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Composting of the organic fraction of municipal solid waste (OFMSW) is accompanied by the emission of large volumes of harmful, hazardous and foul-smelling volatile organic compounds (VOCs). To improve the efficiency of terpenes removal, which constitute a significant part of VOCs, pure cultures of microorganisms dominating in its microbiota were isolated from the microbial community of the biofilter, which has been cleaning such emissions for a long time. Seven pure cultures were isolated and then tested for being able to grow on a mineral medium in the presence of terpene vapor as the only source of carbon and energy. Three of the most actively growing cultures were selected, characterized and identified by the 16S rRNA gene as Rhodococcus erythropolis CA1, Rhodococcus pyridinivorans CA3 and Gordonia sp. CA6. Three identical laboratory biofilters (BF) were inoculated with a mix of these cultures to test the possibility of more complete removal of terpenes. Biofilters were adapting to clearing the model mix of terpineols and geraniol vapors for 45 days. During 45 days the purification efficiency of the model mix reached an average of 91.5% with a contact time (CT) of 3.7 ± 0.2 s and the terpene vapors concentration of 14 ± 2 mg m−3. Then the biofilters number BF2.1 and BF3.1 were connected to real emission from composting OFMSW. The biofilter BF2.1 purified the emission directly, whereas BF3.1 purified similar discharge after the intermediate biofilter of the 1st stage of purification (BF0.0). The BF1.0 was left connected to purification of the model mix as a control. The effectiveness of biofiltration of hard-to-remove terpenes was evaluated by gas chromatography of samples taken at the inlet and outlet of biofilters. The average efficiency of removing terpenes from real emissions by BF2.1 was 93.1 % (CT = 5.5 s). The total efficiency of removing terpenes by (BF0.0 + BF3.1) complex was 93.2 % (total CT = 7.4 s). A study of the microbiota of inoculated biofilters after 60 and 90 days of purification the real emission by cultivation from dilutions, identification by the 16S rRNA gene and fingerprinting showed that in BF2.1 and BF3.1 Rhodococcus erythropolis CA1 and Rhodococcus pyridinivorans CA3 were preserved among living cells at a level of 6.5–12.4 %, and genetically fully corresponded to the original cultures. These results could have a positive impact on improving the results of deodorization of emissions from OFMSW composting by biofiltration, simplifying the design of the biofiltration facility (one stage instead of two) and reducing the total time for effective biofiltration. This, in turn, would contribute to the wider introduction of highly efficient emission purification methods at OFMSW composting facilities in order to create more comfortable and ecologically clean environmental conditions around them. [Display omitted] • Three cultures using hard-to-decompose terpenes have been isolated and identified. • Biofilters with high and stable efficiency of terpenes removal have been obtained. • Isolated cultures are constantly present in microbiota of inoculated biofilters. • Comparable results of 1- and 2-stage biofiltration of terpene mixture have been fixed. [ABSTRACT FROM AUTHOR]

Composting is an effective method for recycling resources in waste management. However, significant nitrogen loss can hinder the overall effectiveness of the composting process. Biofiltration is a promising method for conserving nitrogen in composting owing to its ability to efficiently trap and convert gaseous emissions. This study investigated the efficiency and mechanisms of a composting-biofiltration system to enhance nitrogen retention in distilled grain waste (DGW) compost using pre-composted DGW as biofilter media. The DGW composting-biofiltration system exhibited a lower nitrogen loss (24.9%) than the mono-composting system (40.1%). Additionally, this DGW system achieved a high NH 3 removal efficiency of 94.7%-97.7%, while NO 3 - concentration continuously increased in the biofilter, indicating that biofiltration mainly conserved nitrogen through the conversion of NH 3 emitted from the composter. The analysis of the microbial community and key functional enzymes involved in nitrogen metabolism revealed a significant increase in both nitrification and ammonia assimilation within the biofilter. This resulted in the accumulation of NO 3 - and the formation of organic nitrogen, thereby facilitating nitrogen retention. Genera such as Chryseolinea, Anseongella, Parapusillimonas, Bacillus, and Urebacillus mainly contributed to the generation of NO 3 - and organic nitrogen. The structural equation model analysis revealed that nitrogen retention in DGW compost was mainly facilitated by enhanced nitrification and ammonia assimilation in the biofilter. These results provide insights into underlying mechanisms for enhancing nitrogen retention through a composting-biofiltration approach and present guidance for improving compost quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The efficient removal of volatile sulfur compounds (VSCs), such as dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS), is crucial due to their foul odor and corrosive potential in sewer systems. Biofilters (BFs) offer promise for VSCs removal, but face challenges related to pH control and changing conditions at full scale. Two BFs, operated under acidophilic conditions for 78 days, were evaluated for their performance at varying inlet concentrations and empty bed residence times (EBRTs). BF1, incorporating 4–6 mm marble limestone for pH control, outperformed BF2, which used NaHCO 3 in the nutrient solution. BF1 displayed better resilience, maintained a stable pH of 4.6 ± 0.6, and achieved higher maximum elimination capacities (EC max , 41 mg DMS m−3 h−1 (RE 38.3%), 146 mg DMDS m−3 h−1 (RE 83.1%), 47 mg DMTS m−3 h−1 (RE 93.1%)) at an EBRT of 56 s compared to BF2 (9 mg DMS m−3 h−1 (RE 7.1%), 9 mg DMDS m−3 h−1 (RE 4.8%) and 11 mg DMTS m−3 h−1 (RE 26.6%)). BF2 exhibited pH stratification and decreased performance after feeding interruptions. The biodegradability of VSCs followed the order DMTS > DMDS > DMS, and several microorganisms were identified contributing to VSCs degradation in BF1, including Bacillus (14%), Mycobacterium (11%), Acidiphilium (7%), and Acidobacterium (3%). [Display omitted] • Biofilters can mitigate sewer odors from volatile sulfur compounds. • The use of limestone increases the robustness of the BF. • The use of NaHCO 3 solution leads to pH stratification of the packing material. • The biodegradability order is DMTS > DMDS > DMS. • Bacillus, Mycobacterium, Acidiphilium, and Acidobacterium play key roles. [ABSTRACT FROM AUTHOR]

Biofiltration utilizes natural mechanisms including biodegradation and biotransformation along with other physical processes for the removal of organic micropollutants (OMPs) such as pharmaceuticals, personal care products, pesticides and industrial compounds found in (waste)water. In this systematic review, a total of 120 biofiltration studies from 25 countries were analyzed, considering various biofilter configurations, source water types, biofilter media and scales of operation. The study also provides a bibliometric analysis to identify the emerging research trends in the field. The results show that granular activated carbon (GAC) either alone or in combination with another biofiltration media can remove a broad range of OMPs efficiently. The impact of pre-oxidation on biofilter performance was investigated, revealing that pre-oxidation significantly improved OMP removal and reduced the empty bed contact time (EBCT) needed to achieve a consistently high OMP. Biofiltration with pre-oxidation had median removals ranging between 65% and >90% for various OMPs at 10–45 min EBCT with data variability drastically reducing beyond 20 min EBCT. Biofiltration without pre-oxidation had lower median removals with greater variability. The results demonstrate that pre-oxidation greatly enhances the removal of adsorptive and poorly biodegradable OMPs, while its impact on other OMPs varies. Only 19% of studies we reviewed included toxicity testing of treated effluent, and even fewer measured transformation products. Several studies have previously reported an increase in effluent toxicity because of oxidation, although it was successfully abated by subsequent biofiltration in most cases. Therefore, the efficacy of biofiltration treatment should be assessed by integrating toxicity testing into the assessment of overall removal. [Display omitted] • Review of 120 biofiltration studies offers quantitative insights. • Pre-oxidation enhances OMP removal in biofilters, reducing variability. • Media type and contact time are key factors in micropollutant removal. • Only 19% of studies analysed toxicity alongside micropollutant removal. • Integrated analysis required to assess toxicity and transformation products. [ABSTRACT FROM AUTHOR]

