MEMORANDUM 

From: William Swietlik, USEPA/OW/OST 

Ph: (202) 566-1129, Swietlik.william@epa.gov 

To: Public Docket for the Preliminary 2016 Effluent Guidelines Program Plan 

EPA Docket Number EPA-HQ-OW-2015-0665 (http://www.regulations.gov) 

Date: October 29, 2015 

Re: Hydrogen Sulfide Releases Reported to the Toxics Release Inventory (TRI) in 2013 

As part of EPA’s Office of Water Engineering and Analysis Division (EAD) 2015 

Annual Review of effluent limitations guidelines and standards (ELGs), EAD performed a 

toxicity ranking analysis (TRA) of all industrial categories, including those subject to existing 

ELGs and those not currently regulated by ELGs, consistent with the methodology described in 

Section 2 of the 2015 Annual Effluent Guidelines Review Report (2015 Annual Review Report) 

(U.S. EPA, 2016). EAD used the TRA to identify and prioritize for further review, categories 

discharging high levels of toxic pollutants relative to other categories. In performing the TRA, 

EAD relied on discharge monitoring report (DMR) data pulled from the Integrated Compliance 

Information System for the National Pollutant Discharge Elimination System, and Toxics 

Release Inventory (TRI) data. EAD downloaded the 2013 DMR and TRI industrial rankings data 

from the DMR Pollutant Loading Tool1

 and performed a quality review of the data. During its 

review of the 2013 TRI data, EAD noted that hydrogen sulfide water releases accounted for 

approximately 40 percent of the total 2013 TRI toxic-weighted pound equivalents (TWPE).2

Hydrogen sulfide has not been included in or evaluated as part of EAD’s previous annual 

reviews, but is now included due to recent changes in TRI reporting requirements. 

This memorandum describes EAD’s quality review and evaluation of the hydrogen 

sulfide data reported to TRI in 2013 and EAD’s methodology for incorporating these releases 

into the 2015 Annual Review. 

1.1 Background on Hydrogen Sulfide Reporting to TRI 

Hydrogen sulfide was added to the TRI list of toxic chemicals in a final rule published on 

December 1, 1993. On August 22, 1994, EPA issued an Administrative Stay of the reporting 

requirements for hydrogen sulfide to evaluate issues brought to the Agency's attention after 

promulgation of the final rule. These issues concerned the human health effect basis for the 

listing and the Agency's use of exposure analyses in TRI listing decisions. Although the final 

rule listing hydrogen sulfide under section 313 of the Emergency Planning and Community 

                                                            

1

 See http://cfpub.epa.gov/dmr/psc_ranking.cfm. 2

 EPA evaluates the relative hazard of category discharges by applying toxic weighting factors (TWFs) to annual 

pollutant discharges to calculate the total discharge of toxic pollutants as TWPE. See Section 2 of the 2015 Annual 

Review Report for more information on TWPE.
Memorandum 

October 29, 2015 

Page 2 

Right-to-Know Act (EPCRA) remained in force, the stay deferred the reporting requirements for 

hydrogen sulfide while EPA completed its further evaluation (76 FR 64022). 

From its further evaluation of the environmental toxicity of hydrogen sulfide, EPA 

determined that available data indicate that water with concentrations of more than 2.0 ug/L 

undissociated hydrogen sulfide would constitute a long-term hazard to aquatic organisms despite 

its fate under certain environmental conditions (76 FR 64022). As a result, on October 17, 2011, 

EPA announced it was lifting the Administrative Stay of the reporting requirements for hydrogen 

sulfide under Section 313 of EPCRA (76 FR 64022). Facilities were required to report 

environmental releases of hydrogen sulfide to TRI beginning with the reporting year 2012, 

including releases to water. 

1.2 Hydrogen Sulfide Properties, Generation, and Fate 

Hydrogen sulfide is a soluble, colorless, highly poisonous, gaseous compound having the 

characteristic odor of rotten eggs. Its chemical and physical properties are summarized in Table 

1. 

