissions from biological treatment process were estimated using RWET for uncovered 

biological treatment units with diffused aeration. As with the treatment tanks, the design inputs 

for RWET are dependent on flow rate; they are shown in Table 5. Values for temperature, 

pressure, and wind speed were equal to 25 degrees Celsius, 1.0 atmosphere, and 4.47 meters per 

second. The model biological treatment process was assumed to have a mixed liquor volatile 

suspended solids (MLVSS) concentration of 2,000 grams per cubic meter (g/m3

); this model 

biological treatment process was expected to be indicative of a moderately performing biounit. 

Model runs were also performed assuming MLVSS concentration of 4,000 g/m3 to project the 

emissions for well-performing biological treatment process (those meeting a target fbio).

The variability in performance in existing biological treatment units can be significant due to 

ranges in operating and design parameters, such as the biological degradation rate, surface area 

of the unit, aeration rate, hydraulic residence time, and the active biomass concentration (EPA, 

1994). While the EPA recognizes that many biological treatment units are well-designed and 

operated, some units are not properly designed or well-operated and we wanted to account for 

these units in our emissions estimates and cost impacts.
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Operations at Petroleum Refineries

January 22, 2014

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Table 5. Summary of RWET Inputs for Biological Treatment

Model Facility:

Flow Rate Deptha (m)

Surface Areaa

(m)

Air Flowa

(m3/s)

Wasted Sludge 

Flow Ratea

(m3/s)

1: 0.00127 m3/s 5 4.6 0.0145 0.000033

2: 0.0035 m3/s 5 12.6 0.04 0.00009

3: 0.035 m3/s 5 126 0.70 0.0009

4A: 0.0858 m3/s 5 309 1.0 0.0022

4B: 0.0858 m3/s 5 309 1.0 0.0022

5: 0.121 m3/s 5 436 1.53 0.003

6: 0.406 m3/s 5 1462 5.23 0.01

a

 Metcalf & Eddy, Inc., 2003.

In all model runs, the inlet concentration to the biological treatment process was assumed equal 

to the outlet concentration of the equalization tank. The load to the biological treatment process 

was less for model runs where the drain system and treatment tanks were uncontrolled because 

of losses from these components upstream of the biological treatment unit. We assumed that any 

remaining volatile compounds in the effluent from the biological treatment unit would eventually 

volatilize either in subsequent polishing processes or weirs prior to final wastewater discharge. 

That is, we did not consider any control of process units downstream of the biological treatment 

process and used a worst-case scenario that remaining VOC would be emitted.

A steam stripper was included as part of the wastewater treatment model to determine how 

emissions from the treatment system would change if the streams with the highest VOC 

concentrations were segregated and treated in a steam stripper rather than the traditional model 

wastewater treatment system (API separator, DAF, equalization tank) prior to treating the 

wastewater in a biological treatment unit. We modeled two different scenarios for steam 

strippers. First, we modeled emissions from the model facility assuming all streams expected to 

have a VOC concentration greater than 750 ppmw at the point of generation were segregated and 

treated in a steam stripper. In the second option, we modeled emissions from the model facility 

assuming all streams expected to have a VOC concentration greater than 375 ppmw at the point 

of generation were segregated and treated in a steam stripper. The minimum performing steam 

stripper is expected to achieve VOC removal efficiencies of greater than 98 percent. The total 

flow rate and fraction of the total VOC load directed to a steam stripper is dependent on the size 

and mix of process units at the model facilities. Table 6 summarizes the flow rates and 

concentration of VOC streams directed to a steam stripper for each model facility.
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Operations at Petroleum Refineries

January 22, 2014

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Table 6. Summary of Steam Stripper Flows and Concentration for Model Facility

Model Facility:

Total Flow Rate

Targeting Streams greater than

750 ppmw VOC:

Targeting Streams greater than

375 ppmw VOC:

Flow rate

(gallon/day)

VOC 

concentration

(ppmw)

Flow rate, 

(gallon/day)

VOC 

concentration

(ppmw)

1: 0.00127 m3/s 140 3,150 20,440 540

2: 0.0035 m3/s 1,650 6,350 30,650 840

3: 0.035 m3/s 13,700 3,450 89,700 990

4A: 0.0858 m3/s 27,500 4,080 201,300 1,020

4B: 0.0858 m3/s 68,800 4,660 293,800 1,510

5: 0.121 m3/s 84,800 4,970 384,000 1,520

6: 0.406 m3/s 290,000 5,340 1,100,00 1,810

a

 Metcalf & Eddy, Inc., 2003.

8. Control Costs

Whenever possible, we obtained current cost data from vendors or fairly recent cost algorithms. 

We also collected cost data used for older rules and inflated older costs to 2010 dollars. We then 

compared the escalated cost data to newer cost data to verify the validity of the new cost data.

Cost of Control for Collection Systems

Control options for collection systems include covering or enclosing all components and routing 

vents to a control device, or as an alternative, equipping drains and junction boxes with water 

seals. For this analysis, we estimated costs for retrofitting drains and junction boxes with water 

seals. Manhole covers can either be gasket sealed and vented to a control device or retrofitted 

with a water seal. The costs for sealing manholes were based on costs provided by

Environmental Sealing Systems Co., Inc. (ESSCO) for a water seal system applicable for large 

catch basins and manholes. The cost for controlling lift stations was based on routing one lift 

station vent to a new dedicated carbon adsorber; additional lift stations, if present, were assumed 

to be piped to the new carbon adsorber or other existing control device (ESSCO, 2010).

