Anaerobic Moving Bed Biofilm Reactor Research Articles

Simultaneous methanogenesis and denitrification in an anaerobic moving bed biofilm reactor for landfill leachate treatment: Ameliorative effect of rhamnolipids

In this study, an anaerobic moving bed biofilm reactor (AnMBBR) was developed for simultaneous methanogenesis and denitrification (SMD) to treat high-strength landfill leachate for the first time. A novel strategy using biosurfactant to ameliorate the inhibition of landfill leachate on the SMD performance was proposed and the underlying mechanisms were explored comprehensively. With the help of rhamnolipids, the chemical oxygen demand (COD) removal efficiency of landfill leachate was improved from 86.0% ± 2.9% to 97.5% ± 1.6%, while methane yields increased from 50.1 mL/g-COD to 69.6 mL/g-COD, and the removal efficiency of NO3−-N was also slightly increased from 92.5% ± 1.9% to 95.6% ± 1.0%. The addition of rhamnolipids increased the number of live cells and enhanced the secretion of extracellular polymeric substances (EPS) and key enzyme activity, indicating that the inhibitory effect was significantly ameliorated. Methanogenic and denitrifying bacteria were enhanced by 1.6 and 1.1 times, respectively. Analysis of the microbial metabolic pathways demonstrated that landfill leachate inhibited the expression of genes involved in methanogenesis and denitrification, and that their relative abundance could be upregulated with the assistance of rhamnolipids addition. Moreover, extended Deraguin - Landau - Verwery - Oxerbeek (XDLVO) theory analysis indicated that rhamnolipids reduced the repulsive interaction between biofilms and pollutants with a 57.0% decrease in the energy barrier, and thus accelerated the adsorption and uptake of pollutants onto biofilm biomass. This finding provides a low-carbon biological treatment protocol for landfill leachate and a reliable and effective strategy for its sustainable application.

Combined use of strictly anaerobic MBBR and aerobic MBR for municipal wastewater treatment and removal of pharmaceuticals

An integrated lab-scale wastewater treatment system consisting of an anaerobic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic Membrane Bioreactor (AeMBR) in series was used to study the removal and fate of pharmaceuticals during wastewater treatment. Continuous-flow experiments were conducted applying different temperatures to the AnMBBR (Phase A: 35 °C; Phase B: 20 °C), while batch experiments were performed for calculating sorption and biotransformation kinetics. The total removal of major pollutants and target pharmaceuticals was not affected by the temperature of the AnMBBR. In Phase A, the average removal of dissolved chemical oxygen demand (COD), biological oxygen demand (BOD), and ammonium nitrogen (NH4–N) was 86%, 91% and 96% while in Phase B, 91%, 96% and 96%, respectively. Removal efficiencies ranging between 65% and 100% were observed for metronidazole (MTZ), trimethoprim (TMP), sulfamethoxazole (SMX), and valsartan (VAL), while slight (<30%) or no removal was observed for carbamazepine (CBZ) and diclofenac (DCF), respectively. Application of a mass balance model showed that the predominant mechanism for the removal of pharmaceuticals was biotransformation, while the role of sorption was of minor importance. The AeMBR was critical for VAL, SMX and TMP biodegradation; the elimination of MTZ was strongly enhanced by the AnMBBR. In both bioreactors, Bacteroidetes was the dominant phylum in both bioreactors over time. In the AnMBBR, Cloacibacterium and Bacteroides had a higher abundance in the biocarriers compared to the suspended biomass.

