Anaerobic Biofilm Reactor Research Articles

Techno-Economic Assessment of On-Farm Anaerobic Digestion System Using Attached-Biofilm Reactor in the Dairy Industry

In this study, a techno-economic assessment of an on-farm biogas system using an anaerobic biofilm reactor utilizing cow manure as a fermentation substrate was evaluated. A projection model was developed using Microsoft Excel software with three outputs, the size and dimension of a bioreactor, experimental microbial kinetic studies, and the economic studies based on the experimental results. Characterization analysis of cow manure wastewater showed the total solid (TS), total volatile solid (TVS), total carbohydrate (TC), chemical oxygen demand (COD), and pH values which were 10.95 g/L, 8.65 g/L, 6.65 g/L, 57.80 g/L, and 7, respectively. Using the modified Gompertz equation for the microbial studies, it was found that, at 37 °C and 20 days hydraulic retention time (HRT), the biogas yield was 934.54 mL/gVS, the volume of biogas produced was 11.28 m3/d, and 22.56 kWh of electricity was generated. The Gompertz prediction helps to determine the optimal HRT for the system so that the microorganisms are at their optimum stage to produce biogas. The economic analysis was done, and the results illustrated that, when the rate of cow manure produced was at 55 L/day.cow, the net present value (NPV) was RM 611,936.09, with a 13% internal rate of return (IRR), 0.14 return on investment (ROI), and 7.02 years of payback period (PP). By developing a techno-economic assessment that included all the necessary parameters such as sizing of the bioreactor, microbial kinetic studies, and economics of the plant, farmers could easily implement the system into their farms. This model showed that the anaerobic digestion system utilizing an attached biofilm with cow manure as a fermentation inoculum and substrate was applicable on an industrial scale to generate electricity and reutilize to the farm, at the same time generating additional income from the production of fertilizer.

Performance of an Integrated Settler Based Anaerobic Biofilm Reactor as Onsite Sanitation System

The present study analysed the performance of an integrated settler based anaerobic biofilm reactor (ISBABR) for domestic wastewater treatment at two hydraulic loading conditions as an onsite sanitation system. The ISBABR is designed on the basic concept of conventional septic tanks and anaerobic biofilm reactors. The ISBABR was run on actual sewage after inoculating it with digested sludge, whose COD (Chemical oxygen demand) and VSS (Volatile suspended solids) values were 9.65 and 7.13 g/l respectively. The system was operated on steady and non-steady hydraulic loading conditions while maintaining 24 h HRT for 4 consecutive months. The average removal efficiency of the system in terms of TSS (Total suspended solids), BOD (Biochemical oxygen demand) and COD was found to be 90.09 ± 4.5%, 89.89 ± 3.2% and 87.89 ± 5.2% respectively, under both the hydraulic loading conditions. In bacterial analysis, the removal efficiency of the system in terms of TC (Total coliform) and FC (Fecal coliform) was found to be 85.5 ± 4.9% and 96.36 ± 1.5% respectively. The morphology of the sludge showed the presence of anaerobes, which was a good indicator for the system. The results of the present study prove that the ISBABR is perfect system for onsite sanitation.

Combined effects of volume ratio and nitrate recycling ratio on nutrient removal, sludge characteristic and microbial evolution for DPR optimization