The NSPS QQQ BID (EPA, 1985) has comprehensive data on the cost of retrofitting and 

installing a new water seal on drains and junction boxes. However, because the data from the 

NSPS QQQ BID are from 1985, we collected current data from ESSCO on equipment costs for 

retrofitting an existing drain, junction box and manhole with water seals. The ESSCO data 

included the cost of retrofitting drains, junction boxes, and manholes of different sizes with 

several types of water seal and control configurations (ESSCO, 2010). We averaged the cost for 

these variables to estimate the capital cost to retrofit one drain, one junction box, and one 

manhole with a water seal. For drains and manholes, it was assumed that excavation and 

installation would take 16 labor hours (EPA, 1985) and for junction boxes, it was assumed that 
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Operations at Petroleum Refineries

January 22, 2014

18

no excavation was required (the water seal is above grade on junction boxes using the ESSCO 

technology) and installation would take 8 hours. An operator labor rate of $60.82 was used to 

calculate the total labor cost of excavation and installation (Coburn, 2011). We assumed that 

there are no significant annual operating costs associated with water seals aside from annual 

monitoring costs. If a water seal is found missing during a monitoring event, pouring water 

down the drain is expected to alleviate this issue. The cost to retrofit one drain with a water seal 

from the NSPS QQQ BID escalated to 2010 dollars is $116.83 per drain as compared to the cost 

to retrofit one drain with a water seal using the ESSCO data of $275.04 per drain in 2010 dollars. 

The cost to retrofit one junction box with two water seals using the ESSCO data was estimated to 

be $342.80 per junction box in 2010 dollars. These capital costs were annualized assuming a 

7 percent interest rate and a 10-year useful life.

We used the crude oil throughput from our seven model plants and data from the California Air 

Resources Board (CARB) / Bay Area Air Quality Management District (BAAQMD) (Dunn and 

Breen, 2004) to estimate the number of drains, junction boxes and manholes at each model 

facility. Data from CARB/BAAQMD included comprehensive details for six existing refineries 

in California, including information on facility crude oil throughput in barrels per day (bbl/day), 

and the number of drains, junction boxes, and manholes at each facility. We used the 

CARB/BAAQMD data to correlate the number of drains at a refinery to refinery throughput in 

barrels per day. We then used the CARB/BAAQMD data to correlate the number of drains at a 

refinery to the number of junction boxes and manholes.

For lift stations, we assumed that a cover was in place and the cost for control was based on 

routing the vent to an existing control device or to a new carbon adsorber. Because lift stations 

can be located in more remote areas of a facility, we assumed a pipe diameter of 2 inches and a 

pipe length of 200 feet. Cost also included four tees, a flame arrestor, flanges, a blower and a 

motor (EPA, 1985). Costs from the NSPS QQQ BID were escalated to 2010 dollars and 

compared to the piping costs estimated using more recent online tools. The capital cost in 2010 

dollars for piping each lift station to a control device was estimated to be approximately $6,200. 

We assumed that the three smallest model plants would have one lift station, the three mediumsized plants would have two lift stations, and our large plant would have three lift stations. For 

facilities with one lift station, we made the assumption that the lift stations would be vented to a 

new carbon adsorber. For facilities with two or more lift stations, we assumed a new carbon 

adsorber would be added for one of the lift stations and that the emissions from the other lift 

stations would be piped to this single new carbon adsorber. For our large facility, we assumed a 

new carbon adsorber would be added for one of the lift stations and that the other two lift stations 

would be piped to this single new carbon adsorber for control. A detailed discussion of carbon 

adsorber costs is presented in the discussion of the cost to control treatment tanks and in 

Table 11.

Table 7 presents the total retrofit control costs for the collection systems for our seven model 

facilities.
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Operations at Petroleum Refineries

January 22, 2014

19

Table 7. Summary of Control Costs for Collection Systems

Model 

Facility 

# of 

Drains

# of 

Junction 

Boxes

# of 

Manholes

# of 

Lift 

Stns

Drain 

Cost 

($/yr)

a

Junction 

Box Cost 

($/yr)

b

Manhole 

Cost 

($/yr)

a

Lift Stn 

Cost 

($/yr)

1 166 26 84 1 $45,700 $8,900 $23,100 $24,200

2 237 36 119 1 $65,200 $12,300 $32,700 $27,900

3 473 71 237 1 $130,000 $24,300 $65,000 $36,800

4A 773 116 387 2 $213,000 $39,800 $106,000 $53,500

4B 873 131 437 2 $240,000 $44,900 $120,000 $57,600

5 1073 161 537 2 $295,000 $55,200 $148,000 $64,600

6 2423 363 1212 3 $666,000 $125,000 $333,000 $96,800

a

 Number of drains/manholes × $275.04 b

 Number of junction boxes × $342.80

A 95 percent control efficiency for water seals can only be obtained if the water seals are wellmaintained (i.e., constantly contain water). If the water seals are not maintained, significant 

emissions could occur. Therefore, part of the cost associated with water seals includes 

monitoring the seal to ensure the water level in the seal is adequate. We estimated costs for 

