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Intensive livestock production is a source of water, soil, and air contamination. The first aspect that negatively affects the quality of life of residents in the vicinity of piggeries is malodorous aerosols, which are not only responsible for discomfort but can be an etiological factor in the development of various diseases during prolonged exposure. One of the proven and efficient ways to counteract odor emissions is the usage of air biofiltration. The purpose of this study was to qualitatively analyze the bacterial community colonizing the biofilm of a biofilter operating at an industrial piggery in Switzerland. The study material consisted of biofilm and leachate water samples. The microbiological analysis consisted of DNA isolation, amplification of the bacterial 16S rRNA gene fragment (V3-V4), preparation of a library for high-throughput sequencing, high-throughput NGS sequencing, filtering of the obtained sequencing reads, and evaluation of the species composition in the studied samples. The investigation revealed the presence of the following bacterial genera: Pseudochelatococcus, Methyloversatilis, Flexilinea, Deviosia, Chryseobacterium, Kribbia, Leadbetterella, Corynebacterium, Flavobacterium, Xantobacter, Tessaracoccus, Staphylococcus, Thiobacillus, Enhydrobacter, Proteiniclasticum, and Giesbergeria. Analysis of the microbial composition of biofilters provides the opportunity to improve the biofiltration process., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this study, the first field-scale application of a bio-foam spray (a mixture of microbes and a surfactant) for the reduction of ammonia emitted from manure was investigated on six field swine manure piles. The objective of this study was to evaluate the odor suppression ability of bio-foam and odor degradation ability of odor-degrading bacteria loaded in the surfactant foam after covering manure piles. The size of field manure piles tested in this study ranged from 27 to 300 m 3 . Bio-foam spraying completely suppressed the release of the major odor component, ammonia (NH 3 ), and odor-degrading bacteria in the bio-foam aided in the degradation of NH 3 in field swine manure piles. On average, 85.7-100% of NH 3 was reduced after 24-48 h of serial bio-foam spray application on the swine manure surface, while the control showed 25-42%. The reduction efficiency of NH 3 by the bio-foam application was affected by the bio-foam spray frequency, ambient temperature, ventilation of the field facility, and upward airflow to the pile. The reduction in surface emission of NH 3 also reduced the ambient air concentration of NH 3 at the gate of the compost facility. NH 3 gas measurements at a depth of 50 cm indicated that NH 3 -degrading bacteria infiltrated the manure and were active in biodegradation. Finally, the measured effectiveness of bio-foam application as shown by this study indicates that sprinkling bio-foam via specialized rotating sprinklers may be an efficient and uniform method for the delivery of bio-foam to wide field areas within composting facilities., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Seung-Woo Jeong reports financial support was provided by Korea Smart Farm R&D Foundation. Seung-Woo Jeong has patent ODOR CONTROL DEVICE AND METHOD UTILIZING ODOR CONTROL FOAM licensed to Kunsan National University., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Aldehyde-functionalized cellulose (AFC) was prepared by oxidizing cellulose with sodium metaperiodate. The reaction was characterized by Schiff's test, FT-IR, and UV-vis study. AFC was evaluated as a reactive sorbent for controlling polyamine-based odor from chronic wounds, and its performance was compared with charcoal, one of the most widely utilized odor-control sorbents through physisorption. Cadaverine was used as the model odor molecule. A liquid chromatography/mass spectrometry (LC/MS) method was established to quantify the compound. AFC was found to rapidly react with cadaverine through the Schiff-base reaction, which was confirmed by FT-IR, visual observation, CHN elemental analysis, and the ninhydrin test. The sorption and desorption behaviors of cadaverine onto AFC were quantified. With clinic-relevant cadaverine concentrations, AFC demonstrated much better sorption performance than charcoal. At even higher cadaverine concentrations charcoal showed higher sorption capacity, probably due to its high surface area. On the other hand, in desorption studies, AFC retained much more of the sorbed cadaverine than charcoal. When AFC and charcoal were combined, the pair demonstrated excellent sorption and desorption behaviors. The XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay confirmed that AFC has very good in vitro biocompatibility. These results suggest that AFC-based reactive sorption can be a new strategy to control odors associated with chronic wounds for improved healthcare., 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 © 2023 Elsevier Ltd. All rights reserved.)