The removal of volatile organic compounds (VOCs) in air is of utmost importance to safeguard both environmental quality and human well-being. However, the low aqueous solubility of hydrophobic VOCs results in poor removal in waste gas biofilters (BFs). In this study, we evaluated the addition of (bio)surfactants in three BFs (BF1 and BF2 mixture of compost and wood chips (C + WC), and BF3 filled with expanded perlite) to enhance the removal of cyclohexane and hexane from a polluted gas stream. Experiments were carried out to select two (bio)surfactants (i.e., Tween 80 and saponin) out of five (sodium dodecyl sulfate (SDS), Tween 80, surfactin, rhamnolipid and saponin) from a physical-chemical (i.e., decreasing VOC gas-liquid partitioning) and biological (i.e., the ability of the microbial consortium to grow on the (bio)surfactants) point of view. The results show that adding Tween 80 at 1 critical micelle concentration (CMC) had a slight positive effect on the removal of both VOCs, in BF1 (e.g., 7.0 ± 0.6 g cyclohexane m−3 h−1, 85 ± 2% at 163 s; compared to 6.7 ± 0.4 g cyclohexane m−3 h−1, 76 ± 2% at 163 s and 0 CMC) and BF2 (e.g., 4.3 ± 0.4 g hexane m−3 h−1, 27 ± 2% at 82 s; compared to 3.1 ± 0.7 g hexane m−3 h−1, 16 ± 4% at 82 s and 0 CMC), but a negative effect in BF3 at either 1, 3 and 9 CMC (e.g., 2.4 ± 0.4 g hexane m−3 h−1, 30 ± 4% at 163 s and 1 CMC; compared to 4.6 ± 1.0 g hexane m−3 h−1, 43 ± 8% at 163 s and 0 CMC). In contrast, the performance of all BFs improved with the addition of saponin, particularly at 3 CMC. Notably, in BF3, the elimination capacity (EC) and removal efficiency (RE) doubled for both VOCs (i.e., 9.1 ± 0.6 g cyclohexane m−3 h−1, 49 ± 3%; 4.3 ± 0.3 g hexane m−3 h−1, 25 ± 3%) compared to no biosurfactant addition (i.e., 4.5 ± 0.4 g cyclohexane m−3 h−1, 23 ± 3%; hexane 2.2 ± 0.5 g m−3 h−1, 10 ± 2%) at 82 s. Moreover, the addition of the (bio)surfactants led to a shift in the microbial consortia, with a different response in BF1–BF2 compared to BF3. This study evaluates for the first time the use of saponin in BFs, it demonstrates that cyclohexane and hexane RE can be improved by (bio)surfactant addition, and it provides recommendations for future studies in this field. [Display omitted] • The effect of surfactant addition in 3 BFs treating hydrophobic VOCs was evaluated. • The selection of appropriate (bio)surfactant type and concentration showed to be critical. • A positive effect in all BFs was observed when saponin was added at 3 CMC. • The addition of (bio)surfactants led to a shift in the microbial consortia. • The results show the interplay of different physical-chemical and biological processes. [ABSTRACT FROM AUTHOR]

Bioactive coatings are envisaged as a promising biotechnology to tackle the emerging problem of indoor air pollution. This solution could cope with the low concentrations, the wide range of compounds and the hydrophobicity of some indoor air VOCs, which are the most important bottlenecks regarding the implementation of conventional biotechnologies for indoor air treatment. A bioactive coating-based bioreactor was tested in this study for the abatement of different VOCs (n-hexane, toluene and α-pinene) at different empty bed residence times (EBRT) and inlet VOC concentrations. The performance of this reactor was compared with a conventional biofilm-based bioreactor operated with the same microbial inoculum. After an acclimation period, the bioactive coating-based bioreactor achieved abatements of over 50% for hexane, 80% for toluene and 70% for pinene at EBRTs of 112–56 s and inlet concentrations of 9–15 mg m−3. These results were about 25, 10 and 20% lower than the highest removals recorded in the biofilm-based bioreactor. Both bioreactors experienced a decrease in VOC abatement by ∼25% for hexane, 45% for toluene and 40% for pinene, after reducing the EBRT to 28 s. When inlet VOC concentrations were progressively reduced, VOC abatement efficiencies did not improve. This fact suggested that low EBRTs and low inlet VOCs concentration hindered indoor air pollutant abatement as a result of a limited mass transfer and bioavailability. Metagenomic analyses showed that process operation with toluene, hexane and pinene as the only carbon and energy sources favored an enriched bacterial community represented by the genera Devosia , Mesorhizobium , Sphingobacterium and Mycobacterium, regardless of the bioreactor configuration. Bioactive coatings were used in this work as packing material of a conventional bioreactor, achieving satisfactory VOC abatement similar to a conventional bioreactor. [Display omitted] • Bioactive coatings successfully applied for the abatement of indoor air VOCs. • VOC abatement similar to that achieved in a conventional biofilm-based bioreactor. • VOC removals over 50%, 80% and 70% for hexane, toluene and pinene at EBRT of 56 s. • EBRT, and not VOC concentration, key parameter for bioreactor performance. [ABSTRACT FROM AUTHOR]

Nitrogenous gaseous emissions commonly have an obnoxious odor associated with it, which when discharged into the environment results in serious environmental problems and health hazards. Several strategies for mitigation of nitrogenous odorants have been reported which include physical, chemical and biological methods. Biological treatments are widely employed because of their efficiency even at low concentration, where physical and chemical methods are not effective. Most commonly used biological treatment methods are biofiltration, biotrickling filters and membrane bioreactors with innovative reactor design, mixing pattern, and air sparging, for example FEBR, ALR, etc. These treatment methods require a critical assessment for the mitigation of obnoxious nitrogen emissions, especially in the context of environmental protection. This review offers a critical evaluation of treatment methods for the mitigation of nitrogenous odorous compound with a key emphasis on biological treatment systems. Also, various mathematical modelling techniques required for optimized operation of biotreatment systems has been discussed. [ABSTRACT FROM AUTHOR]