The optimization of volume ratio (VAn/VA/VO) and nitrate recycling ratio (R) in a two-sludge denitrifying phosphorus removal (DPR) process of Anaerobic Anoxic Oxic-Moving Bed Biofilm Reactor (A2/O-MBBR) was investigated. The results showed that prolonged anaerobic retention time (HRTAn: 1.25→3.75 hr) exerted favorable effect on chemical oxygen demand (COD) removal (57.26%→73.54%), poly-β-hydroxyalkanoates (PHA) synthesis (105.70→138.12 mgCOD/L) and PO43− release (22.3→38.9 mg/L). However, anoxic retention time (HRTA) and R exhibited positive correlation with PHA utilization (43.87%-81.34%) and denitrifying phosphorus removal (DPR) potential (ΔNO3−/ΔPO43−: 0.57-1.34 mg/mg), leading to dramatical TN removal variations from 68.86% to 81.28%. Under the VAn/VA/VO ratio of 2:6:0, sludge loss deteriorated nutrient removals but the sludge bioactivity quickly recovered when the oxic zone was recovered. The sludge characteristic and microstructure gradually transformed under the dissolved oxygen (DO) control (1.0-1.5→1.5-2.0 mg/L), in terms of sludge volume index (SVI: 194→57 mL/gVSS), median-particle-size (D50: 99.6→300.5 μm), extracellular polymeric substances (EPS) (105.62→226.18 mg/g VSS) and proteins/polysaccharides (PN/PS) ratio (1.52→3.46). Fluorescence in situ hybridization (FISH) results showed that phosphorus accumulation organisms (PAOs) (mainly Cluster I of Accumulibacter, contribution ratio: 91.79%-94.10%) dominated the superior DPR performance, while glycogen accumulating organisms (GAOs) (mainly Competibacter, contribution ratio: 82.61%-86.89%) was responsible for deteriorative TN and PO43− removals. The optimal HRTA and R assembled around 5-6.5 hr and 300%-400% based on the PHA utilization and DRP performance, and the oxic zones also contributed to PO43− removal although it showed low dependence on DO concentration and oxic retention time (HRTO).

Influence of organic loading rate on ciprofloxacin and sulfamethoxazole biodegradation in anaerobic fixed bed biofilm reactors

Antibiotic compounds, notably sulfamethoxazole (SMX) and ciprofloxacin (CIP), are ubiquitous emerging contaminants (ECs), which are often found in domestic sewage. They are associated with the development of antimicrobial resistance. Operational parameters, e.g. organic loading rate (OLR), hydraulic retention time (HRT) and sludge retention time, may influence EC biodegradation in wastewater treatment plants. This study assessed the impact of the OLR variation on the biodegradation of CIP and SMX, applying two configurations of anaerobic fixed bed reactors: anaerobic packed bed biofilm reactor (APBBR) and anaerobic structured bed biofilm reactor (ASBBR). A significant reduction in the biodegradation of SMX (APBBR: 93–69%; ASBBR: 94–81%) and CIP (APBBR: 85–66%; ASBBR: 85–64%) was observed increasing OLR from 0.6 to 2.0 kgCOD m−3 d−1. The decrease in the HRT from 12 to 4 h resulted in higher liquid-phase mass transfer coefficient (APBBR: ks from 0.01 to 0.05 cm h−1; ASBBR: ks from 0.07 to 0.24 cm h−1), but this was not enough to overcome the decrease in the antibiotic-biomass contact time on biofilm, thus reducing the bioreactors’ performance. The ASBBR favored biomethane production (from 7 to 17 mLCH4 g−1VSS L−1 d−1) and biodegradation kinetics (kbio from 1.7 to 4.2 and for SMX and from 2.1 to 4.8 L g−1VSS d−1 for CIP) due to the higher relative abundance of the archaea community in the biofilm and the lower liquid-phase mass transfer resistance in the structured bed. CIP and SMX cometabolic biodegradation was associated to the hydrogenotrophic methanogenesis (mainly Methanobacterium genus) in co-culture with fermentative bacteria (notably the genera Clostridium, Bacillus, Lactivibrio, Syntrophobacter and Syntrophorhabdus). The anaerobic fixed bed biofilm reactors proved to be highly efficient in biodegrading the antibiotics, preventing them from spreading to the environment.

Continuous treatment of hydrothermal liquefaction wastewater in an anaerobic biofilm reactor: Potential role of granular activated carbon

High strength hydrothermal liquefaction wastewater (HTL-WW) is produced during the hydrothermal liquefaction of biowaste into bio-oil. The presence of complex and refractory organics in HTL-WW limited the conversion efficiency during the anaerobic digestion. An anaerobic biofilm reactor, packed with granular activated carbon (GAC) and polyethylene (PE) rings, was continuously operated over 160 days for HTL-WW treatment in this study. The performance was higher than previous researches in terms of organic loading and methane production, resulting in 285 ± 22 mL/g COD (83.4% of theoretic value) methane yield when operated at a concentration of 10 g COD/L under a 1.7 d HRT. The potential role of GAC on HTL-WW conversion, including absorption, microbial enrichment, and metabolic flux variation via enhancement of direct interspecies electron transfer (DIET), was also discussed. It was found that the GAC played a very important role in the beginning, acting as an adsorbent for the reduction of inhibitors and color. In addition, biofilms developed on the GAC enriched the syntrophic metabolism of bacteria responsible for inhibitors degradation. Over 80% of the COD and 75% of color in HTL-WW were removed by microbes. Furthermore, the difference in microbial structure between the PE and GAC biofilms revealed the potential of establishing DIET on the GAC via enrichment of Anaerolineaceae, Syntrophomonas and Methanosaeta.

