# Air Pollutant Emissions at


# Flowback/Produced Wastewater
Treatment Plants

Water Management for Shale Plays 

### Pittsburgh, PA

Dean Ritts, PE, CEM Principal Engineer

– USAC Water WorleyParsons, Houston , Texas, USA

# Why is this important?

 Wastewater Treatment Plants are considered sources of Air Pollutants, specifically hazardous air pollutants (HAPs) and volatile organic compounds (VOCs )
 Industrial Wastewater Treatment Plants are recognized by EPA as being sources of HAP and VOC emissions and refineries, 

### chemical manufacturing facilities, pharmaceutical manufacturing facilities, etc.
 As such, there are many Air Regulations in effect, with more coming, that target Wastewater Treatment Plants, both industrial and non

- industrial treatment plants

# Key Acronyms

 

## CAA

– Clean Air Act

 

## HAP

– Hazardous Air Pollutant

 

## MACT

– Maximum Achievable Control Technology

 

## NESHAP

– National Emission Standard for Hazardous 

## Air Pollutant

 

## NSPS

– New Source Performance Standards

 

## VOC

– Volatile Organic Compounds

 

## CWA

– Clean Water Act

 

## NPDES

– National Pollutant Discharge Elimination System

# What Should You Know?

 

# Key Regulations in Effect

 MACT/NESHAP Standards

 NSPS

 State/Local Standards


###  

# Air Permitting Issues

– Do they impact you?

 

# Steps in Preparing an Emissions Estimate for your Wastewater Treatment Plant

## POTW MACT The Wastewater Compliance Universe

MON HON BWON

(FF) Pharma MACT



## PAI MACT Rfy 

## MACT

YYY CWA CAA

# Regulatory Drivers

 

## 40 CFR Part 63

– hazardous air pollutants

 

## NSR for Upstream O&G

– 40 CFR Part 60 OOOO

 Product Storage Tanks & Flowback Water Storage Tanks

 Water storage tanks and treatment units

 

## State Regulatory Agencies

 

## Local Regulatory Agencies

# What Kinds of Emissions Might You Have?

 

## Air toxics (HAPS)

 Do you treat wastewater with solvents in it? Are they hazardous chemicals?

 

## Criteria pollutants

- particulate matter, NOx, SOx, VOCs

 Do you have baghouses, boilers, emergency generators, flares, heaters, and mobile equipment?

 

## Greenhouse Gases

– CO 2 

## and Methane

# Mechanisms to Create Air Pollutant Emissions

 

## Volatilization of organic compounds from treatment
processes
 

## Volatilization of organic compounds from collection systems

 

## Amounts emitted depend on loading, turbulence, system design

 

## Combustion devices emit criteria pollutants and hazardous air pollutants

 

## Solids handling operations create dust (Particulate Matter)

# Sources of Air Pollutants

 

### Equalization Tanks

 

### Headworks

 

### Grinders

 

### Flumes

 

### Wet wells

 

### Lift stations

 

### Collection systems

 

### Primary settling tanks

 

### Aeration basins  

### Biofilters

 

### API separators

 

### Boilers

 

### Emergency generators

 

### Aerobic digesters

 

### Disinfection systems

 

### Nutrient addition (ammonia)

 

### Chlorine removal

 

### Steam strippers

# Sources of Air Pollutant Emissions

# Sources of Air Pollutant Emissions

# Sources of Air Pollutant Emissions

# Sources of Air Pollutant Emissions

# How do you estimate emissions?

 

## Modeling: EPA Water9 version 2; TOXCHEM

 

## Spreadsheet calculations: RWET

 

## Stack testing

 

## Ambient Air Monitoring

 

## Isolation Flux Chambers

 

## Mass balance based on material usage

 

## Influent wastewater characteristics and flow monitoring

 

## Emissions Factors based on Production

## Four Steps to Evaluate HAP/VOC Emissions from a Flowback and Produced Water Treatment Plant (WTP)

 

## Step 1

- Evaluate wastewater characteristics for compounds with high vapor pressures (typically organics and reduced sulfur compounds)

 

