Innovative Cost-Effective Control Device for Wastewater VOC Emissions

(As Required by NESHAPs [BWON, HON, MON, MACT] and Other Regulations)

Dr. Carl E. Adams, Jr., PE, Senior Author1 *

Dr. Lial F. Tischler2

Andrew W. Edwards, PE3

1 ENVIRON International Corporation, Nashville, Tennessee2 Tischler/Kocurek, Austin, Texas3 ENVIRON International Corporation, Houston, Texas

VOC Emissions Regulatory Overview

USEPA NESHAP and State RACT typically require:

− Control of Hazardous Air Pollutants (HAP) or VOC off-gases from

storage vessels & sumps

process vents

wastewater equipment

− ≥ 95% removal of VOC or HAP (98% benzene removal for BWON)

Traditionally accepted Control Technologies Traditionally accepted Control Technologies

− Adsorption (e.g., carbon adsorbers)

− Enclosed combustion (oxidizers & fuel gas systems)

− Scrubbers

− Flares

Vapor Phase Adsorption: Granular Activated Carbon

Thermal Oxidizers: Flare or Gaseous Incinerator

Figure 1. Typical Acceptable Control Devices

ThermalOxidizers

Granular Activated Carbon Canisters

Alternative Control Technology Option Can Substantially Lower Cost

Traditional control disadvantages include

− High capital cost

− High operation and maintenance costs• Carbon regeneration/replacement

• Fuel consumption

• Nitrogen loss• Nitrogen loss

− Operational complexity

Regulations specifically allow for “alternative control technology”

− Must demonstrate equal or better emission reduction

− Must obtain approval of Administrative Authority (i.e., EPA and/or State); e.g., BWON requires demonstration of 98% benzene removal

− Must follow USEPA protocols for approval

What is VOC BioTreat?

VOC BioTreat is the process of qualifying an Alternative Control Device, other than Activated Carbon or Thermal Oxidation, for the biodestruction of regulated biodegradable VOC emissions.

The Alternative Control Device is cost-effectively an existing activated sludge process with emission sources in proximity to WWTP.

VOC BioTreat - an Approved Alternative Control Device

The authors have developed new and improved demonstration methods (protocols):

− Bench-scale BOX Test and Core Column Simulation full-scale confirmation

− Provides more realistic and reliable VOC biodegradation rates than the EPA default methodsthe EPA default methods

− Allows for EPA and/or State approval of VOC BioTreat as equivalent treatment technology

Has been approved as BWON alternative control device

− USEPA has accepted improved BOX Test and Full Scale confirmation methods

− State of Louisiana has issued written approval of approach and Alternative Control status

− All states are expected to “sign off” on USEPA-approved protocols

Figure 2. Basic Overview of Alternative Control Device for a Refinery

A Cost-Effective Solution for the Biodestruction of VOC Emissions

Incorporates protocols presented herein to demonstrate an Alternative Control Device

Confirms the use of existing biological wastewater treatment facilities.

Follows exact EPA requirements and protocols for approval

A Cost-effective Solution for the Biodestruction of VOC Emissions

Conclusively demonstrates co-treatment of gaseous emissions or VOCs and aqueous soluble organics in existing wastewater treatment facilities.

Using these protocols, most activated sludge biotreatment systems can be qualified as an Alternative Control Device to treat biodegradable VOCs.biodegradable VOCs.

It is transferable to other VOC/HAP and other regulations.

Approach: High-Level Assessment

Existing WWTP amenable to the technology?

− Diffused aeration system

− Deep tanks

− Existing blowers have adequate air flow treatment capacity (modification may be necessary)

VOC emission sources appropriate for technology?

− Compounds relatively biodegradable− Compounds relatively biodegradable

− Compounds have sufficient solubility (relatively low Henry’s Law constants)

− VOC air volume compatible with WWTP diffused air treatment capacity

Favorable economics?

− Reasonable proximity of VOC sources to WWTP

− Current system O&M costs

− Minimal modifications required to adapt WWTP to technology

VOC BioTreat - The Process

Step 1: High Level Feasibility Evaluation

Step 2: Develop preliminary facility-specific model with assumed biodegradation rate to gauge benzene removal performance requirements and obtain initial Agency concurrence for approach

Step 3: Conduct BOX testing to determine site-specific VOC biodegradation rate and maximize VOC BioTreat effectivenessbiodegradation rate and maximize VOC BioTreat effectiveness

Step 4: Conduct Core Column Simulation Full-scale confirmation testing

Step 5: Obtain final Agency approval of Alternative Control Device

Step 6: Prepare detailed engineering plan and implement Alternative Control Device solution

Step 1 & 2 must be concluded and favorable before proceeding with the rest of the program.

