In this study, biofiltration using a natural wood chip medium and a commercial biofiltration medium was evaluated for the removal of moderate concentrations of hydrogen sulfide (H 2 S) (up to 100 parts per million by volume [ppmv]) in the presence of significant concentrations of ammonia (NH 3 ). These levels were chosen as representative of wastewater lift station emissions in the Brownsville, TX, area. NH 3 -removing portions of the biofilms may compete with H 2 S-removing portions and inhibit H 2 S removal. H 2 S process removal efficiencies for the commercial and natural media ranged from 90 to 96% depending on inlet loading and media type and bed height. Kinetic analysis of the H 2 S removal process followed apparent first-order reaction behavior. The average first-order reaction rates were 0.03 sec Ϫ1 for the commercial medium and 0.09 sec Ϫ1 for the natural medium.Pressure drops across the columns ranged from 0.41 in. H 2 O/ft for the commercial medium to 1.41 in. H 2 O /ft for the natural medium. NH 3 gas levels of up to 80 ppmv did not affect the H 2 S removal process efficiency, and calculated kinetic rate constants for H 2 S removal remained almost the same. The NH 3 gas also was removed simultaneously with the H 2 S up to 98% removal efficiency by the commercial medium.

BACKGROUND Petrochemical refineries and production sites are considered to be the second greatest source of VOC emissions after vehicle exhausts. The feasibility and performance of a novel sequential biotrickling‐biofiltration unit for the treatment of a mixture of VOCs in the headspace of an oil and gas production tank battery was evaluated for three months at the Apache TAMU#2 well storage tank battery in Snook, Texas. RESULTS The results demonstrated that the main VOC constituents of the headspace of the storage tanks were alkanes along with smaller amounts of aromatics such as benzene, toluene and xylenes. Monitoring results for the biotreatment unit showed an average removal efficiency of 50–60% at an empty bed residence time of 120 s in each tank of the unit. After inoculation of the system with wastewater from a sedimentation basin of a local refinery, the removal efficiency of the system increased dramatically which demonstrated the importance of inoculation to achieve a rapid and successful start‐up in industrial biofilters. The most optimal performance was achieved after 77 days, obtaining the highest elimination capacity of 23 g m‐3 h‐1 at total VOCs loading rate of 39 g m‐3 h‐1. CONCLUSION The operation of the field‐scale sequential BTF‐BF unit for more than three months demonstrated the robustness of this technology and the degradation capabilities of a combination of the suspended and attached growth treatment. The project results demonstrated the potential for even more optimization for improved effectiveness of this novel biological treatment technology for removal of highly variable aromatic VOC concentrations. © 2017 Society of Chemical Industry

