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Ana Deletic - One of the best experts on this subject based on the ideXlab platform.
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The impact of stormwater biofilter design and operational variables on nutrient removal - a statistical modelling approach.
Water research, 2020Co-Authors: Kefeng Zhang, Ana Deletic, G I Chandrasena, Tracey Pham, Emily Payne, David Thomas Mccarthy, Yizhou Liu, Belinda E. Hatt, Behzad JamaliAbstract:Abstract Biofiltration systems can help mitigate the impact of urban runoff as they can treat, retain and attenuate stormwater. It is important to select the optimal design characteristics of Biofilters (e.g., vegetation, filter media depth) to ensure high treatment performance. Operational conditions (e.g., infiltration rate) can also lead to significant changes in biofilter treatment performance over time. The impact of specific operational conditions on water quality treatment performance of stormwater Biofilters is still not well understood. Furthermore, despite the importance of design characteristics and operational conditions on biofilter treatment performance, there is a lack of models that can be used to determine the optimal design and operation. In this paper, we developed a series of statistical models to predict the Total Phosphorus (TP) and Total Nitrogen (TN) removal performance of stormwater Biofilters using various numbers of design characteristics and operational conditions. These statistical models were tested using data collected from four extensive laboratory-scale biofilter column studies. It was found that all models performed relatively well with a Nash-Sutcliffe Efficiency (NSE) of 0.42 - 0.61 for TP and 0.37 - 0.63 for TN. The most important design characteristics were filter media type and depth for TP treatment, and vegetation type and submerged zone depth for TN treatment. In addition, infiltration rate and inflow concentrations were the operational conditions that greatly influence outflow TP and TN concentrations from stormwater Biofilters. As such, these variables need to be carefully considered when designing and operating stormwater Biofilters. Sensitivity analysis results indicate that the model was quite sensitive to all regression coefficients and intercepts. Additional modelling exercises show that the model could be further simplified by reducing the number of cross-correlated parameters. These models can be used by practitioners for not just optimising the design, but also operating Biofilters using real-time monitoring and control to achieve optimum performance.
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Real time control of Biofilters delivers stormwater suitable for harvesting and reuse
Water research, 2019Co-Authors: Pengfei Shen, Katia Bratieres, Ana Deletic, David Thomas MccarthyAbstract:Abstract Stormwater Biofilters have great potential to treat stormwater for harvesting and reuse, but their variable performance in pathogen removal requires further optimisation prior to widespread uptake. This paper provides the first evidence that real time control (RTC) of stormwater Biofilters can mitigate the impact of operational characteristics that result in poor microbial removal. We developed two RTC strategies and validated them using long-term laboratory experiments, utilising Biofilters with a raised outlet pipe that creates a submerged zone. The first RTC strategy focuses on delivering the best water quality for harvesting and reuse or for recreational waterways. It has two components which ensure adequate treatment (microbial die-off): (1) it retains water in the biofilter for at least two days before allowing any further inputs into the system, and (2) the input volume is restricted to the submerged zone’s pore volume. This strategy was effective and significantly improved water quality in the biofilter effluent. However, since the system favours bypassing influent to ensure good quality effluent, only 28.4% of the stormwater was treated. This still resulted in a 62.3% reduction in the influent E. coli load because the system was effective at removing E. coli under controlled conditions. The second RTC strategy builds upon the first strategy, and focuses on delivering a balance between good water quality for harvesting and protecting the environment (i.e., lower bypass). Three hours before the next rainfall event begins, the water that has remained in the biofilter’s submerged zone for at least two days is drained and collected for harvesting through a bottom pipe. When stormwater inflow begins, the bottom pipe is closed and the biofilter operates without control, with water leaving the biofilter to the environment via the raised outlet pipe. The harvested effluent of this RTC strategy met the Australian stormwater harvesting guideline requirements for dual reticulation with indoor and outdoor use and irrigation of commercial food crops. Although only 5.4% of stormwater was collected for harvesting in this strategy, the environment was better protected because of a significantly reduced bypass volume. Our experiments also showed that the nutrient and sediment removal was high for both RTC strategies. This study presents the first stepping stone toward RTC of stormwater Biofilters, demonstrating that these systems can deliver safe stormwater for harvesting and reuse, and for active recreational uses.