The study analyses the efficiency of a Sequentional Sedimentation-Biofiltration System (SSBS) built on the Sokolowka river in Lodz (Poland). It was constructed to purify a small urban river whose hydrological regime is dominated by stormwater and meltwater. The SSBS was constructed on a limited area as multi-zone constructed wetlands. The SSBS consists of three zones: sedimentation zone with structures added to improve sedimentation, a geochemical barrier made of limestone deposit and biofiltration zone. The purification processes of total suspended solids (TSS), total phosphorus (TP), total nitrogen (TP) and other nutrients: phosphates (PO 4 3− ), ammonium (NH 4 + ) and nitrates (NO 3 − ) of the SSBS were analyzed. Chloride (Cl − ) reduction was investigated. Monitoring conducted in the first two hydrological years after construction indicated that the SSBS removed 61.4% of TSS, 37.3% of TP, 30.4% of PO 4 3− , 46.1% of TN, 2.8% of NH4+, 44.8% of NO 3 − and 64.0% of Cl − . The sedimentation zone played a key role in removing TSS and nutrients. The geochemical barrier and biofiltration zone each significantly improved overall efficiency by 4–10% for TSS, PO 4 3− , TN, NO 3 − and Cl − . Although the system reduced the concentration of chloride, further studies are needed to determine the circulation of Cl − in constructed wetlands (CWs), and to assess its impact on purification processes. [ABSTRACT FROM AUTHOR]

A biofiltration system was developed to treat benzene, toluene, ethylbenzene, and xylene (BTEX) and Hg° vapour from a petrochemical waste stream during overhaul maintenance. The biofilter compost bed was inoculated with a microbial consortium provided by a petrochemical wastewater treatment plant. The effect of the a BTEX concentration (192.6–973.8 g/m 3 h) and empty bed residence time (EBRT) of 20–100 s were studied under the conditions of steady state, transient, shock BTEX-loading, and off-restart. The findings revealed that during a biofilter start-up, an increase in the influent BTEX concentration to around 334.3 g/m 3 h did not notably affect the biofiltration function at an EBRT of 100 s, and the removal efficiency was higher than 98%. Further, the low EBRT of 60 s did not have adverse effects on the BTEX and Hg° biofiltration (the removal efficiency in both was >93%). For the biofiltration system, the BTEX and Hg° critical attenuation capacity were obtained as 663 g BTEX /m 3 h and 12.6 g Hg° /m 3 h respectively. A maximum attenuation capacity of 774.5 g BTEX /m 3 h was achieved in the biofilter when the BTEX loading rate was 973.8 g BTEX /m 3 h. The parameters of k m and r max of the Michaelis–Menten kinetic model were obtained as 0.099 g/m 3 and 0.578 g/m 3 min respectively. Both BTEX and mercury vapours were completely mass balanced during a continuous biofiltration test. In general, the developed treatment system exhibited a good performance in the treatment of the BTEX stream containing Hg° vapour in the off-gas of a petrochemical company. [ABSTRACT FROM AUTHOR]

Industrial emissions of Volatile Organic Compounds are usually discontinuous. To assess the impact of interruptions in pollutant supply on the performance of biological treatment systems, two identical biofilters previously operated under continuous toluene loadings were subjected for 110 days to extended (12, 24, 36, 48, 60, 72, 84 and 96 h) and for a week to daily (8 h on, 16 h off) toluene starvation/shutdown events. One biofilter was operated under complete shutdowns (both air and toluene supply were interrupted), while the other maintained the air supply under toluene starvation. The biofilter operated under complete shutdowns was able to withstand both the extended and daily pollutant interruptions, while starvation periods >24 h severely impacted the performance of the other biofilter, with a removal efficiency decrease from 97.7 ± 0.1% to 45.4 ± 6.7% at the end of the extended starvation periods. This deterioration was likely due to a reduction in liquid lixiviation (from a total volume of 2380 mL to 1800 mL) mediated by the countercurrent airflow during the starvation periods. The presence of air under toluene starvation also favored the accumulation of inactive biomass, thus increasing the pressure drop from 337 to 700 mm H 2 O.m −1 , while decreasing the wash out of acidic by-products with a significantly higher pH of leachates (Student paired t -test <0.05). This study confirmed the need to prevent the accumulation of inhibitory compounds produced during process perturbation in order to increase biofiltration robustness. Process operation with sufficient drainage in the packing material and the absence of countercurrent airflow are highly recommended during toluene deprivation periods. [ABSTRACT FROM AUTHOR]

The efficacy of wood charcoal (WC) and nutrient-enriched wood charcoal (NWC) as biofilter packing media were assessed for isoprene biodegradation in a bioreactor comprising bioscrubber and a biofilter connected in series and inoculated with Pseudomonas sp. The bioreactors using WC and NWC exhibited >90% removal efficiency and around 369 g m −3 h −1 elimination capacity at around 404 g m −3 h −1 inlet loading rate. In both the bioreactors, the biofilter component showed better degradation capacity compared to the bioscrubber unit. The kinetic parameters, maximum elimination capacity, E C m a x ; substrate constant, K s and E C m a x / K s for Michaelis-Menten model were evaluated. The lower K s for the WC packed bioreactor indicated that E C m a x achieved, was faster compared to others, while higher E C m a x and E C m a x / K s for the NWC packed bioreactor suggests its superiority in isoprene abatement in the continuous mode. A comparison of the available published information on biofiltration of isoprene reflected polyurethane foam as the superior packing media. [ABSTRACT FROM AUTHOR]

In this research paper, a combination of biofiltration (BF) and electrocoagulation (EC) processes was used for the treatment of sanitary landfill leachate. Landfill leachate is often characterized by the presence of refractory organic compounds (BOD/COD < 0.13). BF process was used as secondary treatment to remove effectively ammonia nitrogen (N-NH 4 removal of 94%), BOD (94% removed), turbidity (95% removed) and phosphorus (more than 98% removed). Subsequently, EC process using magnesium-based anode was used as tertiary treatment. The best performances of COD and color removal from landfill leachate were obtained by applying a current density of 10 mA/cm 2 through 30 min of treatment. The COD removal reached 53%, whereas 85% of color removal was recorded. It has been proved that the alkalinity had a negative effect on COD removal during EC treatment. COD removal efficiencies of 52%, 41% and 27% were recorded in the presence of 1.0, 2.0 and 3.0 g/L of sodium bicarbonate (NaHCO 3 ), respectively. Hydroxide ions produced at the cathode electrode reacted with the bicarbonate ions to form carbonates. The presence of bicarbonates in solution hampered the increase in pH, so that the precipitation of magnesium hydroxides could not take place to effectively remove organic pollutants. [ABSTRACT FROM AUTHOR]

Effect of ten extraction methods on flocculation activity and chemical composition of bio-flocculants recovered from backwashed sludge of bio-filtration unit was studied. The results showed that the chemical method was better than physical method with respect to the extracted BFs weight and its flocculation activity. Cell lysis did not affect to the flocculation activity of BFs. Among ten extraction methods, EDTA (20 g/L) was the best one with extracted BFs dry weight of 6242 mg/L and flocculation activity of 83%. Optimization of EDTA concentration showed that 5 g EDTA/L (or 0.2 g EDTA/g SS) was suitable for recovery of BFs from backwashed sludge. The flocculation activity of BFs was 94% when using 2.4 mg of BFs/g of kaolin. The outcome of this study suggested that backwashed sludge of the bio-filtration unit was a potential source for exploiting bio-flocculants. [ABSTRACT FROM AUTHOR]

