Organic Loading Rate Conditions Research Articles

Metabolic effects of Fe0 on simultaneously eliminating excessive acidification and upgrading biogas in mesophilic or thermophilic anaerobic reactor

Excessive acidification and low methane (CH4) percentage are technical challenges restricting anaerobic digestion (AD) of kitchen waste, especially under high organic loading rate (OLR) conditions. Although the contribution of Fe0 powder to excessive acidification elimination and CH4 yield improvement in mesophilic AD (MAD) has been extensively reported, its impact on the thermophilic AD (TAD) process with more frequent excessive acidification problem is rarely studied. Moreover, the difference in microbial interactions and metabolic pathways between MAD and TAD reactors under Fe0 regulation was still unclear. In this study, we compared the performance of Fe0 dosing on excessive acidification elimination and biogas upgrading quality in both MAD and TAD reactors at different OLRs. The results showed that compared with excessive acidification or low CH4 percentage (less than 70%) in control reactors without Fe0 addition, the CH4 yield of MAD and TAD reactors with addition of Fe0 at OLR of 35 gVS/L were 470.88 mLCH4/gVS and 270.40 mLCH4/gVS, with higher CH4 composition of 81.32%–82.23% and 83.68%–88.48% respectively. Microbial diversity analysis showed a sharp distinction between MAD and TAD reactors with addition of Fe0. Analyses of co-occurrence networks and metabolic pathway presented hydrogenotrophic methanogenic pathway, in addition to acetoclastic methanogenesis, was dominant in MAD reactors as results of enhanced interspecies hydrogen transfer between Methanoculleus and some hydrogen producers, especially under high OLR condition. In contrast, syntrophilic acetate oxidization - hydrogenotrophic methanogenesis, which dominated by Methanothermobacter and Alkaliphilus or Pelotomaculum, was the sole methanogenic pathway in TAD reactors. The results will shed lights on the regulation mechanisms of Fe0 in AD of kitchen waste under mesophilic and thermophilic conditions, offering new insight into development of more efficient waste to energy conversion technologies.

Treating Tapioca Starch Industrial Wastewater Using Two-Phase Multi-Staged Up-Flow Anaerobic Sludge Blanket (MS-UASB)

A laboratory-scale, two-phase multi-staged up-flow anaerobic sludge blanket (MS-UASB) treatment system was monitored over time in order to evaluate its treatment efficiency and performance when treating non-diluted industrial tapioca starch wastewater under ambient temperature in Thailand. The system consisted of an acidification (AC) reactor and MS-UASB reactor and was operated for 280 days. The two-phase MS-UASB achieved a maximum organic loading rate (OLR) of 8 kg-COD/m3/day for the overall system and reached 80.5% of chemical oxygen demand (COD) removal efficiency. Based on the inlet wastewater of each reactor, the AC reactor removed 61.85% of suspended solids and achieved acidification of the wastewater to produce volatile fatty acids at over 50%. Meanwhile, the MS-UASB reactor achieved 74.5% COD removal efficiency. Further analysis found that the increase in soluble extracellular polymeric substances per bound extracellular polymeric substances (S-EPS/B-EPS) was related to the floating sludge phenomenon, which occurred under excess OLR condition.

Do increased organic loading rates accelerate aerobic granulation in hypersaline environment?