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retention and survival of e coli in stormwater Biofilters role of vegetation rhizosphere microorganisms and antimicrobial filter media
Ecological Engineering, 2017Co-Authors: G I Chandrasena, Ana Deletic, M Shirdashtzadeh, Jon M Hathaway, David Thomas MccarthyAbstract:The public health risks associated with pathogens in urban stormwater have been well established, making it necessary to ensure adequate treatment of the stormwater before it is discharged into recreational water bodies or is harvested for reuse. Biofilters, also known as stormwater bioretention systems or raingardens, have shown promising, yet variable, results in reducing indicator bacteria in stormwater. Different biofilter design elements, such as filter media composition and vegetation type, have been found to cause this variable removal performance. Although plants play a key role in the treatment of pollutants, relatively little work has been conducted to understand the importance of interactions between vegetation and the biofilter microbial community on fecal microbial removal. A laboratory-scale biofilter experiment was conducted using Escherichia coli as the test fecal microorganism. Biofilter columns with differing soil media and vegetation types were dosed over a two month span, during which inflow and outflow samples were collected to evaluate system performance. The columns were then decommissioned to collect rhizosphere and bulk soil samples. Root exudates were extracted and used in an E. coli survival study to evaluate their contribution to system performance. The study demonstrated that the antagonistic effects of root exudates/rhizosphere microbes and Cu2+ exchanged zeolite antimicrobial filter media adversely impact the survival of E. coli retained within stormwater Biofilters. Furthermore, leaf and flower/seed extracts of L. continentale showed some potential antibacterial activity against E. coli. This work supports the concept that natural processes in biological systems can deliver effective results in the removal of fecal microorganisms, and should be promoted to the extent possible in stormwater green infrastructure.
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Inside Story of Gas Processes within Stormwater Biofilters: Does Greenhouse Gas Production Tarnish the Benefits of Nitrogen Removal?
2017Co-Authors: Emily G. I. Payne, Ana Deletic, Tracey Pham, Belinda E. Hatt, Perran L M Cook, Tim D FletcherAbstract:Stormwater Biofilters are dynamic environments, supporting diverse processes that act to capture and transform incoming pollutants. However, beneficial water treatment processes can be accompanied by undesirable greenhouse gas production. This study investigated the potential for nitrous oxide (N2O) and methane (CH4) generation in dissolved form at the base of laboratory-scale stormwater biofilter columns. The influence of plant presence, species, inflow frequency, and inclusion of a saturated zone and carbon source were studied. Free-draining Biofilters remained aerobic with negligible greenhouse gas production during storm events. Designs with a saturated zone were oxygenated at their base by incoming stormwater before anaerobic conditions rapidly re-established, although extended dry periods allowed the reintroduction of oxygen by evapotranspiration. Production of CH4 and N2O in the saturated zone varied significantly in response to plant presence, species, and wetting and drying. Concentrations of N2O typically peaked rapidly following stormwater inundation, associated with limited plant root systems and poorer nitrogen removal from biofilter effluent. Production of CH4 also commenced quickly but continued throughout the anaerobic interevent period and lacked clear relationships with plant characteristics or nitrogen removal performance. Dissolved greenhouse gas concentrations were highly variable, but peak concentrations of N2O accounted for
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escherichia coli removal in copper zeolite integrated stormwater Biofilters effect of vegetation operational time intermittent drying weather
Ecological Engineering, 2016Co-Authors: Ana Deletic, David Thomas MccarthyAbstract:Existing biofiltration systems have shown variable and often inadequate bacterial removal efficacy. Previous work has shown antimicrobial media copper-zeolite as a promising alternative to reduce the variability and excessive discharge of faecal indicator bacteria such as Escherichia coli. A large-scale biofilter column study was conducted over eight months to investigate the benefits of incorporating copper-zeolite into Biofilters on E. coli removal. The incorporation of copper-zeolite into Biofilters improved E. coli log removal rate by 53% reducing E. coli concentration from 21,800 MPN/100 mL (median inflow) to 126 MPN/100 mL (median outflow) comparable to international primary contact recreational water quality. In addition, the E. coli removal performance of copper-zeolite amended Biofilters increased after intermittent dry weather periods; this is notable, especially considering biofilter performance usually decreases after drying. Furthermore, these designs reduced inflow copper concentration by 91% (comparable to the metal removal performance of traditional Biofilters) and provided a median effluent copper concentration of 8 μg/L. The vegetation in copper-zeolite filters survived. These results validate the use of copper-zeolite as bioretention media, particularly for sites requiring microbial reduction. Future research will include systematic investigation of the processes involved in reduction of bacteria in copper-zeolite filters and optimise filter design to augment the system performance to meet more stringent stormwater reuse requirements.