Odorous emissions from wastewater treatment plants (WWTPs) are an annoyance for neighboring communities. This article, for the first time, quantitatively reports on an evaluation of the presence of fecal odorants identified in air samples from two exemplary WWTPs by the odor profile method (OPM) and chemical analysis. The fecal odorants indole and skatole were identified by Gas Chromatography-Mass Spectrometry. The odor threshold concentration of skatole was determined to be 0.327 ng/L (60 pptV) in Teflon Bags by an expert panel. Skatole was found to be the primary chemical leading to fecal odor, due to its odor concentration to odor threshold concentration ratio that ranged from 2.8 to 22.5. The Weber-Fechner law was followed by pure skatole, but was not applicable when there was a mixture of fecal odorants and other odorant types present in WWTP air emission samples. This is probably caused by antagonism with other odorant types. Several existing odor control treatment methods for fecal odorants were evaluated at different wastewater treatment operations at two WWTPs by the OPM and chemical analysis for indole and skatole. Chemical scrubbing and biofiltration performed best in removing fecal odors among current control technologies. [ABSTRACT FROM AUTHOR]

This paper aims at analysing the environmental benefits and impacts associated with the treatment of malodorous emissions from wastewater treatment plants (WWTPs). The life cycle assessment (LCA) methodology was applied to two biological treatments, namely biofilter (BF) and biotrickling filter (BTF), two physical/chemical alternatives, namely activated carbon tower (AC) and chemical scrubber (CS), and a hybrid combination of BTF + AC. The assessment provided consistent guidelines for technology selection, not only based on removal efficiencies, but also on the environmental impact associated with the treatment of emissions. The results showed that biological alternatives entailed the lowest impacts. On the contrary, the use of chemicals led to the highest impacts for CS. Energy use was the main contributor to the impact related to BF and BTF, whereas the production of glass fibre used as infrastructure material played an important role in BTF impact. Production of NaClO entailed the highest burdens among the chemicals used in CS, representing ∼90% of the impact associated to chemicals. The frequent replacement of packing material in AC was responsible for the highest environmental impacts, granular activated carbon (GAC) production and its final disposal representing more than 50% of the impact in most categories. Finally, the assessment of BTF + AC showed that the hybrid technology is less recommendable than BF and BTF, but friendlier to the environment than physical/chemical treatments. [ABSTRACT FROM AUTHOR]

The filter media in biofiltration systems play an important role in removing potentially harmful pollutants from urban stormwater runoff. This study compares the heavy metal removal potential (Cu, Zn, Cd, Pb) of five materials (potting soil, compost, coconut coir, sludge and a commercial mix) using laboratory columns. Total/dissolved organic carbon (TOC/DOC) was also analysed because some of the test materials had high carbon content which affects heavy metal uptake/release. Potting soil and the commercial mix offered the best metal uptake when dosed with low (Cu: 44.78 μg/L, Zn: 436.4 μg/L, Cd, 1.82 μg/L, Pb: 51.32 μg/L) and high concentrations of heavy metals (Cu: 241 μg/L, Zn: 1127 μg/L, Cd: 4.57 μg/L, Pb: 90.25 μg/L). Compost and sludge also had high removal efficiencies (>90%). Heavy metal leaching from these materials was negligible. A one-month dry period between dosing experiments did not affect metal removal efficiencies. TOC concentrations from all materials increased after the dry period. Heavy metal removal was not affected by filter media depth (600 mm vs. 300 mm). Heavy metals tended to accumulate at the upper 5 cm of the filter media although potting soil showed bottom-enriched concentrations. We recommend using potting soil as the principal media mixed with compost or sludge since these materials perform well and are readily available. The use of renewable materials commonly found in Singapore supports a sustainable approach to urban water management. [ABSTRACT FROM AUTHOR]

Nature-based solutions or Green infrastructure (GI) used for managing stormwater pollution are growing in popularity across the globe. Stormwater GI models are important tools to inform the planning of these systems (type, design, size), in the most efficient and cost-effective manner. MUSIC, an example of such a tool, uses regression and first order decay models. Studies validating MUSIC model performance are, however, scarce, hindering future model development and transferability of the model for systems operating under different design and climatic conditions. To close this gap, this paper evaluates MUSIC for a field scale bioretention system, stormwater wetland and vegetated swale operating under Singapore tropical climate. The treatment modules were able to simulate outflows and effluent pollutant concentrations reasonably well for cumulative event volumes (mostly within ±25%) and cumulative TP and TN loads (within ±30%). Outflow TSS loads were significantly under-estimated as a result of greater variability in measured TSS concentrations across events. The findings indicate that simple empirical models such as MUSIC can be transferred to different regions provided that management decisions are based on long-term modelling efforts. The modules generally simulated the outflow hydrographs and pollutographs of the different inflow and drying/wetting conditions relatively poorly. • MUSIC was used to simulate the performance of Stormwater Green Infrastructure technologies. • A bioretention system, vegetated swale and wetland were tested for a range of storm events under a tropical climate. • Model was able to simulate outflow cumulative event volumes and TP and TN loads reasonably well (within ±30%). • Outflow hydrographs and pollutographs represented the measured data relatively poorly. • Model can be transferred to different geographical regions under long term modelling. [ABSTRACT FROM AUTHOR]

Oyster shell (OS) is a kind of reusable resource that can serve as carbon source, biofilms carrier and basifying agent, suggesting it is an attractive filler option for biofiltration, but studies on its application in drinking water treatment are limited. In this study, one pilot-scale up-flow filter filled with OS media were designed to pretreat surface source water. Filter performance and biological functions were investigated to determine its application scope. The results showed that effluent pH increased and was stable around 7.5 due to the alkalinity provided by OS and its buffering capacity. High and stable removal efficiencies of turbidity (mostly >60%) were achieved. The removal efficiencies of NH 4 +-N changed in a wide range (mostly <30%). TOC and UV 254 removal rate was low (<10%). The biofilms formation period took about 45 days. During this period, this filter mainly removed pollutants through adsorption by OS. High-throughput sequencing results showed that functional taxa did not play a key role after adsorption saturation in early operation period. Functional microbial taxa formed on the OS surface after long-term operation and NH 4 +-N removal rate increased to some extent. Our results suggested that unburned OS filter can be used as rough filter for turbidity removal instead of coagulation and sedimentation process. Preoxidation, calcination of OS, mixed with other filler and are recommended to improve the performance if it would be used for biofiltration. This study provides an insight for the reuse of OS in drinking water treatment. [Display omitted] • Effluent pH kept around 7.5 due to the buffering capacity of oyster shell. • High turbidity removal rates were always achieved. • Oyster shell filter can be used as an alternative to coagulation sedimentation process. • Calcination, mixed fillers and preoxidation is advised when applied for biofiltration. [ABSTRACT FROM AUTHOR]