Enhancing Mesophilic Anaerobic Digestion of Waste-Activated Sludge through Heat Pretreatment and Kinetic Modeling

Sewage sludge is a useful raw material for the production of renewable energy due to its stable annual output. In this study, the enhancement of mesophilic anaerobic digestion of sewage sludge through heat pretreatment at 95 °C for 30 min was tested in an anaerobic moving bed biofilm reactor (hAMBBR). The sludge retention time was set at 20, 15, 10, and 5 days during 300 days of operation and compared to a traditional anaerobic continuous stirred tank reactor (AnCSTR) without pretreatment. Results of this research indicate that the digestion ratio of volatile soluble solids in the hAMBBR process could be improved by 50%, and the average conversion ratio of methane could be increased by 45%. When the sludge retention time (SRT) was shortened to 5 days, the methane production approached twice that of the contrast reactor. The expanded anaerobic digestion model, including activated sludge models, was utilized for operation simulation. The effect of sludge retention time (SRT) shortening on volatile suspended solids (VSS) digestibility and methane production was well reproduced with simulations. The research conclusion reveals the impact of pretreatment and reactor types on anaerobic digestion and provides the scientific basis for improving methane production and process efficiency in anaerobic digestion.

Performance and cost-benefit analysis of anaerobic moving bed biofilm reactor for pretreatment of textile wastewater.

Performance of an anaerobic moving bed biofilm reactor (AnMBBR) was evaluated for pretreatment of real textile desizing wastewater at organic loading rate (OLR) of 1±0.05 to 6.3±0.37 kgCOD/m3/d. After OLR optimization, the performance of AnMBBR was evaluated for biodegradation of reactive dyes. AnMBBR was operated under a mesophilic temperature range of 30 to 36 °C, while the oxidation-reduction potential (ORP) and pH were in the range of 504 to 594 (-mV) and 6.98 to 7.28, respectively. By increasing the OLR from 1±0.05 to 6.3±0.37 kgCOD/m3/d, COD and BOD5 removal was decreased from 84 to 39% and 89 to 49%, respectively. While the production of biogas was increased from 0.12 to 0.83 L/L·d up to an optimum OLR of 4.9±0.43 kgCOD/m3/d. With increase in the dye concentration in the feed, COD, BOD5, color removal and biogas production reduced from 56, 63, 70% and 0.65 L/L·d to 34, 43, 41% and 0.08 L/L·d, respectively. Based on the data obtained, a cost-benefit analysis of AnMBBR was also investigated for the pretreatment of real textile desizing wastewater. Cost estimation of anaerobic pretreatment of textile desizing wastewater indicated a net profit of 21.09 million PKR/yr (114,000 €/yr) and a potential payback period of 2.54 years.

Influence of salinity on biofilm formation and COD removal efficiency in anaerobic moving bed biofilm reactors.

Anaerobic digestion is widely used for wastewater treatment, but this approach often relies on microbial communities that are adversely affected by high-salinity conditions. This study investigated the applicability of an anaerobic moving bed biofilm reactor (AMBBR) to treating high-salinity wastewater. The removal performance and microbial community were examined under salinity conditions of 1000-3000mg/L, and a soluble chemical oxygen demand (sCOD) removal efficiency of up to 8%±2.74% was achieved at high-salinity. Scanning electron microscopy showed that microorganisms successfully attached onto the polyvinyl alcohol gel carrier, and the extracellular polymeric substances on the biofilm increased at higher salt concentrations. The AMBBR also maintained traditionally accepted levels of total alkalinity and volatile fatty acids for stable wastewater processing under these operating conditions. High-throughput sequencing indicated that Desulfomicrobium and three methanogenic groups were the dominant contributors to sCOD removal. Overall, the results showed that the AMBBR can successfully treat fish factory wastewater under varying salinity conditions.

