Anaerobic Batch Reactor Research Articles

Efficacy of magnetite (Fe3O4) nanoparticles for enhancing solid-state anaerobic co-digestion: Focus on reactor performance and retention time

The influence of magnetite nanoparticle (nFe3O4) concentrations (20, 50, and 75 mg/L) on reactor performance and retention time was investigated for the first time in an initially upset solid-state anaerobic batch (SSAB) reactor. nFe3O4 mitigated acidification threat, enhanced reactor stability, ensured rapid volatile fatty acids bioconversion, and modified microbial community. The impacts reduced retention time by 27 days relative to the control. Of the nFe3O4 concentrations, 20 mg/L had the highest hemicellulose degradation (93%) and methane yield (191.2 L/kg VS) with no threat to anaerobic microbes. Besides, existing kinetic models, novel models equally well-described methane yield with low root mean square errors (RMSE) < 1.2 and high coefficients of determination (R2) > 98%, therefore could be used for downstream applications. This study provides useful information on the impact of nFe3O4 on reactor stability and reactor performance in an initially upset SSAB reactor.

Enhanced syntrophic propionate degradation and methane production by granular activated carbon in AnSBR

Syntrophic degradation of propionate has been regarded as a limiting factor for methane formation in anaerobic digestion (AD) processes, due to its easier production but harder degradation than other volatile fatty acids. In the present study, 20 g/L granular activated carbon (GAC) was introduced into an anaerobic sequence batch reactor (AnSBR) and the enhancement of propionate degradation and methane production was evaluated with another AnSBR without GAC as a control. Inoculated with the same excess activated sludge, both AnSBRs were synchronously started up at 35 °C with the fed propionate increased gradually from the initial 340 mg/L to the final 1700 mg/L. The results showed that the introduction of GAC made the AnSBR get steady state 6 days earlier. With the fed propionate of about 1700 mg/L in the steady state, the average specific methane production and biomass was enhanced from 0.20 to 0.25 L/L·d, and 7.72 to7.96 g/L, respectively, by the introduced GAC. The results suggested that the GAC had functioned in stimulating microbial growth and enhancing direct interspecies electron transfer between hydrogen-producing acetogens and methanogens, which had resulted in the enhanced propionate degradation and methane production.

Integrated Anaerobic-Aerobic Sequencing Batch Reactors for Unrestricted Reuse Using Greywater Treatment

This work is carried out to evaluate the efficiency of the pilot scale integrated scheme which comprises of an Anaerobic Sequence Batch Reactor (AnSBR) reactor, Aerobic Sequence Batch Reactor (ASBR), and sand filter for the elimination of organic matter and nutrient in synthetic greywater. The treatment effectiveness of the pilot plant was identified based on its pollutant removal efficiency for 12 months. The AnSBR removes 49.64, 64.24, 55.35, 87.82, 54.36, 32.73, 72.61, 34.88, and 72.11% of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Nitrogen (TN), anionic surfactant, Total Phosphorous (TP), Ammonium Nitrogen (NH4+-N), Total Suspended Solids (TSS), Nitrate Nitrogen (NO3--N) and sulphates, respectively. Moreover, the removal efficiencies are improved to 84.27, 86.04, 80.8, 95.13, 80.55, 90.23, 72.98, and 75.45%, respectively, in the ASBR with an additional aeration period. The removal efficiencies of COD, BOD, TN, anionic surfactant, TP, TSS, NH4+-N, NO3--N, and sulphates have been improved progressively to 89.12, 94.9, 85.15, 99, 86.98, 88.54, 93.52, 94.89, and 80.49%, respectively in the sand filter. In tracer studies, that a total of 29.3% of the salt has been remained in the reactor which suggests a good deal of salt of the integrated system. Furthermore, this hydrodynamic study discloses a moderately low volume (30.3%) for the integrated system with the mean residence time is lesser than theoretical hydraulic residential time. Based on these findings, it is evident that the integrated anaerobic-aerobic system bounded with the sand filter process accomplishes the achievement of efficiency.