Table 1. Physical and Chemical Properties of Hydrogen Sulfide 

Property Value 

CAS registry number 7783-06-4 

Molecular formula H2S 

Molecular weight 34.08 

Vapor pressure 15,600 mm Hg at 25/C 

Density 1.5392 g/L at 0/C, 760 mm Hg 

Boiling point -60.33/C 

Water solubility 3,980 mg/L at 20°C 

Log Kow NA 

Dissociation constants pKa1 = 7.04; pKa2 = 11.96 

NA: Not applicable 

Source: U.S. EPA, 2003 

Hydrogen sulfide is a biologically active compound that is found primarily as an 

anaerobic degradation product of both organic sulfur compounds and inorganic sulfates. Sulfides 

are constituents of many industrial wastes such as those from tanneries, paper mills, chemical 

plants, and gas works. The anaerobic decomposition of sewage, sludge beds, algae, and other 

naturally deposited organic material is a major source of hydrogen sulfide (U.S. EPA, 1986). 

When soluble sulfides are added to water, they react with hydrogen ions to form the 

hydrosulfide ion (HS-

) and hydrogen sulfide (H2S), the proportion of each depending on pH. The 

toxicity of sulfides derives primarily from hydrogen sulfide rather than from the hydrosulfide or 

sulfide ions. At pH 9, approximately 99 percent of the sulfide is in the form of HS-

; at pH 7 the 

sulfide is equally divided between HS-

 and H2S; and at pH 5 about 99 percent of the sulfide is 

present in the form of H2S (U.S. EPA, 1986). In well aerated water, hydrogen sulfide is readily 

oxidized to sulfates and biologically oxidized to elemental sulfur. In anaerobic water, microbial 

reduction of sulfate to sulfide can occur (WHO, 2003). 
Memorandum 

October 29, 2015 

Page 3 

According to the World Health Organization, the major uses of hydrogen sulfide include 

its conversion into sulfur and sulfuric acid and the manufacture of inorganic sulfides, thiophenes, 

thiols, thioaldehydes, and thioketones. It is used in dye manufacturing, tanning, the production of 

wood pulp, chemical processing, and the manufacture of cosmetics (WHO, 2003). A draft 

Toxicological Profile for Hydrogen Sulfide and Carbonyl Sulfide published by the Agency for 

Toxic Substances and Disease Registry (ATSDR, 2014) indicates that facilities where hydrogen 

sulfide is produced, used, or generated include petroleum refineries, natural gas plants, 

petrochemical plants, coke oven plants, kraft paper mills, viscose rayon manufacturing plants, 

sulfur production plants, iron smelters, food processing plants, manure treatment facilities, 

landfills, textile plants, wastewater treatment facilities, and tanneries. Hydrogen sulfide is also 

used as an agricultural disinfectant, in the production of heavy water, and as an additive in 

lubricants and cutting oils. Hydrogen sulfide may also be encountered in various industrial 

processes including the manufacture of dyes and pigments, felt, and artificial silk; in farming, 

brewing, glue making, and rubber vulcanization; and in lithography and photoengraving. 

Discharges from these and other activities can release hydrogen sulfide to receiving waters 

(ATSDR, 2014). 

1.3 2013 TRI Hydrogen Sulfide Data 

In TRI, facilities report annual releases to the environment of each toxic chemical or 

chemical category that meets reporting requirements. TRI requires facilities to report on-site 

releases to air, receiving waters, underground wells, disposal to land, and several other categories 

(direct releases). TRI also requires facilities to report the amount of toxic chemicals in wastes 

transferred to offsite locations, including releases to publicly owned treatment works (POTWs) 

and other off-site locations, such as commercial waste disposal facilities (indirect releases). This 

memorandum focuses on water releases directly to receiving waters and to POTWs. 

EAD identified hydrogen sulfide as a top TRI-reported pollutant during its 2015 TRA. 

Hydrogen sulfide has a TWF of 2.8 and accounted for approximately 40 percent of the total TRI 

TWPE (excluding the point source categories for which EAD has recently revised ELGs).3

 

EAD identified and further evaluated five industrial point source categories with 2013 

TRI reported releases where hydrogen sulfide contributes a significant portion of the category’s 

TWPE. Table 2 lists these point source categories and the percentage of their total TWPE 

attributed to hydrogen sulfide. Table 3 summarizes the reported 2013 TRI hydrogen sulfide 

releases by release type (i.e., direct and indirect releases). 