Biosurfactant-driven synergic roles to accelerate biofilm formation in an anaerobic moving bed biofilm reactor (MBBR): A comprehensive analysis on meso and micro scale

Biofilm formation is a complex and time-consuming process, especially the attachment and growth of anaerobic biofilm, which fundamentally determines the start-up of biofilm reactor. In this study, biosurfactant, rhamnolipid, was introduced into an anaerobic moving bed biofilm reactor (AnMBBR) to promote its start-up, and the results showed that AnMBBR with rhamnolipid (RMBBR) could be successfully started within 25 days. Compared to the control AnMBBR without rhamnolipid, the start-up time was shortened by about half, the attached biomass on biocarriers was increased to 1.5 times, and the pollutants removal efficiencies were all greatly improved in the start-up phase, especially NO3− increased from 86.76 ± 1.04% to 96.93 ± 0.73%, and then these gaps were reduced in the steady-state phase. Under the action of rhamnolipid, the adhesion force of the biofilm increased from 18.9 nN to 27.4 nN eventually, and the interfacial energy between biofilm and biocarriers was transformed from repulsion (6200 KT) to weak attraction (−100 KT) by the evaluation of the extended Derjaguin–Landau–Verwey–Overbeek theory, which significantly promoted the initial attachment of biofilm. The increased metabolic activity, key enzyme activity, extracellular polymeric substances (EPS) and quorum sensing behaviors evidenced that rhamnolipid stimulated microbial internal activities and then regulated biofilm growth process. Moreover, rhamnolipid also significantly enhanced the abundance of functional bacteria in terms of metabolism or quorum sensing, including Thauera, Methylomonas, Desulfomicrobium, Azoarcus, Leptonema. Rhamnolipid would also stimulate the expression of genes that related to membrane transport, biofilm formation and nitrogen metabolism. This work provided a promising strategy for the rapid start-up of anaerobic biofilm reactor.

Impact of the restraint of biofilm volume and thickness on the performance and microbial composition in anaerobic moving-bed biofilm reactors (AnMBBRs)

The effect of limiting biofilm volume using carriers with maximum thickness control on the performance and microbial community composition was investigated in anaerobic moving-bed biofilm reactors (AnMBBRs). Three parallel, continuous AnMBBRs (4 L) were operated (288 d, 24/36 °C) to treat the soluble fraction of a wastewater from a food-manufacturing facility. Two different biofilm carriers controlling maximum biofilm thickness at 200 and 1000 µm (AnoxK™Z-200 and Z-1000) were used in the three reactors, targeting the same projected surface area for biofilm growth (410 m2/reactor): R200 (Z-200), R1000 (Z-1000) and RMix (both Z-200 and Z-1000). The composition of the bacterial (16S rRNA V1-V3) and methanogenic (mcrA gene) communities was analysed using amplicon sequencing. Under relatively constant organic loads (3.6–4.2 gSCOD/Ld, 34–39 gSCOD/m2d, hydraulic retention time=7.7–8 h), R200 presented lower soluble chemical oxygen demand (SCOD) removals (51–60%) than the other reactors (R100 = 91–93%, RMix = 86–91%), likely due to a limited amount of active protected biofilm volume. Lower SCOD removals were associated with higher concentrations of volatile fatty acids in the effluent (R200 =400–800 mgCOD/L; R1000 and RMix<200 mgCOD/L) and lower methane production (R200 =0.66; R1000 =0.72; RMix=0.73 gCH4-COD/gSCODremoved). The Z-200 carriers contained a different fermentative/acidogenic bacterial community abundant in representatives of the families Christensenellaceae, Anaerovoracaceae and Synergistaceae, and led to less amount of biofilm biomass growth, albeit more active than that of carriers allowing for thicker biofilms (Z-1000). In contrast, methanogenic populations were less sensitive to biofilm thickness restraint by these carriers. This study shows for the first time that limiting biofilm volume in MBBR carriers can impact the performance and bacterial community in AnMBBR biofilms.