Solubilization of Heavy Metals during Anaerobic Digestion of Sewage Sludge Using Acidogenesis

Sewage sludge produced by many municipal wastewater treatment plants contains various heavy metals that limit its use on agricultural land. The existing treatment processes for removing heavy metals are not cost-effective or eco-friendly due to the requirement of aeration or the use of various harmful leaching agents. This paper explores the solubilization of heavy metals present in the sewage sludge using the acidogenesis phase of the anaerobic digestion process without using any harmful compounds. To achieve this objective, an anaerobic batch reactor was used, in which sewage sludge was added with different solid concentrations and carbon source (glucose) concentrations. During this process, volatile fatty acids were produced, which decreased the pH of the system. The maximum decrease in the pH was observed in the reactor that had the maximum glucose concentration and the minimum total solid concentration. In this reactor, the pH dropped below 4.5. The solubilization of heavy metals was observed as Zn: 41% (333 mg/kg), Ni: 31% (8.5 mg/kg), Cr: 30% (13 mg/kg), Pb: 29% (11 mg/kg), Co: 28% (1.4 mg/kg), and Cd: 27% (0.5 mg/kg).

Optimizing anammox capacity for weak wastewater in an AnSBBR using aerobic activated sludge as inoculation

Process optimization is essential for improving the efficiency of anaerobic ammonium oxidation (anammox) process in a practical application. In this study, an anaerobic sequence biofilm batch reactor (AnSBBR) inoculated with aerobic activated sludge was chosen as an efficient mainstream anammox reactor for treating low-nitrogen wastewater. To optimize the AnSBBR-anammox process, eight different operation stages lasting for a total of 215 days were conducted by regulating key process parameters. Principal components analysis revealed significant effects of the substrate ratio (SR) and volumetric exchange ratio (VER) on anammox performance, while other parameters (cycle time, hydraulic retention time and nitrogen loading rate) played minor roles. The highest removal efficiencies for ammonia and total nitrogen, respectively, reached 99.8% and 95.3% under optimal conditions. High-throughput sequencing found the anammox species Candidatus Brocadia and Candidatus Kuenenia made up as much as 8.5% and 3.5%, respectively, of the microbial community. Redundancy analysis indicated that these taxa were also greatly influenced by operating parameters, particularly SR and VER. This research helps to decode the correlations among nitrogen removal capacity, process parameters and the microbial community to enhance anammox in an AnSBBR system.

Stream Monitoring and Preliminary Co-Treatment of Acid Mine Drainage and Municipal Wastewater along Dunkard Creek Area

This study investigated coal-mine drainage (AMD) and municipal wastewater (MWW) contaminant concentrations and conducted the combined treatment in phases I and II: phase I, evaluating effects of mixing the two based on extent of acid neutralization and metals removal; phase II: conducting anaerobic batch reactor treatment of AMD and MWW under varying COD/sulfate ratios (0.04-5.0). In phase I, acid mine drainage water quality conditions are as follows: pH 4.5, acidity 467.5 mg/L as CaCO3, alkalinity 96.0 mg/L as CaCO3, Cl- 11.8 mg/L, SO42- 1722 mg/L, TDS 2757.5 mg/L, TSS 9.8 mg/L, BOD 14.7 mg/L, Fe 138.1 mg/L, Mg 110.8 mg/L. Mn 7.5 mg/L, Al 8.1 mg/L, Na 114.2 mg/L, and Ca 233.5 mg/L. Results of the mixing experiments indicated significant removal of selected metals (Fe 85~98%, Mg 0~65%, Mn 63~89%, Al 98~99%, Na 0~30%), acidity (77~95%) from the mine water and pH was raised to above 6.3. The Phase II results suggested under the wide range of COD/sulfate ratios, COD and sulfate removal varied from 37.4%-100% and 0%-93.5% respectively. During biological treatment, alkalinity was generated which leads to pH increase to around 7.6-8.5. The results suggested feasibility of the proposed technology for co-treatment of AMD and MWW. A conceptual design of co-treatment system which is expected to remove a matrix of pollutants has been provided to utilize all the locally available water resources to achieve the optimum treatment efficiency. The technology also offers an opportunity to significantly reduce capital and operating costs compared to the existing treatment methodologies used.