Biological based emissions control has been demonstrated to be an efficient and cost effective alternative to thermal oxidation technology or flaring for volatile organic compounds (VOCs) from the forest products and paint and coatings industries. This type of technology applicationhas promising advantages such as the potential for a low carbon footprint, low secondary pollutants such as NOx and SOx, lower energy demands, and lower cost. The objective of this project was to design and implement a sequential field scale biotrickling-biofilter treatment unit to remove VOCs and hazardous air pollutants (HAPs) emissions at the Apache TAMU#2 well storage tank battery in Snook, Texas. The field scale biotreatment system included a biotrickling filter followed by a biofilter with the total treatment volume of 100 ft3, skid mounted on a 22 foot trailer. The biotrickling filter was packed with structured cross flow media with large surface area and high void fraction designed to remove the more water soluble compounds and control the humidity and temperature variations of the inlet gas stream. The biofilter unit was loaded with plastic spheres packed with compost which is referred to as the engineered media. Each of the bio-oxidation units was operated at the air flow rate of 25 CFM and empty bed residence time (EBRT) of 2 minutes. The system was inoculated with local stormwater and wastewater from a sedimentation basinclarifier of a local refinery to provide a mixed culture of microorganisms for degradation of the VOC emissions. VOC emissions were collected from the headspace of a storage tank battery leading into a pressure relief vent system. Based on the photo ionization detector (PID) measurements at the inlet of the bio-oxidation unit, the VOC concentration loadings was cyclic and appeared to be correlated to the gas lift cycle of liquid loading to the crude oil storage tank. During the evaluation period, the biotrickling unit demonstrated a surprisingly higher removal efficiency compared to the biofilter. This may be related to the more stable and higher density of biomass growth observed on the surface of the cross flow media. The lower removal efficiency in the biofilter unit could be due to the lack of uniform moisture and nutrients in the second vessel as a result of spray nozzle inefficiency. This aspect of operation can be further optimized by changing the nozzle and the frequency of watering/spraying of the compost media. A removal efficiency of 50-60% for the total VOCs, across the complete unit, was achieved during the 3 month evaluation period while the unit was operated at an average inlet VOC concentration of 400 ppm. The relatively high concentration of alkenes and alkanes (compared to aromatics and water soluble organics in this crude oil vapor), may have decreased the degradation of the total VOCs in the bio-oxidation unit because these long-chain compounds are more difficult to biodegrade by bacterial biofilms in an aerobic environment. The results suggest biological emission treatment systems may be cost effective when compared to thermal oxidizers and flares and should be evaluated as a Maximum Achievable Control Technology (MACT) to mitigate HAPs (and VOCs) from some oil and gas operations. This innovative biological emissions control technology effectively controlled the cyclic emissions produced at the remote site. The strong increase in removal of VOCs after the oil refinery wastewater inoculation suggests an important optimization parameter for more rapid acclimation and increased efficiency for the system in the future applications.

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The U.S. wood products industry is a leader in the production of innovative wood materials. New products are taking shape within a growth industry for fiberboard, plywood, particle board, and other natural material-based energy efficient building materials. However, at the same time, standards for clean air are becoming ever stricter.Emissions of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) during production of wood products (including methanol, formaldehyde, acetylaldehyde, and mercaptans) must be tightly controlled.Conventional VOC and HAP emission control techniques such as regenerative thermal oxidation (RTO) and regenerative catalytic oxidation (RCO) require significant amounts of energy and generate secondary pollutants such as nitrogen oxides and spent carbon.Biological treatment of air emissions offers a cost-effective and sustainable control technology for industrial facilities facing increasingly stringent air emission standards. A novel biological treatment system that integrates two types of biofilter systems, promises significant energy and cost savings. This novel system uses microorganisms to degrade air toxins without the use of natural gas as fuel or the creation of secondary pollutants.The replacement of conventional thermal oxidizers with biofilters will yield natural gas savings alone in the range of $82,500 to $231,000 per year per unit. Widespread use of biofilters across the entire forest products industry could yield fuel savings up to 5.6 trillion Btu (British thermal units) per year and electricity savings of 2.1 trillion Btu per year. Biological treatment systems can also eliminate the production of NOx, SO 2 , and CO, and greatly reduce CO 2 emissions, when compared to conventional thermal oxidizers. Use of biofilters for VOC and HAP emission control will provide not only the wood products industry but also the pulp and paper industry with a means to costeffectively control air emissions.The goal of this project was to demonstrate the effectiveness of a novel sequential treatment technology that integrates two types of biofilter systems -biotrickling filtration and biofiltration -for controlling forest product facility air emissions with a water-2 recycling feature for water conservation. This coupled design maximizes the conditions for microbial degradation of VOCs and odor causing compounds at specific locations.Water entering the biotrickling filter is collected in a sump, treated, and recycled back to the biotrickling filter. The biofilter serves as a polishing step to remove more complex organic compounds (i.e., terpenes). Specific Project ObjectivesThe gaseous emissions from the hardboard mill presses at lumber plants such as that of the Stimson Lumber Company contain both volatile and condensable organic compounds (VOC and COC, respectively), as well as fine wood and other very small particulate material. In applying bio-oxidation technology to these emissions Texas A&M University-Kingsville (TAMUK) and Bio•Reaction (BRI) evaluated the potential of t...