Accumulation of antibiotic-resistant genes in anaerobic biofilm reactor fed with household chemical products.

This research aims to determine the presence of antibiotic-resistant genes (ARG) in anaerobic biofilm reactors (ABR) fed with household chemical products (HCP) such as laundry detergents and handwash without any influx of antibiotics. The ABR comprised a three-chamber design with bottom sludge, a middle chamber containing fluidized PVC spiral, and a top chamber with packed coir fiber as a biofilm support medium, respectively. Four different ABRs were simultaneously operated for a prolonged period (200 day) and subjected to variations in physicochemical conditions. The ABRs fed with HCP exhibited solitary accumulation of log (4.4–7.5) ermC gene copies/g VS whereas, ARG was undetectable in glucose fed ABRs indicating that HCP exhibited antimicrobial activities synonyms to Erythromycin. Accumulation of Erythromycin-C (ermC) was relatively higher on the biofilm inhabiting PVC support medium and further accentuated by effluent recycling to log 7.5 ermC gene copies at a ratio of ermC/16S gene copies of 0.65. Physico-chemical factors such as substrate composition, biofilm support medium, and effluent recycling simultaneously elevated the concentration of ermC genes. The results indicated that HCP augments the accumulation of ARG in the microbiome, subsequently, increasing the risk in ARG transmission from sewage treatment plants to the ecology and humans.Electronic supplementary materialThe online version of this article (10.1007/s42452-020-3143-z) contains supplementary material, which is available to authorized users.

Comparative analysis of brewing wastewater and lactate as carbon sources for microbial community treating acid mine drainage in anaerobic MBBR systems

ABSTRACT This study investigated the effect of carbon sources (n = 2) on the performance of a microbial community in an anaerobic moving-bed biofilm reactor (MBBR) treating acid mine drainage (AMD). The 1.5 L anaerobic MBBR was operated across a range of hydraulic retention times – HRT’s (3–18 days), using different substrates, i.e. brewing wastewater and lactate as sole carbon sources and electron donors. Maximum sulphate reduction and chemical oxygen demand (COD) consumption rate was 21.94 and 24.28 mg L−1 h−1, and 0.473 and 0.697 mg COD L−1 d−1 for brewing wastewater and lactate supplemented bioreactors, respectively, at an HRT of 3 days. The maximum COD/ ratio was found to be 2.564 in the bioreactor supplemented with brewing wastewater at an HRT of 15 days. The metal removal above 70% in the system supplemented with brewing wastewater followed the order; Be2+ > Fe2+ > Sr2+ > Pb2+ > Mg2+ > Cu2+ > Zn2+ > Li1+ > Ca2+ in comparison to the system supplemented with lactate, Be2+ > Fe2+ > Sr2+ > Mg2+ > Cu2+ > Li1+ > Zn2+ > Pb2+ after an HRT of 18 days. Complete removal of beryllium (II) was observed irrespective of the carbon source used. The results clearly showed that brewing wastewater can be deployed as a nutritional supplement in environmental remediation of AMD.

A high-rate anaerobic biofilm reactor for biomethane recovery from source-separated blackwater at ambient temperature.