                                                            

3

 EAD has recently reviewed the following point source categories: 423 – Steam Electric Power Generating; 449 – 

Airport Deicing; and 450 – Construction and Development. 
Memorandum 

October 29, 2015 

Page 4 

Table 2. Top 2013 TRI Point Source Categories with Reported Hydrogen Sulfide Water 

Releases 

Point Source Category 

Total 

TWPE 

H2S TWPE Percentage of 

Total TWPE 

Attributed to 

Direct Indirect Total H2S 

430 – Pulp, Paper and Paperboard 4,280,000 1,170,000 964,000 2,140,000 50%

419 – Petroleum Refining 580,000 27,700 163,000 191,000 33%

406 – Grain Mills 276,000 176,000 97,900 274,000 99%

432 – Meat and Poultry Products 213,000 35,900 133,000 169,000 79%

407 – Canned and Preserved Fruits 

and Vegetables Processing 

68,700 - 64,200 64,200 93%

Total TRI TWPE for Top 

Categories with Reported 

Hydrogen Sulfide Releases 

5,420,000 1,410,000 1,420,000 2,840,000 52%

Total TRI TWPE 7,160,000 1,440,000 1,430,000 2,870,000 40%

Table 3. Summary of 2013 TRI Hydrogen Sulfide Water Releases by Release Type 

Type of Release 

Number of Facilities 

Reporting H2S Releases 

Pounds of Reported H2S 

Releases H2S TWPE 

Direct 146 513,000 1,440,000

Indirect 26 511,000 1,430,000

Total H2S Releases 172 1,024,000 2,870,000

Total TRI TWPE 7,160,000

As shown in Table 2, hydrogen sulfide releases from these five point source categories 

account for 99 percent of the hydrogen sulfide TRI TWPE and 40 percent of the total TRI 

TWPE. Table 3 shows that the total reported quantity of hydrogen sulfide released (in pounds) is 

equally distributed between direct and indirect releasing facilities. The data also indicate that a 

higher number of direct discharging facilities (146) reported releasing hydrogen sulfide as 

compared to indirect discharging facilities (26). 

EAD further investigated the 2013 TRI reported hydrogen sulfide releases by direct and 

indirect releases, as discussed in the sections below. EAD evaluated the completeness, 

comparability, accuracy, and reasonableness of the data, as it relates to facilities reporting both 

direct and indirect releases to water, and assessed the implications and use of the data for EAD’s 

2015 Annual Review. 

. 

1.4 Hydrogen Sulfide Data Reported by Facilities with Direct Water Releases 

As shown in Table 3, 85 percent of the facilities reporting water releases of hydrogen 

sulfide are directly discharging to receiving waters. However, these facilities only account for 

approximately 50 percent of hydrogen sulfide water releases reported to TRI in 2013. As part of 

the TRA supporting the 2015 Annual Review, EAD contacted industry trade associations and 

companies with facilities reporting the greatest direct release of hydrogen sulfide for the pulp and 

paper, grain mills, and meat and poultry products point source categories. EAD did not contact 
Memorandum 

October 29, 2015 

Page 5 

companies or facilities in the petroleum refining and canned and preserved fruits and vegetables 

processing categories because a majority of the facilities in these categories reported indirect 

releases of hydrogen sulfide to POTWs. Table 4 lists the companies EAD contacted and their 

relevant facilities and releases. EAD contacted the companies to 1) confirm their 2013 TRI 

hydrogen sulfide direct releases and 2) determine whether the reported releases are based on 

direct measurements or estimates and accurately represent potential releases directly to receiving 

waters. 

