Upflow Anaerobic Sludge Blanket Reactor Research Articles

Efficacies of a locust bean gum polymer on the startup of a novel upflow anaerobic sludge blanket reactor treating municipal sewage.

The present study investigates the potential of locust bean gum (LBG), in accelerating the startup of a novel upflow anaerobic sludge blanket (UASB) reactor handling municipal sewage. Under identical conditions, two lab-scale UASB reactors were operated in parallel, to substantiate this idea. The novel reactor (RH) with an inner centric hybrid UASB module and an outer concentric downflow hanging sponge (DHS) unit started off with an LBG polymer as an additive. Its performance was compared with a conventional system (RC). RH outclassed with an accelerated startup in 40 days, with the highest COD removal of 89% by the UASB compartment and 95% by the entire system (UASB + DHS). RC took nearly 85 days to achieve the highest COD removal of 83%. The polymer also succeeded with a dense sludge bed fastening most of the anaerobes, read by the least sludge volume index (SVI) of 26 mL/g. Specific methanogenic activity (SMA) (RH - 0.715 ± 0.05 and RC - 0.670 ± 0.07 g CH4-COD/g VSS/ day) and extracellular polymer (ECP) concentration (0.30-0.32 g/g VSS) of biomass in both reactors were almost similar. This further confirmed that early granulation was induced solely by the polymer and it also had no deleterious impact on substrate transfer.

New attempts on acidic anaerobic digestion of poly (butylene adipate-co-terephthalate) wastewater in upflow anaerobic sludge blanket reactor

Poly (butylene adipate-co-terephthalate) (PBAT) wastewater is a highly concentrated, acidic, and toxic wastewater generated from biodegradable plastics production. Large amounts of alkali would be consumed when treating PBAT wastewater by anaerobic digestion due to the low pH value. This study employed acidic anaerobic digestion to treat PBAT wastewater and compared to neutral anaerobic digestion. The results indicated that the COD removal rates in the acidic upflow anaerobic sludge blanket (UASB) reactor were 65.5% and 59.9%, respectively at influent pH 6.0 and 5.0 with the COD concentration of around 11,000 mg L−1, and the methane conversion efficiency were 172.5 and 183.8 mLCH4/gCODr (gCODr: COD removed amount), respectively. Correspondingly, the average COD removal and methane conversion efficiency in the neutral UASB reactor were 63.2% and 188.0 mLCH4/gCODr, respectively. The treatment efficiency of acidic and neutral UASB reactors for PBAT wastewater was similar. The hydrogenotrophic methanogenic activity was further enhanced in the acidic UASB reactor compared to the neutral one. The increase of alkalinity in the acidic UASB reactor (2.4 mmol L−1) was higher than the neutral (2.0 mmol L−1). A higher level of syntrophic acetate oxidation bacteria and hydrogenotrophic methanogen was enriched in the acidic UASB reactor, ensuring efficient treatment and saving costs.

Enhancing bio-hydrogen and bio-methane production of concentrated latex wastewater (CLW) by Co-digesting with palm oil mill effluent (POME): Batch and continuous performance test and ADM-1 modeling

This study aimed at investigating the biohydrogen and biomethane potential of co-digestion from palm oil mill effluent (POME) and concentrated latex wastewater (CLW) in a two-stage anaerobic digestion (AD) process under thermophilic (55 ± 3 °C) and at an ambient temperature (30 ± 3 °C) conditions, respectively. The batch experiments of POME:CLW mixing ratios of 100:0, 70:30, 50:50, 30:70, and 0:100 was investigated with the initial loadings at 10 g-VS/L. The highest hydrogen yield of 115.57 mLH2/g-VS was obtained from the POME: CLW mixing ratio of 100:0 with 29.0 of C/N ratio. While, the highest subsequent methane production yield of 558.01 mLCH4/g-VS was achieved from hydrogen effluent from POME:CLW mixing ratio of 70:30 0 with 21.8 of C/N ratio. This mixing ratio revealed the highest synergisms of about 9.21% and received maximum total energy of 19.70 kJ/g-VS. Additionally, continuous hydrogen and methane production were subsequently performed in a series of continuous stirred tank reactor (CSTR) and up-flow anaerobic sludge blanket reactor (UASB) to treat the co-substate. The results indicated that the highest hydrogen yield of POME:CLW mixing ratio at 70:30 of 95.45 mL-H2/g-VS was generated at 7-day HRT, while methane production was obtained from HRT 15 days with a yield of 204.52 mL-CH4/g-VS. Thus, the study indicated that biogas production yield of CLW could be enhanced by co-digesting with POME. In addition, the two-stage AD model under anaerobic digestion model no. 1 (ADM-1) framework was established, 9.10% and 2.43% of error fitting of hydrogen and methane gas between model simulation data and experimental data were found. Hence, this research work presents a novel approach for optimization and feasibility for co-digestion of POME with CLW to generate mixed gaseous biofuel potentially.