William M Moe - One of the best experts on this subject based on the ideXlab platform.
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performance of low ph Biofilters treating a paint solvent mixture continuous and intermittent loading
Journal of Hazardous Materials, 2006Co-Authors: William M MoeAbstract:Two Biofilters packed with a reticulated polyurethane foam medium were inoculated with a compost-derived enrichment culture grown under acidic conditions (pH 3.0) and then operated over a period lasting 63 days. Both Biofilters were supplied with a humidified gas stream containing a five-component mixture of acetone, methyl ethyl ketone, toluene, ethylbenzene, and p-xylene at a total VOC loading rate 80.3 gm(-3)h(-1) to simulate treatment of air emissions resulting from manufacture of reformulated paint. One biofilter was operated under continuous loading conditions and the other received intermittent loading with contaminants supplied only 8 h/day. Nutrient solution with pH 3.0 was supplied approximately once per week to provide nitrogen and other nutrients. Data are presented which demonstrate that undefined mixed cultures acclimated at low pH can successfully treat paint solvent mixtures in Biofilters. The biofilter receiving continuous loading reached high overall removal efficiency (greater than 90% overall removal) 3 weeks after startup, and performance increased over time reaching overall removal in the range of 97-99% after 50 days. Performance of the intermittently loaded biofilter developed more slowly, requiring 6 weeks to stabilize at an overall removal efficiency in excess of 90%. In both Biofilters, ketone components were more rapidly degraded than aromatic components, and removal of aromatic compounds was somewhat unstable even after 2 months of biofilter operation. Scanning electron microscopy (SEM) revealed that fungi dominated the microbial populations in both Biofilters.
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Treatment of Paint Spray Booth Off-Gases in a Fungal Biofilter
Journal of Environmental Engineering, 2005Co-Authors: William M Moe, Kerry A. KinneyAbstract:Biological processes, most notably Biofilters and biotrickling filters, are increasingly used to remove and biodegrade a wide variety of volatile organic compounds (VOCs) present in gas streams emitted from industrial operations. In the research described herein, a laboratory-scale biofilter was operated for a period of more than 180 days to treat a waste gas comprised of a four-component VOC mixture representative of solvents present in off-gases emitted by painting operations. The biofilter, packed with a cubed polyurethane foam media and initially inoculated with a pure culture of the fungus Cladosporium sphaerospermum, was maintained under acidic conditions throughout the duration of the experiments. The system was supplied with a mixture of n-butyl acetate, methyl ethyl ketone, methyl propyl ketone, and toluene with influent concentrations of 124, 50.5, 174, and 44.6 mg m−3 , respectively. The biofilter’s empty bed residence time (EBRT) was varied from 2.0 min to 15 s. When the influent gas stream wa...
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comparison of continuous and sequencing batch operated Biofilters for treatment of gas phase methyl ethyl ketone
Journal of Environmental Engineering, 2004Co-Authors: William M MoeAbstract:Although biofiltration has been used successfully to remove and biodegrade a wide variety of gas-phase organic contaminants generated by industrial facilities and environmental remediation efforts, the ability of conventional Biofilters to maintain high removal efficiency during short-term, unsteady-state, elevated loading conditions is limited. A promising alternative for improving biofilter performance during transient elevated loading conditions while minimizing the disadvantages of conventional treatment technologies is utilization of adsorption packing media and implementation of sequencing batch operating strategies. In the studies described herein, a continuous-flow biofilter (CFB) and a sequencing batch biofilter (SBB) were operated for more than 300 days to treat a methyl ethyl ketone (MEK) contaminated gas stream. The packing medium for both Biofilters consisted of activated carbon coated polyurethane foam cubes. Both Biofilters exhibited stable long-term performance with greater than 99% remova...