Method 21 monitoring and for visual monitoring at different monitoring intervals, including 

weekly, monthly, quarterly, semi-annually, and annually. Method 21 capital costs were 

estimated assuming that each refinery would have a monitoring instrument but would have to 

purchase a data collection system. The capital cost also includes the cost for initial tagging and 

accounting of the water seals. The cost of the data collection system ($14,500, from Shine, et al., 

2003) was divided by the total number of water seals to estimate the cost per seal ($14,500/3,300 

= $4.39). The CARB/BAAQMD data was used to estimate the average number of drains and 

junction boxes at a refinery (2500 drains + 400 junction boxes = 3300 total seals, assuming two

seals per junction box). A cost for initial tagging and accounting of $23.80 per seal was used (an 

update from the value in Eastman Chemical Co, 1999). The annualized capital cost was 

estimated using an interest rate of 7 percent and a useful life of 10 years. The total annual cost to 

monitor one water seal equals the annualized capital cost plus an annual labor cost to physically 

monitor the water seal. The annual labor cost is $1.50 per water seal for each time the seal is 

monitored (Parrish, 2006). For visual monitoring, we assumed that the cost was the same as 

Method 21 monitoring without the initial cost of the data collection system.

Monitoring costs at different frequencies are presented in Table 8. The analysis shows that the 

Method 21 and visual monitoring costs are fairly equivalent. As some seals may be difficult to 

inspect visually (e.g., seal is underground), Method 21 monitoring is expected to be more 

effective because a leak can be detected via Method 21 monitoring even though the seal is not 

directly visible. Given the similarities in costs, we assumed all required monitoring would be 

performed via Method 21 for the purposes of estimating the total cost of a control requirement.
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Operations at Petroleum Refineries

January 22, 2014

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Table 8. Summary of Monitoring Costs for Collection Systems

Monitoring Frequency

Method 21 Cost per 

Seal ($/yr)

a

Visual Cost per Seal 

($/yr)

b

Cost to monitor one seal weekly $82.00 $81.38

Cost to monitor one seal monthly $22.00 $21.38

Cost to monitor one seal quarterly $10.00 $9.38

Cost to monitor one seal semi-annually $7.00 $6.38

Cost to monitor one seal annually $5.50 $4.88

a

 Total capital investment (TCI) per seal = cost of new instrument ($14,500/3,300) + 1-time cost for initial tagging and 

accounting ($23.80 per seal) = $28.19/component. Annualizing these initial costs using a 7% interest rate and 

a 10 year life, yields an annualized cost for the initial outlays of $4.00/component/year. Total annual cost for the 

monitoring program per seal = $4.00 + ($1.50 × number of times monitored per year) b

 TCI per seal = cost for initial tagging and accounting ($23.80 per seal × 0.142) = $3.38. Total annual cost per seal 

= $3.38 + ($1.50 × number of times monitored per year)

In an effort to identify an appropriate monitoring frequency for drain components, we assumed 

that the control efficiency of seals would increase based on the monitoring frequency. We

assumed that monthly monitoring of water seals would allow the water seal controls to achieve 

an overall 95 percent control efficiency. Weekly monitoring was assumed to yield a 98 percent

control efficiency, while quarterly or semi-annually would reduce the overall control efficiency 

to 90 percent and 80 percent, respectively. The monitoring costs for our 7 model refineries were 

estimated by applying the costs in Table 8 to the total number of seals at the model refineries. 

The total number of water seals at each of the 7 model refineries was calculated using the total 

number of drains and junction boxes per model facility shown in Table 7 and applying the fact 

that each junction box will have 2 seals. Based on this analysis, either quarterly or monthly 

monitoring appeared to be the most cost effective monitoring options. The Method 21 

monitoring costs for our 7 model refineries for these two monitoring options are shown in 

Table 9. Quarterly monitoring costs are approximately 2 percent of the annualized costs for the 

drain system controls; monthly monitoring costs are approximately 4 percent of the annualized 

costs for the drain system controls.
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Operations at Petroleum Refineries

January 22, 2014

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Table 9. Summary of Monitoring Costs for Collection Systems

Model 

Facility

Drain 

Emissions 

for 

Quarterly 

Monitoring 

(tpy)

a

Quarterly 

Monitoring 

Costs ($/yr)

Quarterly 

Monitoring

Cost

Effectiveness

($/ton)

Drain 

Emissions 

for 

Monthly

Monitoring 

(tpy)

a

Monthly 

Monitoring 

Costs 

($/yr)

Monthly 

Monitoring 

Cost

Effectiveness 

($/ton)

Incremental 

Cost

Effectiveness of 

Monthly 

Monitoring

($/ton)

1 1.0 $1,660 $184 0.50 $3,650 $383 $3,970

2 3.1 $2,370 $85 1.5 $5,210 $177 $1,840

3 9.4 $4,730 $56 4.7 $10,400 $116 $1,200

4A 24 $7,730 $36 12 $17.000 $75 $780

4B 42 $8,730 $23 21 $19,200 $49 $500

5 56 $10,730 $21 28 $23,600 $44 $460

6 187 $24,200 $14 93 $53,300 $30 $310

a tpy = tons per year.

Cost of Control for Treatment Tanks

Treatment tanks include an oil-water separator, an air flotation unit, and an equalization basin;

the control costs for treatment tanks include equipping the tanks with a fixed roof and equipping 

the tanks with a fixed roof and venting emissions to a control device. Costs for both an existing 

and a new control device were estimated. An alternative control option for a fixed roof vented to 

a control device is equipping the tank with a floating roof. Due to the presence of weirs, 

skimmers and mixers on treatment tanks, it is not always easy to configure a floating roof to 

these types of tanks. Therefore, we chose to use a fixed roof routed to a control device as the 

basis of our cost analysis for treatment tanks.