A pilot-scale anaerobic moving-bed biofilm reactor with PVA gel beads as media for the treatment of fish canning industry wastewater

Abstract This research aims to investigate the performance of a pilot-scale anaerobic moving-bed biofilm reactor (AnMBBR) using PVA gels as media for the treatment of real wastewater from a fish canning factory. The chemical oxygen demand (COD) removal efficiencies at different organic loading rates (OLRs) were investigated at 3.0, 4.3, 6.5, and 8.7 kg COD/m3day by adjusting the flow rates to 350, 500, 750 and 1,000 L/d, respectively. The soluble COD removal efficiencies of the system at flow rates of 350, 500, 750, and 1,000 L/d were 81.0 ± 12.4%, 76.8 ± 8.2%, 74.7 ± 6.2%, and 70.6 ± 12.4%, respectively. According to the residence time distribution (RTD) tests at the highest and lowest flow rates, the mean residence times of both flow rates were significantly higher than the theoretical residence time, indicating very strong external recirculation inside the AnMBBR. The results suggest a 3-pass flow pattern through the AnMBBR. From 16S rRNA gene amplicon sequencing (MiSeq, Illumina) and scanning electron microscopy (SEM) analysis, Methanosaeta, acetoclastic methanogens, were the predominant microorganisms in the system. Most of the microorganisms were located within a 1.994 ± 0.266 mm depth from the PVA gel surface, with two distinct layers.

Performance evaluation and substrate removal kinetics in a thermophilic anaerobic moving bed biofilm reactor for starch degradation

Abstract A laboratory-scale anaerobic moving bed biofilm reactor (AnMBBR) was installed and operated at various hydraulic retention times (HRTs) of 20 to 1.5 d with surface area loading rate (SALR) of 0.86 to 11.43 gCOD/m2/d. Synthetic starch containing desizing wastewater with chemical oxygen demand (COD) of 12.75 g/L was prepared and fed into the reactor. Monod, modified Stover-Kincannon, Grau second-order and First-order substrate removal models were used to evaluate the results of AnMBBR. COD removal efficiency of bioreactor was dwindled by increasing the SALR or reducing the HRT. Decay coefficient (Kd) and yield coefficient (Y) for the Monod model were 0.027 1/d and 1.01 mgVSS/mgCOD, respectively. Maximum substrate utilization rate (Umax) and kinetic constant (Kb) for the Modified Stover-Kincannon model were estimated as 12.57 and 15.22 g/L/d, respectively. The constants (a and b) for the Grau second-order model were found to be 1.09 and 1.31 whilst kinetic coefficient for the Second-order model and First-order substrate removal model were 1.62 and 1.55 1/d, respectively. Modified Stover-Kincannon model and Grau second-order model were found to be the best fit for experimental data with R2 value of 0.99. The findings suggest that these models can be applied to predict the behaviour of AnMBBRs on various scales.

Treatment of textile wastewater using combined anaerobic moving bed biofilm reactor and powdered activated carbon-aerobic membrane reactor

In this study, treatment of textile wastewater using sequencing anaerobic moving bed biofilm reactor (AnMBBR) and powdered activated carbon – aerobic membrane bioreactor (PAC-AeMBR) was investigated. MBBR was composed by an anaerobic bioreactor with a biocarrier K1 with a filling ratio of 40% (v:v) and operated with 5 different aeration rates (0–0.55 m3air/m3reactor.min), at a constant HRT of 6 h to evaluate the effect of oxygen on AnMBBR system. The AnMBBR effluent was fed to the PAC-AeMBR for further treatment. In the AnMBBR operation, the adverse effect of aeration on anaerobic color removal was observed when ORP values increased over − 300 mV corresponding to aeration rates over 0.019 m3air/m3reactor.min, showing high toleration of biofilm layer. Limited aerated MBBR pretreatment provided long-term operation of MBR by decreasing frequency of membrane fouling. The relative abundance of EPS-producing bacteria namely Alphaproteobacteria (68%) was remarkably high in PAC-AeMBR. Considering the obtained results, it was concluded that the AnMBBR and PAC-AeMBR systems with high removals presented itself as a stable system.