It is a common sense that high organic loading rate (OLR) leads to the faster formation of aerobic granular sludge (AGS), while the effects of increased OLR on the direct development of salt-tolerant aerobic granular sludge (SAGS) in hypersaline wastewater is still unknown. In this study, four identical sequencing batch reactors (SBRs) were directly fed with 3% salinity wastewater and operated at different OLRs to cultivate SAGS. Granules firstly appeared on Day 10, 7, 5, and 8, and dominated on Day 23, 16, 10, and 13 in four SBRs operated under OLR of 2.4, 3.6, 4.8, and 7.2 kg COD/m3·d, respectively. The former three granules matured on Day 29 (D50 of 550 µm), 25 (D50 of 639 µm), and 25 (D50 of 808 µm), respectively, while the loose and fluffy filamentous granules cultivated under the highest OLR failed to reach the traditional criterion of AGS. Overall, increased OLR could accelerate the formation of AGS that had larger sizes and lower microbial diversities. However, unlike salt-free wastewater, the appropriate OLR for rapid formation of compact AGS in hypersaline wastewater was only 3.6 kg COD/m3·d, since the higher OLRs with higher hydraulic selection pressure led to the massive sludge loss and the formation of instable fluffy granules during granulation period. Bacterial community analysis revealed Corynebacterium, Marinobacterium, Paracoccus, Halomonas, and Vibrio were the main genera in four SBRs, in which Corynebacterium had certain abundance at all OLRs, and Vibrio and Paracoccus favored low OLR, while Halomonas and Marinobacterium dominated the SBRs with high OLRs. This study contributed to a better understanding of SAGS granulation under different OLR conditions in hypersaline wastewater.

Efficient aerobic granular sludge production in simultaneous feeding and drawing sequencing batch reactors fed with low-strength municipal wastewater under high organic loading rate conditions

To establish rapid and efficient aerobic granular sludge (AGS) production for augmentation strategy to mainstream activated sludge process, AGS production was evaluated under high organic loading rate (OLR) conditions in a side-stream simultaneous feeding and drawing sequencing batch reactor (SFD-SBR) fed with low-strength municipal wastewater. Specifically, three SFD-SBRs were operated under different OLRs (≥ 1.3 kg-tCOD m−3 d−1) with a 100% volume exchange ratio (VER). Rapid granulation (SVI30 < 80 mL g−1 and granule fraction of ~ 70%) was achieved within 40 days in all reactors. However, an excessively high OLR (2.0 kg-tCOD m−3 d−1) tended to labilize the AGS settleability (SVI5 of ~ 120 mL g−1) despite the larger AGS size due to the outgrowth of fluffy flocs and filamentous bacteria. Furthermore, after granulation, application of a long settling time (10 min) to maintain a low sludge blanket level during the feeding period was key for stable and efficient AGS production (0.17 g-SS g-tCOD−1) under a high OLR of 1.6 kg-tCOD m−3 d−1 compared to AGS production with a short settling time (0.10 g-SS g-tCOD−1). Taken together, this study demonstrated that application of low selection pressure and moderate up-flow linear velocity enables stable and efficient AGS production in SFD-SBRs fed with low-strength municipal wastewater under high VER and OLR conditions.

Improving simultaneous N, P, and C removal and microbial population dynamics in an anaerobic–aerobic–anoxic SBR (A-O-A-SBR) treating municipal wastewater by altering organic loading rate (OLR)

To assess the impacts of the influent organic loading rate (OLR) on the performance of an improved sequencing batch reactor (A-O-A-SBR system), four OLRs (1.35, 2.03, 2.70, and 3.38 g-COD/L/d) were used for enhancing simultaneous N, P, and C removals in the system. Results showed that high simultaneous N, P, and C removal efficiencies of the A-O-A-SBR were achieved with an OLR of 2.03 g-COD/L/d. The corresponding TN, TP, and COD removal efficiencies were 98.10%, 87.01%, and 93.43%, respectively. Dominant phyla, including Proteobacteria, Planctomycetes, Candidatus Saccharibacteria, Bacteroidetes, and critical genus Thiothrix, and essential classes such as Gammaproteobacteria, Betaproteobacteria, Sphingobacteriia, contributed to the excellent A-O-A-SBR performance. Functional genes forecasts demonstrated that the metabolic potential on pollutants degradation metabolism improved with the proper OLR condition.

