# Air Pollutant Emissions at
Flowback/Produced Wastewater

Treatment Plants

Water Management for Shale Plays WEST

- 2014 Denver, CO

Dean Ritts, PE, CEM Principal Engineer

– USAC Water WorleyParsons, Houston , Texas, USA

# Why is this important?

 Reality, Costs and Risks

 Reality

– Fracking emits air pollutants

 Costs

– Controlling air pollutants is costly



###  Risk

– Lawsuits, NOVs, difficult permits, emissions control systems


##  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 I ndustrial Wastewater Treatment Plants, both process tanks and wastewater storage tanks.

# 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



# NSPS

# 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 extend the 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
4 8

-

May

14

## 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 flowrates

### Case 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