## Step 2

- Based on design flows and actual flows 

## calculate emissions assuming all influent compounds volatilizes (within reason, e.g. benzene, toluene)

- worst case scenario

# Four Step Process (continued)

 

## Step 3

- Refine Estimate by Modeling

- System design specifications and dimensions, collection system information

 

## Step 4

- Air Pollutant Emissions Sampling

- equipment 

## intensive, analytically challenging, sophisticated sample plan, trained sampling team

### Importance of Accurate Estimates of Air Pollutant Emissions from Wastewater Treatment Plants

 

## Permit Compliance

 

## Regulatory Compliance

 

## Increasingly lower emissions limits for HAPS and VOCs are being established by regulatory agencies

 

## Increasing control requirements

 

## Greenhouse gas limits

 

## Risk assessments

 

## Facilitate better compliance strategy

# Importance of Wastewater Characterization

 

## Use the most accurate data available for:

 Flow rate

 Chemical Characterization

 Wastewater variation (avg vs max )



###  Well data for produced water and flowback water

 Water quality data for influent that will enter the IWTP

 

## DO NOT RELY ON A SINGLE SAMPLE SET!

# Example

– Benzene Emissions from a Treatment Tank

 

## Lb/day load = X ppm chemical x Q mgd x 8.34

 

## For Benzene example of 10 ppm in 100,000 gpd wastewater, the daily load is:

 8.34 lb/day = 10 x 0.1 mgd x 8.34



###  IF 80% is shown to be emitted to the air then the daily benzene emission is 6.67 lb/day

 That is 0.27 lb/hr

# Example

– continued

 

## But what if the next day your wastewater sample has 100 ppm benzene? Then the daily load is 83.4 lb/day and the emissions could be 66.7 pounds/day or 2.7 lb/hr

# The Relevance Factor

 

## So 66.7 lbs per day? Big deal?

 

## Yes, it can be a REAL big deal when you consider that
many air permits are written with maximum HOURLY limits (not daily maximum like in a NPDES permit)

 

## Some benzene permit limits are as low as 0.1 lbs/hr so 66.7 lbs per day is well over a 0.1 lb/hr emission rate. You are out of compliance with your permit

.  

## Here is the limit from a Permit by Rule form for TCEQ

– 0.17 lb/hr

PBR Emission Limits

Chemical PBR Claimed L, mg/m 3 Emission Limit (E = L/K), lb/hr Emission Limit tpy Actual Emissions

lb/hr Actual Emissions

tpy
benzene § 106.262 3 0.17 0.73 0.01 0.04

BTEX (as benzene) § 106.262 3 0.17 0.73 0.05 0.20

C 6 - C 12 Hydrocarbons (as naphtha) § 106.261 350 6.0 5.0 0.06 0.28

C 12 - C28 Hydrocarbons (as kerosene) § 106.262 100 5.56 5.0 0.06 0.25

# The Ramification Factor

 

## Now extrapolate 66.7 lb/day benzene emitted to 365 days and the benzene emission rate is 12.2 tpy.

 

## This puts the treatment unit in the Major Source category and it will require a Title V operating permit

 

## This is a regulatory program you really want to avoid and you have been pulled in because one 100 ml sample came back with a high benzene concentration

# KNOW Your Wastewater for Air Permitting Purposes

 

### Take the time to properly characterize your wastewater stream;

 

### Document your sources of information and keep it available since recordkeeping is a key part of air permit compliance;

 

### Make sure that critical wastewater characterization equipment such as water meters and wastewater flow meters are well maintained and operational; and,

 

### Remember that existing wastewater data can be used but it may have been collected for different reasons and probably will not give you all the information you need.Understand the Differences Between the Requirements of an Air Permit and a NPDES or SIU Permit

 

### For a NPDES Permit Application you can often take one sample set.

 

### For air permitting data, if you rely on ONE sample to develop your permit limits then you may be far off of the mark and left with a permit limit you will never make.