Anaerobic bioreactors for source-separated blackwater are mostly operated at low organic loading rates (OLRs) due to low biodegradability and the potential of ammonia inhibition. In this study, an anaerobic biofilm reactor having conductive carbon fibers as the media was investigated for the high-rate treatment of blackwater collected from vacuum toilets. The bioreactor was operated at different OLRs ranged from 0.77 to 3.01g COD/L-d in four stages for a total operating period of~250days. With the increase of OLRs, the specific methane production rate increased from 105.3 to 304.6ml/L-d with high methane content in biogas (75.5%-83%). The maximum methane yield was achieved at hydraulic retention time (HRT) of 15days. Highest organics and suspended solids removal (80%-83%) were achieved at 20-days HRT, while increased OLRs resulted in diminished removal efficiencies. The state variables, including pH, total ammonia nitrogen, short-chain volatile fatty acids, and soluble chemical oxygen demand, indicated the system had a great capability to withstand the high OLRs. Microbial community analysis revealed that the high performance might be attributed to direct interspecies electron transfer (DIET) facilitated by potentially electroactive bacteria (e.g., Syntrophomonas, Clostridium) and electrotrophic archaea (e.g., Methanosaeta and Methanosarcina species) enriched on the carbon fibers. PRACTITIONER POINTS: An anaerobic biofilm reactor was investigated for biomethane recovery from source-separated blackwater. Conductive carbon fibers were utilized as the media to stimulate enrichment of potentially electroactive methanogenic communities. The bioreactor was operated at ambient temperature for over 250days. High methane production rate and high-quality biogas were achieved at OLRs ranged from 0.77 to 3.01g COD/L-d. Microbial community analysis suggested direct interspecies electron transfer (DIET) between specific electroactive bacteria and electrotrophic archaea.

REMOVAL OF ORGANIC MATTERS FROM PIGGERY WASTEWATER IN ANAEROBIC MOVING BED BIOFILM REACTOR (MBBR)

The objective of this study is to investigate the performance of Anaerobic Moving Bed Biofilm Reactor (MBBR) on the removal of organic matters (using COD and TSS values) in piggery wastewater using two kinds of carrier: Polyurethane (PU) and Polyethylene (PE) - Different organic loading rates (OLRs) varying from 4 to 10 gCOD/l/day with controlled temperature 37±2oC, pH 7.0-7.5 were investigated. The seeded sludge was collected at the anaerobic tank of the wastewater treatment plant of the Sabeco Beer Manufacturing Plant (Nam Tu Liem district, Hanoi) and grown in the MBBR for 15 days. For porous PU material, the COD and TSS removal efficiencies achieved 69.7 and 67.3% and 54.9 and 65.5% at OLR 4 and 6 gCOD/l/day, respectively. Whereas for wheel shape PE material, it was found that the COD removal efficiencies were slightly higher with OLR of 6 gCOD/l/day (71%%), even with higher OLR at 10 gCOD/l.day, the COD removal efficiency didn‘t seem to significantly increase (73.3 %). For TSS removal, in comparison between PU and PE, the later found slightly better with the same OLRs of 4 and 6 gCOD/l/day, reaching 63.2 and 67 %, respectively. However, TSS removal efficiencies were found to be higher with PE carrier at higher OLR, reaching 72% at 10 gCOD/l/day.

Effect of Intermittent Aeration in a Hybrid Vertical Anaerobic Biofilm Reactor (HyVAB) for Reject Water Treatment

Water from anaerobic sludge dewatering (reject water that is recycled to the inlet main process treatment) from the Knarrdalstrand municipal wastewater treatment plant in Porsgrunn, Norway, contains 2.4 g/L of total chemical oxygen demand (TCOD) and 550 mg/L NH4-N (annual average). The high concentration of ammonium causes disturbances in the mainstream physical and chemical processes, while only a small fraction of the organics is biodegradable. A pilot-scale hybrid vertical anaerobic biofilm (HyVAB) reactor combining anaerobic and aerobic treatment was tested for reject water treatment to reduce process disturbances. The pilot HyVAB was prepared for the study with continuous aeration of the aerobic part of the reactor for 200 days, while two intermittent aeration schemes were applied during the three-month test period. Ammonium removal efficiency increased from 8% during the continuous aeration period to 50% at the end of the test when a short (7 min) aeration cycle was applied. COD removal was close to 20%, which was mainly obtained in the anaerobic stage and not significantly influenced by the aerations schemes. Simultaneous partial nitrification and denitrification were established in the biofilm that alternated between aerobic and anoxic conditions. The observed high ammonium removal is explained by two alternative shortcut processes via nitrite. The lack of biodegradable organics in the aerated stage suggests that most of the nitrogen removal was via the anammox pathway (autotrophic denitrification). The HyVAB, combining an anaerobic sludge bed and an intermittently aerated biofilm, appears to be an efficient process to treat high ammonium containing reject water.