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assessment of microbial populations in methyl ethyl ketone degrading Biofilters by denaturing gradient gel electrophoresis
Applied Microbiology and Biotechnology, 2004Co-Authors: William M MoeAbstract:Denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction-amplified genes coding for 16S rRNA was used to assess differences in bacterial community structure as a function of spatial location along the height of two Biofilters used to treat a model waste gas stream containing methyl ethyl ketone (MEK). One of the laboratory-scale Biofilters was operated as a conventional continuous-flow biofilter (CFB) and the other was operated as a sequencing batch biofilter (SBB). Both Biofilters, inoculated with an identical starting culture and operated over a period lasting more than 300 days, received the same influent MEK concentration and same mass of MEK on a daily basis. The systems differed, however, in terms of the fraction of time during which contaminated air was supplied and the overall operating strategy employed. DGGE analysis indicated that microbial community structures differed as a function of height in each of the Biofilters. The DGGE banding patterns also differed between the two Biofilters, suggesting that operating strategies imposed on the Biofilters imparted a sufficiently large selective pressure to influence microbial community structures. This may explain, in part, the superior performance of the SBB over the CFB during model transient loading conditions, and it may open new possibilities for purposely manipulating the microbial populations in Biofilters treating gas-phase contaminants in a manner that leads to more favorable treatment performance.
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effect of nitrogen limitation on performance of toluene degrading Biofilters
Water Research, 2001Co-Authors: William M Moe, Robert L IrvineAbstract:The literature reports conflicting observations regarding the need for nutrient addition to Biofilters treating contaminated gases. Such conflicts are often based on quasi-steady-state performance data collected on Biofilters operated under continuous loading conditions. In the studies described herein, the impact of nitrogen limitations on two toluene-fed Biofilters was assessed over a 97-day period. The Biofilters were packed with polyurethane foam medium and contained different initial levels of nitrate-nitrogen. Toluene and CO2 concentration profiles were monitored during both normal steady loading conditions and short-term, unsteady-state transient loading conditions (e.g., shock loads). Packing medium samples were periodically removed and analyzed to quantify changes in nitrate-nitrogen content over time. Data are presented which show that over long-time periods (several months), nutrient-induced kinetic limitations diminished biofilter performance during transient, unsteady-state conditions even when performance during normal steady loading was not adversely affected. Elemental analysis of biomass removed from the Biofilters support nitrate-nitrogen and CO2 concentration profile data and clearly illustrate how kinetically limited Biofilters fail during shock loads even when there is an overall stoichiometric excess of nutrients.
David Thomas Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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The impact of stormwater biofilter design and operational variables on nutrient removal - a statistical modelling approach.
Water research, 2020Co-Authors: Kefeng Zhang, Ana Deletic, G I Chandrasena, Tracey Pham, Emily Payne, David Thomas Mccarthy, Yizhou Liu, Belinda E. Hatt, Behzad JamaliAbstract:Abstract Biofiltration systems can help mitigate the impact of urban runoff as they can treat, retain and attenuate stormwater. It is important to select the optimal design characteristics of Biofilters (e.g., vegetation, filter media depth) to ensure high treatment performance. Operational conditions (e.g., infiltration rate) can also lead to significant changes in biofilter treatment performance over time. The impact of specific operational conditions on water quality treatment performance of stormwater Biofilters is still not well understood. Furthermore, despite the importance of design characteristics and operational conditions on biofilter treatment performance, there is a lack of models that can be used to determine the optimal design and operation. In this paper, we developed a series of statistical models to predict the Total Phosphorus (TP) and Total Nitrogen (TN) removal performance of stormwater Biofilters using various numbers of design characteristics and operational conditions. These statistical models were tested using data collected from four extensive laboratory-scale biofilter column studies. It was found that all models performed relatively well with a Nash-Sutcliffe Efficiency (NSE) of 0.42 - 0.61 for TP and 0.37 - 0.63 for TN. The most important design characteristics were filter media type and depth for TP treatment, and vegetation type and submerged zone depth for TN treatment. In addition, infiltration rate and inflow concentrations were the operational conditions that greatly influence outflow TP and TN concentrations from stormwater Biofilters. As such, these variables need to be carefully considered when designing and operating stormwater Biofilters. Sensitivity analysis results indicate that the model was quite sensitive to all regression coefficients and intercepts. Additional modelling exercises show that the model could be further simplified by reducing the number of cross-correlated parameters. These models can be used by practitioners for not just optimising the design, but also operating Biofilters using real-time monitoring and control to achieve optimum performance.
