Allen, Jeffrey

Jeff Allen is a industrial water and wastewater consultant with Brown and Caldwell. His specialty is projects for petroleum refineries. He has over 30 years of total experience and in the last 20 years has worked on projects for 37 different refineries. Jeff received his bachelor's degree in chemical engineering from Worcester Polytechnic Institute and his master's degree in chemical engineering from the University of Connecticut. He is a professional engineer in multiple states.

Titles from this speaker

Benzene Removal in a Petroleum Refinery Moving Bed Biofilm Reactor System

Abstract

Executive Summary A study was performed to evaluate benzene removal and biomass concentrations in two parallel moving bed biofilm reactors (MBBRs) at the Valero Ardmore Refinery, Ardmore, OK (the Refinery). Three rounds of daily testing were completed between July and November 2022. Study results indicated greater than or equal to 99.8 percent benzene biodegradation across the MBBRs. Effluent benzene concentrations were generally below the analytical limit of detection. The average MBBR biomass concentration was 478 milligrams per liter (mg/L) as total suspended solids (TSS), with an approximate 50:50 split between biomass in the bulk liquid and that attached to the MBBR media. Study results led to the State of Oklahoma making a regulatory determination that the MBBRs as operated by Valero meet the definition of an 'Enhanced Biodegradation Unit' under the federal Benzene Waste Operations National Emissions Standard for Hazardous Air Pollutants (BWON). Thus, going forward, air emissions controls are not required for the MBBR off gas. Introduction The Refinery operates a wastewater treatment plant (WWTP) to manage process wastewater, with final effluent discharged to the Washita River. The WWTP includes two parallel bioreactors, former aeration tanks converted to MBBR technology circa 2006 with the addition of 328 cubic meters (m3) of AnoxKaldnes K1 media to each unit. In early 2022, an additional 160 m3 of World Water Works WWW-05 media was added to Reactor 2. Both media types have 500 m2/m3 of specific surface area. Treatment of the Refinery's wastewater is subject to 40 CFR Part 61 Subpart FF, also known as BWON. This rule allows for an exemption from air emission controls for bioreactors meeting the definition of enhanced biodegradation. As MBBR technology does not recycle biomass, it was originally believed that the Refinery's bioreactors did not qualify for the BWON exemption. Accordingly, the MBBRs were designed with covers and a thermal oxidizer to control air emissions from the combined vent gas. This study was performed to evaluate the fate of benzene in the MBBRs, with the goal of demonstrating that vent gas control could be eliminated while satisfying BWON requirements. Three rounds of testing were performed around each reactor to collect the following data: Influent benzene, Effluent benzene, Benzene in vent gas, Amount of MBBR media in each reactor, Biofilm mass on the MBBR media, TSS. The data obtained allowed for calculation of percent benzene biodegradation and total biomass quantity in each MBBR. Methodology Table 1 summarizes sample locations and parameters analyzed during each sampling round. Vent gas samples were collected using evacuated Summa cannisters equipped with flow regulators that provided for sample collection over a 1-hour period. The sampler tubing was connected to an existing tap on the common vent gas header from the two bioreactors, upstream of off-gas treatment. The wastewater samples were collected from existing sample taps. Media samples were taken from the aerated bioreactors using a Kemmerer sampling device. To quantify the attached biofilm growth on the MBBR media, the World Water Works procedure was used. The percent media fill in each reactor was estimated based on counting the number of individual media pieces collected per Kemmerer sampler grab. Results Table 2 contains wastewater benzene results from the three rounds of testing. Influent benzene concentrations were 6,950 to 10,900 micrograms per liter. Effluent benzene concentrations were generally non-detectable (detection limit of 0.33 µg/L or 0.66 µg/L), apart from one measurement of 1.33 µg/L on the Round 3, Reactor 2 effluent sample. Table 3 shows vent gas benzene results. Although results varied somewhat between the two MBBRs and among the different sampling rounds, values were low in all cases, with a maximum benzene content of 960 µg/m3. Table 4 summarizes results of the TSS and volatile suspended solids (VSS) analyses performed on wastewater samples. Data presented are the averages of triplicate determinations. Table 5 provides results of biomass analyses on the MBBR media. The biomass on K1 media was reasonably consistent between the two reactors, averaging 3.42 grams per square meter (g/m2) for Reactor 1 and 2.76 g/m2 for Reactor 2. The amount of biomass was also reasonably consistent between the two types of media in Reactor 2 when normalized to specific surface area, 2.76 g/m2 for K1 and 2.27 g/m2 for WWW-05. It was estimated that Reactor 1 had a 15.1 percent media fill and Reactor 2 had 18.9 percent fill. To calculate the benzene mass balance around the bioreactors, wastewater and vent gas flow rates were available through existing on-line flow meters. Table 6 summarizes benzene removal by biodegradation based on mass balances. Benzene biodegradation was greater than or equal to 99.8 percent for each of the testing rounds. Table 7 summarizes combined TSS results to quantify the total biomass in each reactor during each round of testing. Total biomass concentration averaged 478 mg/L TSS. On average, 54 percent of the biomass is biofilm attached to the media, and the balance is suspended growth in the bulk liquid.