Bio-failure or Bio-fuel? Economic Feasibility of Converting Palm Oil Waste to Biogas

This study aimed to investigate the economic feasibility of using an Up-Flow Anaerobic Sludge Blanket (UASB) reactor to convert liquid waste from palm oil processing plants into biogas containing methane. The study examined total capital investment (TCI), working capital investment (WCI), and production costs at different capacities (3, 30, and 300 liters per day) to determine if the process could generate a profit. The results showed that the biogas production from palm oil industrial liquid waste using the UASB reactor did not result in a profit due to the large capital costs and low biogas production. The implication of this study is that further research is needed to find ways to reduce the capital costs of the process and increase biogas production to make it economically feasible.

Performance enhancement of up-flow anaerobic sludge blanket reactor for psychrophilic temperature during the dry season: Kality wastewater treatment plant

The main purpose of wastewater treatment plant (WWTP) is to reduce organic and inorganic pollutants to meet standards. But WWTPs employing up flow anaerobic sludge blanket (UASB) reactors under psychrophilic temperature are currently removing about 55% chemical oxygen demand (COD) and 70% total dissolved solids (TSS). The research was done to increase the treatment efficiencies of UASB reactor working under psychrophilic conditions through optimization of operational parameters like temperature, organic loading rate (OLR), pH and hydraulic retention time (HRT). Experimentation was carried out in a 0.0486 m3 square-shaped pilot-scale UASB reactor. Experimental design response surface method (RSM) for performance enhancement and optimization of UASB reactor operational parameters through five levels of central composite design (CCD) was used. The optimized operational parameters obtained from CCD-RSM were as follows: temperature of 21.58 °C, OLR of 2.99 kg COD/m3.d, HRT of 4.37hrs and pH of 6.3. Using optimized parameters, tests yielded efficiencies of 92.70%, 99.06%, and 94.50% for COD, TSS, and volatile suspended solid (VSS) respectively. The outlet concentrations of alkalinity, and volatile fatty acids (VFA), were found to be lower than the inlet concentrations. The alkalinity in the system accepts the hydrogen ion released by acids and the system is taken over by methanogensis to maintain the pH. The outlet concentration of sulfate ion was found to be increasing due to inhabitation of sulfur-reducing bacteria by an anaerobic condition of VFA and alkalinity at a pH less than 7.8.This process favors the production of CH4 than H2S gas. In general, there was a high likelihood of improving the performance of UASB reactor operating at psychrophilic temperature by optimizing operational parameters.

Effect of Coconut Fiber as an Inert Media on Hybrid Upflow Anaerobic Sludge Blanket Reactor

Effect of Coconut Fiber as an Inert Media on Hybrid Upflow Anaerobic Sludge Blanket Reactor

Study on preliminary economic availability of electric energy use from drying bed sludge by biogas from anaerobic digestion and incineration in Brazil

This study aimed to analyze electrical energy generation derived from anaerobic biogas digestion and the incineration of drying bed sludge (DBS) from an Upflow Anaerobic Sludge Blanket (UASB) reactor using samples from a Wastewater Treatment Plant in Itajubá, Minas Gerais, Brazil. Some data including Automatic Methane Potential Test System (AMPTS II) were obtained from Moni Silva et al. (2021). An experimental apparatus comprised of a biodigester and gasometer was elaborated to conduct quali-quantitative evaluation of DBS biogas generation. Economic analysis was conducted on the Thermal Power Plant (TPP) electrical generation system, powered by biogas with data from i. experimental apparatus, and ii. AMTPS, as well as an incineration power plant. Greenhouse Gas (GHG) emission reductions were assessed. The results demonstrate that TPP from biogas with biodigestion without temperature control (experimental apparatus) was not economically feasible, even when considering ICMS tax exemptions; nonetheless, it would be capable of mitigating GHG emissions. Biodigestion with temperature control enabled TPP projects economic viability with payback in 20 years (178.67 kW, 9% IRR) considering a minimum population of 3,000,000 inhabitants. In all cases, the ICMS taxation reduces project feasibility.