To investigate the influences of sulfide oxidizing bacteria on H 2 S odor control in sewage sludge composting, a facultative chemolithotroph strain was isolated and identified as Cohnella thermotolerans LYH-2. Strain LYH-2 decreased the initially added sulfide by 94.6% when glucose and NH 4 Cl were used as the optimal energy substrates. The biotransformation of sulfide substrates followed first-order reaction kinetics, and the highest degradation rate constant (0.0537 h -1 ) and bacterial dry weight (0.745 g/L) were obtained at 300 mg/L of initial sulfide. The C. thermotolerans strain was inoculated as the bacterial agent into the sewage sludge and rice husk composting in forced ventilation composting reactors for 25 d; the bacterial inoculation prolonged the thermophilic period by 2 d, decreased 35.4% of H 2 S odor emission, and accelerated the composting process compared to the control group. The results demonstrated that C. thermotolerans inoculants effectively controlled H 2 S emission and promoted maturity in sewage sludge composting., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objectives: Malodors stemming from soiled cat litter are a major frustration for cat owners, despite the widespread use of absorbent litters with claims of odor control. Technologies for effective litter odor control have not been rigorously evaluated. Here, we report on the effectiveness of a novel litter formulation of 1-monochlorodimethylhydantoin (MCDMH)-modified clinoptilolite zeolite (MCDMH-Z) to control the odors of 3-mercapto-3-methylbutanol (3M3MB) and ammonia, the principal products generated by the enzymatic breakdown of felinine and urea, respectively., Methods: The efficacy of MCDMH-Z for the odor control of 3M3MB was determined by solid-phase microextraction and gas chromatography mass spectrometry analysis, colorimetric analysis and a sensory panel. Enzyme inhibition was monitored by a colorimetric coupled assay for ammonia. The antimicrobial properties were measured by a reduction in colony-forming units (CFUs)., Results: 3M3MB proved highly susceptible to modification by MCDMH-Z granules. Headspace above litter exposed to MCDMH-Z showed no detectable 3M3MB; levels >59 ng were detected in commercially available products. Urease activity decreased by >97% after incubation with MCDMH-Z to 0.14 mg/ml. Cat litter F showed comparable inhibition (0.13 mg/ml); others showed less inhibition, producing up to 4.8 mg/ml of ammonia. MCDMH-Z reduced the CFUs of Proteus vulgaris by six log reduction values in 30 mins; in the same amount of time, no reduction was seen with commercial products tested. The odor control capability of the MCDMH-Z granules was further supported by a sensory panel scoring 3M3MB-spiked litters., Conclusions and Relevance: Samples of commercially available litter products showed an effect on malodor, or inhibition of urease, or contained antimicrobial activity; no samples were capable of accomplishing these concurrently. In contrast, MCDMH-Z granules were effective in all three test categories. Control of felinine-derived odors, in particular, has the potential to improve cat owner satisfaction, and may beneficially affect cat behaviors provoked by pheromonally active sulfurous metabolites deposited in the litter.