 

### Be cognizant of the different data needs for each permit type (e.g., 

### maximum daily average vs hourly maximum emission rate) and how you gather that data.

## Texas Air Emission Limits for O&G Facilities

TCEQ Air Quality Permit Regulations for Oil and Gas Operations

Permit

- By

- Rule Emission Limits: < 250 tpy of carbon monoxide (CO) or nitrogen oxides (NO
x ); < 25 tpy of VOCs, SO 2 or PM 10 ; < 25 tpy of total HAPS (such as BTEX) and 10 tpy of individual HAPS; and < 25 tpy of any other air pollutant except CO 2 , water, nitrogen, methane (CH 4 ), ethane (C 2 H 6 ), hydrogen (H 2 ) or oxygen (O 2 ).

Reference: Title 30, Texas Administrative Code, Ch. 106, Subchapter A.

2 5 11

-

Oct

12

### Importance of Obtaining Reliable Air Pollutant Emissions Values Can Not Be Overstated

 

## Data is used by regulators to set air permit limits

 

## Data is used by regulators to push for air pollution controls on wastewater treatment systems (e.g., covers)

 

## Data is used by regulators to develop regional air 

## pollution control strategies and emission limits

# Conservative Assumptions in Estimating Procedure with Water9

 

## NO LOSS of HAP as it passes through 3

- phase separator at CPF, the implication being the WTP sees full load of HAP instead of 30 to 50% of load.

 

## Double concentration of highest TAP concentration recorded

 

## Run all estimates with maximum flowratesCase Study for Flowback and Produced Water Treatment System Planned for EagleFord: Model Inputs

Case Study Values have been altered from project values

# Flowback and Produced Water Treatment System

# Water9 v2 Model Drawing of Case

Study WTP

PW Model

# Water9 v2 Model Drawing of WTP

FB Model

# Case Study: Results Summary

Scenario 1

- Design Case

Compound* Design Case Produced Water Design Case Flowback Water

WW System Emissions (Total)

ppm ppm (lb/hr) (tons/year)

Benzene 70.00 15.00 5.8E

- 03 2.1E

- 02

Toluene 500.00 26.00 3.15E

- 02 1.38E

- 01

Ethyl benzene 40.00 10.00 8 .5E

- 03 3.9E

- 02

Xylene 772.00 60.00 5.1E+00 1.9E+01

Total VOCs 4.65E+00 2.15E+01

Total HAPs 4.66E+00 2.15E+01

Total Emissions 4.66E+00 2.15E+01

* HAPs and VOCs

Scenario 1 illustrates the design case with high concentration levels and peak flow of 235 gpm.

# Scenario 2

– Double Design Case

Scenario 2

- Doubled Design Case Concentrations

Compound* Double Design Case

Concentrations Produced

Water Double Design Case

Flowback Water

WW System Emissions (Total)

ppm ppm (lb/hr) (tons/year)

Benzene 140.00 30.00 1.1E

- 02 4.7E

- 02

Toluene 1000.00 52.00 5.9E

- 02 2.6E

- 01

Ethyl benzene 80.00 20.00 1.5E

- 02 6.6E

- 02

Xylene 1600 120.00 1.1E+01 5.0E+01

Total VOCs 1.1E+01 5.0E+01

Total HAPs 1.1E+01 5.0E+01

Total Emissions 1.1E+01 5.0E+01

* HAPs and VOCs

Scenario 2 illustrates doubling the design case concentration levels with peak flow of 235 gpm.

# Scenario 2 Without Well #1

Scenario 3

- Doubled Design Case Concentrations Without Outlier Well #1

Compound* Doubled Design Case

Concentrations Produced Water Double Design Case

Concentrations Flowback Water

WW System Emissions (Total)

ppm ppm (lb/hr) (tons/year)

Benzene 60.80 30.00 5.7E

- 03 2.5E

- 02

Toluene 150.60 52.00 1.1E

- 02 4.9E

- 02

Ethyl benzene 20.10 20.10 5.8E

- 03 2.6E

- 02

Xylene 376.00 122.00 3.5E+00 1.6E+01

Total VOCs 3.5E+00 1.6E+01

Total HAPs 3.5E+00 1.6E+01

Total Emissions 3.5E+00 1.6E+01

* HAPs and VOCs

Scenario 3 illustrates doubling the design case concentration levels without outlier well with peak flow of 235 gpm.