Biohydrogen and biogas production from mashed and powdered vegetable residues by an enriched microflora in dark fermentation

This study conducted the utilization of vegetable residues by an enriched microflora inoculum to produce biohydrogen via anaerobic batch reactor. Dark fermentation processes were carried out with 3 kinds of vegetable residue substrates including broccoli (Brassica oleracea var. italica.), onion (Alium cepa Linn.), and sweet potato (Ipomoea batatas (L.) Lam). Vegetable wastes were pretreated into 2 forms, i.e. mashed and powdered vegetable, prior to the fermentation. The substrate used for the biohydrogen production were vegetable residues and inoculum at the vegetable residues/inoculum ratio of 1:1 (based on TS). The digestion processes were performed under 120 rpm speed of shaking bottle in the incubator with control temperature of 35๐C. In this work, the maximum hydrogen production was achieved by anaerobic digestion at mashed onion with bioreactor inoculum that produced total hydrogen of 424.1 mL H2 with hydrogen yield and hydrogen concentration of 151.67 mL H2/g VSadded and 43.54%, respectively. In addition, the hydrogen production continues took only 7 days for the vegetables blended with the bioreactor inoculum. Finally, it was found that the high potential of degradation of vegetable wastes an enriched microflora in dark fermentation also showed alternative solution to eliminate agricultural wastes to produce green energy.

Electric Field-Driven Direct Interspecies Electron Transfer for Bioelectrochemical Methane Production from Fermentable and Non-Fermentable Substrates

The bioelectrochemical methane production from acetate as a non-fermentable substrate, glucose as a fermentable substrate, and their mixture were investigated in an anaerobic sequential batch reactor exposed to an electric field. The electric field enriched the bulk solution with exoelectrogenic bacteria (EEB) and electrotrophic methanogenic archaea, and promoted direct interspecies electron transfer (DIET) for methane production. However, bioelectrochemical methane production was dependent on the substrate characteristics. For acetate as the substrate, the main electron transfer pathway for methane production was DIET, which significantly improved methane yield up to 305.1 mL/g chemical oxygen demand removed (CODr), 77.3% higher than that in control without the electric field. For glucose, substrate competition between EEB and fermenting bacteria reduced the contribution of DIET to methane production, resulting in the methane yield of 288.0 mL/g CODr, slightly lower than that of acetate. In the mixture of acetate and glucose, the contribution of DIET to methane production was less than that of the single substrate, acetate or glucose, due to the increase in the electron equivalent for microbial growth. The findings provide a better understanding of electron transfer pathways, biomass growth, and electron transfer losses depending on the properties of substrates in bioelectrochemical methane production.

High Efficiency of Food Waste Fermentation and Biohydrogen Production in Experimental-industrial Anaerobic Batch Reactor