TOXCHEM+ Is Model of Choice TOXCHEM+ is used on all VOC BioTreat projects

TOXCHEM+ Proprietary model - Hydromantis, Inc.

Approved by EPA for wastewater unit emissions estimates (V.4 is current)

Must input and use EPA (WATER9) physical and chemical properties for VOCs being modeled (TOXCHEM+ has its own database but allows entry of modified chemical properties)allows entry of modified chemical properties)

Advantages− Easy to use interface

− Assumes non-equilibrium for rising air bubbles

− Allows modeling of contaminated gases

Disadvantages− Poor simulation of surface aerator emissions

− Must input WATER9 chemical characteristics to use for inventories, compliance

− May incorporate a questionable KG / KL

Case History

Marathon Petroleum Company Garyville Refinery (MPC)

Garyville, Louisiana

Figure 3. Current/Proposed Benzene Control Devices

MPC requested that ENVIRON develop the protocols to qualify the existing activated sludge system (AIS) as an Alternative Control Device.

Table 1. Economic Impacts for VOC Control Devices MPC-Garyville Refinery WWTP

Process Technology

Cost-Effective Impact

Capital cost ($) Annual Operating Cost ($)

Thermal Oxidizer 600,000 340,000

Granular Activated Carbon (6 carbon canisters on each of two API separators,22 change-outs/yr per API) + Maintenance of a N2 blanket

240,000 500,000

Biological (piping, fans and connection to blowers)

600,000 Minimal

Figure 4. Develop Site-Specific Biodegradation Rate Select Appropriate EPA-Recommended Approach

Source: EPA 40 CFR part 63, Appendix C, Figure 1

Major Variables

Benzene Biodegradation Rate

– Table 2 represents various experimentally-determined biorates from API and ENVIRON databases

Other Significant Variables

Air Distribution in Zones

Depth of BioReactor

Aeration Tank Surface Area

Temperature

Inputs to Site-Specific Model

ENVIRON databases

Air Flow

Biomass Concentrations

Potential Benzene Injection Locations into AIS

Benzene Loadings

– See Figure 5.

Temperature

Hydraulic Flow Rate & COD Loading

Figure 5. Reliable Data on Benzene CriticalBenzene Mass Balance for MPC Garyville

Table 2. Various Benzene Biodegradation Rates for BWON Modeling

Benzene Biodegradation Rates – Experimental Values

Refinery Test Type Date Runs

K1 (L/g VSS-hr) @ 20 oC

Average for Multiple Runs

Value Selected for

Model Evaluation

API-A BOX Nov-06 2 48.9 -----

API-A Method304A

Nov-06 1 120.1 84.5

API -B BOX Oct-97 1 79.1 79.1

API-C BOX Oct-97 2 78.4 78.4

API-D EKR Jul-96 4 17.3 17.3

API-D BOX Jul-96 5 122 -----

API-E BOX Sept-94 5 122 -----

Data referred to as API is from Table 5 of the API/NPRA comments to EPA

API-E BOX Nov-94 2 31 -----

API-E BOX Dec-94 6 199 -----

API-E BOX Apr-95 5 199 -----

API-E BOX Apr-95 7 172

API-E BOX Jun-95 4 206 185.5

API-F BOX Jul-95 3 4.4 4.4

API-G Mar-00 3 64 64

ENVIRON- 1 BOX Jul-09 2 23.4 23.4

ENVIRON- 2 BOX Mar-11 1 19.7 19.7

ENVIRON- 3 BOX Aug-11 1 10.8 10.8

ENVIRON-4 BOX Aug-11 1 6.4 6.4

API Water 9 Default Rate 1.4

comments to EPA dated December 28, 2007.

Figure 16. Benzene Removal with Preliminarily Assumed Rates

Figure 7. Actual Site-Specifc Benzene BioRate BOX Test Apparatus as typically used

High quantity of off-gas per bioreactor volume (increases potential for air stripping)

Bioreactor approximately 2 L Volume

Figure 8. BOX Test Apparatus Recommended and Designed by ENVIRON Approved by USEPA & State of Louisiana

Continuous gas sample collected for on-line

benzene analysis

Deeper liquid depth and larger bioreactor diameter, along with

recycle capability, (minimizes potential

Bioreactor approximately 22.2 L Volume

(minimizes potential for non-representative

air stripping)Considered more

realistic of full-scale conditions

Size– 15.4“ (39 cm) long, 10.6“

(27 cm) wide, 5.9“ (15 cm) high

Display– 128 x 64 element graphical

LCD with backlighting

Serial Output

Figure 9. Specifics of the on-line Photovac Voyager GC

Serial Output– RS-232, for connection to

Windows™ based PC and communication to SiteChartsoftware

Detectors– Photoionization detector

with quick-change electrodeless discharge

– UV lamp, 10.6 eV(standard); Electron Capture Detector (optional)