Table 4. 2013 TRI Direct Discharging Facilities Contacted 

Point Source Category Firm Name 

Facility 

Location 

Pounds of 

Reported 

H2S Releases 

H2S 

TWPE

430 – Pulp, Paper and 

Paperboard 

Georgia-Pacific Monticello 

LLC Monticello, MS 115,000 323,000 

406 – Grain Mills Cargill Inc Wet Corn Milling Wahpeton, ND 62,500 175,000 

432 – Meat & Poultry Products Tyson Fresh Meats Inc Hillsdale, IL 5,320 14,900 

432 – Meat & Poultry Products Tyson Fresh Meats Inc Lexington, NE 3,350 9,380 

432 – Meat & Poultry Products Tyson Fresh Meats Inc 

Columbus 

Junction, IA 2,220 6,220 

432 – Meat & Poultry Products John Morrell & Co Sioux Falls, SD 1,600 4,490 

Total TRI Direct H2S Releases 513,000 1,440,000

The pulp, paper and paperboard point source category accounts for approximately 80 

percent of the total direct releases of hydrogen sulfide reported to TRI in 2013 as shown in Table 

2. As part of the TRA, EAD contacted the pulp, paper and paperboard trade associations, 

American Forest and Paper Association (AF&PA) and National Council for Air and Stream 

Improvement (NCASI). The trade associations contacted the Georgia-Pacific mill in Monticello, 

MS to discuss the hydrogen sulfide releases. The mill confirmed the 2013 TRI hydrogen sulfide 

releases of 115,000 pounds and stated that this value was based on direct measurements of the 

treated effluent at the facility. Since 2013 the facility has improved their wastewater treatment 

system and releases have decreased to 32,000 pounds per year (Schwartz and Wiegand, 2014). 

 The Cargill, Inc. facility in Wahpeton, ND manufactures high fructose corn syrup and has 

an onsite wastewater treatment plant with aerobic and anaerobic systems. The facility contact 

confirmed the 2013 hydrogen sulfide release and stated that the hydrogen sulfide concentrations 

are a result of the wastewater treatment plant processes, not from manufacturing. To calculate the 

2013 hydrogen sulfide release reported to TRI, the facility collected four samples from their 

outfall from the wastewater treatment plant. Hydrogen sulfide concentrations from the four 

samples were averaged and then multiplied by the facility flow and number of days per year to 

calculate the total pounds per year release reported to TRI (Razink, 2014). 

 The Tyson Fresh Meats contact confirmed the 2013 hydrogen sulfide releases for all 

three facilities listed in Table 4 and stated that the TRI releases are based on direct samples of 

soluble sulfide and corresponding pH values at each facility. The facilities are not required to 

sample their effluent for hydrogen sulfide, so a limited number of samples were collected for 

TRI reporting purposes. The contact indicated the facilities have a consistent effluent quality; 
Memorandum 

October 29, 2015 

Page 6 

therefore, the collected samples were assumed to be representative of their annual release. At all 

the Tyson facilities reviewed, the measured soluble sulfide concentrations were converted to 

hydrogen sulfide; the hydrogen sulfide concentrations were then multiplied by flow to calculate a 

total release per year for each facility. The company contact also stated that wastewater treatment 

processes at the Tyson facilities in Hillsdale, IL and Lexington, NE each include a covered 

anaerobic lagoon, biogas handling, anoxic processes, aeration processes, secondary clarification, 

chlorination, and dechlorination. Wastewater treatment processes at the Tyson facility in 

Columbus Junction, IA includes an uncovered anaerobic lagoon along with aeration processes, 

secondary clarification, chlorination, and dechlorination (Dirks, 2014). 

 The facility contact for John Morrell and Co. also confirmed the 2013 hydrogen sulfide 

releases reported by the facility. The facility calculates the hydrogen sulfide releases using 

published emission factors; the reported releases were not a result of direct sampling (Schulz, 

2014). 

 These facility contacts indicate that the majority of facilities reporting direct releases of 

hydrogen sulfide to TRI are calculating their hydrogen sulfide releases based on direct sampling 

at the facilities, and that facilities are collecting the samples from onsite wastewater treatment 

systems. These facility contacts also suggest that direct releases of hydrogen sulfide reported to 

TRI accurately represent potential releases directly to receiving waters. 

EAD further investigated direct releases of hydrogen sulfide reported to TRI in 2013 as 

part of the 2015 Annual Review for the Grain Mills, Meat and Poultry, and Pulp and Paper Point 

Source Categories. See Sections 3.3, 3.6, and 3.11 of the 2015 Annual Review Report, 

respectively, for more information on EAD’s review. EAD did not further investigate direct 

hydrogen sulfide releases reporting to TRI in 2013 for the Petroleum Refining Category because 

EAD is currently conducting a detailed study of the industry. 