Landfilling is the most common option for solid waste disposal worldwide. Landfill sites can emit significant quantities of greenhouse gases (GHGs; e.g., methane, carbon dioxide, and nitrous oxide) and release toxic and odorous compounds (e.g., sulfides). Due to the complex composition and characteristics of landfill surface gas emissions, the quantification and control of landfill emissions are challenging. This review attempts to comprehensively understand landfill emission quantification and control options by primarily focusing on GHGs and odor compounds. Landfill emission quantification was highlighted by combining different emissions monitoring approaches to improve the quality of landfill emission data. Also, landfill emission control requires a specific approach that targets emission compounds or a systematic approach that reduces overall emissions by combining different control methods since the diverse factors dominate the emissions of various compounds and their transformation. This integrated knowledge of emission quantification and control options for GHGs and odor compounds is beneficial for establishing field monitoring campaigns and incorporating mitigation strategies to quantify and control multiple landfill emissions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The objective of this study was to develop a machine learning (ML) application to determine the optimal dosage of sodium hypochlorite (NaOCl) to curtail corrosion and odor by H 2 S in the headworks of a water resource recovery facility (WRRF) without overly consuming volatile fatty acids (VFAs) that are essential for the enhanced biological phosphorus removal. Given the highly diverse datasets available, three subproblems were formulated, and three cascaded ML modules were developed accordingly. The final ML models, chosen based on performance, were able to predict various targeted variables. More specifically, in Module 1, a recurrent neural network (RNN) was designed to predict wastewater characteristics. In Module 2, a random forest (RF) classifier and a support vector machine (SVM) classifier were built with the information from Module 1 along with other datasets to predict the concentrations of VFAs and H 2 S, respectively. Finally, in Module 3, with the information obtained from Module 2, another RF classifier was developed to predict NaOCl dosage to reduce H 2 S but keeping VFAs within the target range. These efforts are relevant and informative for WRRFs that are considering developing Intelligent Water Systems to predict the wastewater characteristics to make operational improvements. PRACTITIONER POINTS: A recurrent neural network (RNN) using long short-term memory (LSTM) successfully predicted influent wastewater parameters. A support vector machine classifier predicted hydrogen sulfide (H 2 S) with 97.6% accuracy. The concentration of VFAs, an important parameter in EBPR, was predicted using a random forest classifier with 93.4% accuracy. The optimal NaOCl dosage for H 2 S control can be predicted with a random forest classifier using H 2 S, VFAs, and flow., (© 2021 Water Environment Federation.)

In this study an innovative sensing network consisting of eight photoionization detectors, meteorological sensors, a video camera and a telephonic system able to systematize the population complaints was developed for the monitoring of odor emissions. The development of monitoring approaches with high temporal and spatial resolution and actively involving citizens, is strategic in areas where relevant and also short-term emissive events frequently occur and the conventional approaches fail due to the high variability of fugitive emissions. Moreover, even if unpleasant odors are not necessarily direct triggers of health effects, they could be associated with the release of other harmful compounds. Monitoring approaches also involving citizens are thus strategic tools because odors annoyance perceived by population may be a potential health risk warning. Therefore, the developed sensing network was set up in Val d'Agri (Basilicata, Italy) where a petroleum pre-treatment plant (COVA) rises in a rural and inhabited area. The data collected during the monitoring campaign from the 16th February to the 30th July 2017, showed Total Volatile Organic Compounds (TVOCs) concentrations decreasing moving away from the plant and up to five times higher than levels registered in the closest municipality (Viggiano). Moreover, recurrent short-term critical events characterized by concentration values far above the average of the period and with maximum values ranging from 0.92 to 1.89 ppm, were registered in correspondence with high levels of benzene (up to 23.9 μg/m 3 ) and anemometric conditions able to transport pollutants from COVA to each receptor site. The spatial and temporal distribution of TVOC concentrations proved to be affected by the distance from COVA, wind direction and industrial activities verified using video reportage and citizen claims. Therefore, the developed approach has proven to be a useful tool to credit people's perception of odors and also to quantify citizen exposure to VOCs during short-term events., Competing Interests: Declaration of competing interest The authors declare they have no conflict of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Open anaerobic lagoons are widely used for liquid manure storage and treatment, with excess greenhouse gas (GHG) and odor emissions. In this study, liquid manure was valorized through hybrid nitrogen and phosphorous recovery as value-added products using an airlift reactor. Also, the organic load of liquid manure was reduced before discharging into anaerobic lagoons, which simultaneously