Alarm Output– Internal audio - 85 decibels– Alarm LED

Operating Temperature Range– 41°F to 105°F (5°C to 40°C)

Operating Humidity– 0-100% Relative Humidity (non-condensing)

Figure 10. Setup of the BOX Test

BOX Test Column (without aeration)

Air Supply Tank(Supplies BOX Test

Column & GC)

Voyager Photovac On-

Line Photo-ionization GC

Sample Syringes

Fine-Bubble Air Diffuser

(Off)

Figure 11. Comparative Results of Benzene Stripping with and without Biomass

150

200

250

BE

NZ

EN

E I

N O

FF

-GA

S E

MIS

SIO

NS

(p

pm

v)

Off-Gas in Head SpaceWITHOUT BIOMASS ~2 mg/L Benzene added to filtered effluentpH = 7.8Dissolved Oxygen = 10.6 mg/L

Temperature = 21.0 oCOff-Gas in Head SpaceWITH BIOMASS

0

50

100

150

0 50 100 150 200 250 300 350 400 450

TIME (min)

BE

NZ

EN

E I

N O

FF

-GA

S E

MIS

SIO

NS

(p

pm

v)

Temperature = 21.0 CWITH BIOMASS ~2 mg/L Benzene added to biomassMLVSS concentration of 800 mg/LAir flow through diffuser = 1 L/min pH = 7.3Dissolved Oxygen = 7.5 mg/L

Temperature = 26.0 oC

Figure 12. Smoothed Data Fit as per USEPA Criteria for Fbio Calculation

Development of Preliminary Site-SpecificBenzene Control Model

The site-specific biodegradation rate, corrected to 20 oC, is

- 22.6 L / g VSS-hr @ 20 oC at Marathon-Garyville

- USEPAA Default rate is 1.4 L Benzene / g VSS-hr @ 20 oC

The Toxchem+ model will adjust the rate to the selected temperature for full-scale operating conditions.

Figure 13. Benzene Removal with Preliminarily Assumed Rates vs. Actual Site-Specific Rate (Corrected to 20 oC)

Figure 14. Full-Scale Confirmation Flux Chamber: Less Desirable Option

Figure 15. Full-Scale Confirmation

Performance Validation of Full-Scale System Using VOC BioTreat Column Protocols

Figure 16. Full-Scale Confirmation

Figure 17. Full-Scale Confirmation

Table 3. Full-Scale Confirmation ResultsBenzene Analytical Results of Full-Scale Confirmation

Run #

Benzene Concentration, ppbv

Benzene Biodestruction

(%)

Percent of Design

Condition

Performance Versus Regulatory

Requirements Blower Inlet Outlet Vent

1 21 < 2.0 > 90.6 100%Inconclusive due to analytical limitations

3A 121 < 2.0 > 98.3 >500% Exceeds3A 121 < 2.0 > 98.3 >500% Exceeds

3B 153 < 2.0 > 98.7 >700% Exceeds

4A 156 < 2.0 > 98.7 >700% Exceeds

4B 482 13.3 > 97.2 >2200% Below

5A 182 < 2.0 > 98.9 >800% Exceeds

5B 226 < 2.0 > 99.1 >1000% Exceeds

Design Inlet Benzene Concentration to Bioreactor (after mixing with inlet air) = 14 ppbv

Conclusions The information provided herein achieved required benzene removal

goals under maximum stress conditions at the MAP-Garyville site.

The methodology developed and employed have been approved by the state and federal agencies. The methods and results confirm compliance with 40 CFR § 61.340:

These methods delineate more realistic and reliable benzene biodegradation rates (fbio) than the EPA default rates.

The biorates, thus determined, are more representative of full-scale conditions than the typical USEPA approach.

It is premised that any properly configured activated sludge system can be qualified as an Alternative Control Device when qualified with the protocols herein.

Conclusions (cont’d)

The approach, presented herein, is an environmental-friendly, sustainable VOC Control Device

− Negligible additional energy usage

− Minimal carbon footprint

The site-specific benzene biodegradation rate for MPC at Garyville, LA is 29.3 L / g VSS-hr @ 26 oC (22.6 L/gm-hr, corrected to 20 oC).

This value compares to the USEPA default rate of 1.4 L/gm-hr.

The activated sludge system herein provides excellent configuration and flexibility to achieve benzene removals >99+% even under benzene loadings >16 times projected design levels.