Calcium hypochlorite pretreatment improves thermophilic digestion of waste activated sludge in an upflow anaerobic sludge blanket reactor

Anaerobic wasted activated sludge (WAS) digestion has been widely applied to reduce sludge volume and generate bioenergy in the form of methane. However, anaerobic WAS digestion performance is often challenged with poor hydrolysis of biomass cellular structures. In the present study, the feasibility of using calcium hypochlorite (Ca(ClO)2) to improve the thermophilic digestion of WAS was studied. Two thermophilic upflow anaerobic sludge bed (UASB) reactors (one with and one without Ca(ClO)2 pretreatment) were operated for 120 days under low and high organic loading rate (OLR) conditions, corresponding hydraulic retention time (HRT) of 10 days and 6 days, respectively. Both reactors achieved satisfied performance during the studied period. Under the low OLR condition, Ca(ClO)2 pretreatment significantly improved WAS total volatile solids (VS) removal efficiency (from 48.06 ± 2.63% to 57.34 ± 3.54%) and methane yield (from 289.2 ± 27.6 to 362.2 ± 36.7 N mL/g VS). However, no significant improvement was observed under the high OLR condition. g_S1 and g_Fervidobacterium were predominant bacteria in the thermophilic UASB reactor fed with Ca(ClO)2 pretreated WAS. Methanosarcina was dominant archaea in both reactors. The treatment mechanism and application potential of using Ca(ClO)2 to enhance the WAS digestibility were further discussed.

The effect of static mixer on the properties and performance of aerobic granules under different organic loading rates in treating synthetic textile wastewater

Biogranulation is considered a promising technology in biological wastewater treatment due to its high effluent treatment quality, strong ability to withstand organic loading, strong microbial structure and high capability to remove organics, nitrogen and phosphate. Organic loading rate (OLR) is known as one of the significant factors in biogranulation process. Aerobic granules can be developed under different OLR conditions. Microorganisms are starved at low OLR while microbial growth accelerates at high OLR. The main objective of this study was to investigate the effect of various OLRs on the physical characteristics and treatment performance of aerobic granules in treating synthetic textile wastewater. Two reactors named as R4Y and R4N were used, where R4Y was a reactor with static mixer and R4N was without the static mixer. The OLR of 2.0, 2.5 and 3.0 kg/m3.day were examined during the post development study. The study demonstrated that OLR affected the performance of biogranules. The physical characteristics of biogranules and removal efficiencies of the reactor with static mixer seemed to be better as compared to the reactor without static mixer with increasing of OLR. The granules of R4Y had better physical strength with IC of 19.6% and more excellent settling ability with SV of 82.7 m/h and SVI of 24.6 mL/g. The findings proved that static mixer had a positive influence in biogranulation system and therefore, will lower the energy consumption and operational cost.

Role of live cell colonization in the biofilm formation process in membrane bioreactors treating actual sewage under low organic loading rate conditions.

Biofilm development on the membrane surface is one of the main reasons for membrane fouling in membrane bioreactors (MBRs) and it is a big problem for their stable operation. Precise information on the microbial community composition of the biofilm is needed for a better understanding of biofilm development. However, there have been limited investigations of the relationship between the biofilm formation process and the microbial community of activated sludge and biofilm in MBRs treating real sewage. In this study, relationships between the microbial community structure of biofilm and activated sludge at each biofilm formation stage were investigated and biofilm growth was elucidated by nondestructive observations. Two anoxic/oxic MBRs were operated and membrane fouling was induced. Permeability rapidly decreased in both reactors and live cell microcolonies were formed on dead cell conditioning film on the membrane surface. Principal component analysis based on 16S rRNA gene sequences showed that the biofilm microbial community changed significantly from middle stage to mature biofilm when compared with that of activated sludge. The abundance of specific bacteria, such as unclassified Neisseriaceae, increased in middle-stage biofilm and the diversity indexes of middle-stage biofilm were lower than those of mature biofilm and activated sludge. These results suggested that the presence of specific bacteria with colonization ability played a crucial role in biofilm formation. Strategies are needed to target membrane fouling mitigation during early- and middle-stage biofilm formation to reduce MBR membrane fouling. KEY POINTS: • Microbial community of mature biofilm was approached to that of activated sludge. • In the middle-stage biofilm, live cells colonized on a dead-cell-conditioning-film. • Microbial diversity was lower in live cell colonizing stage than in activated sludge.