mitigated GHG emissions. The results showed that 14.5% of total nitrogen (TN) was recovered as ammonium sulfate, while 38.8% of TN and 79.3% of total phosphorus (TP) were recovered as phosphorus-rich sludge. After the pre-treatment in the reactor, the odor could be controlled effectively due to a 94.2% decrease in total VFAs. In addition, 59.0% of COD was removed, which decreased the theoretical modeled GHG emissions by 51.7% compared to the traditional direct discharging. The application is promising for upgrading anaerobic lagoons of liquid manure., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Wastewater collection systems can be a source of odors that lead to complaints from plant workers, the public, and nearby property owners. The primary source of odors released from such systems is the presence of hydrogen sulfide (H 2 S) gas at high concentrations. This study was conducted in the main pumping station in Kuwait with a capacity of 570,000 m 3 /day to assess H 2 S gas emission, determine factors affecting H 2 S generation, and evaluate the effectiveness of the odor control system comprising stripping using sodium hydroxide and carbon adsorption. Yearly data on wastewater flow rate, temperature, pH, BOD 5 , and H 2 S were obtained from plant records over the years 2013-2015, as well as monthly data measurements were conducted during May to December 2016, and weekly data were collected during a plant monitoring program in March and April 2017. Statistical analysis showed seasonal, daily, and hourly variations in H 2 S concentrations, with higher values reported in summer, cyclic hourly patterns obtained daily, and peak H 2 S level of 10 ppm recorded at 7 pm and 40 °C. The ANOVA test indicated that the wastewater temperature, flow rate, and BOD 5 were statistically significant factors affecting the formation of hydrogen sulfide gas because of the strong correlation and a p value less than the significance level of 0.05. It was evident that the wastewater temperature is the most influential factor. A model was developed to predict H 2 S emission. The odor control system used in the station proved to be highly effective and able to remove up to 99.9% of H 2 S released from wastewater.

Peracetic acid (PAA) is an environmentally friendly disinfectant and oxidizer used in several water and wastewater treatment applications. In the present study, PAA was utilized for the conditioning of municipal wastewater sludge before thickening and dewatering. It was shown that PAA can effectively prevent odor formation (i.e., H 2 S and NH 3 ) and provide hygienization (using E. coli and Salmonella as indicators). Phytotoxicity can be prevented by controlling the amount PAA-conditioned sludge that is mixed in the soil to be fertilized. The required PAA dose for hygienization was relatively high (480 mg 100% PAA perL sludge) but the results indicated that other sludge stabilization processes are not necessarily required. Therefore, the proposed process involving PAA could be feasible in cases where limited land area is available for sludge processing or quick conditioning of sludge is required., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Animals experience complex odorant stimuli that vary widely in composition, intensity and temporal properties. However, stimuli used to study olfaction in the laboratory are much simpler. This mismatch arises from the challenges in measuring and controlling them precisely and accurately. Even simple pulses can have diverse kinetics that depend on their molecular identity. Here, we introduce a model that describes how stimulus kinetics depend on the molecular identity of the odorant and the geometry of the delivery system. We describe methods to deliver dynamic odorant stimuli of several types, including broadly distributed stimuli that reproduce some of the statistics of naturalistic plumes, in a reproducible and precise manner. Finally, we introduce a method to calibrate a photo-ionization detector to any odorant it can detect, using no additional components. Our approaches are affordable and flexible and can be used to advance our understanding of how olfactory neurons encode real-world odor signals., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

The Kennebunk Sewer District collection system experienced H 2 S-induced corrosion downstream of terminus manholes for the Wells Road and Boothby Road pumping stations. An automated odor control system using sodium hydroxide (NaOH) was developed to mitigate further corrosion. System performance was quantified by recording the [H 2 S] in the terminus manholes before and after NaOH treatment. Preliminary evaluation at the Wells Road facility demonstrated significant (p < 0.001) reduction in the average [H 2 S] between the treatment (4.8 ± 0.3 ppm) and control (67 ± 1.5 ppm). Permanent systems installed at both facilities in 2017 yielded similar positive results. The average [H 2 S] in the Wells and Boothby Road terminus manholes reduced from 89.4 ± 1.0 to 8.0 ± 0.1 ppm and from 7.9 ± 0.2 to 0.82 ± 0.06 ppm, respectively. This work demonstrates the ability of the NaOH system presented here to minimize emission of corrosive H 2 S gas in small collection systems. PRACTITIONER POINTS: Biologically-produced hydrogen sulfide (H 2 S) gas corrodes sewer collection system components and results in premature asset failure. Maintaining wastewater pH above 8.5 by injecting sodium hydroxide (NaOH) minimizes H 2 S emission by shifting the molar distribution of sulfur species and partially inhibiting the anaerobes that produce H 2 S. The practical application of this approach may be limited to small wastewater collection systems., (© 2019 Water Environment Federation.)