The cost of installing a fixed roof on a treatment tank was calculated by comparing current 

vendor data and fixed roof costs from older rules. First, current vendor data for the cost to install 

a fixed roof on a new oil-water separator for several sized separators was used to calculate an 

average fixed roof equipment cost of $49 per square foot (Vanderhooft, 2011). This cost did not 

include the installation cost. Retrofit costs are expected to be 25 to 40 percent higher than new 

construction (EPA, 1985) so the average retrofit cost (installing a fixed roof on an existing tank) 

from the vendor data, assuming a 33 percent (average of 25 percent and 40 percent) increase 

over new construction, is $65 per square foot. Second, the NSPS QQQ BID contains a range of 

costs of $11 to $45 per square foot to install a fixed roof on an oil-water separator (EPA, 1985). 

These costs were expressed in 1985 dollars and included the labor and installation cost. When 

inflated to 2010 dollars (Chemical Engineering Plant Cost Index (CE index) 1985 = 325.3 and 

CE index 2010 = 550.7), the range of costs to install a fixed roof from the NSPS QQQ BID is 

$19 to $76 per square foot. Therefore, for this analysis, a value of $76 per square foot was used 

to estimate the cost of retrofitting an open top tank with a fixed roof, since the more current 

vendor data ($65 per square foot) did not include the labor and installation cost. We also added a 
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Operations at Petroleum Refineries

January 22, 2014

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fixed cost of $20,000 to the capital costs for the fixed roofs to cover facility planning, vendor 

selection, and site preparation costs. (This cost includes approximately 140 technical hours for 

evaluating rule requirements and control needs, soliciting offers from vendors, and overseeing 

installation. It also includes 140 maintenance hours to prepare the tank for cover installation, 

including emptying and cleaning the tank, if necessary, and preparing wastewater storage and 

flow diversions as necessary.)

The cost to install a fixed roof on open top treatment tanks from our seven model facilities are 

shown in Table 10. The annualized capital cost was estimated using assuming an interest rate of 

7 percent and a useful life of 20 years. Annual operating and maintenance (O&M) costs were 

estimated at 14 percent of the total capital cost (PEDCo, 1983).

Table 10. Summary of Cost to Retrofit Open Top Tanks with a Fixed Roofa

Model 

Facility

Oil-Water 

Separator 

Roof Size 

(ft2)

Equal 

Tank 

Roof Size

(ft2)

Air Flotation 

Unit Roof 

Size

(ft2)

Total 

Capital 

Investment 

($)

b

Annualized 

Capital 

Investment 

($/yr)

c

Annual

O&M

Cost 

($/yr)

d

Total 

Annual 

Cost ($/yr)

1 18 10 237 $40,100 $3,800 $5,600 $9,400 

2 49 27 656 $75,700 $7,100 $10,600 $17,700 

3 506 275 6,596 $580,700 $54,600 $81,300 $135,900 

4A 1,205 509 12,200 $1,079,000 $101,000 $151,000 $253,000 

4B 1,205 509 12,200 $1,079,000 $101,000 $151,000 $253,000 

5 1,700 936 22,400 $1,923,000 $181,000 $269,000 $450,000 

6 5,700 3,140 75,400 $6,425,000 $604,000 $899,000 $1,503,000 

a See Table 4 for model plant tank sizes. Sizes were converted from square meters (m2

) to square feet (ft2) for this 

table. b Total roof size ft2 × $76/ft2 + $20,000 c

 Annualized capital investment = TCI × capital recovery factor (CRF) (CRF = 0.094, 7%, 20 years useful life) d

 Taxes, insurance and administrative cost = 4% of capital cost; O&M cost =10% of capital cost (PEDCo, 1983).

The cost of routing the vent on a fixed roof treatment tank to a control device was estimated for 

both routing the vent to an existing control device and routing the vent to a new, dedicated 

control device. The cost of routing the vent on a fixed roof treatment tank to an existing control 

device consists mainly of piping costs. Piping costs to an existing control device were estimated 

for lift stations, and we assumed that the piping costs for routing treatment tanks to a control 

device would be comparable to that of lift stations ($6,200 per tank).

A new carbon adsorption system was used as the basis for estimating the control emissions from 

treatment tank vents. Due to the variability in the concentration of wastewater, it is difficult to 

estimate the concentration of organics in the headspace of treatment tanks. With regards to 

calculating a control device cost in the NSPS QQQ BID for treatment tanks, the VOC 
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January 22, 2014 

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concentration and flow rate of gas from an oil-water separator were estimated to be 

880 milligrams per liter and 300 standard cubic feet per minute (scfm), respectively. These 

values were also used for this analysis and are expected to be most representative of the flow 

from the median-sized (80,000 bbl/day) refinery. The Air Compliance Advisor software (EPA, 

2003) was used to estimate the cost of various carbon adsorption control systems; these costs are 

presented in Table 11. 