Background: Multicomponent organic waste is a significant environment hazard. Natural mechanisms can no longer ensure the processing of increasing volumes of such waste. The accumulation of multicomponent organic waste to environment pollution with toxic gases and leachate. Therefore, there is an urgent need to develop cost-effective technologies for the rapid treatment of huge volumes of toxic waste. Moreover, multicomponent organic waste can be used as the substrate for the production of green energy - biohydrogen. Objective: To scale up the technology of biohydrogen production from multicomponent organic waste in experimental-industrial anaerobic batch reactor and to establish fermentation parameters of its operation. Methods: An experimental-industrial anaerobic batch reactor was designed and the method of thermodynamic prognosis was applied to determine the most effective microbial pathway for hydrogen synthesis. The efficiency of the fermentation was evaluated by the pH and redox potential (Eh, mV) of culture medium, the concentration and volume of synthesized gas. Results: The experimental-industrial anaerobic batch reactor with a volume of 240 L was successfully applied to scale up the process of obtaining hydrogen via fermentation of organics. The duration of the technological cycle (T) was 1.5-4 days. The coefficient of waste destruction (Kd) that is the ratio between the initial and final weight of waste was high and ranged from 86 to 140. Hydrogen yield was 45-90 L/kg of dry weight of waste. The maximum concentration of hydrogen (H2max) was 50-58%. Conclusion: The developed approach and scaling of the biotechnology is promising for industrial application for effective hydrogen production via dark fermentation of multicomponent organic waste. Its industrial application might help to solve the problem of toxic multicomponent organic waste destruction and simultaneously to produce green energy H2.

Effect of different vegetable wastes on the performance of volatile fatty acids production by anaerobic fermentation

Volatile fatty acids (VFAs) are intermediates of anaerobic fermentation with high value and wide range of usage. VFA production from vegetable wastes (VW) is an effective way to dispose of wastes and recover resources. The organic matter composition of the substrate influences VFA yield and distribution, which is related to the separation and purification of the downstream steps and the application of the product. Hence, potato peels, carrots, celery, and Chinese cabbage were selected to investigate the effect of VW types on the performance of the VFA production in a batch anaerobic fermentation reactor with continuous stirring at 37 °C, total solid (TS) of 4.5%. A VFA yield of 452 mg COD/g VSfeed (chemical oxygen demand (COD); volatile solids (VS)) was achieved from potato peels, which was 40.1%, 21.5%, and 124.9% higher than that of carrots, celery, and Chinese cabbage, respectively. The rapid acidification of carrots caused a sharp decline in pH and led to inhibition of VFA production. The acidification of celery started slowly, and the yield of hexanoic acid increased rapidly in the later stage of fermentation. The VFA yield of Chinese cabbage was inhibited due to the low initial pH, but the ethanol concentration reached 7577.04 mg COD/L. According to the VFA profile, the fermentation of potato peels, carrots, celery, and Chinese cabbage can be classified as propionate-type, butyrate-type, mixed-acid type, and ethanol-acetate type metabolic pathway, respectively. The results of this study suggest that a suitable combination of vegetable waste types is important for selective VFA production.

Effects of different forms of vegetable waste on biogas and methane production performances in a batch anaerobic digestion reactor

ABSTRACT Vegetable waste has a high biodegradation ability and moisture content and causes soil and underground water pollution. High moisture vegetable waste could be separated into juice and residual material for efficient disposal and energy recovery by anaerobic digestion (AD). In this study, two kinds of vegetables (Chinese cabbage and mustard) wastes in three different forms (juice, residue, and their mixture) were used to determine their AD process performances and methane production potential. The results showed that the biogas production rate of the Chinese cabbage residue (CR) was the highest, reaching 800 ± 62 mL/g VS. The biogas production rate of mustard juice (MJ) was the lowest, as low as 498 ± 60 mL/g VS. The results also suggested that the biogas and methane production potential in the residue groups of both vegetable wastes treatments was higher than that in the juice groups. Furthermore, the results also showed that the average biogas and methane production rates of the residue treatments of both Chinese cabbage and mustard wastes were much higher than those of their mixtures. The concentrations of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN) in the juice treatments groups were much higher than those in the residue treatments groups, resulting in the lowest biogas and methane production potential being in the juice treatments groups. With the modified Gompertz equation fitting analysis, the results also confirmed that the highest biogas and methane production ability in the CR treatment groups among all the six treatments, with a correlation coefficient (R2) above 0.992. The results of this study provide new insights into the efficient disposal and energy recovery of vegetable wastes with AD for further industrial biogas engineering applications.