An aboveground pilot-scale biofilter filled with wood chips was tested to treat ammonia emissions from a piggery located in Brittany (France). Two long-term tests (“summer” and “autumn” experiments) were carried out to improve biofilter applications for agriculture. The influence of climatic conditions on biofilter performance was taken into account. During summer 2012, the biofilter was operated for 74 days at different empty bed residence times (EBRTs) from 6 to 15 s. Inlet NH3 concentrations were relatively constant (around 15 mg m−3). Significant NH3 reductions were achieved at EBRT = 12 s (removal efficiencies, RE, ranged between 90 and 100% for loading rates, LR, of around 4 g m−3 h−1). At a lower EBRT (6 s), RE dropped to roughly 30–50%. This was due to the dramatic increase in the loading rate (LR up to 12 g m−3 h−1) but the results showed that the change in atmospheric conditions (temperature and relative humidity) also had a significant influence on biofilter performance. It was evidenced that the use of a humidifier upstream of the biofilter must be taken into account for large-scale biofilter design, but only for specific conditions (the spraying of the biofilter having to be carried out exceptionally). During autumn 2012, the biofilter was operated for 116 days at EBRT = 12 s. RE were around 80% for LR of around 3 g m−3 h−1. In such autumnal atmospheric conditions, a demister system should be installed upstream of the biofilter in order to avoid water accumulation in the bed material. Although biofiltration was suitable for NH3 treatment of piggery air, the need to control accurately the medium moisture content implies that biofilters would not be easily managed by a pig farmer. [Copyright &y& Elsevier]

The abiotic deterioration of three conventional organic packing materials used in biofiltration (compost, wood bark and Macadamia nutshells) caused by their interaction with toluene (used as a model volatile organic compound) was here studied. The deterioration of the materials was evaluated in terms of structural damage, release of co-substrates and increase of the packing biodegradability. After 21 days of exposure to toluene, all packing materials released co-substrates able to support microbial growth, which were not released by the control materials not exposed to toluene. Likewise, the exposure to toluene increased the packing material biodegradability by 26% in wood bark, 20% in compost and 17% in Macadamia nutshells. Finally, scanning electron microscopy analysis confirmed the deterioration in the structure of the packing materials evaluated due to the exposure to toluene, Macadamia nutshells being the material with the highest resistance to volatile organic compound attack. [Copyright &y& Elsevier]

Abstract: The application of floating treatment wetlands (FTWs) in point and non-point source pollution control has received much attention recently. Although the potential of this emerging technology is supported by various studies, quantifying FTW performance in urban retention ponds remains elusive due to significant research gaps. Actual urban retention pond water was utilized in this mesocosm study to evaluate phosphorus and nitrogen removal efficiency of FTWs. Multiple treatments were used to investigate the contribution of each component in the FTW system with a seven-day retention time. The four treatments included a control, floating mat, pickerelweed (Pontederia cordata L.), and softstem bulrush (Schoenoplectus tabernaemontani). The water samples collected on Day 0 (initial) and 7 were analyzed for total phosphorus (TP), total particulate phosphorus, orthophosphate, total nitrogen (TN), organic nitrogen, ammonia nitrogen, nitrate-nitrite nitrogen, and chlorophyll-a. Statistical tests were used to evaluate the differences between the four treatments. The effects of temperature on TP and TN removal rates of the FTWs were described by the modified Arrhenius equation. Our results indicated that all three FTW designs, planted and unplanted floating mats, could significantly improve phosphorus and nitrogen removal efficiency (%, E-TP and E-TN) compared to the control treatment during the growing season, i.e., May through August. The E-TP and E-TN was enhanced by 8.2% and 18.2% in the FTW treatments planted with the pickerelweed and softstem bulrush, respectively. Organic matter decomposition was likely to be the primary contributor of nutrient removal by FTWs in urban retention ponds. Such a mechanism is fostered by microbes within the attached biofilms on the floating mats and plant root surfaces. Among the results of the four treatments, the FTWs planted with pickerelweed had the highest E-TP, and behaved similarly with the other two FTW treatments for nitrogen removal during the growth period. The temperature effects described by the modified Arrhenius equation revealed that pickerelweed is sensitive to temperature and provides considerable phosphorus removal when water temperature is greater than 25 °C. However, the nutrient removal effectiveness of this plant species may be negligible for water temperatures below 15 °C. The study also assessed potential effects of shading from the FTW mats on water temperature, DO, pH, and attached-to-substrate periphyton/vegetation. [Copyright &y& Elsevier]

Treatment of ventilation air from livestock production by biological airfiltration has emerged as a cost-effective technology for reduction of emissions of odorants and ammonia. Volatile sulfur compounds from livestock production include H2S and methanethiol, which have been identified as potentially important odorants that are not removed sufficiently by biological air filters. Light-expanded clay aggregates (Leca®) is a biotrickling filter material that contains iron oxides, which can oxidize H2S and methanethiol, and thus potentially may help to remove these two compounds in biological air filters. This study used on-line PTR-MS measurements to investigate the performances of two Leca® biotrickling filters (abraded Leca® filter and untreated Leca® filter) for removal of odorants and ammonia emitted from an experimental pig house. The results indicated that the abraded Leca® filter had a similar or slightly better capability for removing odorants than the untreated Leca® filter. This may be due to the enlargement of the surface area by the friction process. The volatile sulfur compounds, however, were not removed efficiently by either of the two Leca® filters. Kinetic analysis of a ventilation controlled experiment during the first period indicated that Grau second-order kinetics could be applied to analyze the removal of sulfur compounds and other odorants, whereas the Stover-Kincannon model could only be applied to analyze the removal of odorants other than sulfur compounds, partly due to the limitation of mass transfer of these compounds in the biotrickling filters. In the last measurement period, a production of dimethyl disulfide and dimethyltrisulfide coinciding with strongly enhanced removal of methanethiol was observed for the untreated filter. This was assumed to be enhanced by an incidence of low local air velocity in the filter and indicated involvement of iron-catalyzed reactions in the removal of sulfur compounds. [Copyright &y& Elsevier]

The effectiveness of different treatment processes on assimilable organic carbon (AOC) removal and bacterial diversity variations was evaluated in a water treatment plant. The van der Kooij technique was applied for AOC analysis and responses of bacterial communities were characterized by the metagenomics assay. Results show that the AOC concentrations were about 93, 148, 43, 51, 37, and 38 μg acetate-C/L in effluents of raw water basin, preozonation, rapid sand filtration (RSF), ozonation, biofiltration [biological activated carbon (BAC) filtration], and chlorination (clear water), respectively. Increased AOC concentrations were observed after preozonation, ozonation, and chlorination units due to the production of biodegradable organic matters after the oxidation processes. Results indicate that the oxidation processes were the main causes of AOC formation, which resulted in significant increases in AOC concentrations (18–59% increment). The AOC removal efficiencies were 47, 28, and 60% in the RSF, biofiltration, and the whole system, respectively. RSF and biofiltration were responsible for the AOC treatment and both processes played key roles in AOC removal. Thus, both RSF and biofiltration processes would contribute to AOC treatment after oxidation. Sediments from the raw water basin and filter samples from RSF and BAC units were collected and analyzed for bacterial communities. Results from scanning electron microscope analysis indicate that bacterial colonization was observed in filter materials. This indicates that the surfaces of the filter materials were beneficial to bacterial growth and AOC removal via the adsorption and biodegradation mechanisms. Next generation sequencing analyses demonstrate that water treatment processes resulted in the changes of bacterial diversity and community profiles in filters of RSF and BAC. According to the findings of bacterial composition and interactions, the dominant bacterial phyla were Proteobacteria (41% in RSF and 56% in BAC) followed by Planctomycetes and Acidobacteria in RSF and BAC systems, which might affect the AOC biodegradation efficiency. Results would be useful in developing AOC treatment and management processes in water treatment plants. [Display omitted] • Ozonation and chlorination cause increase in AOC concentrations in water plant. • Rapid sand filtration (RSF) and biofiltration can cause significant AOC removal. • RSF and biofiltration units cause changes of bacterial diversity and community. • Filtration and biodegradation mechanisms cause AOC removal in RSF/biofiltration. • Proteobacteria, Planctomycetes, and Acidobacteria may cause AOC biodegradation. [ABSTRACT FROM AUTHOR]