To evaluate and mitigate odor formation and emission in sewers, several sewer models have been developed. Although these models can predict the immediate effects of chemical dosing on odor emission control, the long-term effects due to the variation of biofilm dynamics were generally underestimated. Therefore, in this study, we developed a dynamic model to simulate sewer processes initiated by sewer. The dynamic sewer process model was calibrated and validated with experimental data collected from two pressurized mains in actual operation in Hong Kong (TCS and MH17). The results show that the dynamic model can satisfactorily predict the dynamic concentrations of sulfide and ammonium (with measured and simulated values differing by less than 6%). The model was employed to systematically assess the long-term effects of three commonly used control strategies, i.e. addition of nitrate salts, addition of biocides, and hydraulic flushing, on sulfide formation and to predict sewer biofilm compositions. The modeling results reveal that the effect of odor mitigation measures on sulfide control varied with time due to the re-establishment of sulfate-reducing bacteria community in sewer biofilm. The long-term effect of nitrate addition would be diminishing because of the growth of heterotrophic denitrifies in sewer biofilms (increased from 7% to 21% after 55 days of nitrate addition) to consumed more nitrate. After dosing biocide or hydraulic flushing in sewers, sulfide production would rebound in the following several days due to the regrowth of sewer biofilms, indicating that the optimization of odor mitigation strategies is necessary. This study highlights that the biofilm dynamics shall be involved in the simulation of odor formation and emission, to evaluate and optimize the long-term effects of mitigation measures., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

One of the most notable Indoor Air Quality problems is odor emission. This study investigated the potential contribution of skin squames to the production of ammonia (NH 3 ) and volatile organic acids (VFAs) by 7 bacteria isolated from air-cooling (AC) units with complaints of urine and body odors. Our previous study showed that keratinolytic activity is higher in AC units with odor complaints than those without. In the offices where these units are located, the most likely source of keratins is from human skin squames. Most bacteria can produce NH 3 and VFAs in the skin squame culture. Some correlations between the levels of NH 3 , NH4+, VFAs, and keratinolytic activity were found. The odor production pathway with skin squames was proposed. Staphylococcus haemolyticus was abundant in the AC units with odor problems and had a high level of keratinolytic activity in addition to odor production. For long-term odor control, it is important to reduce the level of skin squames entering the AC units., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Production and build-up of sulfide in wastewater systems, especially downstream of rising mains, may lead to severe odour nuisance, toxic environments and high risk of corrosion. Due to increased population migration towards cities and lower area availability for treatment facilities, rising mains for the conveyance of wastewater sludge are becoming more frequent, and research on sulfide build-up in such cases is needed. In this paper the findings of the work carried out in a full scale wastewater sludge rising main, operated during different seasons and under distinct conditions are presented (comprising both the start-up and normal operation stages of the facility). Results showed a sulfide build-up rate of 3.24 g S -2 m -2 d -1 in the summer and of 2.30 g S -2 m -2 d -1 during the winter. The ratio of sulfate reduction to sulfide production (SO 4 -2 /S -2 ) was of roughly 3 to 1, as expected. Furthermore, obtained results allowed adjusting a second order polynomial empirical equation for the forecasting of sulfide build-up within the sludge rising main. The obtained equation for sludge significantly differs from existing equations obtained for wastewater. Moreover, this work also allowed obtaining new insight into the positive influence of biofilm and hydraulic retention time in the biological sulfide generation, as well as into its variation along the length of the rising main., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Monitoring and control of odorous compound emissions have been enforced by the Korean government since 2005. One of the point sources for these emissions was from food waste composting facilities. In this study, a pilot-scale scrubber installed in a composting facility was evaluated for its performance in the removal of malodorous compounds. The exhaust stream contained ammonia and methylamine as the major odorants detected by the threshold odor test and various instrumental techniques (GC-FID, FPD, MS and HPLC/UV). For the scrubber operation, the column was randomly packed with polypropylene Hi-Rex 200, while aqueous sulfuric acid was selected as the scrubbing solution. To achieve 95% removal, the scrubber must be operated by using H 2 SO 4 solution with pH at < 6.5, liquid to gas ratio > 4.5, gas loading rate < 1750 m 3 /m 3 -hr and contact time < 0.94 s. The scrubber performance was further evaluated by determining the mass transfer coefficients and then monitoring for 355 days of operation. The pilot-scale scrubber maintained > 95% ammonia and methylamine removal efficiencies despite the fluctuations in the inlet (from composting facility exhaust stream) concentration. The optimum operating conditions and scrubber performance indicators determined in this study provides a basis for the design of a plant-scale scrubber for treatment of composting facility gas emissions.

