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  • 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 Henrys 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 base

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