This research focuses on the identification and quantification of odorous components in rendering plant emissions by GC/MS and other analytical methods, as well as the description of phenomena occurring in biofilter in order to improve the removal efficiency of industrial biofilters. Among the 36 compounds quantified in the process air stream, methanethiol, isopentanal and hydrogen sulfide, presented the major odorous contributions according to their high concentrations, generally higher than 10 mg m−3, and their low odorous detection thresholds. The elimination of such component mixtures by biofiltration (Peat packing material, EBRT: 113 s) was investigated and revealed that more than 83% of hydrogen sulfide and isopentanal were removed by biofilter. Nevertheless, the incomplete degradation of such easily degradable pollutants suggested inappropriate conditions as lack of nutrients and acidic pH. These inadequate conditions could explain the lack of performance, especially observed on methanethiol (53% of RE) and the production of oxygenated and sulfur by-products by the biofilter itself. [Copyright &y& Elsevier]

Abstract: Lagoons are widely used in rural area for wastewater treatment; however, the odor problem has hampered its application. The root of odor emission from lagoons varies from one to another. The key of controlling the odor is to find out the cause and accordingly provide strategies. Various physical, chemical, and biological methods have been reported and applied for odor control. Physical technologies such as masking, capturing and sorption are often employed to mitigate the pressure from compliant while not to cut off the problem. Chemical technologies which act rapidly and efficiently in odor control, utilize chemicals to damage the odorant production root or convert odorant to odorless substances. Biological methods such as aeration, biocover and biofiltration control the odor by enhancing aerobic condition or developing methanogens in lagoon, and biologically decomposing the odorants. Comparing to physical and chemical methods, biological methods are more feasible. [Copyright &y& Elsevier]

Biowaste such as animal manure poses an environmental threat, due to among others, uncontrolled emissions of ammonia and additional hazardous gases to the atmosphere. This study presents a quantitative analysis of an alternative biowaste management approach aimed at nitrogen recovery and reduction of contamination risks. The suggested technology combines anaerobic digestion of nitrogen-rich biowaste with biofiltration of the resulting gaseous ammonia. A compost-based biofilter is used to capture the ammonia and convert it to nitrate by nitrifying microorganisms. Nitrogen mass balance was applied to quantify the system's capacity under various fowl manure-loading regimes and ammonia loading rates. The produced nitrate was recovered and its use as liquid fertilizer was evaluated with cucumber plant as a model crop. In addition, emissions of other hazardous gases (N2O, CH4 and H2S) were monitored before and after biofiltration to evaluate the efficiency of the system for treating these gases. It was found that nitrate-rich liquid fertilizer can be continuously produced using the suggested approach, with an over 67 percentage of nitrogen recovery, under an ammonia loading rate of up to 40 g NH3 per cubic meter biofilter per hour. Complete elimination of NH3, H2S, CH4 and N2O was achieved, demonstrating the potential of the suggested technology for mitigating emission of these gases from fowl manure. Moreover, the quality of the recovered fertilizer was demonstrated by higher yield performance of cucumber plant compared with control plants treated with a commonly applied organic liquid fertilizer. [Copyright &y& Elsevier]

Abstract: Biofilters have been widely employed for the treatment of malodorous emissions from sludge handling activities in wastewater treatment plants (WWTPs), although their optimized design has been usually hindered by the lack of information about the dynamics of odorant formation. Besides, the odour abatement efficiency of biofilters has been rarely assessed on an individual odorant elimination basis. In this context, the characterization of odours from WWTP sludge in this study revealed the occurrence of a wide range of chemicals, including reduced sulphur compounds and volatile organic compounds (VOCs), with a dynamic concentration profile. The abatement of these odorants was evaluated in a compost-based biofilter at different empty bed residence times (EBRTs). Removal efficiencies (REs) higher than 99% were recorded for limonene, ketones and benzene, while toluene and DMTS REs exceeded 80% at an EBRT of 60 s. A stable biofilter performance was recorded despite the inlet odorant concentration fluctuations. Conversely, DMS and acetic acid were poorly removed due to their likely formation within the biofilter packing material. No correlation between the odorant elimination efficiency and their individual partition coefficients was herein observed. [Copyright &y& Elsevier]

Greywater reuse is becoming an increasingly important factor for potable water saving in many countries. Syria is one of the most water scarce countries in the Middle East. However, greywater reuse is still not common in the country. Regulations and standards for greywater reuse are not available. Recently, however, several stakeholders have started to plan for greywater reuse. The main objective of this paper is to evaluate the potential for potable water saving by using greywater for toilet flushing in a typical Syrian city. The Sweida city in the southern part of Syria was chosen for this purpose. Interviews were made in order to reflect the social acceptance, water consumption, and the percentage of different indoor water uses. An artificial wetland (AW) and a commercial bio filter (CBF) were proposed to treat the greywater, and an economic analysis was performed for the treatment system. Results show that using treated greywater for toilet flushing would save about 35% of the drinking water. The economic analyses of the two proposed systems showed that, in the current water tariff, the payback period for AW and CBF in block systems is 7 and 52 years, respectively. However, this period will reduce to 3 and 21 years, respectively, if full water costs are paid by beneficiaries. Hence, introducing artificial wetlands in order to make greywater use efficient appears to be a viable alternative to save potable water. [Copyright &y& Elsevier]

The effect of using ground tire rubber (GTR) as an adsorptive material in the removal of a 2:1:1 weight mixture of n-butyl acetate, toluene and m-xylene by using a peat biofilter under different intermittent conditions was investigated. The performance of two identical size biofilters, one packed with fibrous peat alone and the other with a 3:1 (vol) fibrous peat and GTR mixture, was examined for a period of four months. Partition coefficients of both materials were measured. Values of 53, 118 and 402 L kg−1 were determined for n-butyl acetate, toluene and m-xylene in peat, respectively; and values of 40, 609 and 3035 L kg−1 were measured for the same compounds in GTR. Intermittent load feeding of 16 h per day, 5 days per week working at an EBRT of 60 s and an inlet VOC concentration of 0.3 g C m−1, resulted in removal efficiencies higher than 90% for both biofilters, indicating that the addition of GTR did not adversely affect the behavior of the bioreactor. Full removal of n-butyl acetate was obtained for both biofilters. GTR improved the removal of the aromatics in the first part of the biofilter, facilitating lower penetration of the toluene and m-xylene into the bed. A 31-day starvation period was applied and intermittent operation subsequently restarted. In both biofilters, high removal efficiencies after a re-acclimation period of two days were achieved. A shock loading test related to 1-h peaks of three- and four-fold increases in its baseline concentration (0.30 g C m−3) was applied in both biofilters. For the biofilter packed with the peat and GTR mixture, attenuation greater than 60% was observed in the maximum outlet concentration when compared to the biofilter packed with peat alone. [Copyright &y& Elsevier]

Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr0] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis–Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor. [Copyright &y& Elsevier]

A protocol was developed with the purpose of assessing the main costs implied in the set-up, operation and maintenance of a waste gas-treating conventional biofilter. The main operating parameters considered in the protocol were the empty bed residence time and the gas flow rate. A wide variety of investment and operating costs were considered. In order to check its reliability, the protocol was applied to a number of scenarios, with biofilter volumes ranging from 8.3 to 4000 m3. Results show that total annualized costs were between 20¿000 and 220¿000 ¿/year and directly dependent, among other factors, on the size of the system. Total investment and operating costs for average-size compost biofilters were around 60¿000 ¿ and 20¿000 ¿/year, respectively, which are concordant with actual costs. Also, a sensitivity analysis was performed in order to assess the relative influence of a series of selected costs. Results prove that operating costs are those that influence the total annual costs to a higher extent. Also, packing material replacement costs contribute significantly to the total yearly costs in biofilters with a volume higher than 800 m3. Among operating costs, the electricity consumption is the main influencing factor in biofilters with a gas flow rate above 50¿000 m3/h, while labor costs are critical at lower gas flow rates. In addition, the use of a variety of packing materials commonly employed in biofiltration was assessed. According to the results obtained, special attention should be paid to the packing material selected, as it is the main parameter influencing the medium replacement costs, and one of the main factors affecting investment costs. [Copyright &y& Elsevier]

Raw biogas generated in the anaerobic digestion (AD) process contains several undesired constituents such as H 2 S, CO 2 , NH 3 , siloxanes and VOCs. These gases affect the direct application of biogas, and are a prime concern in biogas utilization processes. Conventional physico-chemical biogas purification methods are energy-intensive and expensive. To promote sustainable development and environmental friendly technologies, biological biogas purification technologies can be applied. This review describes biological technologies for both upstream and downstream processing in terms of pollutant removal mechanisms and efficiency, bioreactor configurations and different operating conditions. Limitations of the biological approaches and their future scope are also highlighted. A conceptual framework Driver-Pressure-Stress-Impact-Response (DPSIR) and Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis have been applied to analyse the present situation and future scope of biological biogas clean-up technologies. • Recent advancements in biological technologies for biogas purification are overviewed. • Suitable feedstock and process optimization in AD significantly reduce biogas impurities. • Biofiltration systems efficiently remove H 2 S, NH 3 , VMS and VOCs from biogas. • Operational parameters influence both H 2 assisted and photosynthetic biogas upgrading performance. • DPSIR-SWOT analysis identifies a holistic approach for biological biogas purification. [ABSTRACT FROM AUTHOR]

Stormwater biofiltration systems (SBS) are a popular technology for mitigating the negative effects of urbanization on the hydrological processes and water quality in urban areas. However, little is known about SBS's long-term performance in actual field conditions. The findings of a review of the scientific literature on the long-term performance of SBS are presented in this paper. The findings show that only a few studies have investigated the performance of SBS and its change over time, and that the results of laboratory and field experiments differed due to the presence of plants, regular maintenance, and some uncertain environmental factors. Based on the existing knowledge gaps in this field, the main challenges observed was the lack of long-term field data series, and the existing mathematical models are not able to accurately forecast the long-term performance of SBS. This could be owing to the difficulties in monitoring activities, the high costs involved and the unpredictability around the operational timeframe. Future study should concentrate on the implementation of simulation and modeling-based research in pilot and full-scale SBS, and the inclusion of new performance indicators should be considered as a priority. [Display omitted] • The performance of stormwater biofiltration systems (SBS) change with time. • There is a knowledge gap between laboratory and field-scale SBS experiments. • Existing models cannot forecast the long-term performance of SBS accurately. • Challenges and future directions for long-term performance of SBS are provided. [ABSTRACT FROM AUTHOR]

The discharge of high levels of heavy metals into the environment is of concern due to its toxicity to aquatic life and potential human health impacts. Biofiltration systems have been used in urban environments to address nutrient contamination, but there is also evidence that such systems can be effective in reducing heavy metals concentration in stormwater. However, the accumulation pattern of heavy metals and lifespan of such systems, which are important in engineering design, have not been thoroughly explored. This study investigated the accumulation patterns of lead (Pb), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe), which are common in urban runoff, in non-vegetated filtration columns using three different types of filter media, namely sand (S), and mixtures of sand with fly ash (sand-fly ash mix, SF), and with zeolite (sand-zeolite mix, SZ). The columns were assessed in terms of infiltration rate, the mass of heavy metals accumulation at different depths, and formation of crust layer (schmutzdecke) at the surface. The results show that most of the heavy metals accumulated at the top 5–10 cm of the filter media. However, Zn was found adsorbed to a depth of 15 cm in S and SZ columns, while Mn and Fe were present in column S throughout the entire 30 cm depth of the filter media. The presence especially of Zn, Mn, and Fe in the deeper portions of the filter media before the top 5 cm layer reached its maximum adsorption capacity, hints that transport to the deeper layers is not necessarily dependent on saturation of the upper layers for these heavy metals. SF accumulated heavy metals most at the top 5 cm of the filter media layer, and retained twice the mass of heavy metals in the crust layer, compared to S and SZ columns. SF also yielded the lowest value of infiltration rate of 31 mm/h. Considering both metals accumulation and clogging potential of the filter media, the periodic maintenance of these systems is suggested to be approximately between 1.5 and 3 years. • The study is focused on studying laboratory scale tropical biofiltration system. • Three sand-based filter media are considered. • The experiments were conducted under simulated conditions in tropics. • Metals' accumulation pattern in the depth of filter media is studied. • The effective lifespan of filter media is estimated based on potential metal saturation trends in filter media. [ABSTRACT FROM AUTHOR]

This study examined the biodegradation of two pharmaceuticals-acetaminophen, and ibuprofen, and one natural organic surrogate-salicylic acid, by bacteria seeded from backwash water collected from a full-scale biofiltration plant. The degradation was studied in the presence of oxygen. Complete removal of salicylic acid was observed in 27–66 h depending on the seasonality of the collected backwash water, while 90–92% acetaminophen removal was observed in more than 225 h. Ibuprofen demonstrated poor removal efficiencies with only 50% biodegradation after 230 h. Adenosine tri phosphate (ATP) in the reactor was found to be linked with the biodegradation rate. ATP was found to be correlated with oxygen uptake rate (OUR). ATP also had a correlation with each of extracellular polymeric substances (EPS), protein and polysaccharides. These results highlight the potential for increasing the biodegradation rates to achieve enhanced contaminant removal. [Display omitted] • Slower biodegradation was observed in winter compared to other seasons. • Adenosine Tri Phosphate (ATP) can be used as an indication of Oxygen Uptake Rate (OUR). • ATP was well correlated with OUR, Extracellular Polymeric Substances (EPS), protein and polysaccharides. • EPS production and ATP provided insights for better pollutant removal. [ABSTRACT FROM AUTHOR]