ALLODUST augmented activated sludge single batch anaerobic reactor (AS-SBAnR) for high concentration nitrate removal from agricultural wastewater

Nitrate is among the most widespread contaminants that threaten water bodies and waterways. Under favourable environmental conditions, high nitrate concentrations in water can contribute to eutrophication, thus presenting a high potential for risk to ecosystems and human health. Low-cost allophanic soil material and carbon-based bio-wastes have great potential to reduce nutrient concentrations from contaminated waters. This study investigated the mechanisms that underpin the reduction of nitrate concentrations and nitrous oxide (N2O) emission in the presence of novel developed media in an activated sludge process. A new operating approach, employing a newly developed media (ALLODUST), was evaluated for enhanced NO−3-N removal from agricultural wastewater. Two anaerobic-aerobic batch reactors were developed, where the coupled bottom aeration method was used for efficient agitation and aeration in the aerobic reactor. The reactor was run at high NO−3-N concentrations (110 mg L−1), under anoxic conditions at low- to long-term contact times (2, 12, and 22 h), while the aerobic period (clarification) was constant for all the experimental designs (2 h). ALLODUST retained its integrity and stability over the long-term operation. Low ALLODUST concentrations (5.95 g L−1) removed 87% of the NO−3-N from the wastewater within 12 h. Further exploration revealed that the same amount of the media was optimal for decreasing N2O emissions from the anaerobic activated sludge reactor by 80%.

1,3-Propanediol production from glycerol in polyurethane foam containing anaerobic reactors: performance and biomass cultivation and retention.

The use of batch and upflow anaerobic reactors filled with polyurethane foam for pure glycerol fermentation was evaluated. The best reactor operational conditions to obtain high yield and productivity of 1,3-propanediol (1,3-PDO) as the main product and the role of the polyurethane foam in the growth and retention of suspended and attached biomass in the reactors were investigated. In the experiment at 30°C with a batch reactor (700mL), biomass growth was mostly as immobilized attached cells, and the achieved 1,3-PDO yield was up to 0.58molmol-gly-1. In the experiment (30°C) with an upflow anaerobic reactor (717mL), glycerol loading rates (gly-LR) ranging from 6.94 to 15.47g glyL-1day-1 were applied during a 102-day period. During the operation, average 1,3-PDO yield was 0.47molmol-gly-1, reaching a maximum of 0.51molmol-gly-1 at gly-LR of 13.57g glyL-1day-1. High 1,3-PDO productivity (5.35 to 5.44gL-1day-1) was obtained when gly-LR was 13.57 to 15.47g glyL-1day-1. Comparing the close yield values in both batch and continuous reactors and based on microbial evaluation, it is concluded that most of the 1,3-PDO generated in the continuous reactor was due to the suspended biomass retained by the foam cubes. The Clostridium genus was the predominant 1,3-PDO producer. Good yields and productivities with packed reactors were attributed to polyurethane foam used for mixed culture growth and retention. Consequently, they are worth considering for 1,3-PDO production from pure glycerol.

Removal of tetramethylammonium hydroxide (TMAH) from thin-film transistor liquid crystal display (TFT-LCD) industry wastewater by hydrolysis acidification-aerobic and anaerobic processes