Enhanced anaerobic degradation of quinoline and indole with the coupling of sodium citrate and polyurethane

ABSTRACT A coupling system of sodium citrate and biofilm based on polyurethane was prepared to analyse the coupling enhancement degradation on quinoline and indole. Four reactors (R1: sludge, R2: sludge + sodium citrate, R3: biofilm on polyurethane, and R4: biofilm + sodium citrate) were operated 120 days to compare the degradation efficiency. During whole running phases, R4 showed high degradation efficiency on quinoline (≥98.55%) and indole (≥95.44%). Analysis of bacterial colony showed anaerobic sludge reactors benefited the enrichment of Aminicenantes, Levilinea, and Longilinea, while anaerobic biofilm reactors benefited the enrichment of Giesbergeria and Comamonas. Furthermore, analysis of archaea colony showed acetic acid metabolism to produce methane was the main mode in anaerobic sludge reactors, while acetic acid and hydrogen metabolism to produce methane were both the main modes in biofilm reactors. This study can provide some references for the treatment of nitrogen heterocyclic wastewater.

Removal of high concentrations of NO3− from nuclear industrial wastewater by using a fixed-bed bioreactor

In this work, a down-flow fixed bed anaerobic biofilm reactor filled by biological ceramsites were prepared to remove the high concentration of NO3− (> 20 g/L) from nuclear industry wastewaters. The effects of hydraulic retention time, the concentration of NO3−, the molar ratio of C/N and temperature on the removal efficiencies of NO3− were investigated. The results showed that the removal rate of NO3− with the initial concentration of 6 g/L can reach 99% or more by controlling the hydraulic retention time at 0.75 h, the molar ratio of C/N at 1.5 and the temperature over 18 °C. In the process, the NO2− was not accumulated, and the autotrophic denitrifying bacteria grow well in anaerobic biofilm reactors, proving a usable method for removing the high concentration NO3− from nuclear industrial wastewaters.

Speciation and conversion of carbon and nitrogen in young landfill leachate during anaerobic biological pretreatment

There is an increasing need for landfill leachate pretreatment prior to discharge to wastewater treatment plants due to increasingly stringent sewer discharge limits. Lab-scale tests have shown that the anaerobic biological processes can effectively remove chemical oxygen demand and dissolved organic carbon from landfill leachate. Our work expands the knowledge in anaerobic leachate pretreatment by systematically studying the conversion of carbon and nitrogen species, particularly their recalcitrant fractions in a submerged anaerobic biofilm reactor using real-world leachate from a typical young municipal solid waste landfill. After reaching steady state, the reactor removed 41.7% of the fulvic acids (i.e., 1290 mg C/L). While compounds with a low degree of oxidation (O:C < 0.2) and compounds with a low degree of saturation (H:C < 1) were removed, compounds that were more oxidized (O:C > 0.2) and more saturated (H:C > 1) were produced. At steady state, 98% of recalcitrant dissolved organic nitrogen (i.e., rDON = 222 mg N/L) was removed. Compared to the DON in the raw leachate, the produced DON in the pre-treated leachate were more oxidized (O:C > 0.35) and more bioavailable (N:C > 0.07). The submerged anaerobic biofilm reactor may be an efficient leachate pretreatment method if rDON removal is needed.

Design and evaluation of degassed anaerobic membrane biofilm reactors for improved methane recovery

Anaerobic treatment of domestic wastewater (DWW) produces dissolved methane that needs to be recovered for use as an energy product. Membrane-based recovery systems have been reported in the literature but are often limited by fouling. The objective of this study was to develop a methane producing biofilm on the shell side surface a membrane to allow for immediate recovery of methane as it was produced, negating mass transfer resistance caused by fouling. Between 89 and 96% of total methane produced was recovered via in-situ degassing without the need for fouling control or cleaning throughout 72 weeks of operation. High methane recovery efficiencies led to predictions of net positive energy yield in one reactor and a 32–61% reduction in energy demand in the others compared to the control. This research demonstrates the feasibility and usefulness of combining attached growth anaerobic wastewater treatment processes with hollow fiber membrane methane recovery systems for improved operation.