High-Efficiency Mixotrophic Denitrification for Nitrate Removal in High-Sulfate Wastewater Using UASB Reactor

The efficient removal of nitrate from industrial wastewater containing high concentrations of both sulfate and nitrate presents a major challenge in the field of water treatment. In this study, we investigated the use of an Upflow Anaerobic Sludge Blanket (UASB) reactor for the removal of nitrate from wastewater by gradually increasing the sulfate concentration (ranging from 1 g/L to 10 g/L) and the NO3−-N concentration (ranging from 30 mg/L to 300 mg/L). Through this approach, the activated sludge was successfully acclimated to tolerate high-sulfate conditions. The results demonstrated a remarkable NO3−-N removal capacity of 288 mg/L·d in wastewater with a high sulfate concentration of 10 g/L, leading to a nitrate removal efficiency exceeding 96.0%. The analysis of sulfate and sulfide concentrations, as well as the characterization of the microbial community, revealed the occurrence of autotrophic and heterotrophic denitrification processes in the reaction system. The autotrophic denitrifying bacteria found were Raoultella and Shinella, while the heterotrophic denitrifying bacteria included Klebsiella, Simplicispira, and Thauera. The organic carbon sources were found to be a critical factor influencing the denitrification performance of the system. Furthermore, the effects of different chemical oxygen demand (COD)/SO42− ratios (0.3, 0.5, and 1) were examined in wastewater containing a sulfate concentration of 10 g/L and a NO3−-N concentration of 300 mg/L. The results showed that increasing the COD/SO42− ratio enhanced the removal rate of NO3−-N, maintaining it above 98.0% when COD/SO42− was 1. Additionally, the enhancement of the sulfate reduction reaction in the system was observed, and the enrichment of heterotrophic microorganisms such as Megasphaera, Lactobacillus, and Buttiauxella was observed.

Microbial interactions play a keystone role in rapid anaerobic ammonium oxidation sludge proliferation and biofilm formation

Two mature anaerobic ammonium oxidation (anammox) consortia with high/low relative abundance of anammox bacteria were inoculated for the rapid sludge proliferation and biofilm formation in this study, named up-flow anaerobic sludge blanket reactor (UASB1) (high) and UASB2 (low), respectively. Results showed that the nitrogen removal efficiency of UASB2 reached 90.94% after the 120-day operation, which was 13% higher than that of UASB1. Moreover, its biomass amounts were 22.18% (biofilm) and 40.96% (flocs) higher than that of UASB1, respectively. Ca. Kuenenia possessed relative abundances of 29.32% (flocs), 27.42% (biofilm) and 31.56% (flocs), 35.20% (biofilm) in the UASB1 and UASB2, respectively. The relative abundances of genes involved in anammox transformation (hzs, nir) and carbon metabolism (fdh, lgA/B/C, acs) were higher in the UASB2, indicating that Ca. Kuenenia might produce acetate and glycogen to enhance microbial interactions. These findings emphasized the importance of microbial interactions in anammox sludge proliferation and biofilm formation.

Ketoprofen and diclofenac removal and toxicity abatement in a real scale sewage treatment Plant by photo-Fenton Process with design of experiments