Low-strength influence on nitrogen removal performance and bacterial community structure of the anammox process

ABSTRACT The effect of low strength on anaerobic ammonium oxidation (anammox) was investigated in an anaerobic moving bed biofilm reactor (AMBBR) treating artificial wastewater. Influent -N concentration with 10.74 ± 2.73 mg L−1 adversely impacted nitrogen removal permanence, the total nitrogen removal efficiency was significantly increased from 61.4% to 80.0%, when influent nitrogen increased to 22.36 ± 5.83 mg·L−1. -N removal efficiency decreased obviously while that of -N was basically unaffected by the influent nitrogen concentration decrease. Illumina high-throughput sequencing results revealed that the predominant bacterial (64.71%) phylum was Proteobacteria and the dominant functional microorganisms were Nitrosospira, Nitrospira, and Candidatus Brocadia. Simple model simulation results showed that the inhibition effect of the low substrate was most likely due to the increase of bulk DO, which comes from influent and gas–liquid transfer. The reversible inhibition effect of low strength on nitrogen removal performance in an anammox reactor was demonstrated, and strictly regulation of the bulk DO was presumed to be critical to achieve a successful and stable operating performance under low strength.

Kinetics of organics removal in swine wastewater treatment using anaerobic moving bed biofilm reactor

Kinetics of organics removal in swine wastewater treatment using anaerobic moving bed biofilm reactor

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.

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.

Anaerobic treatment of oil-contaminated wastewater with methane production using anaerobic moving bed biofilm reactors

Oil-contaminated wastewaters are generally treated by a combination of physico-chemical and biological methods. Interest in the anaerobic treatment of oily wastewaters has increased since it complements aerobic treatment and produces energy in the form of methane. The objectives of this study were to characterise the anaerobic process spontaneously occurring in a full-scale storage tank at a facility treating waste oil and oil-contaminated effluents, and to evaluate the applicability of an anaerobic moving bed biofilm reactor (AnMBBR) and an anaerobic contact reactor (ACR) for treating the oil contaminated wastewater feeding the storage tank. Three lab-scale reactors were operated in parallel over 465 days: one mesophilic and one thermophilic AnMBBR, and one thermophilic ACR. The wastewater had a high strength with an average chemical oxygen demand (COD) of 36 g/L with a soluble fraction of 80%. The BOD7/COD ratios varied between 0.1 and 0.5, indicating low aerobic degradability. However, biomethane potential tests indicated some level of anaerobic degradability with methane yields between 150 and 200 NmL/gCOD. The full-scale storage tank operated at low organic loading rates (0.35–0.43 kgCOD/m3d), and long hydraulic retention times (HRT = 83–104 d). In comparison, the AnMBBRs achieved similar COD reductions (60%) as the full-scale tank but at a much shorter HRT of 30 d. Similar efficiency could only be reached at longer HRTs (43 d) in the ACR due to low biomass levels resulting from poor sludge settleability. The methane yield was higher (210 NmLCH4/COD removed) in the AnMBBR operated at 37 °C, compared to the other reactors working at 50 °C (180 NmLCH4/COD removed). This reactor also maintained a higher COD removal (67%) at an increased OLR of 1.1 kgCOD/m3d than the AnMBBR at 50 °C. The microbial composition of the biomass from the full-scale tank and the laboratory reactors provided evidence for the conversion of oil-contaminated wastewater into methane with a relatively high abundance of hydrogenotrophic methanogens.