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Real time control of Biofilters delivers stormwater suitable for harvesting and reuse
Water research, 2019Co-Authors: Pengfei Shen, Katia Bratieres, Ana Deletic, David Thomas MccarthyAbstract:Abstract Stormwater Biofilters have great potential to treat stormwater for harvesting and reuse, but their variable performance in pathogen removal requires further optimisation prior to widespread uptake. This paper provides the first evidence that real time control (RTC) of stormwater Biofilters can mitigate the impact of operational characteristics that result in poor microbial removal. We developed two RTC strategies and validated them using long-term laboratory experiments, utilising Biofilters with a raised outlet pipe that creates a submerged zone. The first RTC strategy focuses on delivering the best water quality for harvesting and reuse or for recreational waterways. It has two components which ensure adequate treatment (microbial die-off): (1) it retains water in the biofilter for at least two days before allowing any further inputs into the system, and (2) the input volume is restricted to the submerged zone’s pore volume. This strategy was effective and significantly improved water quality in the biofilter effluent. However, since the system favours bypassing influent to ensure good quality effluent, only 28.4% of the stormwater was treated. This still resulted in a 62.3% reduction in the influent E. coli load because the system was effective at removing E. coli under controlled conditions. The second RTC strategy builds upon the first strategy, and focuses on delivering a balance between good water quality for harvesting and protecting the environment (i.e., lower bypass). Three hours before the next rainfall event begins, the water that has remained in the biofilter’s submerged zone for at least two days is drained and collected for harvesting through a bottom pipe. When stormwater inflow begins, the bottom pipe is closed and the biofilter operates without control, with water leaving the biofilter to the environment via the raised outlet pipe. The harvested effluent of this RTC strategy met the Australian stormwater harvesting guideline requirements for dual reticulation with indoor and outdoor use and irrigation of commercial food crops. Although only 5.4% of stormwater was collected for harvesting in this strategy, the environment was better protected because of a significantly reduced bypass volume. Our experiments also showed that the nutrient and sediment removal was high for both RTC strategies. This study presents the first stepping stone toward RTC of stormwater Biofilters, demonstrating that these systems can deliver safe stormwater for harvesting and reuse, and for active recreational uses.
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retention and survival of e coli in stormwater Biofilters role of vegetation rhizosphere microorganisms and antimicrobial filter media
Ecological Engineering, 2017Co-Authors: G I Chandrasena, Ana Deletic, M Shirdashtzadeh, Jon M Hathaway, David Thomas MccarthyAbstract:The public health risks associated with pathogens in urban stormwater have been well established, making it necessary to ensure adequate treatment of the stormwater before it is discharged into recreational water bodies or is harvested for reuse. Biofilters, also known as stormwater bioretention systems or raingardens, have shown promising, yet variable, results in reducing indicator bacteria in stormwater. Different biofilter design elements, such as filter media composition and vegetation type, have been found to cause this variable removal performance. Although plants play a key role in the treatment of pollutants, relatively little work has been conducted to understand the importance of interactions between vegetation and the biofilter microbial community on fecal microbial removal. A laboratory-scale biofilter experiment was conducted using Escherichia coli as the test fecal microorganism. Biofilter columns with differing soil media and vegetation types were dosed over a two month span, during which inflow and outflow samples were collected to evaluate system performance. The columns were then decommissioned to collect rhizosphere and bulk soil samples. Root exudates were extracted and used in an E. coli survival study to evaluate their contribution to system performance. The study demonstrated that the antagonistic effects of root exudates/rhizosphere microbes and Cu2+ exchanged zeolite antimicrobial filter media adversely impact the survival of E. coli retained within stormwater Biofilters. Furthermore, leaf and flower/seed extracts of L. continentale showed some potential antibacterial activity against E. coli. This work supports the concept that natural processes in biological systems can deliver effective results in the removal of fecal microorganisms, and should be promoted to the extent possible in stormwater green infrastructure.