An experimental study on Bio-gas production by anaerobic digestion of RiceMill Wastewater (RMW)

&lt;p&gt;With the rising interest for sustainable power source and ecological security, anaerobic digestion of biogas technology has attracted considerable attention within the scientific researchers. This paper proposes a new research achievement on biogas production from Rice Mill Wastewater (RMW) with the utilization of anaerobic digester. An anaerobic digester is maintained with RMW and distillery anaerobic sludge at mesophilic temperature condition for 15 days as stabilization mode. After attaining stabilization stage, studies continued to examine the effect of Organic Loading Rate (OLR) and Hydraulic Retention Time (HRT) on the mesophilic anaerobic digestion of RMW. The OLR of the anaerobic reactor increased stepwise from 0.25 to 3.91 Kg COD/m3/dayand HRT ranged from 1 to 32.0 days. The total chemical oxygen demand (TCOD) utilized was higher than 75% and the CH4 percentage of the biogas was 62.00-63.00% for the OLRs studied. The efficient working volume of the digester is preserved as 25% of distillery anaerobic sludge and 75% of rice mill wastewater, loaded at Mesophilic temperature conditions for study purpose. By changing the conditions of OLR and HRT, biogas production, methane yield and percentage of COD reduction is examined. An anaerobic sludge is utilized as a seeding material to biodegrade the organic pollutants present in the wastewater. It will enhance the biological treatment of effluent with anaerobic sludge in a continuous mode of activity.The result showed that the proposed analysis obtains more biogas production with reduced COD when compared with existing approaches.&lt;/p&gt;&#x0D;

Field-scale anaerobic baffled reactor for domestic wastewater treatment: effect of dynamic operating conditions

Abstract A 45 m3/d field-scale anaerobic baffled reactor (ABR) was studied for its performance to remove carbonaceous organic content and suspended solids under a dynamic hydraulic loading rate (HLR) and organic loading rate (OLR). Sludge granulation effect was also assessed with and without sand as a bio-carrier aided with poly aluminium chloride. ABR was subjected to a significant variation in HLR (0.26 to 7.72 m3/m2.d) and OLR (0.03 to 8 kg COD/m3.d). Tracer study showed flow-through time was 50% of theoretical hydraulic retention time. The initial compartments of ABR were more effective for the removal of organic carbon. An overall CODTotal removal of 60 to 90% was possible for OLR in the range 1 to 8 kg COD/m3.d irrespective of low/high HLR. OLR dominated the performance of ABR compared to HLR. The compartmentalized nature of ABR was visualized through a two-phase system of anaerobic digestion as alkalinity increased while VFA decreased from the first to last compartment even under dynamic conditions. Sludge granulation with sand and PAC increased the size of granule from 629 to 1,471 μm, decreased sludge depth by 20% and enhanced CODTotal removal within a month. ABR is sturdy to sustain low/high HLR with low/high OLR conditions without impairing CODTotal removal efficiency significantly.