Simultaneous removal of atrazine and organic matter from wastewater using anaerobic moving bed biofilm reactor: A performance analysis

In this study, an anaerobic moving bed biofilm reactor (AMBBR) was designed to biodegrade atrazine under mesophilic (32 °C) condition and then it was evaluated for approximately 1 year. After biofilm formation, acclimation, and enrichment of microbial population within the bioreactor, the effect of various operation conditions such as changes in the concentration of influent atrazine and sucrose, hydraulic retention time (HRT), and salinity on the removal of atrazine and chemical oxygen demand (COD) were studied. In optimum conditions, the maximum removal efficiency of atrazine and COD was 60.5% and 97.4%, respectively. Various models were developed to predict the performance of atrazine removal as a function of HRT during continuous digestion. Also, coefficients kinetics was studied and the maximum atrazine removal rate was determined by Stover - Kincannon model (rmax = 0.223 kgATZ/m3d). Increasing salinity up to 20 g/L NaCl in influent flow could inhibit atrazine biodegradation process strongly in the AMBBR reactor; whereas, the reactor could tolerate the concentrations less than 20 g/L easily. Results showed that AMBBR is feasible, easy, affordable, so suitable process for efficiently biodegrading toxic chlorinated organic compounds such as atrazine. There was no accumulation of atrazine in the biofilm and the loss of atrazine in the control reactor was negligible; this shows that atrazine removal mechanism in this system was due to co-metabolism.

Optimization of surface area loading rate for an anaerobic moving bed biofilm reactor treating brewery wastewater

Three acclimated anaerobic moving bed biofilm reactors filled to 40% by volume with cubic AC920 media (protected surface area of 680 m2 m−3) were studied to treat brewery wastewater at hydraulic retention times of 6–24 h and mesophilic condition (35.0 ± 0.1 °C). The reactors were seeded with media that had developed mature anaerobic biofilm prior to the start of this study. Soluble chemical oxygen demand of the brewery wastewater was equal to 4.0 ± 1 kg m−3, total chemical oxygen demand 5.2 ± 2.1 kg-COD m−3, and the ratio of 5-day biological oxygen demand to chemical oxygen demand was equal to 0.77 ± 0.02. Dissolved oxygen concentration in the influent wastewater was below detection limit (0.1 mg-O2 L−1). This study focused on the assessment of optimal design surface area loading rates for an anaerobic moving bed biofilm process by varying the hydraulic retention times from 6 to 24 h. Volumetric removal rates of 3.0 ± 0.2, 4.2 ± 0.3, 7.2 ± 0.6, 12.4 ± 0.8, 13.4 ± 1.0, and 12.0 ± 1.1 g-sCOD d−1 were achieved at 24, 18, 12, 10, 8, and 6 h hydraulic retention times. Hydraulic retention time of 18 h exhibited the highest chemical oxygen demand removal, at 88 ± 2.5%, and the highest carbon conversion into methane at 0.34 ± 0.06 m3-CH4 kg-sCOD−1. At this hydraulic retention time the specific surface area activity was 13 ± 1 g-sCOD m−2d−1, considering that the organic loading rate was 4.0 ± 0.3 kg-sCOD m−3d−1. Biogas composition was 71 ± 2% methane and 26 ± 4% carbon dioxide. Media clogging and mass transfer limitations due to overgrowing biomass in the interior media channels was observed at surface area loading rates above 54 g-sCOD m−2 d−1. However, kinetic tests revealed that mass transfer limitation started at surface area loading rate of 44 g-sCOD m−2d−1. Anaerobic moving bed biofilm reactor has been shown to be a reliable treatment option for high-strength wastewaters and could be used in brewery wastewater management as a resource to comply with the discharge limit regulation.

Performance and design considerations for an anaerobic moving bed biofilm reactor treating brewery wastewater: Impact of surface area loading rate and temperature