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escherichia coli removal in copper zeolite integrated stormwater Biofilters effect of vegetation operational time intermittent drying weather
Ecological Engineering, 2016Co-Authors: Ana Deletic, David Thomas MccarthyAbstract:Existing biofiltration systems have shown variable and often inadequate bacterial removal efficacy. Previous work has shown antimicrobial media copper-zeolite as a promising alternative to reduce the variability and excessive discharge of faecal indicator bacteria such as Escherichia coli. A large-scale biofilter column study was conducted over eight months to investigate the benefits of incorporating copper-zeolite into Biofilters on E. coli removal. The incorporation of copper-zeolite into Biofilters improved E. coli log removal rate by 53% reducing E. coli concentration from 21,800 MPN/100 mL (median inflow) to 126 MPN/100 mL (median outflow) comparable to international primary contact recreational water quality. In addition, the E. coli removal performance of copper-zeolite amended Biofilters increased after intermittent dry weather periods; this is notable, especially considering biofilter performance usually decreases after drying. Furthermore, these designs reduced inflow copper concentration by 91% (comparable to the metal removal performance of traditional Biofilters) and provided a median effluent copper concentration of 8 μg/L. The vegetation in copper-zeolite filters survived. These results validate the use of copper-zeolite as bioretention media, particularly for sites requiring microbial reduction. Future research will include systematic investigation of the processes involved in reduction of bacteria in copper-zeolite filters and optimise filter design to augment the system performance to meet more stringent stormwater reuse requirements.
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the validation of stormwater Biofilters for micropollutant removal using in situ challenge tests
Ecological Engineering, 2014Co-Authors: Kefeng Zhang, David Thomas Mccarthy, Anja Randelovic, Declan Page, Ana DeleticAbstract:Stormwater harvesting is becoming a popular alternative water resource in water stressed regions. Stormwater Biofilters have been recognized as being among the most promising pre-treatment technologies. In this study, a series of challenge tests were conducted as part of a validation framework of stormwater Biofilters for selected micropollutants. Two biofilter configurations were studied: a configuration with loamy sand and no submerged zone (LS-noSZ) and another configuration that uses sand and a submerged zone (S-SZ). Biofilter challenge conditions were: (i) treatment volume set at 95th percentile of all treated events and (ii) the maximum and minimum durations of dry period between two events, both based on hydrology simulations using 30 years rainfall data for Melbourne. The hydraulic performance of S-SZ was stable and not affected by either prolonged wet or dry periods, while the outflow rate of LS-noSZ was largely reduced during prolonged wet periods. Biofilters had a removal efficiency of >80% for total petroleum hydrocarbons (TPHs), glyphosate, dibutyl phthalate (DBP), bis-(2-ethylhexyl) phthalate (DEHP), pyrene and naphthalene loads by both configurations under the most challenge conditions; the removal of pentachlorophenol (PCP) and phenol loads was >80% in LS-noSZ and 50–80% in S-SZ, while chloroform had load removal rates between 20% and 50%. Biofilters were less effective in removing atrazine and simazine with load removal 20–50% in LS-noSZ and <20% in S-SZ. Prolonged dry periods benefited the removal of micropollutants while very short dry periods adversely affected micropollutants removal. The study contributes to the development of the overall framework for validation of stormwater Biofilters, which is required if these systems are to be applied in stormwater treatment systems for higher end water uses such as drinking water.
Sergio Revah - One of the best experts on this subject based on the ideXlab platform.
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a comparative study of fungal and bacterial biofiltration treating a voc mixture
Journal of Hazardous Materials, 2013Co-Authors: Jose M Estrada, Sergio Hernandez, Raul Munoz, Sergio RevahAbstract:Abstract Bacterial Biofilters usually exhibit a high microbial diversity and robustness, while fungal Biofilters have been claimed to better withstand low moisture contents and pH values, and to be more efficient coping with hydrophobic volatile organic compounds (VOCs). However, there are only few systematic evaluations of both biofiltration technologies. The present study compared fungal and bacterial biofiltration for the treatment of a VOC mixture (propanal, methyl isobutyl ketone-MIBK, toluene and hexanol) under the same operating conditions. Overall, fungal biofiltration supported lower elimination capacities than its bacterial counterpart (27.7 ± 8.9 vs 40.2 ± 5.4 g C m−3 reactor h−1), which exhibited a final pressure drop 60% higher than that of the bacterial biofilter due to mycelial growth. The VOC mineralization ratio was also higher in the bacterial bed (≈63% vs ≈43%). However, the substrate biodegradation preference order was similar for both Biofilters (propanal > hexanol > MIBK > toluene) with propanal partially inhibiting the consumption of the rest of the VOCs. Both systems supported an excellent robustness versus 24 h VOC starvation episodes. The implementation of a fungal/bacterial coupled system did not significantly improve the VOC removal performance compared to the individual biofilter performances.