Wastewater treatment by microalgal membrane bioreactor: Evaluating the effect of organic loading rate and hydraulic residence time

Current microalgal based photobioreactors focus on the secondary treated effluent while limited researches attempted for treating the raw domestic wastewater. This study aimed to assess the microalgal biomass production, removal performance, and fouling characteristics of microalgal membrane bioreactors (MMBRs) for treating synthetic wastewater under different conditions of organic loading rate (OLR) and hydraulic residence time (HRT). The 12h/12 h dark/light cycle continuous experiments were performed for four MMBRs at different OLRs and three MMBRs at different HRTs. Results showed that microalgal biomass production rate (as TSS and chlorophyll-a) decreased with increasing OLR and increased with decreasing of HRT. Regardless of the OLR and HRT conditions, MMBRs can achieve up to 94% organic removal by bacterial oxidation without external aeration. Total nitrogen (TN) and total phosphorus (TP) removals were significantly decreased with increasing OLR. Highest TN removal (68.4%) achieved at the OLR of 0.014 kg/(m3 d) which was reduced to 58.1% at 0.028 kg/(m3 d). Removals of total phosphorous significantly decreased from 48.2% to 37.7% with an increase in OLR from 0.011 to 0.014 kg/(m3 d). TN removal was reduced at shorten HRT (2 d), while, the effect of HRT was found insignificant at higher HRT. An effective removal of P can only be achieved at higher HRTs, i.e., 7 days. OLR up to 0.014 kg/(m3 d) and 2 days HRT was found suitable for maintaining the fouling frequency at an optimal level of 0.016/d. Overall the OLR and HRT need to be carefully selected to achieve optimal efficiency of MMBR. The results of this study provide guidelines for designing the microalgal-based membrane bioreactors for the treatment of domestic wastewater.

Resource recovery from an aerobic granular sludge process treating domestic wastewater

This study presents the application of resource recovery from domestic wastewater such as irrigation water, structural extracellular polymeric substances (EPS), and polyhydroxyalkanoates (PHAs). The resource recovery system consisted of an aerobic granular sludge (AGS) reactor processing domestic wastewater and an external membrane reactor receiving the AGS effluent. The AGS effluent contained large numbers of biomass patches detached from the granular sludge. Therefore, the external membrane served to eliminate the biomass patches and individual bacteria from the AGS effluent. The permeate of the membrane reactor was compared with the national irrigation water standards. The results showed that the membrane effluent was suitable to be used as irrigation water, but the boron parameter should be checked for long-term irrigation. Extracellular polysaccharides recovered from the granular sludge were characterized as structural EPS. The analyses showed that PHA accumulating organisms, namely Uncultured Candidatus Competibacter sp. and Competibacteraceae, were dominant in the AGS reactor, and the PHA content of the AGS was approximately 10 % when operated under high organic loading rate conditions. PHAs, therefore, may also be obtained from AGS. For the management of membrane concentrate and zero-waste discharge approach, it is recommended to investigate the recovery possibilities of structural EPS and PHA biopolymers from the membrane concentrate further because the effluent of AGS contained mostly biomass patches detached from granular sludge.

Redox-active biochar facilitates potential electron tranfer between syntrophic partners to enhance anaerobic digestion under high organic loading rate

Sawdust-based biochar prepared (SDBC) at three pyrolytic temperatures were compared as additives to mesophilic anaerobic digestion (AD). SDBC prepared at 500 °C performed better in enhancing CH4 production than other SDBCs. Analyzing the crucial electro-chemical characteristics of the SDBCs revealed that the excellent electron transfer capacity of SDBC was significant to stimulate methanogenesis promotion. A long-term semi-continuous operation further confirmed that adding SDBC to AD system increased the maximum organic loading rate (OLR) from 6.8 g VS/L/d to 16.2 g VS/L/d, which attributed to the extremely low volatile fatty acids (VFA) accumulation. Microbial community succession analysis found that SDBC addition altered both bacterial and archaea structure greatly. More importantly, the syntrophic and electro-active partners of Petrimonas and Methanosarcina synergistically enriched under high OLR condition were responsible for the high-efficient VFA degradation, which suggested that SDBC likely acted as redox-active mediator to facilitate direct interspecies electron transfer between the syntrophic partners for high-efficient syntrophic methanogenesis process.