Table 11. Costs of a 300 scfm Carbon Adsorption System

Equipment Type

Capital Cost

(2008$) 

Annualized 

Capital Cost 

(2008 $/yr)

a

Annual 

Operating & 

Maintenance 

Cost

(2008 $/yr) 

Total 

Annualized

Cost

(2008 $/yr) 

Total 

Annualized

Cost

(2010 $/yr)

b

2-Bed CA 95% $60,700 $5,710 $60,300 $66,000 $63,200

2-Bed CA 98% $60,700 $5,710 $59,900 $65,600 $62,800

3-Bed CA 95% $66,200 $6,220 $61,300 $67,500 $64,600

3-Bed CA 98% $66,200 $6,220 $60,900 $67,100 $64,300

a

 Annualized capital investment = TCI × CRF (CRF = 0.094, 7%, 20 years useful life) b

 Chemical engineering cost index for 2008 = 575.4 and for 2010 = 550.7.

Based on the costs presented in Table 11, a representative capital investment cost of $60,000 and 

an annualized cost of $64,000 per yr were used for a basic carbon adsorption system for the 

80,000 bbl/day refinery. Carbon adsorption system costs for other model facilities were 

estimated using the following power function for both the capital and annualized costs. 

4.0

80,000

X Throughput for Cost Model Plant bbl/d 80,000for Cost = X Throughput Plant × 



 





Each model plant was assumed to have to control each of the three treatment tanks. We assumed 

that one treatment tank would install a new carbon adsorption system and that the other two 

tanks would be piped to this new carbon adsorption system. Therefore, each model plant was 

assumed to incur the costs of one carbon adsorption system and the costs of piping two treatment 

tanks to an “existing” control device.

Cost of Upgrading and Monitoring Biological Treatment Processes

Control costs were developed for upgrading an existing biological treatment unit by adding 

50 percent additional flow capacity to an existing biological treatment unit if the design of the 

existing unit is such that it cannot meet the specified fbio. The capital cost of the wastewater 

treatment system capacity expansion was estimated using CapdetWorks Version 2.5 

(Hydromantis, 2007) for a system designed to process 50 percent of the total refinery wastewater 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

24

flow. The annualized capital cost was calculated using an interest rate of 7 percent and a useful 

life of 20 years. The cost of upgrading the biological treatment unit for the model facilities is 

presented in Table 12 . Costs to build a new unit biological treatment unit to handle 100 percent 

of the refinery wastewater flow are approximately 65 percent higher than the upgrade costs 

identified in Table 12. Costs to build a new biological treatment system may be incurred for 

refineries that currently send their wastewater off-site for biological treatment and the off-site 

facility elects to no longer accept the wastewater due to the added fbio control requirements. 

Nonetheless, it was assumed that upgrade costs (increasing the capacity of the biological 

treatment unit by 50 percent) would generally apply for facilities needing to improve their 

biological treatment unit in order to meet a specific fbio. Having to meet a specific fbio

requirement would also require facilities to perform and initial performance demonstration and 

may also require additional parameter monitoring. For the model plant assessment of the option 

to require a specific fbio, it was assumed that these costs were negligible compared to the costs of 

upgrading the biological treatment unit.

Table 12. Cost to Upgrade a Biological Treatment Unit

Model 

Facility Capital Cost ($)a O&M Cost ($/yr)a

Annualized Capital 

Cost ($/yr)b

Total Annual Cost 

($/yr)

1 $536,000 $11,000 $50,000 $61,000

2 $1,124,000 $26,000 $106,000 $132,000

3 $6,090,000 $186,000 $572,000 $759,000

4A $11,608,000 $396,000 $1,091,000 $1,487,000

4B $11,608,000 $396,000 $1,091,000 $1,487,000

5 $14,864,000 $528,000 $1,397,000 $1,925,000

6 $36,061,000 $1,485,000 $3,390,000 $4,875,000

a

 EPA, 1980, escalated to 2010 $. b

 Annualized capital investment = TCI × CRF (CRF = 0.094, 7%, 20 years useful life)

Cost of Control for Steam Strippers

The cost of the steam stripper was based on algorithms developed for the National Emission 

Standards for Organic Hazardous Air Pollutants from the Synthetic Organic Chemical 

Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and 

Wastewater (HON) (Pelt, 1994). Steam stripper cost is dependent on the total flow rate to the 

steam stripper. The total cost of the steam stripper includes an air emissions control device 

which was assumed to be an existing combustion device. Piping cost to the existing control 

device is included in the HON algorithm.

As described previously, each model plant has a slightly different mix of process units, and 

therefore different proportion of different strength (i.e., VOC concentration) wastewater streams. 

Table 6 presented the projected flow rate and average VOC concentration for each model plant 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014 

25 

based on VOC thresholds of 375 and 750 ppmw. These data were used as inputs to estimate the 

steam stripper costs for each model plant/concentration threshold combination. The July 1989 

costs in the HON algorithm were escalated to July 2010 using the cost index for specific 

equipment types (e.g., pumps and heat exchangers) and using the overall cost index for plants. 

The estimated steam stripper costs are presented in Table 13. 