Electrical Conductivity for Monitoring the Expansion of the Support Material in an Anaerobic Biofilm Reactor

This article describes the use of the electrical conductivity for measuring bed expansion in a continuous anaerobic biofilm reactor in order to prevent the exit of support material from the reactor with the consequent loss of biomass. The substrate used for the tests is obtained from a two-stage anaerobic digestion (AD) process at the pilot scale that treats the liquid fraction of fruit and vegetable waste (FVW). Tests were performed with the raw substrate before anaerobic treatment (S1), the effluent from the hydrolysis reactor (S2), and the effluent from the methanogenic reactor (S3) to evaluate its effect on the electrical conductivity values and its interaction with colonized support material. The tests were carried out in a 32 L anaerobic inverse fluidized bed reactor (IFBR), which was inoculated with colonized support material and using two industrial electrodes at different column positions. The results with the previously digested samples (S2 and S3) were satisfactory to detect the presence of support material at the points where the electrodes were placed since the electrical conductivity values showed significant changes of up to 0.5 V, while with substrate S1 no significant voltage differences were appreciated. These results demonstrate that electrical conductivity can be used as an economic and simple mean for monitoring the support material expansion in order to avoid over expansion in the IFBR. It was also demonstrated that the conditions of the substrate in the methanogenic stage (pH and presence of volatile fatty acids) do not affect the operation of the electrical conductivity detection system.

Bioremediation of AOX from pulp and paper industry wastewater and AOX contaminated soils

Bleaching of paper pulp with chlorine/ chlorine derivatives leads to formation of severalorganochlorine compounds. These compounds are collectively termed as "Adsorbable OrganicHalides" (AOX). Toxic effects of AOX are well documented. Analysis of various wastewaters,soils irrigated with wastewater and sludge show significant levels of AOX. This is a potentialthreat to the environment. Physical and chemical methods of AOX removal are not economical.Hence, bioremediation technology needs to be developed for effective, ecofriendly andeconomical management of AOX containing waste. With this aim, anaerobic biofilm reactors(7.2L) were developed in our laboratory. Anaerobic cultures degrading chlorophenols wereenriched and a consortium of such enrichments was used as the inoculum for the reactors. Thereactors were fed with nutrient medium and run at 20 days HRT and at 30 °c. Degradation of 2,4dichlorophenol (2,4 DCP) was studied at 100 ppm, 300 ppm and 600 ppm and 96.7, 74.5 and56.8 % dechlorination was observed, respectively. Anaerobic degradation at varyingconcentration of AOX from bleach composite wastewater (BCWW) was studied. Reactors fedwith 12.5, 25, 50 and 75 % BCWW v/v showed 62.9, 56.5, 55.9 and 27.1% AOX degradation,respectively. The results suggest feasibility of treating the BCWW stream separately in anaerobicreactor and then mixing the effluent with composite wastewater. The treatment will ensureprevention of AOX pollution. Fish toxicity bioassays are being carried out to study safe disposalof treated wastewater in natural water bodies. Aerobic cultures degrading different chlorophenolswere isolated. Using a consortium of these cultures bioremediation studies on AOX contaminatedsoils have been initiated.

Experimental biogas production from recycled pulp and paper wastewater by biofilm technology.

The main objective of this study is the evaluation of RPPW anaerobic digestion feasibility at laboratory scale under Mesophilic condition. The experiment is conducted using a two-stage biofilm digester of 5L capacity with mobile support material. Anaerobic treatment of wastewater from recycled pulp and paper industry in Morocco was tested using a laboratory-scale anaerobic biofilm digester that operated under mesophilic conditions over a 70-day. Chemical oxygen demand (COD) efficiency, volatile and total solid (VS, TS) elimination of the substrate during the process were: 78%, 52% and 48% respectively. The system was stable throughout its operating cycle with an optimum pH (7.24), alkalinity (1750mg CaCO3/L) and a volatile fatty acid value (760mg/L). The experimental daily biogas production measured reaches a value of 5 L/day with a composition of 71% methane, 27.6% carbon dioxide, 0.2 oxygen and 7713ppm of the H2S. The study results show that the anaerobic biofilm reactor is a suitable technique for recycled pulp and paper wastewater (RPPW) treatment. The reactor shows high performances in terms of process stability, removal efficiency (> 70%) and biogas production. Anaerobic digestion is an efficient waste treatment technology that uses natural anaerobic decomposition to reduce the volume of waste while producing biogas. However, research is needed to strengthen microbial metabolism, biochemistry and the functioning of the rector to improve biogas production. The RPPW AD experiment with biofilm digester technology was stable throughout the operation period. The digester knows an overloaded in the last phase of the experiment which leads to an inhibition of biogas production.