Mechanism of biofouling enhancement in a membrane bioreactor under constant trans-membrane pressure operation

In a membrane bioreactor, flux and organic loading rate conditions essentially affect membrane fouling. In constant TMP mode, flux and organic loading rate dynamically change, while they are rather static in constant flux mode. This study investigated fouling mechanism in MBR under these different filtration modes. Fouling development was more significant in constant TMP mode than in constant flux mode when MBR was operated under an equal flux condition in average. In constant TMP mode, microbial community in cake sludge was distinct from bulk sludge and had higher abundance of biofilm-forming bacterial group. The cake sludge contained more SMP and LB-EPS with high polysaccharide contents in constant TMP mode. These results suggested that, in constant TMP mode, (i) initially high flux in a filtration cycle enhanced initial deposition of bacterial cells and rapid development of fouling layer, which resulted in distinct microbial community in cake sludge; (ii) the high abundance of the biofilm-forming bacteria in cake sludge and fluctuation of organic loading rate stimulated polysaccharide production, (iii) higher polysaccharide contents in cake layer caused faster development of fouling layer and increase of hydraulic resistance by compression.

Construction and evaluation of efficient solid-state anaerobic digestion system via vinegar residue

Anaerobic digestion is a feasible method for vinegar residue disposal. However, its treatment efficiency is limited significantly by the low degradation of lignocellulose. In this study, a stable and efficient anaerobic digestion system for vinegar residue was constructed. The continuous solid-state reactor achieved a specific production of 418 mL·g-1 VS biogas and 223 mL·g-1 VS methane at a high organic loading rate (OLR) of 5.83 gVS·(L·d)−1. The stable degradation of lignocellulose between 39.5% and 36.4% was key factor for stable anaerobic digestion at high OLR. This stability under optimum OLR was due to the increase in the degradation of hemicellulose, which compensated for the loss of lignocellulose degradation. The enrichment of microorganism related to lignocellulose hydrolysis and the stable microbial community structure ensured efficient anaerobic digestion under high OLR condition. Digestion efficiency can be further improved mainly by increasing cellulose degradation. This investigation provided the theoretical basis for practical application of this digestion system for solid vinegar residue treatment.

Influence of organic loading rates on the production of methane from anaerobic digestion of sewage concentrate

This study investigated the efficiency of biogas production from sewage concentrate through anaerobic digestion. A continuous stirred tank reactor with a 900-mL working volume was used. The experiment was designed to investigate the influence of organic loading rate on the efficiency of biogas production and to determine the most suitable organic loading rate condition for methane production from sewage concentrate by using continuous stirred tank reactor. The reactor was operated at different organic loading rates of 1.8, 0.8, and 0.6 gCOD/(L.d). The methane composition of the biogas produced from the treatment organic loading rate (OLR). The beginning of the experiment recorded low methane production because of the high organic loading rate. However, the later part of the experiment recorded high and stable biogas production because of the relatively low OLR. Results suggested that a 0.6 gCOD/(L.d) OLR was the most efficient setup parameter for ideal methane production from sewage concentrate by using continuous stirred tank reactor.

Effects of organic loading rate on hydrogen and volatile fatty acid production and microbial community during acidogenic hydrogenesis in a continuous stirred tank reactor using molasses wastewater.

Microbial community associated with hydrogen production and volatile fatty acids (VFAs) accumulation was characterized in acidogenic hydrogenesis using molasses wastewater as a feedstock. Hydrogen and VFAs production were measured under an organic loading rate (OLR) from 19 to 35g-CODl-1 day-1 . The active microbial community was analysed using RNA-based massively parallel sequencing technique, and their correlation patterns were analysed using networking analysis. The continuous stirred tank reactor achieved stable hydrogen production at different OLR conditions, and the maximum hydrogen production rate (HPR) was 1·02L-H2 l-1 day-1 at 31·0g-CODl-1 day-1 . Butyrate (50%) and acetate (38%) positively increased with increase in OLR. Total VFA production stayed around 7135mgl-1 during the operation period. Although Clostridiales and Lactobacillales were relatively abundant, the HPR was positively associated with Pseudomonadaceae and Micrococcineae. Total VFA and acetate, butyrate and propionate concentrations were positively correlated with lactic acid bacteria (LAB) such as Bacillales, Sporolactobacillus and Lactobacillus. The close relationship between Pseudomonadaceae and Micrococcineae, and LAB play important roles for stable hydrogen and VFA production from molasses wastewater. Microbial information on hydrogen and VFA production can be useful to design and operate for acidogenic hydrogenesis using high strength molasses wastewater.