Table 13. Steam Stripper Control Cost Estimates (2010$)

Model 

Facility

750 ppmw VOC Threshold Option 375 ppmw VOC Threshold Option

Total Capital 

Investment 

($)

Annual 

O&M Costs

($/yr)

Total 

Annualized 

Costa

($/yr)

Total 

Capital 

Investment 

($)

Annual 

O&M Costs

($/yr)

Total 

Annualized 

Costa

($/yr)

1 $290,000 $113,000 $145,000 $794,000 $167,000 $254,000 

2 $446,000 $122,000 $171,000 $895,000 $188,000 $286,000 

3 $711,000 $153,000 $231,000 $1,289,000 $301,000 $443,000 

4A $866,000 $182,000 $277,000 $1,883,000 $509,000 $716,000 

4B $1,171,000 $262,000 $391,000 $2,231,000 $676,000 $921,000 

5 $1,263,000 $292,000 $431,000 $2,634,000 $841,000 $1,130,000 

6 $2,219,000 $670,000 $913,000 $5,060,000 $2,116,000 $2,671,000 

a

 Total Annualized Cost = TCI × CRF + Annual O&M, where CRF = 0.094 based on 7%, 20 years. 

9. Impact Estimates for Industrial Wastewater Treatment Plants

Emission and cost impacts were estimated for each of the six options presented in Section 7 

considering the entire wastewater collection and treatment plant. The emissions for each of the 

six options were compared to a totally uncontrolled wastewater collection and treatment plant

(“baseline”) to obtain the emission reductions for that option. A brief summary of the six control 

options are summarized in Table 14 for easy reference.

The environmental and cost impacts for each model facility for each control option are shown in 

Table 15. Overall, each of the options is more cost effective as the size of the facility increases. 

Controlling only the collection system is not a viable option because it only suppresses emissions 

to the treatment tanks where most of the volatile compounds will be emitted if these tanks remain 

uncontrolled. Controlling the collection system and the treatment tanks is also a more cost 

effective option than controlling the collection system alone. Controlling the collection system 

and covering and controlling the wastewater treatment tanks was always the control option with 

the lowest overall cost per ton of VOC reduced regardless of the size of the model plant facility. 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014 

26 

Table 14. Control Options for Model Wastewater Treatment Plants

Control 

Option Control Option Description

Baseline Uncontrolled drains and treatment tanks

1 Control of the drain system components only

2 Control of the drain system components and equipping oil-water separators, flotation units, 

and equalization tanks with fixed roofs

3 Control of the drain system components; equipping oil-water separators, flotation units, and 

equalization tanks with fixed roofs that vent to a control device

4 

Control of the drain system components; equipping oil-water separators, flotation units, and 

equalization tanks with fixed roofs that vent to a control device; and requiring open 

biological treatment processes to meet a specified fbio.

5 

Control of the drain system components; equipping oil-water separators, flotation units, and 

equalization tanks with fixed roofs that vent to a control device; and steam stripping 

wastewater streams with VOC concentrations exceeding 750 ppmw

6 

Control of the drain system components; equipping oil-water separators, flotation units, and 

equalization tanks with fixed roofs that vent to a control device; and steam stripping 

wastewater streams with VOC concentrations exceeding 375 ppmw

Table 15. Impacts for Control Options for Each Model Facility

Control 

Option

Emission 

Reduction

(tpy)

Total Capital 

Investment

Cost ($/yr)

Total 

Annualized 

Cost ($/yr)

Cost 

Effectiveness 

($/ton VOC)

Incremental 

Cost 

Effectiveness

($/ton)

Model Plant 1: 16.6 Mg/yr VOC wastewater generated; 9.0 Mg/yr VOC load for Option 1 

Baseline 0 Baseline Emissions = 16.4 tpy (14.9 Mg/yr)

1 3.2 $570,000 $105,500 $33,100 $33,100

2 8.4 $610,000 $115,000 $13,700 $1,800

3 11.5 $637,000 $139,000 $12,200 $8,000

4 13.2 $960,000 $175,000 $13,300 $21,1001

5 11.7 $928,000 $285,000 $24,400 $751,1001

6 15.3 $1,597,000 $394,000 $25,700 $29,6001

Model Plant 2: 51.2 Mg/yr VOC wastewater generated; 26.2 Mg/yr VOC load for Option 1

Baseline 0 Baseline Emissions = 50.8 tpy (46.1 Mg/yr)

1 9.3 $803,000 $143,000 $15,400 $15,400

2 25.1 $878,000 $161,000 $6,400 $1,100

3 36.2 $910,000 $189,000 $5,200 $2,500

4 41.1 $1,588,000 $267,000 $6,500 $16,1001

5 40.5 $1,355,000 $360,000 $8,900 $39,8001

6 46.0 $1,805,000 $476,000 $10,300 $20,8001

(continued)
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries 

January 22, 2014 

27 

Table 15. Impacts for Control Option for Each Model Facility (continued) 

Control 

Option 

Emission 

Reduction 

(tpy) 

Total Capital 

Investment 

Cost ($/yr) 

Total 

Annualized 

Cost ($/yr) 

Cost 

Effectiveness 

($/ton VOC) 

Incremental 

Cost 

Effectiveness 

($/ton) 

Model Plant 3: 156 Mg/yr VOC wastewater generated; 69.5 Mg/yr VOC load for Option 1 

Baseline 0 Baseline Emissions = 156 tpy (142 Mg/yr) 

1 26.5 $1,580,000 $267,000 $10,100 $10,100 

2 89.7 $2,160,000 $402,000 $4,500 $2,100 

3 134.8 $2,200,000 $440,000 $3,300 $830 

4 144.1 $5,872,000 $888,000 $6,200 $48,2001

5 142.1 $2,910,000 $671,000 $4,700 $31,9001

6 145.8 $3,490,000 $883,000 $6,100 $56,1001

Model Plant 4A: 394 Mg/yr VOC wastewater generated; 178 Mg/yr VOC load for Option 1 

