Performance study of biofilter developed to treat H2S from wastewater odour

Simultaneous biofiltration of H2S, NH3, and toluene using compost made of chicken manure and sugarcane bagasse as packing material

Offensive odors from wastewater treatment plants (WWTP) are caused by volatile inorganic compounds such as hydrogen sulfide and ammonia and volatile organic compounds (VOCs), such as toluene. To treat these pollutants, biofiltration is an effective and economical technology used worldwide due to its low investment and environmental impact. In this work, a laboratory-scale prototype biofilter unit for the simultaneous biofiltration of hydrogen sulfide, ammonia, and toluene was evaluated by simulating the emission concentrations of the El Salitre WWTP Bogotá, Colombia, using a compost of chicken manure and sugarcane bagasse as packing material for the biofilter. The prototype biofilter unit was set to an operation flow rate of 0.089 m3/h, an empty bed residence time (EBRT) of 60 s, and a volume of 0.007 m3 (6.6 L). The maximum removal efficiency were 96.9 ± 1.2% for H2S, at a loading rate of 4.7 g/m3 h and a concentration of 79.1 mg/m3, 68 ± 2% for NH3, at a loading rate of 1.2 g/m3 h and a concentration of 2.0 mg/m3, and 71.5 ± 4.0% for toluene, at a loading rate of 1.32 g/m3 h and a concentration of 2.3 mg/m3. The removal efficiency of the three compounds decreased when the toluene concentration was increased above 40 mg/m3. However, a recovery of the system was observed after reducing the toluene concentration and after 7 days of inactivity, indicating an inhibitory effect of toluene. These results demonstrate the potential use of the prototype biofilter unit for odor treatment in a WWTP.

Anaerobic digestion biogas upgrading using a two-stage membrane system under pilot-scale conditions

In the present work, the construction, and operation of a pilot-scale biogas upgrading system is presented, employing 2 commercial polyimide (PI) membranes. The Upgrading system treats biogas produced via anaerobic digestion of the sludge, produced from the treatment of municipal wastewater in the facilities of Thessaloniki's Wastewater Treatment Plant. The goal of the separation unit is the production of high purity biomethane (>95%) for potential reuse in terms of energy. The fabrication of the pilot scale system includes the scale up of a laboratory setup separating CO2 from binary CH4-CO2 gas mixture. After the stability tests of the process, for the operation of 5 months (February to June 2023) the purity and recovery of CH4 in the final gas product. The experimental results showed an average recovery of CH4 of 95.7% for an average 55% feed composition, whereas the average purity in the final product was equal to 82.4%. The purity results were lower because of the N2 presence in the product stream (average 17.5%). After normalization with the help of the lab-scale binary results, the expected results assuming N2 absence would be 99.8% CH4 purity and 67% CH4 recovery. Finally, 3 different membrane configurations are compared in terms of their energy production, concluding to the efficiency of 2-stage configuration with recycling stream for the optimal combination of theoretical stage cut fractions.

Air Pollutants Removal Using Biofiltration Technique: A Challenge at the Frontiers of Sustainable Environment

Air pollution is a central problem faced by industries during the production process. The control of this pollution is essential for the environment and living organisms as it creates harmful effects. Biofiltration is a current pollution management strategy that concerns removing odor, volatile organic compounds (VOCs), and other pollutants from the air. Recently, this approach has earned vogue globally due to its low-cost and straightforward technique, effortless function, high reduction efficacy, less energy necessity, and residual consequences not needing additional remedy. There is a critical requirement to consider sustainable machinery to decrease the pollutants arising within air and water sources. For managing these different kinds of pollutant reductions, biofiltration techniques have been utilized. The contaminants are adsorbed upon the medium exterior and are metabolized to benign outcomes through immobilized microbes. Biofiltration-based designs have appeared advantageous in terminating dangerous pollutants from wastewater or contaminated air in recent years. Biofiltration uses the possibilities of microbial approaches (bacteria and fungi) to lessen the broad range of compounds and VOCs. In this review, we have discussed a general introduction based on biofiltration and the classification of air pollutants based on different sources. The history of biofiltration and other mechanisms used in biofiltration techniques have been discussed. Further, the crucial factors of biofilters that affect the performance of biofiltration techniques have been discussed in detail. Finally, we concluded the topic with current challenges and future prospects.

Complete genome sequence of Pseudomonas stutzeri S116 owning bifunctional catalysis provides insights into affecting performance of microbial fuel cells

Background

Pseudomonas stutzeri S116 is a sulfur-oxidizing bacteria isolated from marine sludge. It exhibited excellent electricity generation as bioanode and biocathode applied in microbial fuel cells (MFCs). Complete genome sequencing of P. stutzeri and cyclic voltammetry method were performed to reveal its mechanism in microbial fuel cells system.