This study evaluated benzene removal and biomass concentrations in two parallel moving bed biofilm reactors (MBBRs) at a petroleum refinery. Three rounds of testing were performed including measurements of media TSS and percent fill. Study results indicated ≥99.8% benzene biodegradation, with MBBR effluent benzene concentrations generally below detection limits. The results led to the regulatory agency's determination that the MBBRs met the definition of an enhanced biodegradation unit.

SpeakerAllen, Jeffrey

Presentation time

08:30:00

09:00:00

Session time

08:30:00

10:00:00

SessionPetroleum Refinery Problem Wastewater Constituent Removal Advances

Session number307

Session locationRoom 240

TopicIndustrial Issues and Treatment Technologies, Intermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS)

Author(s)

Allen, Jeffrey, Elliott, Greg, Marrs, David

Author(s)J.S. Allen1, G. Elliott2, D.R. Marrs3

Author affiliation(s)1BROWN AND CALDWELL, MN, 2Valero Energy Corp, OK, 3Valero Energy Corp, TX

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159484

Volume / Issue

Content sourceWEFTEC

Word count12

Description: Dissolved Air Flotation for Secondary Clarification of Refinery Wastewater:...

Dissolved Air Flotation for Secondary Clarification of Refinery Wastewater: Technology Selection Through Full-scale Performance

Abstract

This paper is a case study on the implementation of a new dissolved air flotation (DAF) system to replace a secondary gravity clarifier in the activated sludge process at a petroleum refinery. Technology selection, process design, start-up issues, chemical conditioning requirements, fullscale performance, and lessons learned are presented. The DAFs met the effluent total suspended solids (TSS) objectives and the site’s goal of providing process equipment redundancy within the limited footprint available.

A case study on the implementation of a new dissolved air flotation (DAF) system to replace a secondary gravity clarifier in the activated sludge process at a petroleum refinery. Technology selection, process design, start-up issues, chemical conditioning requirements, full-scale performance, and lessons learned are presented. The DAFs met the effluent total suspended solids (TSS) objectives and the site's goal of providing process equipment redundancy within the limited footprint available.

SpeakerAllen, Jeffrey

Presentation time

15:30:00

16:00:00

Session time

15:30:00

17:00:00

SessionThe A to Z's of Refinery Wastewater Treatment

Session locationRoom S501d - Level 5

TopicFacility Operations and Maintenance, Intermediate Level, Sustainability and Climate Change, Water Reuse and Reclamation

Author(s)

Allen, Jeffrey

Author(s)J. Allen 1; P. Gagnon 2 ; D. Marrs 3; R. Ramos 4; J. Allen 1;

Author affiliation(s)Brown and Caldwell 1; Valero Bill Greehey Refineries 2 ; Valero 3; Veolia Water Technologies 4; Brown and Caldwell 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159140

Volume / Issue

Content sourceWEFTEC

Word count15

Selenium in Petroleum Refineries: Pervasiveness, Treatment Approaches, and Regulatory Status