Nitrate-driven sulfide oxidation has been proved a cost-effective way to control sediments odor which has long been a universal problem for urban rivers in south China areas. In this work, sediments treatment experiments under a dynamic variation of temperature from 5 °C to 35 °C with 3% of calcium nitrate added were conducted to reveal the influence of temperature variation on this process. The results showed that microbial community was remarkably restructured by temperature variation. Pseudomonas (15.56-29.31%), Sulfurimonas (26.81%) and Thiobacillus (37.99%) were dominant genus at temperature of ≤15 °C, 25 °C and 35 °C, respectively. It seemed that species enrichment occurring at different temperature gradient resulted in the distinct variation of microbial community structure and diversity. Moreover, nitrate-driven sulfide and ferrous oxidation were proportionally promoted only when temperature increased above 15 °C. The dominant bacteria at high temperature stage were those genus that closely related to autotrophic nitrate-driven sulfide and ferrous oxidizing bacteria (e.g.Thiobacillus, Sulfurimonas and Thermomonas), revealing that promotion of sulfide/ferrous oxidation could be attributed to the change of dominant bacteria determined by temperature variation. Thus, a higher treatment efficiency by calcium nitrate addition for odor control would be achieved in summer than any other seasons in south China areas., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We examined the effects of ultrasound (U), Fenton oxidation (F), and ultrasound coupled with Fenton oxidation (U + F) pre-treatments (prior to anaerobic digestion) on the elimination of odorous compounds. The results demonstrated that U promoted odor release, while the coupled treatment and F alone decreased odor release. After 20-min treatments, the concentration of dissolved sulfide (S(2-)) under the coupled U + F treatment declined from 17.4 mg/L to 8.1 mg/L, decreasing by more than 50% and 34%, respectively, for U alone and F alone. In addition, the dissolved sulfate (SO4(2-)) concentration under couple U + F treatment significantly increased in sewage sludge from 200 mg/L to 390.6 mg/L, up 95.3% compared to U alone and 5% compared to F alone. This illustrates the oxidation process from S(2-) to SO4(2-). Throughout experimentation, SO4(2-) was odorless and stable, highlighting the mechanism of odor control. Thus, combining U and F into a single coupled treatment proved to be a better alternative pretreatment for controlling sludge odor compared to the U and F alone and can effectively decrease potential odor release., (Copyright © 2016. Published by Elsevier Ltd.)