Optimization of Denitrifying Phosphorus Removal Performance Based on ABR-MBR Combined Process

An integrated process based on combination of the anaerobic baffled reactor(ABR)-membrane bioreactor(MBR) was adopted to treat domestic sewage with low C/N ratio. In order to realize the function of highly efficient denitrifying phosphorus removal, nitrate recycling ratio and sludge recycle ratio were optimized in this study. The results indicated that the optimized denitrifying phosphorus removal efficiency was achieved under the conditions of organic loading rate of 2.0 kg·(m3·d)-1 in ABR, total hydraulic retention time (HRT) of ABR-MBR at 9 h, the SRT at 15 d, sludge reflux ratio of 100%, and nitrate recycling ratios set to 300%. The average removal rates of TN and soluble PO43--P were 84% and 94%, the amount of phosphorus removed by denitrifying accounted for 87% of the total phosphorus removed, and the average effluent concentration for TN and soluble phosphorus were 12.98 mg·L-1 and 0.43 mg·L-1 respectively.

Energy-positive food wastewater treatment using an anaerobic membrane bioreactor (AnMBR)

An immersed-membrane anaerobic membrane bioreactor (AnMBR) achieved 88–95% of COD removal for meat-processing wastewater at organic loading rate (OLR) of 0.4–3.2 kgCOD m−3 d−1. Membrane flux was stable for low OLR (0.4 and 1.3 kgCOD m−3 d−1), but irrecoverable fouling occurred at high OLR of 3.2 kgCOD m−3 d−1. Methane gas yield of 0.13–0.18 LCH4 g−1CODremoved was obtained, which accounted for 33–38% of input COD, the most significant electron sink. Dissolved methane was only 3.4–11% of input COD and consistently over-saturated at all OLR conditions. The least accumulation of dissolved methane (25 mg L−1 and saturation index 1.3) was found for the highest OLR of 3.2 kgCOD m−3 d−1 where biogas production rate was the highest. Energy balances showed that AnMBR produced net energy benefit of 0.16–1.82 kWh m−3, indicating the possibility of energy-positive food wastewater treatment using AnMBRs.

비귀금속촉매 미생물연료전지의 연속운전을 통한 전기 생산

ABSTRACT In this study, continuous microbial fuel cells (MFCs) were operated using non-precious metal catalysts such as iron(II) phthalocyanine (FePc) and cobalt tetramethoxyphenylporphyrin (CoTMPP)) as alternative cathode catalysts for platinum. To evaluate MFCs performance, operational conditions of organic loading rate (OLR) (0.5∼3 g COD/L/d) and hydraulic retention rate (HRT) (0.25∼1 day) were changed. Power density of MFCs were determined by cathode electrode performance. The maximum power density was 3.3 W/m 3 with platinum at OLR 3 g COD/L/d. Given each HRTs at 1 g COD/L/d, FePc showed to be a better alternative for platinum than CoTMPP because the power density of MFC with FePc was similar to that of MFC with platinum. CoTMPP catalyst, however, showed the lowest power density due to increase of internal resistance during continuous operation. Keywords : microbial fuel cell, iron(II) phthalocyanine, cobalt tetramethoxyphenylporphyrin, organic loading rate, hydraulic retention time, internal resistance