Treatment of household greywater laden with household chemical products in a multi-chambered anaerobic biofilm reactor

Anaerobic treatment of greywater (GW) is challenging due to the presence of recalcitrant household chemical products (HCP) that inhibit the activity and growth of organic pollutant degrading anaerobic microbes. This research attempted to overcome this challenge through a novel, multi-chambered anaerobic biofilm reactor (AnBR) containing fluidized PVC media and packed bed lignocellulosic fiber (Cocus nucifera) as biofilm support. The long-term effects of feeding HCP laden GW and effluent recycling on the performance of AnBR were corroborated with the bioconversion data and microbial community dynamics. The results indicated that the composition of wastewater and recycling both determine the rates of COD removal, microbial population, and diversity in AnBR. The inhibitory effects exhibited by GW constituents reduced the COD removal efficiencies by 74–94% in comparison to standard substrates (SS), while simultaneously reducing microbial population and diversity by 30–40%. Effluent recycling in GW and SS fed AnBR enhanced the rates of COD removal from 160 mg/L·day to 214 mg/L·day, and 627 mg/L·day to 3540 mg/L·day respectively, with the selective enrichment of Proteobacteria sp. and Methanogenic sp. The GW fed AnBR was dominated by aromatics degrading species of α-Proteobacteria, Synergistetes, etc., whereas, SS fed AnBR were inhabited by fermentative species of δ-Proteobacteria, Bacteroidetes, etc.

A novel MBBR–MFC integrated system for high-strength pulp/paper wastewater treatment and bioelectricity generation

ABSTRACT In this study, a system combining an anaerobic moving-bed biofilm reactor and a microbial fuel cell (MFC) was designed for simultaneous bioelectricity generation and pulp/paper wastewater (PPW) treatment. After 22 days, when hydraulic retention time (HRT) was set at 72 h, ceramsite-added MFC (C-MFC) showed better bioelectricity performance with power density of 94.5 mW/m2 and internal resistance of 35.7 Ω, as compared to the control without ceramsite (W-MFC) (56.1 mW/m2, 54.3 Ω). Chemical oxygen demand (COD) removal efficiencies of C-MFC and W-MFC were 65.6% and 51.3%, respectively. The C-MFC demonstrated its superior electrochemical performance compared to the W-MFC.

Monitoring Opportunistic Pathogens in Domestic Wastewater from a Pilot-Scale Anaerobic Biofilm Reactor to Reuse in Agricultural Irrigation

Wastewater reuse for agricultural irrigation in many developing countries is an increasingly common practice. Regular monitoring of indicators can help to identify potential health risks; therefore, there is an urgent need to understand the presence and abundance of opportunistic pathogens in wastewater, as well as plant phyllosphere and rhizosphere. In this study, an anaerobic biofilm reactor (ABR) was developed to treat rural domestic wastewater; the performance of pollutants removal and pathogenic bacteria elimination were investigated. Additionally, we also assessed the physicochemical and microbiological profiles of soil and lettuces after wastewater irrigation. Aeromonas hydrophila, Arcobacter sp., Bacillus cereus, Bacteroides sp., Escherichia coli, Legionella sp., and Mycobacterium sp. were monitored in the irrigation water, as well as in the phyllosphere and rhizosphere of lettuces. Pathogens like B. cereus, Legionella sp. and Mycobacterium sp. were present in treated effluent with relatively high concentrations, and the levels of A. hydrophila, Arcobacter sp., and E. coli were higher in the phyllosphere. The physicochemical properties of soil and lettuce did not vary significantly. These data indicated that treated wastewater irrigation across a short time period may not alter the soil and crop properties, while the pathogens present in the wastewater may transfer to soil and plant, posing risks to human health.