Results

This study indicated that the MFCs generated a maximum output voltage of 254.2 mV and 226.0 mV, and maximum power density of 765 mW/m² and 656.6 mW/m² respectively. Complete genome sequencing of P. stutzeri S116 was performed to indicate that most function genes showed high similarities with P. stutzeri, and its primary annotations were associated with energy production and conversion (6.84%), amino acid transport and metabolism (6.82%) and inorganic ion transport and metabolism (6.77%). Homology of 36 genes involved in oxidative phosphorylation was detected, which suggests the strain S116 possesses an integrated electron transport chain. Additionally, many genes encoding pilus-assembly proteins and redox mediators (riboflavin and phenazine) were detected in the databases. Thiosulfate oxidization and dissimilatory nitrate reduction were annotated in the sulfur metabolism pathway and nitrogen metabolism pathway, respectively. Gene function analysis and cyclic voltammetry indicated that P. stutzeri probably possesses cellular machinery such as cytochrome c and redox mediators and can perform extracellular electron transfer and produce electricity in MFCs.

Conclusion

The redox mediators secreted by P. stutzeri S116 were probably responsible for performance of MFCs. The critical genes and metabolic pathways involved in thiosulfate oxide and nitrate reduction were detected, which indicated that the strain can treat wastewater containing sulfide and nitrite efficiently.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02552-8.

Biological elimination of a high concentration of hydrogen sulfide from landfill biogas

Hydrogen sulfide (H₂S) is one of the main contaminants found in biogas, which is one of the end products of the anaerobic biodegradation of proteins and other sulfur-containing compounds in solid waste. The presence of H₂S is one of the factors limiting the valorization of biogas. To valorize biogas, H₂S must be removed. This study evaluated the performance of a pilot-scale biotrickling filter system on H₂S removal from landfill biogas. The biotrickling filter system, which was packed with stainless-steel pall rings and inoculated with an H₂S-oxidizing consortium, was designed to process 1 SCFM of biogas, which corresponds to an empty bed residence time (EBRT) of 3.9 min and was used to determine the removal efficiency of a high concentration of hydrogen sulfide from landfill biogas. The biofiltration system consisted of two biotrickling filters connected in series. Results indicate that the biofiltration system reduced H₂S concentration by 94 to 98% without reducing the methane concentration in the outlet biogas. The inlet concentration of hydrogen sulfide, supplied to the two-phase bioreactor, was in the range of 900 to 1500 ppmv, and the air flow rate was 0.1 CFM. The EBRTs of the two biotrickling filters were 3.9 and 0.9 min, respectively. Approximately 50 ± 15.7 ppmv of H₂S gas was detected in the outlet gas. The maximum elimination capacity of the biotrickling filter system was found to be 24 g H₂S·m^-3·h^-1, and the removal efficiency was 94 ± 4.4%. During the biological process, the performance of the biotrickling filter was not affected when the pH of the recirculated liquid decreased to 2-3. The overall performance of the biotrickling filter system was described using a modified Michaelis-Menten equation, and the K_s and V_m values for the biosystem were 34.7 ppmv and 20 g H₂S·m^-3·h^-1, respectively.

Full-Scale Odor Abatement Technologies in Wastewater Treatment Plants (WWTPs): A Review

The release of air pollutants from the operation of wastewater treatment plants (WWTPs) is often a cause of odor annoyance for the people living in the surrounding area. Odors have been indeed recently classified as atmospheric pollutants and are the main cause of complaints to local authorities. In this context, the implementation of effective treatment solutions is of key importance for urban water cycle management. This work presents a critical review of the state of the art of odor treatment technologies (OTTs) applied in full-scale WWTPs to address this issue. An overview of these technologies is given by discussing their strengths and weaknesses. A sensitivity analysis is presented, by considering land requirements, operational parameters and efficiencies, based on data of full-scale applications. The investment and operating costs have been reviewed with reference to the different OTTs. Biofilters and biotrickling filters represent the two most applied technologies for odor abatement at full-scale plants, due to lower costs and high removal efficiencies. An analysis of the odors emitted by the different wastewater treatment units is reported, with the aim of identifying the principal odor sources. Innovative and sustainable technologies are also presented and discussed, evaluating their potential for full-scale applicability.

Development of a feedback control system for a differential biofilter degrading toluene contaminated air

In this study, a proportional - integral feedback control system was implemented on a lab-scale differential biofilter to control the gas phase toluene concentration in the soil bed through online manipulation of the inlet toluene concentration. The feedback control system was based on a cascade controller that manipulated the setpoint of an air bath diffusion system to manipulate the inlet toluene concentration. The controller performed well for toluene concentrations in the reactor of 10 - 300 ppm for both setpoint changes and disturbance rejections; however, the system was nonlinear requiring different tuning parameters at different outlet concentrations. Feedback control of the toluene concentration in the differential reactor was used to explore the impact of concentration on start-up and long-term biofilter operation in a rigorous fashion. Starting at an reactor concentration of 20 ppm and then increasing to 65 ppm increased the toluene removal rate (33 ± 1.6 g m^-3h^-1) compared to starting the reactor at an outlet concentration of 81 ppm before settling at 65 ppm (42 ± 0.9 g m^{- 3}h^-1). The toluene removal rate increased with increasing outlet toluene concentration and then eventually decreased when reaching the inhibitory toluene concentration (ranged from 80 to 250 ppm).