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removal of n hexane by fusarium solani with a gas phase biofilter
Journal of Industrial Microbiology & Biotechnology, 2005Co-Authors: Sonia Arriaga, Sergio RevahAbstract:A gas-phase biofilter inoculated with the fungus Fusarium solani, isolated from a consortium grown on hexane vapors, was used to degrade this compound. The biofilter, packed with perlite and operated with an empty bed residence time of 60 s, was supplied with hexane concentrations between 0.5 g m−3 and 11 g m−3. Biofilter performance was evaluated over 100 days of operation. Several strategies for supplying the nutritive mineral medium were assayed to maintain favorable conditions for the fungal growth and activity. The Fusarium system was able to sustain an average elimination capacity of 90 g m−3reactor h−1 with a maximum of 130 g m−3reactor h−1 . The mass transfer limitations due to high biomass development in the biofilter were confirmed in batch experiments. Bacterial contamination was observed, but experiments in the biofilter and in batch reactors using selective inhibitors and controlled pH confirmed the predominant role of the fungus. Results indicate that fungal Biofilters can be an effective alternative to conventional abatement technologies for treating hydrophobic compounds.
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improving hexane removal by enhancing fungal development in a microbial consortium biofilter
Biotechnology and Bioengineering, 2005Co-Authors: Sonia Arriaga, Sergio RevahAbstract:The removal of hydrophobic pollutants in bio- filters is often limited by gas liquid mass transfer to the biotic aqueous phase where biodegradation occurs. It has been proposed that the use of fungi may improve their removal efficiency. To confirm this, the uptake of hexane vapors was investigated in 2.6-L perlite-packed Biofilters, inoculated with a mixed culture containing bacteria and fungi, which were operated under neutral or acid condi- tions. For a hexane inlet load of around 140 g.m � 3 .h � 1 , elimination capacities (EC) of 60 and 100 g.m � 3 .h � 1 were respectively reached with the neutral and acid systems. Increasing the inlet hexane load showed that the maxi- mum EC obtained in the acid biofilter (150 g.m � 3 .h � 1 ) was twice greater than in the neutral filter. The addition of bacterial inhibitors had no significant effect on EC in the acid system. The biomass in the acid biofilter was 187 mg.g � 1 dry perlite without an important pressure drop (26.5 mm of water.m � 1 reactor). The greater efficiency ob- tained with the acid biofilter can be related to the hydro- phobic aerial hyphae which are in direct contact with the gas and can absorb the hydrophobic compounds faster than the flat bacterial biofilms. Two fungi were isolated from the acid biofilter and were identified as Cladospo- rium and Fusarium spp. Hexane EC of 40 g.m � 3 .h � 1 for Cladosporium sp. and 50 g.m � 3 .h � 1 for Fusarium sp. were obtained in short time experiments in small Biofilters (0.230 L). A biomass content around 30 mg.g � 1 dry perlite showed the potential for hexane biofiltration of the strains.
Gang Sun - One of the best experts on this subject based on the ideXlab platform.
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performance evaluation of a wood chip based biofilter using solid phase microextraction and gas chromatography mass spectroscopy olfactometry
Bioresource Technology, 2008Co-Authors: Lide Chen, Brian Zelle, Lingshuang Cai, Steven J Hoff, Jacek A. Koziel, Gang SunAbstract:Abstract A pilot-scale mobile biofilter was developed where two types of wood chips (western cedar and 2 in. hardwood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The Biofilters were operated continuously for 13 weeks at different air flow rates resulting in a variable empty bed residence time (EBRT) from 1.6 to 7.3 s. During this test period, solid-phase microextraction (SPME) PDMS/DVB 65 μm fibers were used to extract volatile organic compounds (VOCs) from both the control plenum and biofilter treatments. Analyses of VOCs were carried out using a multidimentional gas chromatography–mass spectrometry–olfactometry (MDGC–MS–O) system. Results indicated that both types of chips achieved significant reductions in p -cresol, phenol, indole and skatole which represent some of the most odorous and odor-defining compounds known for swine facilities. The results also showed that maintaining proper moisture content is critical to the success of wood-chip based Biofilters and that this factor is more important than media depth and residence time.