Anaerobic digestion (AD) is an effective way to recover energy and nutrients from organic waste; however, several issues including the solubilization of bound nutrients and the production of corrosive, highly odorous and toxic volatile sulfur compounds (VSCs) in AD biogas can limit its wider adoption. This study explored the effects of adding two different doses of ferric chloride, aluminum sulfate and magnesium hydroxide directly to the feed of complete mix semi-continuously fed mesophilic ADs on eight of the most odorous VSCs in AD biogas at three different organic loading rates (OLR). Ferric chloride was shown to be extremely effective in reducing VSCs by up to 87%, aluminum sulfate had the opposite effect and increased VSC levels by up to 920%, while magnesium hydroxide was not shown to have any significant impact. Ferric chloride, aluminum sulfate and magnesium hydroxide were effective in reducing the concentration of orthophosphate in AD effluent although both levels of alum addition caused digester failure at elevated OLRs. Extensive foaming was observed within the magnesium hydroxide dosed digesters, particularly at higher doses and high OLRs. Certain metal salt additions may be a valuable tool in overcoming barriers to AD and to meet regulatory targets., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Traditional physical/chemical end-of-the-pipe technologies for odor abatement are relatively expensive and present high environmental impacts. On the other hand, biotechnologies have recently emerged as cost-effective and environmentally friendly alternatives but are still limited by their investment costs and land requirements. A more desirable approach to odor control is the prevention of odorant formation before being released to the atmosphere, but limited information is available beyond good design and operational practices of the wastewater treatment process. The present paper reviews two widely applicable and economic alternatives for odor control, Activated Sludge Recycling (ASR) and Oxidized Ammonium Recycling (OAR), by discussing their fundamentals, key operating parameters and experience from the available pilot and field studies. Both technologies present high application potential using readily available plant by-products with a minimum plant upgrading, and low investment and operating costs, contributing to the sustainability and economic efficiency of odor control at wastewater treatment facilities., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Biological treatment of odorous gas is an alternative to conventional physicochemical processes. A newly-isolated and identified Brevibacillus borstelensis GIGAN1 was seeded on active carbon (AC) and ceramic particle (CP) in a twin biotrickling filter (BTF) to comparatively probe the removal performance of gaseous thioanisole, respectively. At empty bed residence time (EBRT) of 66 s, 100% of thioanisole (⩽ 3mg L(-1)) could be removed on AC; while 100% of thioanisole could only be achieved for ⩽ 1.2 mg L(-1) on CP. Further increase thioanisole concentration to 3 mg L(-1), higher elimination capacity was obtained on AC (162.51 g m(-3)h(-1)) than CP (139.93 g m(-3)h(-1)). Further, longer EBRT was also beneficial to thioanisole removal. Additionally, the biomass accumulation did not lead to the column clogging. The bio-deodorization mechanism of thioanisloe were also tentatively proposed. Overall, an unprecedented performance could be achieved by the novel GIGAN1 in BTF for thioanisole biodegradation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Intensified nutrient removal and odor control in a novel electrolysis-integrated tidal flow constructed wetland were evaluated. The average removal efficiencies of COD and NH4(+)-N were above 85% and 80% in the two experimental wetlands at influent COD concentration of 300 mg/L and ammonium nitrogen concentration of 60 mg/L regardless of electrolysis integration. Effluent nitrate concentration decreased from 2.5mg/L to 0.5mg/L with the reduction in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2). This result reveals the important role of current intensity in nitrogen transformation. Owing to the ferrous and ferric iron coagulant formed through the electro-dissolution of the iron anode, electrolysis integration not only exerted a positive effect on phosphorus removal but also effectively inhibited sulfide accumulation for odor control. Although electrolysis operation enhanced nutrient removal and promoted the emission of CH4, no significant difference was observed in the microbial communities and abundance of the two experimental wetlands., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study on the detailed characteristics of a laminated film-electrode and a laminated film-electrode packed-bed nonthermal plasma reactor, which are types of dielectric barrier discharge (DBD) reactor used for odor control. These plasma reactors can be potentially used for the decomposition of volatile organic compounds (VOCs) and reduction of NO(x). The reactor is driven by a low-cost 60-Hz neon transformer. Removal efficiencies under various experimental conditions are studied. The complete decomposition of the main odor component, namely, NH(3), is achieved in a dry environment. The retention times are investigated for the complete removal of NH(3) in the case of the film-electrode plasma reactor and the film-electrode packed-bed plasma reactor. The removal efficiency of the former reactor is lower than that of the latter reactor. Mixing another odor component such as CH(3)CHO in the gas stream has no significant effect on NH(3) removal efficiency.