Baseline 0 Baseline Emissions = 395 tpy (358 Mg/yr) 

1 66.2 $2,580,000 $429,000 $6,500 $6,500 

2 227.0 $3,660,000 $682,000 $3,000 $1,600 

3 338.5 $3,720,000 $736,000 $2,200 $480 

4 363.6 $10,720,000 $1,613,000 $4,400 $35,0001

5 356.2 $4,590,000 $1,010,000 $2,800 $15,7001

6 366.8 $5,600,000 $1,452,000 $4,000 $41,2001

Model Plant 4B: 686 Mg/yr VOC wastewater generated; 309 Mg/yr VOC load for Option 1 

Baseline 0 Baseline Emissions = 687 tpy (623 Mg/yr) 

1 115.1 $2,910,000 $482,000 $4,200 $4,200 

2 362.3 $3,990,000 $682,000 $1,900 $810 

3 556.2 $4,060,000 $793,000 $1,400 $570 

4 620.4 $11,060,000 $1,670,000 $2,700 $13,7001

5 632.3 $5,230,000 $1,183,000 $1,900 $5,1001

6 644.1 $6,290,000 $1,714,000 $2,700 $45,0001

Model Plant 5: 927 Mg/yr VOC wastewater generated; 416 Mg/yr VOC load for Option 1 

Baseline 0 Baseline Emissions = 927 tpy (841 Mg/yr) 

1 158.0 $3,570,000 $586,000 $3,700 $3,700 

2 492.1 $5,500,000 $1,036,000 $2,100 $1,300 

3 755.1 $5,570,000 $1,101,000 $1,500 $250 

4 839.9 $14,530,000 $2,236,000 $2,700 $13,4001

5 852.2 $6,830,000 $1,532,000 $1,800 $4,4001

6 868.2 $8,200,000 $2,232,000 $2,600 $43,9001

(continued) 
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014 

28 

Table 15. Impacts for Control Option for Each Model Facility (continued)

Control 

Option

Emission 

Reduction 

(tpy)

Total Capital 

Investment 

Cost ($/yr)

Total 

Annualized 

Cost ($/yr)

Cost 

Effectiveness 

($/ton VOC)

Incremental 

Cost 

Effectiveness 

($/ton)

Model Plant 6: 3,086 Mg/yr VOC wastewater generated; 1,377 Mg/yr VOC load for Option 1

Baseline 0 Baseline Emissions = 3,089 tpy (2,802 Mg/yr)

1 525.6 $8,020,000 $1,274,000 $2,400 $2,400

2 1,640.4 $14,450,000 $2,778,000 $1,700 $1,300

3 2,523.8 $14,560,000 $2,874,000 $1,100 $110

4 2,801.2 $36,300,000 $5,741,000 $2,050 $10,3001

5 2,856.6 $16,780,000 $3,788,000 $1,300 $2,7001

6 2,894.6 $19,620,000 $5,546,000 $1,900 $46,2001

1 The incremental cost-effectiveness of Options 3 and 4 are calculated relative to Option 3; the incremental costeffectiveness of Option 6 is calculated relative to Option 5.

10. Current Control Levels Under the Benzene NESHAP

Emissions from wastewater collection and treatment operations at refineries are currently 

regulated under the Benzene Waste NESHAP Operations (BWON). In general, the BWON 

requires control of wastewater collection and treatment units for facilities with a total annual 

benzene (TAB) of greater than or equal to 10 megagrams per year (Mg/yr). Individual waste 

streams at refineries with a TAB greater than or equal to 10 Mg/yr are exempt from control if the 

flow-weighted annual average benzene concentration is less than 10 ppmw or the flow rate is 

less than 0.02 liters per minute at the point of generation. Because benzene is in nearly all 

refinery wastewater streams, the model plant analysis suggested that 96 to 100 percent of the 

HAP loading to the wastewater treatment system would be captured under these BWON streamspecific threshold levels. Therefore, for refineries with tab greater than or equal to 10 Mg/yr, the 

BWON control provisions are essentially equivalent to Control Option 3 (requiring suppression 

controls up to a biological treatment unit). For refineries with a TAB of less than 10 Mg/yr, the 

baseline (uncontrolled) scenario would best project the potential (allowable) emissions for these 

facilities.

In the BWON, the biological treatment system must meet the criteria of an “enhanced biological 

unit (EBU)” (i.e., an activated sludge treatment unit) or, as an alternative to meeting the criteria 

of an EBU, affected wastewater streams are required to be treated using a steam stripper or other 

control device that achieves a 98 percent removal of benzene. Refinery MACT 1 provides 

identical applicability thresholds to the BWON and references the BWON control requirements. 

There are very limited requirements for an EBU in the BWON, so the biodegradation efficiency 

of the EBU may vary widely between different facilities. Some facilities are expected to have 

well-performing EBU (emissions equivalent to Control Option 4) while other facilities may have 

emissions more similar to those in Control Option 3.
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

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29

Based on the existing requirements in the BWON (and in Refinery MACT 1), we identified the 

following “nationwide (NW) control options” (not to be confused with the “model plant” control 

options previously discussed:

1. Requiring wastewater drain and tank controls at refineries with a total annualized 

benzene quantity of less than 10 Mg/yr.