The disposal of effluent and sludge containing emerging contaminants (ECs) are the main problems associated with most traditional treatment methods. Non-steroidal anti- inflammatory drugs (NSAIDs) require more complete treatments integrated with conventional processes to enable circular economy and the water-energy-food (WEF) nexus. Different options to traditional technologies have been employed in the treatment of effluents, such as advanced oxidation processes (AOPs). However, few studies use real scales integrated with existing technologies. This work evaluated the use of AOPs for the degradation of ketoprofen (KET), diclofenac (DCF), and the DCF+KET mixture in an anaerobic effluent matrix, post-treated by an Upflow Anaerobic Sludge Blanket Reactor (UASB) in a real-scale Sewage Treatment Plant (STP). A Factorial Experimental Design was proposed and after 2 h of treatment the efficiency was evaluated by the decrease in total organic carbon (TOC), decrease of drugs concentration, physicochemical and ecotoxicity parameters. As a result, the photo-Fenton process showed greater efficiency in the degradation of KET (97.2% ± 1.6), DCF (72.7% ± 4.9), and the mixture of the two drugs DCF+KET (66.0% ± 2.5), improved the quality of the effluent in the removal of COD, BOD, and turbidity, and reduced toxicity in tests performed with Artemia sp. and Lactuca sativa. The integration between AOPs and UASB as a sewage treatment technology widely used as primary and secondary treatment, allowed to optimize the sewage treatment system for an ideal arrangement. As a consequence, it possesses the capacity to eliminate conventional organic matter and efficiently degrade emerging pollutants.

Decolorization of azo Direct Blue 71 dye in aqueous solutions using sequential upflow anaerobic sludge blanket reactor and UV/H2O2 process

In this research, decolorization of synthetic textile wastewater was investigated by upflow anaerobic sludge blanket (UASB) reactor and advanced oxidation UV/H2O2. In the acclimation phase, an 18 L UASB reactor with a discharge of 18 cm3/min was fed with a colorless synthetic wastewater for 40 days. Then the reactor was fed with wastewater containing Direct Blue 71 as the coloring agent at 6 consecutive steps with concentrations of 10, 50, 100, 200, 300 and 400 mg/L. In the first step, the removal efficiency was the least due to the low inflow dye concentration. However, by further increment of dye concentration in the influent to greater than 200 mg/L, the removal efficiency gradually increased and reached above 80 %. Since the treated effluent from steps 4–6 did not meet regulations, it was discharged into a UV/H2O2 reactor for further treatment. The results showed that with increasing H2O2 concentration, the removal efficiency increased, although excessive increase in H2O2 concentration reduced the removal efficiency. The pseudo-first order kinetic model was in good agreement with the degradation data with the optimal reaction rate constant at a concentration of 2225 mg/L of H2O2.

Granules as Precursors in the Working of Upflow Anaerobic Sludge Blanket Reactor: A Review on the Impacts of Granulation

High-rate anaerobic digesters are of great concern these days—due to their high loading capacity, reduced carbon footprints and lower sludge production. Among them, the most preferred is the upflow anaerobic sludge blanket (UASB) reactor. However, there are still unresolved issues that inhibit the widespread of this technology. To start with the granular sludge bed fostering the microflora forms the prime seat in the working of UASB reactors. These microflora have a predominant role in the treatment of wastewater, hence the factors governing their growth, survival, and distribution are to be studied. Thus it seemed as due important to analyse the granular sludge for its particle size, particle density, and microfilm characteristics, to enhance the reactor’s efficiency. This has made scientists across the world put an eye on factors that shape the granules and how the granules contribute to wastewater treatment. The state-of-the-art is presented in this study.

The impact of semi-continuous and alternating microbial feeding patterns on methane yield from UASB reactors

Feeding strategy represents one of the most important bioreactor operation parameters, however, how different feeding patterns impact reactor microbiome development and treatment performance in up-flow anaerobic sludge blanket (UASB) reactors has not been systematically investigated. In the present study, three feeding strategies, including continuous feeding, semi-continuous feeding (with starvation-feast cycles), and alternate feeding (with high loading-low loading cycles) were assessed and compared using three laboratory-scale UASB reactors. It was observed that both long and short starvation-feast cycles provided by a semi-continuous feeding strategy failed to sustain stable anaerobic digestion under the conditions examined in the present study, while alternate feeding with high and low loading cycles supported microbial development. This feeding pattern resulted in an average methane yield of 74 ± 8.5% and an effluent COD removal efficiency of 89 ± 2.8%, which is comparable to the reactor operated under a continuous feeding pattern (Methane yield of 72 ± 2.4% and a COD removal efficiency of 87 ± 7.7%). Interestingly, as compared to continuous operation, reactors experienced starvation/feast stress (i.e., semi-continuous feeding) developed significantly higher methanogenic activities once continuous feeding was presumed, with dominant methanogens shifted from Methanosaeta in continuous feeding UASB to Methanosarcina in reactors undergone semi-continuous feeding. It was concluded that reactor feeding strategies can significantly impact microbiome communities in UASB, and an alternate feeding pattern is preferred, as compared to semi-continuous operation when reactor feeding cannot be continuously supplied.