Tetramethylammonium Hydroxide (TMAH) is widely used as a developer in the thin-film transistor liquid crystal display (TFT-LCD) industry, which is a corrosive alkaline and neuronal toxic compound. In this study, the performances of combined hydrolysis acidification-aerobic and anaerobic batch reactors for synthetic TMAH wastewater treatment were evaluated. It also investigated the real TMAH wastewater treatment in the anaerobic batch reactor. The batch tests focused on the removal efficiencies and intermediate products of TMAH biodegradation during different processes. Furthermore, microbial community structures were identified. The long-term monitoring of 380 days results demonstrated that TMAH degraded can be stably achieved by hydrolysis acidification-aerobic and anaerobic processes, and the total organic carbon removal efficiencies were both higher than 91%. The pretreatment by hydrolysis acidification process could avoid the inhibition of high concentration TMAH on subsequent aerobic treatment. Main intermediate products during the hydrolysis acidification-aerobic and anaerobic treatments included trimethylamine, dimethylamine, monomethylamine, which can be degraded easily by biotreatment. Consequently, nearly 70% organic nitrogen in the influent TMAH transferred to ammonium or nitrate, while the mineralization of intermediates caused methane and carbon dioxide generation. The study also proposed TMAH degradation pathways by different processes based on the intermediate’s identification. Analysis of 16s rRNA gene sequencing revealed that mixed microbe contributed in TMAH degradation. At the phylum level, proteobacteria and bacteroidetes were abundant in all the reactors. Besides, patescibateria, cloacimonetes and acidobacteria were dominant in anaerobic reactors as well. This study suggests that traditional combined or single activated sludge processes could be used for TMAH-containing wastewater treatment. Especially, anaerobic process may be favored over other processes.

Biological treatment of a brominated micropollutant α-hexabromocyclododecane (α-HBCDD) from a raw hospital wastewater

The brominated micropollutants were not removed with conventional biological treatment processes. In this study it was aimed to treat the α-HBCDD which is a hydrophobic organic substance using a sequential treatment process consisting from an upflow anaerobic batch reactor (UASB) and a completely stirred tank reactor (CSTR) since α-HBCDD is a hydrophobic brominated micropollutant and its removals was very low under long retention times in anaerobic sediments (in monitored natural attenuation environments) and under aerobic stimulated environments (in conditions adding limiting nutrient and electron acceptors for support the microorganisms growth), separately, a sequential anaerobic/aerobic reactor system proses was choosen. The anaerobic and aerobic removals of α-HBCDD were 7% and 12%, respectively, at a SRT of 55 days. The effects of SRTs on α-HBCDD and its metabolite removals was investigated. The yields increased as the SRT was increased from 5 days up to 55 days. The total α-HBCDD yields in the whole sequential biological system was recorded as 18,3%. The metabolite of α-HBCDD is α2-Bromocyclododecan-1-ol (2-BCD). This metabolite was produced under anaerobic conditions and it was removed in aerobic reactor with a yield of 17% at 55 days SRT. The maximum 2-BCD removal efficiency was 63,6% in the sequential reactor process.

Characterization and evaluation of biogas generation of Arba Minch Town slaughterhouse wastewater, Ethiopia

Abstract This study was carried out to characterize raw and treated Arba Minch town slaughterhouse wastewater and to assess its methane generation potential with lab-scale anaerobic batch reactors. The methane was collected by downward displacement of an alkaline water column. The methane generation potential of the slaughterhouse wastewater was 270.6 mL methane per gram of volatile solids at hydraulic retention time (HRT) of 20 days at 37 °C. The organic loading rate was 0.48 g and the organic matter removal efficiency of the reactor was COD (93.5%), BOD5 (88.5%), and TVS (94.7%). The result demonstrated that installation of a biogas reactor to treat slaughterhouse wastewater can recover methane, reduce pollutants and protect the environment. The result can be a demonstration for untreated slaughterhouse wastewaters in developing countries like Arba Minch Town to use anaerobic treatment and supplement their scarce energy options.

Red mud-based inorganic polymer spheres: Innovative and environmentally friendly anaerobic digestion enhancers

Red mud-based inorganic polymer spheres were used as alternative pH regulators and process enhancers in sequencing batch anaerobic reactors treating cheese whey. This byproduct tends to quickly acidify under anaerobic conditions, and the common route to control pH and ensure suitable conditions for methane production involves the use of commercial alkaline raw materials. The spheres were synthesized using significant amounts of hazardous and toxic waste, red mud (50 wt% of solid components), whose recycling is challenging. The inorganic polymeric spheres, when compared to virgin alkaline raw materials, improved organic matter removal by 44%, prevented VFA accumulation (acidification degree less than 20%), maintained pH values in a range (6.5–7.2) to ensure maximum methanogenic activity by archaea microorganisms, and boosted the methane volume by ~90%. These promising results demonstrate the feasibility and performance advantages of using these innovative spheres instead of virgin raw materials, which is an important tool towards sustainable development.