The influence of bed material on the odor removal performance of a biofilter was studied. A compost-wood biofilter and a wood biofilter were treated with a gaseous stream contaminated with butyric acid and comparatively evaluated at pilot scale using olfactometric, physico-chemical and microbiological approaches. The variables analyzed in both biofilters were correlated with specific families of their microbiota composition. In addition to a higher nutrients content (nitrogen and phosphorus), the compost-wood biofilter registered maximum values in number of aerobic microorganisms (3.6·108 CFU/g) and in aerobic microbiological activity (≈40 mg O 2 /g VS of cumulative oxygen demand at 20 h). This may explain the higher performance of this biofilter compared to the wood biofilter, withstanding odor loads of up to 1450 ou E /m2·s with odor removal efficiencies close to 100%. The analysis of the microbial community showed that Actinobacteria, particularly the mostly aerobic Microbacteriaceae family, might play an important role in butyric acid degradation and hence reduce odor impact. The multidisciplinary analysis carried out in this work could be a very useful strategy for the optimal design of biofiltration operations. • Compost-wood biofilter showed better odor removal performance than wood biofilter. • Compost-wood packed bed showed the highest aerobic microbial activity. • The phylum Actinobacteria played an important role in butyric acid degradation. • Proteobacteria and Firmicutes were predominant at the end of the process. • Microbial family trends were correlated with the analyzed biofilter variables. [ABSTRACT FROM AUTHOR]

Bioretention is a popular stormwater management strategy that is often utilized in urban environments to combat water quality and hydrological impacts of stormwater. This goal is achieved by selective designing of a system, which consists of suitable vegetation at the top planted on an engineered media with drainage system and possible underdrain at the bottom. Bibliometric analysis on bioretention studies indicates that most of the original research contributions are derived from a few countries and selected research groups. Hence, most of the bioretention systems installed in diverse geographical locations are based on guidelines from climatically different countries, which often lead to operational failures. The current review critically analyzes recent research findings from the bioretention literature, provides the authors' perspectives on the current state of knowledge, highlights the key knowledge gaps in bioretention research, and points out future research directions to make further advances in the field. Specifically, the role and desired features of bioretention components, the importance of fundamental investigations in laboratory, field-based studies and modeling efforts, the real-time process control of bioretention cells, bioretention system design considerations, and life cycle assessment of full-scale bioretention systems are discussed. The importance of local conditions in guiding bioretention designs in difference climates is emphasized. At the end of the review, current technical challenges are identified and recommendations to overcome them are provided. This comprehensive review not only offers fundamental insights into bioretention technology, but also provides novel ideas to combat issues related to urban runoff and achieve sustainable stormwater management. [Display omitted] • Bioretention is used to combat water quality and hydrological impacts of stormwater. • The role of bioretention components such as vegetation and media should be assessed. • Long-term research studies are relatively limited in the bioretention field. • Models aid in simulating the hydrologic and runoff quality aspects of bioretention. [ABSTRACT FROM AUTHOR]

Methane gas is a very effective greenhouse gas and the second-largest contributor to global warming. Biofiltration is an effective technology that uses microorganisms to degrade the pollutant by oxidizing it. In this work, the performance of a biofilter with supporting filter media, consisting of composted sawdust, is evaluated at three different sampling ports. Furthermore, a transient model is developed to predict methane concentration at various heights and times. The developed model is validated with the experimental data and shows good agreement with the experimental data. The highest removal efficiency and elimination capacity was found to be 72% and 0.108 g m−3 h−1 respectively. The effect of parameters such as specific surface area, the reaction rate constant, biofilm thickness and airflow rate were studied on the outlet methane concentration. Under similar conditions, the simulations showed that the removal efficiency of 95% might be achieved for the height of 2 m. [Display omitted] • Biofilter media composed of mainly compost and saw dust for methane degradation. • From experiments, the highest removal efficiency was found to be 72%. • A transient model showed good agreement with the experimental data. • Sensitivity of the parameters on the model were evaluated. • Simulation showed up to 95% removal efficiency for 2 m biofilter height. [ABSTRACT FROM AUTHOR]

Increasing urban growth and lifestyle expectations have led to an increase in public complaints against odours from sewer infrastructure. Gas phase odour abatement in sewer networks, particularly at sewer pumping stations, is most commonly achieved by using biofilters, biotrickling filters or activated carbon filters. When odour complaints are received, a typical response is to close vents, leading to biogenic corrosion in sewers, which increases operating costs. A three-year study of the performance of odour control systems has allowed a comparison of the removal efficiency for the most common treatment systems. An analysis of the treatment system robustness has also been conducted. It has been found that biofilters, biotrickling filters and activated carbon all remove hydrogen sulfide and methyl mercaptan, however residual odours can still lead to complaints particularly during 'spikes' of the inlet, where a particular compound's inlet concentration is high. This analysis has led to an odour abatement technology selection flowchart being proposed for the treatment of sewer network emissions. • Odour abatement systems studied remove hydrogen sulfide and methyl mercaptan well. • Activated carbon has high dimethyl sulfide concentration in exhaust air. • Biological systems have dimethyl sulfide and methyl mercaptan in their exhaust. • Activated carbon systems remove spikes of volatile organic compounds well. • Biological systems remove spiles of volatile organic compounds poorly. [ABSTRACT FROM AUTHOR]

An aboveground pilot-scale biofilter filled with wood chips was tested to treat ammonia emissions from a piggery located in Brittany (France). Two long-term tests ("summer" and "autumn" experiments) were carried out to improve biofilter applications for agriculture. The influence of climatic conditions on biofilter performance was taken into account. During summer 2012, the biofilter was operated for 74 days at different empty bed residence times (EBRTs) from 6 to 15 s. Inlet NH3 concentrations were relatively constant (around 15 mg m(-3)). Significant NH3 reductions were achieved at EBRT = 12 s (removal efficiencies, RE, ranged between 90 and 100% for loading rates, LR, of around 4 g m(-3) h(-1)). At a lower EBRT (6 s), RE dropped to roughly 30-50%. This was due to the dramatic increase in the loading rate (LR up to 12 g m(-3) h(-1)) but the results showed that the change in atmospheric conditions (temperature and relative humidity) also had a significant influence on biofilter performance. It was evidenced that the use of a humidifier upstream of the biofilter must be taken into account for large-scale biofilter design, but only for specific conditions (the spraying of the biofilter having to be carried out exceptionally). During autumn 2012, the biofilter was operated for 116 days at EBRT = 12 s. RE were around 80% for LR of around 3 g m(-3) h(-1). In such autumnal atmospheric conditions, a demister system should be installed upstream of the biofilter in order to avoid water accumulation in the bed material. Although biofiltration was suitable for NH3 treatment of piggery air, the need to control accurately the medium moisture content implies that biofilters would not be easily managed by a pig farmer., (Copyright © 2014 Elsevier Ltd. All rights reserved.)