Enhancing methane production from food waste with iron-carbon micro-electrolysis in a two-stage process

A two-stage process, consisting of a leach-bed reactor (LBR) and an up-flow anaerobic sludge blanket reactor (UASB), has been commonly adopted to improve food waste anaerobic digestion. However, its application is limited due to low hydrolysis and methanogenesis efficiencies. This study proposed a strategy of incorporating iron-carbon micro-electrolysis (ICME) into the UASB and recirculating its effluent to the LBR to improve the two-stage process efficiency. Results showed that the integration of the ICME with the UASB significantly increased the CH4 yield by 168.29%. The improvement of the food waste hydrolysis in the LBR mainly contributed to the enhanced CH4 yield (approximately 94.5%). The enrichment of hydrolytic-acidogenic bacterial activity, facilitated by the Fe2+ generated through ICME, might be the primary cause of the improved food waste hydrolysis. Moreover, ICME enriched the growth of hydrogenotrophic methanogens and stimulated the hydrogenotrophic methanogenesis pathway in the UASB, contributing partially to the enhanced CH4 yield.

Application of the Hybrid Chemical-Biocatalytic Approach for Conversion of Nitrocellulose-Containing Sewage Sludge

Waste containing explosive chemicals are hazardous to the environment. We suggested and implemented a hybrid approach for the destruction of nitrocellulose-containing sewage sludge (NCS) from a real chemical industrial complex. Combining chemical alkaline hydrolysis and mesophilic anaerobic digestion in a up-flow anaerobic sludge blanket (UASB) reactor allowed us to successfully achieve the balance between the environmental safety and economic efficiency of the stages of the treatment. After the alkaline treatment of waste at 50 °C with 1.5 M KOH, the solid residue contained mostly just sand and no nitrocellulose (NC). The liquid phase accumulated 2869 ± 24 mg N-NO2−/L and 1698 ± 51 mg N-NO3−/L. Bioconversion of the liquid phase neutralized with acetic acid and diluted with water by a factor of 50 in a 1 L UASB reactor ensured 99% efficiency of extracting N(NO2− + NO3−) and chemical oxygen demand (COD). Further, biogas with high methane content (>70%) was obtained. The establishment of the operational regime in the UASB reactor was achieved in two stages. The suggested hybrid approach to denitrification and methanogenesis is aimed at implementing the sustainable development concept in industrial chemical cycles. The results of this study are significant for researchers and technologists interested in developing hybrid processes for waste treatment that involve chemical catalysis as the first stage.

Performance of a Series of Polishing Ponds in the Treatment of Sanitary Sewage

The main objective of this research was to evaluate the functioning of a system of polishing ponds on a pilot scale in the post-treatment of urban sewage discharged from an up-flow anaerobic sludge blanket reactor and followed by a submerged aerated filter. The following variables were analyzed: transparency, temperature, dissolved oxygen (DO), pH, alkalinity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammonia (NH3), organic nitrogen, nitrate (N-NO3), total phosphorus (TP), orthophosphate (PO43-), total suspended solids (TSS) and chlorophylla. In addition, the planktonic communities were also identified and quantified. During the study period, the pond system registered the following mean and standard deviation of the removal efficiencies: 32.9±31.7% of BOD, 26.5±33.9% of COD, and 29.0±49.6% of TSS; good performance was observed in the removal of nitrogen compounds, and the following results were obtained: 58.4±28.1%, 87.5±15.4%, 24.4±42.6%, and 9.4±51.8%, respectively for TKN, NH3, organic nitrogen, and N-NO3; and 26.9±25.8 of TP and 34.3±32.7% of PO4 3-. During the research period, the planktonic community was represented by the following classes: Chlorophyceae, Euglenophyceae, Cyanobacteria, Cryptophyceae, Zygnemaphyceae, Chrysophyceae, and Dinophyceae; concurrently, the zooplankton registered low densities and was represented by the Rotiferous, Copepod, and Cladocera groups. The results help us understand the performance of polishing ponds in treating sanitary effluents.