Abstract

Introduction In petroleum refining facilities, selenium is a naturally occurring constituent of crude oil that is transferred to wastewater streams through refining processes, largely through sour water streams from control of overhead gases from the crude distillation, fluidized catalytic cracking, hydrotreating, and reforming processes. Other smaller sources of selenium in refineries are waters from crude preparation (e.g., washing, desalting, and dewatering) operations. Based on the firm's research and experience, this paper presents an overview of selenium pervasiveness, regulatory status, and treatment approaches in US petroleum refineries. Selenium Presence in Refineries In 2019 there were 143 US refineries. Of those 143, 90 refineries discharge their wastewater directly to waterways or through off-site industrial wastewater treatment plants that later discharge to waterways1. Most of the remaining refineries send their process wastewater to a municipal wastewater treatment plant, and a handful inject their wastewater underground into waste disposal wells or into oil and gas formations. The US EPA identified 39 refinery discharge permits with monitoring requirements and/or numeric limits for selenium1. A report from the Environmental Integrity Project (EIP) recorded selenium discharge concentrations and flows from 81 refineries that were operating in 2021 and considered direct discharges of process wastewater or discharges through an off-site industrial wastewater treatment plant that primarily treated refinery wastewater. EIP reported that average selenium discharge concentration from the refineries was 52 µg/L with a range of average concentrations from non-detect to 394 µg/L. The average daily selenium loading rate from the refineries was 2.1 lb/d with the highest refinery average discharge rate being 14 lb/d2. A complete list of all the identified direct discharge refineries along with their corresponding operable capacity, flow, selenium concentration, and selenium loading will be presented in the full-length paper. Regulatory Status EPA sets the minimum requirements for each industry to reduce pollutants in wastewater. States can raise this bar by setting stricter limits or limiting additional pollutants, but many choose not to. Instead, many states rely entirely on EPA's minimum standards when writing permits. EPA first established effluent limitations guidelines and standards (ELGs) for the Petroleum Refining Point Source Category in 1974 and last updated them in 1985. Selenium is not one of the pollutants currently restricted in these guidelines. To keep pace with improvements in treatment technology, EPA is required to review the effluent limits for industries at least every five years and update effluent guidelines if appropriate. EPA most recently decided not to revise the refinery effluent guidelines on January 20, 2023. There is regulatory momentum for more stringent selenium standards that will affect numerous industries including petroleum refineries based on the 2016 final EPA Aquatic Life Ambient Water Quality Criterion for selenium3 replacing previous recommended National Water Quality Criterion4 under the Clean Water Act. EPA's recommended water quality criteria are not rules, nor do they automatically become part of a state's water quality standards. States must adopt into their standards water quality criteria that protect the designated uses of the water bodies within their area. The new Criterion, summarized in Table 1, provides recommendations to states and tribes authorized to establish water quality standards under the Clean Water Act and includes both fish tissue elements and water column elements. EPA recommends that when implementing the criterion, the fish tissue elements take precedence over the water column, elements, except in certain circumstances. As shown in Figure 1, as of November 2023, 26 states have, or are in the process of adopting all, or variations of the Criterion with more expected near term5. Selenium Treatment in Petroleum Refining Table 2 presents a summary of known full-scale selenium treatment technologies installed at US refineries, based on the firms knowledge. Table 3 describes some more commonly used selenium treatment technologies for refineries. Other refineries have avoided needing to install a selenium treatment system at their refinery by making modifications to eliminate or reduce the applicable selenium discharge requirements (e.g., indirect discharge to POTW in lieu of direct discharge, relocation of outfall to a larger receiving water body, and creation of a mixing zone). Conclusions Historically, many refineries have not had selenium discharge limits because the Petroleum Refining Point Source Category ELGs do not include selenium. However, as more states begin to adopt the 2016 EPA Aquatic Life Ambient Water Quality Criterion for selenium, more refineries are expected to begin to receive selenium discharge limits. Treatment for selenium reduction can become complex and there are many treatment options to consider for a refinery. Most refineries are either treating the stripped sour water by oxidation followed by precipitation or treating at the wastewater treatment system with iron co-precipitation. A few refineries have avoided installing selenium treatment through different regulatory approaches.

EPA's Aquatic Life Selenium Water Quality Criterion and state specific criteria are requiring refineries to add or enhance selenium treatment. A summary of full-scale selenium treatment systems in US refineries is provided along with data on selenium concentrations in refineries' wastewater effluent. A variety of chemical, physical, and biological selenium treatment approaches and technologies as applied in refineries are provided.

SpeakerPontarolo, Dominic

Presentation time

15:30:00

16:00:00

Session time

15:30:00

17:00:00

SessionEmerging Technical and Regulatory Issues in Petroleum Refinery Wastewater Management

Session number226

Session locationRoom 240

TopicIndustrial Issues and Treatment Technologies, Intermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS)

Author(s)