Effects of temperature, proportion and organic loading rate on the performance of anaerobic digestion of food waste

In Brazil, a significant amount of organic waste is produced in households and restaurants. This study thus aimed to determine the ideal conditions for generating methane from the treatment of household waste by anaerobic digestion, under mesophilic (37 °C) and thermophilic (55 °C) conditions, to determine the maximum organic loading rate (OLR) in the reactors, and to evaluate kinetic parameters by statistical models: Modified Gompertz, First-Order, Logistic and Transference functions. The experiments were conducted in anaerobic batch reactors. Different proportions of pre-prepared waste (PPW)/leftover waste (LW) were used: 100/0, 75/25, 50/50, 25/75, and 0/100 and different ORL: 0.15; 0.30; 0.45; 0.60; and 0.90 g TVS (Total Volatile Solids).L−1.d−1. For both conditions, the optimal proportions of PPW/LW were 100/0 and 75/25 %. Under mesophilic condition, the best results were observed (869 mL of CH4.g TVS−1). The maximum organic load was 0.30 g TVS.L−1.d−1. The best data adjustment was performed by the Transference function.

Effect of Electrostatic Field Strength on Bioelectrochemical Nitrogen Removal from Nitrogen-Rich Wastewater

The effect of electrostatic fields on the bioelectrochemical removal of ammonium and nitrite from nitrogen-rich wastewater was investigated at strengths ranging from 0.2 to 0.67 V/cm in bioelectrochemical anaerobic batch reactors. The electrostatic field enriched the bulk solution with electroactive bacteria, including ammonium oxidizing exoelectrogens (AOE) and denitritating electrotrophs (DNE). The electroactive bacteria removed ammonium and nitrite simultaneously with alkalinity consumption through biological direct interspecies electron transfer (DIET) in the bulk solution. However, the total nitrogen (ammonium and nitrite) removal rate increased from 106.1 to 166.3 mg N/g volatile suspended solids (VSS).d as the electrostatic field strength increased from 0.2 to 0.67 V/cm. In the cyclic voltammogram, the redox peaks corresponding to the activities of AOE and DNE increased as the strength of the electrostatic field increased. Based on the microbial taxonomic profiling, the dominant genera involved in the bioelectrochemical nitrogen removal were identified as Pseudomonas, Petrimonas, DQ677001_g, Thiopseudomonas, Lentimicrobium, and Porphyromonadaceae_uc. This suggests that the electrostatic field of 0.67 V/cm significantly improves the bioelectrochemical nitrogen removal by enriching the bulk solution with AOE and DNE and promoting the biological DIET between them.

RESPONSE FROM ANAEROBIC DIGESTION OF LAYING HEN MANURE WITH BIOCHAR ADDITION

ABSTRACT This study aimed to assess the anaerobic digestion response of laying hen manure with different inclusion levels of biochar in batch reactors as measured by physicochemical parameters, biogas production and digestate quality. Four levels of biochar inclusions (0, 2.5, 5.0 and 7.5%) were tested with 3 replicates each. Twelve two-liter anaerobic batch reactors were used for 86 days at 35°C. Substrate and digestate of each treatment were assessed for monitored parameters, biogas production and digestate quality. Increased levels (0, 2.5, 5.0 and 7.5%) of biochar were found to gradually reduce total ammonia nitrogen (1794.33, 140.84, 950.81 and 509.32 mg.L-1, respectively). Despite the positive effect of biochar to accelerate initial biogas production, its use at any inclusion rate did not contribute significantly to biogas production in terms of biogas yield or digestate quality as compared to control treatment.