Three 4 L anaerobic moving bed biofilm reactors (AMBBR) treated brewery wastewater with AC920 media providing 680 m2 protected surface area per m3 of media. Different hydraulic retention times (HRT; 24, 18, 12, 10, 8 and 6 h) at 40% media fill and 35 °C, as well as different temperatures (15, 25 and 35 °C) at 50% media fill and 18 h HRT were examined. Best performance at 35 °C and 40% media fill was observed when HRT was 18 h, which corresponded with 92% removal of soluble COD (sCOD). Organic loading rates (OLR) above 24 kg-COD m−3d−1 decreased performance below 80% sCOD removal at 35 °C and 40% media fill. The reason was confirmed to be that surface area loading rates (SALR) above 50 g-sCOD m−2d−1 caused excessive biofilm thickness that filled up internal channels of the media, leading to mass transfer limitations. Temperature had a very significant impact on process performance with 50% media fill and 18 h HRT. Biomass concentrations were significantly higher at lower temperatures. At 15 °C the mass of volatile solids (VS) was more than three times higher than at 35 °C for the same OLR. Biofilms acclimated to 25 °C and 15 °C achieved removal of 80% sCOD at SALR of 10 g-sCOD m−2d−1 and 1.0 g-sCOD m−2d−1, respectively. Even though biomass concentrations were higher at lower temperature, biofilm acclimated to 25 °C and 15 °C performed significantly slower than that acclimated to 35 °C.

An integrated AMBBR and IFAS-SBR process for municipal wastewater treatment towards enhanced energy recovery, reduced energy consumption and sludge production

The conventional activated sludge (CAS) process has been widely employed for wastewater treatment for more than one hundred years. Recently, more and more concerns have been raised on the CAS process due to its high energy consumption and production of huge amount of waste activated sludge, which are inevitably linked to the issue of environmental sustainability and global climate change. Facing to such emerging and challenging situation, this study reported a novel A-B process in which an anaerobic moving bed biofilm reactor (AMBBR) served a lead A-stage for COD capture towards biogas production and an integrated fixed-biofilm and activated sludge sequencing batch reactor (IFAS-SBR) was employed as B-stage for biological nitrogen removal. Results showed that about 85% of wastewater COD was removed in the steady-state AMBBR with a total energy production rate of 0.28 kWh/m3 wastewater treated, while 85% of N-removal was achieved when the stable nitrite shunt was established in the IFAS-SBR. Moreover, 90% of dissolved methane in the AMBBR effluent could be removed by the proposed flash chamber at the lower energy demand of 0.12 kWh/m3 which could be offset by the potential energy harvested from produced methane. Compared to the CAS process, the production of waste sludge was reduced by about 75% in the proposed A-B process due to the efficient COD capture at the A-stage, leading to significant energy savings from aeration for COD oxidation and post-treatment of waste sludge at the B-stage. Consequently, this study offers in-depth insights into A-B process which should be considered as an ideal candidate for achieving the energy-neutral or even energy positive operation of a municipal wastewater treatment. Given the complex situation in A-B process, future study is needed to look into the system optimization towards the operational synergy between A- and B-stage in terms of energy recovery and nitrogen removal.

Start-Up of an Anaerobic Moving Bed–Biofilm Reactor and Transition to Brewery Wastewater Treatment

Two 4-L anaerobic moving bed–biofilm reactors (AMBBR) with different quantities of cubic media (25 and 35% by volume) were examined. Reactors were fed synthetic protein-based feed and both were shown to be capable of treating up to 20 kg/m3 day of chemical oxygen demand (COD), achieving 80% COD removal. Beyond that load the performance began to decrease. The maximum biogas production observed was 9.25 m3 CH4/m3 day at an organic loading rate (OLR) of 20 kg COD/m3 day. The methane composition varied between 60 and 70%. Averaged methane yields of 0.36±0.07 m3 CH4/kg COD removed and specific removal rates from 0.4 to 20 kg COD/m3 day were achieved. At the maximum OLR above 20 kg COD/m3 day, the specific surface area activity was calculated as 98 and 75 g COD/m2 day in the 25 and 35% reactors, respectively. Kinetic tests performed at the maximum OLR revealed that free-floating suspended biomass contributed to no more than 2.5% of the total removal. The reactors were also capable of treating brewery wastewater, reliably attaining 80% COD removal with methane yields of 0.36±0.06 and 0.39±0.03 m3 CH4/kg COD from the 35 and 25% reactors, respectively.