1.5 Hydrogen Sulfide Data Reported by Facilities with Indirect Releases 

As shown in Table 3, only 15 percent of the facilities reporting water releases of 

hydrogen sulfide are indirectly discharging to POTWs. However, these facilities account for 

approximately 50 percent of hydrogen sulfide water releases reported to TRI. As a first step in 

assessing the quality of the hydrogen sulfide data reported by the indirect discharging facilities to 

TRI and its utility for the 2015 Annual Review, EAD evaluated whether the reported releases 

downloaded from the DMR Pollutant Loading Tool for the TRA take into account any treatment 

and removal that is likely to occur at the receiving POTW. 

As discussed in Section 3.4 of Technical Users Background Document for the Discharge 

Monitoring Report (DMR) Pollutant Loading Tool (U.S. EPA, 2012), the DMR Loading Tool 

adjusts, if possible, the TRI pollutant releases reported by indirect discharging facilities to 

account for pollutant removal that occurs at POTWs prior to release to receiving waters. Table 

C-1 in Appendix C of the Technical Users Background Document for the Discharge Monitoring 

Report (DMR) Pollutant Loading Tool lists the POTW removals used for the TRI chemicals 

reported as transferred to POTWs (U.S. EPA, 2012). The adjusted releases are incorporated into 
Memorandum 

October 29, 2015 

Page 7 

the industrial rankings presented in the DMR Loading Tool that EAD then downloads to form 

the basis for its TRA. 

EAD reviewed the POTW pollutant removals in Table C-1 in Appendix C of the 

Technical Users Background Document for the Discharge Monitoring Report (DMR) Pollutant 

Loading Tool and did not identify a removal specific to hydrogen sulfide. Accordingly, the 2013 

TRI hydrogen sulfide data for indirect discharging facilities downloaded from the DMR Loading 

Tool do not account for treatment occurring at POTWs. Because hydrogen sulfide in water 

readily oxidizes to sulfates and is biologically oxidized to elemental sulfur under low to neutral 

pH and well aerated conditions, hydrogen sulfide removal rates at POTWs are likely significant, 

which would greatly reduce ultimate releases to receiving waters. Therefore, EAD determined it 

was necessary to identify a removal efficiency that it could apply to the indirectly released 

hydrogen sulfide data reported in TRI, to account for hydrogen sulfide removed at POTWs. 

To determine a removal efficiency that EAD could apply to the reported releases of 

hydrogen sulfide from indirect discharging facilities to account for removal at POTWs, EAD 1) 

evaluated updates to the data sources that form the current basis for the POTW removals EAD 

uses in its annual reviews, and 2) contacted POTWs that are receiving wastewaters from the 

industrial facilities reporting the releases of hydrogen sulfide to TRI. The results of these 

evaluations are discussed in the subsections below. 

1.5.1 Data Sources for Current POTW Removals 

EAD reviewed the data sources that it has historically used to develop POTW removals 

as a starting point to determine a removal rate for hydrogen sulfide. These data sources include 

EPA’s National Risk Management Research Laboratory (NRMRL) Treatability Database (U.S. 

EPA, 2004), EPA’s “50 POTW Study” (U.S. EPA, 1982), and POTW removals incorporated 

into EPA’s Office of Pollution Prevention and Toxic’s (OPPT) Risk Screening Environmental 

Indicators (RSEI) model. EAD relies on the RSEI model for POTW removals only in the 

absence of actual performance data. EAD most recently updated the POTW removal efficiencies 

it uses in its annual reviews of effluent guidelines in 2005 (ERG, 2005). During this update, 

EAD incorporated the most recent POTW performance data developed in support of 

promulgated ELGs as well as more recent data compiled in the NRMRL Treatability Database, 

Version 5.0. EAD did not identify any more recent updates to the NRMRL Treatability 

Database, nor has EPA promulgated any more recent ELGs that regulate the release of hydrogen 

sulfide; therefore these data sources did not provide any new information regarding POTW 

removals of hydrogen sulfide. 