Culturing partial-denitrification (PD) granules in continuous flow reactor with waste sludge as inoculum: performance, granular sludge characteristics and microbial community

ABSTRACT Partial denitrification granular sludge (PDGS) can provide long-term stable nitrite for anaerobic ammonia oxidation (anammox). The cultivation of ordinary activated sludge from wastewater treatment plants into PDGS can further promote the application of PD in practical engineering. In this study, the feasibility of fast start-up of PDGS was explored by inoculating waste sludge in up-flow anaerobic sludge blanket (UASB) reactor with synergistic control of nitrogen load rate (NLR, 0.05–0.65 kg N/m3/d) and electron donor starvation (EDS) (240–168 mg L−1), and system performance, particle characteristics and microbial structure were studied. The results showed that PD-UASB started successfully within 48 days, the average nitrite accumulation rate (NTR) and nitrate removal ratio (NRR) reached 79.6% and 82.5% after successful initiation, accompanied by high abundance of PD bacteria (Thauera, Pseudomonas, unclassflied commamonadaceae and Limnobacter) (25.3%). The increase of PD activity, and the difference between nitrate reductase (NAR) and nitrite reductase (NIR) contributed to nitrite production. Besides, the sludge shifted from flocculated (≤0.5 mm, 95.37%) to granulated state (0.5–2 mm, 64.74%), which could be due to the increase of extracellular polymers (EPS) (especially T-EPS) and metabolism of specific microorganisms (Bacteroidota and Chloroflexi, 19.92%). Good sludge granulation promoted the settleability of PD (the SVI5 was 47.248 mL/ g. ss after successful start-up). In summary, good PD sludge granulation process could be achieved in a short time by synergistically controlling NLR and EDS.

Demand-driven biogas production from Upflow Anaerobic Sludge Blanket (UASB) reactors to balance the power grid

Future energy systems necessitate dispatchable renewable energy to balance electrical grids with high shares of intermittent renewables. Biogas from anaerobic digestion (AD) can generate electricity on-demand. High-rate methanogenic reactors, such as the Upflow Anaerobic Sludge Blanket (UASB), can react quicker to variations in feeding as compared to traditional AD systems. In this study, experimental trials validated the feasibility of operating the UASB in a demand-driven manner. The UASB was operated with leachate produced from a hydrolysis reactor treating grass silage. The UASB demonstrated a high degree of flexibility in responding to variable feeding regimes. The intra-day biogas production rate could be increased by up to 123% under 4 hours in demand-driven operation, without significant deterioration in performance. A model based on kinetic analysis was developed to help align demand-driven operation with the grid. The findings suggest significant opportunities for UASBs to provide positive and negative balance to the power grid.

Evaluation of the effect of copper on the restart of a novel combined two‐stage anaerobic digester

AbstractThe performance of the modified upflow anaerobic sludge blanket (MUASB) reactor–static granular bed reactor (SGBR) series was evaluated during the restart after a starvation period of 6 months. The steady‐state chemical oxygen demand (COD) removal of the reactor series obtained during the restart with copper was 98 ± 1.96% with the corresponding biogas production and copper removal of 0.218‐m3/kg CODdigested and 81.5%, respectively. Even though the biogas production of the reactor series with copper decreased because of the inhibitory effect of the accumulated copper on the methanogens, the reactor series was maintained stable throughout the operation with the effluent characteristics well within the discharge standards. The resumption of feed after starvation was sufficient for the recovery of the biomass from a dormant to an active state when operated with and without copper. The restart of the reactor series with copper was achieved in 35 days, indicating robustness and sustainability even after starvation.

Bioenergy Recovery from Anaerobic Co-Digestion of Sugarcane Vinasse and Dairy Cattle Wastewater in Two Up-Flow Anaerobic Sludge Blanket Reactors in Series

Bioenergy Recovery from Anaerobic Co-Digestion of Sugarcane Vinasse and Dairy Cattle Wastewater in Two Up-Flow Anaerobic Sludge Blanket Reactors in Series