# Scenario 4

– Expected Operating Conditions

Scenario 4

- Expected Operating Conditions

Compound* Average Case Produced Water Average Case Flowback Water WW System Emissions (Total)

ppm ppm (lb/hr) (tons/year)

Benzene 15.00 10.00 1.5E

- 04 6.0E

- 04

Toluene 50.00 14.00 1.8E

- 04 6.5E

- 04

Ethyl benzene 11.00 8.00 3.9E

- 05 1.5E

- 04

Xylene 85.00 15.20 4.6E

- 01 2.2E+00

Total VOCs 4.6E

- 01 2.2E+00

Total HAPs 4.6E

- 01 2.2E+00

Total Emissions 4.6E

- 01 2.2E+00

* HAPs and VOCs

Scenario 4 illustrates expected operating conditions with flowrate of 149 gpm.

# Document your Results

 

## Water9 v2 Model Results are Provided in an Excel Sheet that has:

 Model Input

− Wastewater Concentration Data

− Wastewater Flowrate Data

− Assumptions

− Treatment System Data

− EPA Default Data



###  Model Output for All units, All compounds



###  Model Output summarized for each operating condition

 Annual Average Emissions (TPY)

 Maximum Hourly Emissions (lb/hr)

# Case study: 2 nd 

# Look

– additional light VOCs

Scenario 4

- Expected Operating Conditions

Compound* Average Case Produced Water Average Case Flowback Water WW System Emissions (Total)

ppm ppm (lb/hr) (tons/year)

Benzene* 16.00 10.40 1.2E

- 04 5.4E

- 04
Toluene * 53.00 12.00 1.5E

- 04 6.7E

- 04 Ethyl benzene* 10.00 9.00 4.1E

- 05 1.8E

- 04 Xylene * 81.00 17.20 2.8E

- 01 1.2E+00 Butane 5.50 5.4E

- 08 2.4E

- 07 Heptane 0.81 8.8E

- 08 3.8E

- 07 Hexane * 2.15 2.3E

- 07 1.0E

- 06 Octane 0.29 4.3E

- 08 1.9E

- 07 Pentane 1.59 2.2E

- 06 9.4E

- 06 Propane 8.19 2.2E

- 08 9.4E

- 08 Decane (C10 &C10+) 1.57 2.4E

- 06 1.0E

- 05 Isopentane 1.87 1.1E

- 07 4.6E

- 07 Isobutane 32.74 9.9E

- 07 4.4E

- 06

Total VOCs 2.9E

- 01 1.5E+00

Total HAPs 2.9E

- 01 1.5E+00
* HAPs and VOCs
VOC

Scenario 4 illustrates expected operating conditions with flowrate of 149 gpm.

# Main Data Requirements

 

## Flowback/Produced Water Compounds

– compounds, compounds characteristics, flow rates

 

## System Design and Layout

 

## Unit dimensions

# Recap: Estimation Methods

 

## Modeling: EPA Water9 version 2; TOXCHEM

 

## Spreadsheet calculations: RWET

 

## Stack testing

 

## Ambient Air Monitoring

 

## Isolation Flux Chambers

 

## Mass balance based on material usage

 

## Influent wastewater characteristics and flow monitoring

 

## Emissions Factors based on Production

# Recap: Know Your Data Quality

 

## Need correct data for system design

 

## Need correct data for wastewater characteristics

 

## Need correct data for compound characteristics

 

## Need to determine when/where it is acceptable to accept model default values

# Identify Critical and Controlling Parameters

 

## High energy inputs to the system

 

## Compound properties

 

## Wind speed

 

## Specific treatment units

 

## Temperatures (wastewater and ambient)

# Summary: UCOG IWTP Results

 

## VOC emissions range from < 1 tpy to >50 tpy

 

## Individual HAP emissions can range from <1 tpy to >10 tpy

 

## BTEX are important as contributors to HAPS

 

## Light hydrocarbons are important contributors to VOC emissions

 

## Emissions depend on the treatment system design

 

## Emissions depend on the concentration of volatile compounds

 

## Emissions depend on flowrate of wastewater through system