EAD also reviewed the RSEI model to determine if new data were available for the 

removal of hydrogen sulfide at POTWs. The RSEI model primarily relies on POTW removals 

obtained from the NRMRL Treatability Database, but also relies on Syracuse Research 

Corporation’s (SRC’s) Sewage Treatment Plant Fugacity Model (STPWIN) for those chemicals 

not in the NRMRL Treatability Database (U.S. EPA, 2013). EAD did not identify any recent 

updates to the NRMRL Treatability Database; therefore EAD investigated POTW removal rates 

for hydrogen sulfide that may be available in the STPWIN model. 
Memorandum 

October 29, 2015 

Page 8 

EAD downloaded the latest version of SRC’s STPWIN model (U.S. EPA, 2013), which 

is integrated into EPA’s Estimation Program Interface (EPI) Suite4 (EPI Suite Version 4.11 

(November 2012)). The EPI Suite is a suite of physical/chemical property and environmental fate 

estimation programs developed by the EPA’s OPPT and SRC. The STPWIN model in particular 

predicts the removal of chemicals by typical activated sludge-based sewage treatment plants. 

OPPT caveats that the EPI Suite is a screening-level tool and should not be used if acceptable 

measured values are available. In addition, OPPT emphasizes the importance of understanding 

the estimation methods and their appropriate application. 

According to the general information provided in the EPI Suite, the STPWIN model is 

based on fugacity principles and attempts to predict the fate of chemicals in an “evaluative 

environment.” In this case, the evaluative environment is a conventional wastewater treatment 

plant that uses activated sludge secondary treatment. The model estimates the fate of chemicals 

present in the influent as they are removed by evaporation, biodegradation or other degradation 

processes, sorption to sludge, and loss in the final effluent. The most critical and uncertain 

variable is the biodegradation rate and its dependence on biomass concentration. 

This model is useful for establishing the general features of a chemical's behavior in an 

activated sludge sewage treatment plant. It is not intended to provide an accurate simulation of 

chemical fate in a specific plant. Rather, it is a screening-level model that seeks to provide rough 

estimates of the proportions of the chemical likely to leave the system by biodegradation or other 

degradation processes, in sludge, by evaporation, and in the water outflow. These proportions 

are dictated by both the properties of the substance and the characteristics of the treatment plant. 

STPWIN uses a combination of default parameters and input parameters that may be user 

defined or estimated by other programs within EPI Suite. 

The STPWIN model uses the following default POTW system properties (EPI Suite 

Version 4.11 (November 2012)): 

Table 5. STWPIN Model Default POTW System Properties 

Parametera Tank 1 (primary) Tank 2 (aeration) Tank 3 (settling)

Tank area (m2) 266.7 800 727.3 

Tank depth (m) 3.8 10 3.8 

VSS concentration (g/m3) 50,000 -- 5,500 

VSS biomass (fraction) 0.005 0.0025 0.00055 

Outflow MLVSS concentration (g/m3) 80.2 2500 15 

VSS aeration rate (m3/hr) -- 8960 -- 

Fraction of influent flow recycled -- -- 0.8 

                                                            

4

 For more information on EPI and to download the model see: http://www.epa.gov/oppt/exposure/pubs/episuite.htm 
Memorandum 

October 29, 2015 

Page 9 

Table 5. STWPIN Model Default POTW System Properties 

Parametera Tank 1 (primary) Tank 2 (aeration) Tank 3 (settling)

Fraction of influent flow removed 0.0024 -- 0.015 

VSS−volatile suspended solids 

MLVSS−mixed liquor volatile suspended solids

a

 Other system properties: influent total flow = 1,000 m3/hr; influent volatile suspended solids concentration = 200 

g/m3

; gas phase mass transfer coefficient = 5 m/hr; liquid phase mass transfer coefficient = 0.05 m. 

 The model requires input values for vapor pressure, water solubility, and log Kow. These 

can be entered by the user or estimated by other models in the EPI Suite. The tool also contains a 

database of chemical properties (PHYSPROP database) that can be imported. For the purpose of 

running the model, EAD used the PHYSPROP database to provide the default chemical property 

data for hydrogen sulfide. These values are shown in Table 6 and are consistent with the values 

identified in Table 1. 