Effect of Packing Material Composition on the Aerodynamic Processes in a Wavy Lamellar Plate-Type Biofilter

Reducing the pressure drop in biofilters is important for the reduction of the energy consumption of these devices. Usually, the pressure drop increases with time due to the biomass growth within the packing material. The aim of this study was to evaluate the aerodynamic processes in a laboratory-scale wavy lamellar (WL) plate-type biofilter equipped with a capillary system for humidifying the packing material. The packing material of a designed biofilter consisted of wavy polymer plates (WPP) vertically arranged next to each other. The pattern of arrangement of the plates allowed sufficiently large spaces, and therefore, the use of such structure had an impact on a decrease in the pressure drop of the biofilter. WPP were coated with three different kinds of materials, namely (I) wood fiber (WF), (II) non-woven caulking material (NWCM) and WF, and (III) linen material (LM) and WF. The results showed that the composition of the packing material influenced pressure drop of the biofilter. The packing material, which consisted of WPP covered with WF, had the lowest pressure drop compared with the other two packing material compositions. In this study, the experimental results were also compared with the results of the performed mathematical modeling of airflow movement.

Removal of Odors (Mainly H2S and NH3) Using Biological Treatment Methods

This study reviews the available and most commonly used methods of gas deodorization. Comparing various methods of odor removal, undoubtedly biological methods of pollution degradation have an advantage over others—chemical and physical. This advantage is manifestedmainly in ecological and economic terms. The possibility of using biological methods to remove H2S and NH3, as the most common emitted by the municipal sector companies, was analyzed in terms of their removal efficiency. The method of bio-purification of air in biotrickling filters is more advantageous than the others, due to the high effectiveness of VOCs and odors degradation, lack of secondary pollutants, and economic aspects—it is a method competitive to the commonly used air purification method in biofilters.

Removal of H2S by vermicompost biofilter and analysis on bacterial community

The vermicompost collected from dewatered domestic sludge as packing material in biofilter was investigated for hydrogen sulfide (H2S) removal. No nutrients or microbial inoculation was added throughout the experiment. The corresponding bacterial community characteristics in the vermicompost biofilter of different spatial levels were evaluated by Miseq high-throughput sequencing technique. The results showed that the vermicompost biofilter performed well during operation. The H2S removal efficiency reached nearly 100% under condition of the inlet concentration <350 mg m−3 and 0.25−0.35 m3 h−1 gas flow rate. The maximum elimination capacity of 20.2 g m−3 h−1 was observed at a flow rate of 0.35 m3 h−1. Furthermore, the amounts of biodegraded products and pH varied accordingly. In addition, the results from high-throughput sequencing revealed pronouncedly spatial variation of the vermicompost, and the Rhodanobacter, Halothiobacillus, Mizugakiibacter as well as Thiobacillus, which can play an important role in removing H2S, were predominant in the final vermicompost. These results imply that the vermicompost with diverse microbial communities has a good potential for eliminating H2S.

Evaluation of a hybrid physicochemical/biological technology to remove toxic H2S from air with elemental sulfur recovery

The removal of toxic hydrogen sulfide (H₂S) from the air at pilot-scale with elemental sulfur recovery was evaluated using Fe-EDTA chelate as a single treatment at a pH of about 8.5. This was later combined with a compost biofiltration process for polishing the pre-treated air. Experiments were performed in a unique container system that allowed deploying either Fe-EDTA chelate or Fe-EDTA chelate/biofiltration treatment (hybrid system). The results showed the feasibility of H₂S removal at concentrations between 200 and 5300 ppmv (H₂S loading rates of 7-190 g m^-3 h^-1) present in fouled air. The Fe-EDTA chelate as a single treatment was able to remove nearly 99.99% of the H₂S at inlet concentrations ≤ 2400 ppmv (107 g m^-3 h^-1), while the hybrid system archived undetectable outlet H₂S concentrations (<1 ppmv) at inlet levels of 4000 and 5300 ppmv. At 5300 ppmv, the Fe-EDTA chelate process H₂S removal efficiency decreased to 99.20% due to the limitation of oxygen mass transfer in the Fe(III) regeneration reaction. Under the previous conditions, the pH was required to be controlled by the addition of NaOH, due to the likely occurrence of undesirable parallel reactions. The elemental sulfur yield attained in the physicochemical module was 75-93% with around 80% recovered efficiently as a solid.

Technologies for deodorization of malodorous gases

There is an increasing number of citizens' complaints about odor nuisance due to production or service activity. High social awareness imposes pressure on entrepreneurs and service providers forcing them to undertake effective steps aimed at minimization of the effects of their activity, also with respect to emission of malodorous substances. The article presents information about various technologies used for gas deodorization. Known solutions can be included into two groups: technologies offering prevention of emissions, and methodological solutions that enable removal of malodorous substances from the stream of emitted gases. It is obvious that the selection of deodorization technologies is conditioned by many factors, and it should be preceded by an in-depth analysis of possibilities and limitations offered by various solutions. The aim of the article is presentation of the available gas deodorization technologies as to facilitate the potential investors with selection of the method of malodorous gases emission limitation, suitable for particular conditions.

Selection of odour removal technologies in wastewater treatment plants: a guideline based on Life Cycle Assessment

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.