2. Requiring specific performance parameters (minimum fbio) for an EBU beyond those 

required in the BWON.

3. Requiring wastewater streams above a VOC content of 750 ppmv to be treated by steam 

stripping prior to any other treatment process for facilities with high organic loading rates

(i.e., facilities with TAB of 10 Mg/yr or more).

Option 1 was evaluated because refineries with TAB of less than 10 Mg/yr are not required to 

install any controls on their wastewater treatment system. Option 2 is intended to improve the 

performance of wastewater treatment systems that use an EBU, and thereby achieve additional 

emission reductions. Option 3 considers segregated treatment of high strength wastewater 

streams directly in a steam stripper (i.e., not allowing these streams to be mixed and treated in 

the EBU). For the most part, the options are independent of each other, so the costs and cost 

effectiveness of each these options are considered separately. In fact, NW Option 3 could be 

considered an alternative means to limit the use of potentially poor-performing EBU compared 

to NW Option 2.

11. Estimating Nationwide Impacts for Petroleum Refineries

The first step in developing nationwide impact estimates was to estimate the TAB and HAP 

loading for each of the refineries in the U.S. The process unit capacities as reported in the 

2009 Refinery Capacity Report (EIA, 2009) was used together with the factors presented in the 

EPA’s Locating and Estimating Air Emissions from Sources of Benzene (EPA, 1998b) to 

estimate the organic HAP loading and projected VOC loading to the wastewater treatment 

system for each refinery. Each refinery was then assigned to a model plant based on the total 

VOC loading. Table 16 shows the estimated TAB (benzene loading) and VOC loading for each 

of the seven model facilities and how the ranges used to assigning the model plants to the 

facilities. There were no refineries that had projected VOC loadings between 400 and 

800 Mg/yr, so the model plant assignments were shifted slightly to provide a mix between model 

facilities 4A and 4B.

As shown in the table, the two smallest model facilities have a TAB of less than 10 Mg/yr. 

Refineries assigned to these model plants would not require control under the BWON based on 

the calculated TAB, and these facilities were all assumed to be uncontrolled for the NW baseline 

emission estimate. Under NW Option 1, these refineries would be required to meet the “model 

plant” Control Option 3 (costs for which are summarized in Table 15).
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

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Table 16. Benzene and VOC Load for Model Facilities and Assignments of Model 

Facilities to Specific Refineries

Model 

Facility

Benzene Load at 

Generation 

(Mg/yr)

VOC Load at 

Generation 

(Mg/yr)

Assigned if Refinery 

VOC Loading (Mg/yr) 

was:

Number of 

Refineries Assigned 

to Model Plant

1 2.62 16.6 VOC < 50 18

2 9.22 51.2 50≤VOC<80 9 

3 24.8 156 80≤VOC<250 15

4A 63.9 394 250≤VOC<300 30

4B 56.0 686 300≤VOC<800 9

5 97.1 927 800≤VOC<2000 42

6 271 3,086 VOC > 2000 19

It is unclear what the actual performance level of refinery EBU are, given the lack of specific 

operating or performance limits. For the baseline analysis, we assumed that 80 percent of the 

refineries assigned to model facilities 3 through 6 had EBU performance comparable to “model 

plant” Control Option 4, while 20 percent had performance comparable to “model plant” Control 

Option 3. Therefore, under NW Option 2, 20 percent of the refineries with TAB greater than 

10 Mg/yr were projected to need to upgrade their EBU (incremental costs as provided in 

Table 12, since these facilities are already expected to have controlled drains and tanks). 

Although some refineries currently use steam stripping for certain waste streams, we assumed all 

refineries would have to add a steam stripper in order to comply with Option 3 (incremental costs 

as provided in Table 13, since these facilities are already expected to have controlled drains and 

tanks). 

Based on these assumptions and the number of each model plant (as provided in Table 16), the 

projected baseline emissions and impacts for the NW options were calculated. These impacts are 

summarized in Table 17. 

Table 17. Nationwide Impacts of Wastewater Control Options for Petroleum Refineries

Control 

Option

Capital 

Cost 

(million $)

Annualized 

Costs 

(million $/yr)

Emissions 

Reduction, 

VOC (tpy)

Emissions 

Reduction, 

HAP (tpy)

Cost Effectiveness 

($/ton VOC)

Cost Effectiveness 

($/ton HAP)

Baseline Baseline Emissions: 13,865 tpy VOC and 3,697 tpy HAP

NW 1 19.7 4.2 592 158 7,100 26,600

NW 2 223 28.6 2,060 549 13,900 52,100

NW 3 142 50.7 3,480 929 14,500 54,500
Technical Memorandum – Technology Review for Industrial Wastewater Collection and Treatment 

Operations at Petroleum Refineries

January 22, 2014

31

The cost effectiveness for NW Option 1 (requiring wastewater controls for the small refineries 

with a TAB less than 10 Mg/yr) is approximately $26,600 per ton of HAP reduced. NW 

Options 2 and 3 are each projected to have cost effectiveness over $50,000 per ton of HAP 

reduced. Based on this technology review, the BWON control requirements appear to be the 

most cost-effective control requirements. We did not identify any development in technologies 

or practices that would cost-effectively reduce HAP emissions from wastewater treatment

systems at petroleum refineries beyond the existing requirements in Refinery MACT 1 (i.e., 

BWON).

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January 22, 2014

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