Table 6. PHYSPROP Database Chemical Properties for Hydrogen Sulfide 

Property PHYSPROP Database Value 

Melting Point -85.49oC 

Boiling Point -60.33oC 

Water Solubility 3,740 mg/L at 21oC 

Vapor Pressure 15,600 mm Hg at 25oC 

LogKow -- 

 The model also allows the user to vary the assumptions for the degradation half-life of 

the chemical. There are three options available, as indicated below (Option 1 is the default): 

 Option 1: 10,000 hours for the primary clarifier, aeration vessel and settling tank. 

These values are used to signify no biodegradation, normally considered a worst case 

scenario. 

 Option 2: Estimates based on BIOWIN5

 output. Half-lives are assigned based upon an 

EPA method using BIOWIN output. 

 Option 3: User-entered values. The user enters the half-lives for the primary clarifier, 

aeration vessel and settling tank. Documentation available for the model includes the 

following guidance for selecting half-lives for conventional activated sludge 

treatment: for rapid biodegradation use 1 hour; for moderate use 3 hours; for 

moderate-to-slow use 10 hours; for slow use 30 hours. 

                                                            

5

 BIOWIN estimates aerobic and anaerobic biodegradability of organic chemicals using a combination of 

techniques. 
Memorandum 

October 29, 2015 

Page 10 

To calculate a hydrogen sulfide POTW removal using the STWPIN model, EAD entered 

the chemical properties for hydrogen sulfide shown in Table 6 and used the default option 

(option 1) for the degradation half-life of hydrogen sulfide, which provides a conservative 

removal rate. The resulting POTW removal calculated by the STWPIN model for hydrogen 

sulfide is 98.64 percent. 

1.5.2 Data Collected from POTWs Receiving Hydrogen Sulfide Releases from Industrial 

Facilities 

As part of the review of hydrogen sulfide releases in TRI, EAD contacted one POTW that 

receives wastewaters from industrial facilities reporting releases of hydrogen sulfide to TRI, and 

one POTW reporting hydrogen sulfide discharges on its DMR, listed below. 

 Lafayette Wastewater Treatment Plant in Lafayette, IN; and 

 City of Tolleson Wastewater Treatment Plant, Tolleson, AZ. 

The Lafayette Wastewater Treatment Plant did not have any treatment data for hydrogen 

sulfide and was not concerned about hydrogen sulfide loads received from industrial facilities 

(Beeler, 2014). The City of Tolleson Wastewater Treatment Plant provided 2013 and 2014 

hydrogen sulfide treatment data: raw influent hydrogen sulfide concentrations range from 0.23 – 

0.742 mg/L, and the treated effluent concentrations are 0.01 mg/L or less (Tyler, 2014). These 

data present a hydrogen sulfide percent removal at the POTW ranging from 95.7 to 98.7. These 

data suggest that the estimated removal rate of 98.64 percent for hydrogen sulfide at a POTW 

obtained from the STPWIN model is reasonable for EAD’s use in adjusting the indirect releases 

of hydrogen sulfide reported to TRI. 

1.6 Hydrogen Sulfide POTW Removal Adjustment 

After reviewing available data regarding POTW removals of hydrogen sulfide and 

contacting several POTWs that are receiving wastewaters from the industrial facilities reporting 

the releases of hydrogen sulfide to TRI, EAD determined that it was appropriate to incorporate 

into the 2015 TRA a POTW percent removal for hydrogen sulfide of 98.64 percent for indirect 

releases of hydrogen sulfide reported to TRI. EAD derived this removal from an underlying 

model (STPWIN) that OPPT uses in its RSEI model to estimate POTW removals of TRI 

chemicals. EAD has historically relied on RSEI as a data source for POTW removals in the 

absence of actual performance data from EPA/ORD’s NRMRL Treatability database or the 50 

POTW Study. Further, the underlying assumptions EAD entered into the STPWIN model 

provide a conservative estimate of the removal of hydrogen sulfide from a POTW and are 

consistent with removals achieved by at least one POTW treating indirect releases of hydrogen 

sulfide from facilities reporting to TRI. Table B-1 in Appendix B of the 2015 Annual Review 

Report (U.S. EPA, 2016), lists the facilities with indirect hydrogen sulfide releases, adjusted to 

account for POTW removals. EAD used these adjusted values to develop the final 2015 point 

source category rankings for the TRA, supporting the 2015 Annual Review. 
Memorandum 

October 29, 2015 

Page 11 

1.7 References 

1. ATSDR. 2014. U.S. Department of Health and Human Services, Agency for Toxic 

Substances and Disease Registry. Draft Toxicological Profile for Hydrogen Sulfide and 

Carbonyl Sulfide. Atlanta, GA. (October). Available online at: 

http://www.atsdr.cdc.gov/ToxProfiles/tp114.pdf. EPA-HQ-OW-2015-0665. DCN 08125. 

2. Beeler, Brian. 2014. Telephone and Email Communication with Brian Beeler, Lafayette 

WWTP, and Kimberly Bartell, Eastern Research Group, Inc., Re: 2013 Hydrogen Sulfide 

Discharges at POTWs. (December 19). EPA-HQ-OW-2015-0665. DCN 08217. 

3. Dirks, Kim. 2014. Telephone and Email Communication with Kim Dirks, Tyson Fresh 

Meats, and Kimberly Bartell, Eastern Research Group, Inc., Re: 2013 TRI Hydrogen 

Sulfide Discharges for Tyson Fresh Meats in Hillsdale, IL. (January 8). EPA-HQ-OW2015-0665. DCN 08220. 

4. ERG. 2005. Memorandum to the 2006 Effluent Guidelines Program Plan Docket, EPA 

Docket Number OW-2004-0032, from Ellie Codding and Deb Bartram, Eastern Research 

Group, Inc., Re: Publicly Owned Treatment Works (POTW) Percent Removals Used for 

the TRIReleases2002 Database. (August 12). EPA-HQ-OW-2004-0032-0967. 

5. Razink, Jonathan. 2014. Telephone and Email Communication with Jonathan Razink, 

Cargill, Inc., and Kimberly Bartell, Eastern Research Group, Inc., Re: 2013 TRI 

Hydrogen Sulfide Discharges for Cargill Inc., in Wahpeton, ND. (December 22). EPAHQ-OW-2015-0665. DCN 08127. 

6. Schulz, Charles. 2014. Telephone and Email Communication with Charles Schulz, John 

Morrell and Co., and Kimberly Bartell, Eastern Research Group, Inc., Re: 2013 TRI 

Hydrogen Sulfide Discharges for John Morrell and Co. (December 22). EPA-HQ-OW2015-0665. DCN 08158. 

7. Schwartz, Jerry, and Paul Wiegand. 2014. Telephone and Email Communication between 

Jerry Schwartz, American Forest and Paper Association, Paul Wiegand, National Council 

for Air and Stream Improvement, and Kimberly Bartell, Eastern Research Group, Inc., 

Re: 2013 DMR and TRI Pulp and Paper Discharges. (December). EPA-HQ-OW-2015-

0665. DCN 08201. 

8. Tyler, David. 2014. Telephone and Email Communication with David Tyler, Tolleson 

WWTP, and Kimberly Bartell, Eastern Research Group, Inc., Re: 2013 Hydrogen Sulfide 

Discharges at POTWs. (December 19). EPA-HQ-OW-2015-0665. DCN 08229. 

9. U.S. EPA. 1982. Fate of Priority Pollutants in Publicly Owned Treatment Works (EPA 

440/1-82/303). Washington, D.C. (September). EPA-HQ-OW-2004-0032-2097. 
Memorandum 

October 29, 2015 

Page 12 

10. U.S. EPA. 1986. Quality Criteria for Water. Washington, D.C. (May). EPA-HQ-OW2004-0032-2619. 

11. U.S. EPA. 2003. Toxicological Review of Hydrogen Sulfide. Washington, D.C. (June). 

EPA-HQ-OW-2015-0665. DCN 08276. 

12. U.S. EPA. 2004. Office of Research and Development. NRMRL Treatability Data Base, 

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