Upflow Anaerobic Packed Bed Reactor Research Articles

Integrated Kinetic Modelling and Microbial Profiling Provide Insights Into Biological Sulfate-Reducing Reactor Design and Operation.

Biological sulfate reduction (BSR) is an attractive approach for the bioremediation of sulfate-rich wastewater streams. Many sulfate-reducing microorganisms (SRM), which facilitate this process, have been well-studied in pure culture. However, the role of individual members of microbial communities within BSR bioreactors remains understudied. In this study we investigated the performance of two up-flow anaerobic packed bed reactors (UAPBRs) supplemented primarily with acetate and with lactate, respectively, during a hydraulic retention time (HRT) study set up to remediate sulfate-rich synthetic wastewater over the course of 1,000 + days. Plug-flow hydrodynamics led to a continuum of changing volumetric sulfate reduction rates (VSRRs), available electron donors, degrees of biomass retention and compositions of microbial communities throughout these reactors. Microbial communities throughout the successive zones of the reactors were resolved using 16S rRNA gene amplicon sequencing which allowed the association of features of performance with discrete microorganisms. The acetate UAPBR achieved a maximum VSRR of 23.2 mg.L−1. h−1 at a one-day HRT and a maximum sulfate conversion of the 1 g/L sulfate of 96% at a four-day HRT. The sulfate reduction reactions in this reactor could be described with a reaction order of 2.9, an important observation for optimisation and future scale-up. The lactate UAPBR achieved a 96% sulfate conversion at one-day HRT, corresponding with a VSRR of 40.1 mg.L−1. h−1. Lactate was supplied in this reactor at relatively low concentrations necessitating the subsequent use of propionate and acetate, by-products of lactate fermentation with acetate also a by-product of incomplete lactate oxidation, to achieve competitive performance. The consumption of these electron donors could be associated with specific SRM localised within biofilms of discrete zones. The sulfate reduction rates in the lactate UAPBR could be modelled as first-order reactions, indicating effective rates were conferred by these propionate- and acetate-oxidising SRM. Our results demonstrate how acetate, a low-cost substrate, can be used effectively despite low associated SRM growth rates, and that lactate, a more expensive substrate, can be used sparingly to achieve high VSRR and sulfate conversions. We further identified the preferred environment of additional microorganisms to inform how these microorganisms could be enriched or diminished in BSR reactors.

Photodegradation of chloramphenicol and paracetamol using PbS/TiO2 nanocomposites produced by green synthesis

The present study describes the photocatalytic potential of the successfully synthesized nanocrystalline PbS/TiO2 nanocomposites in the photodegradation of chloramphenicol and paracetamol. PbS and PbS/TiO2 nanoparticles were synthesized using biological sulphide produced by sulphate-reducing bacteria in batch and in a coupled bioremediation system (upflow anaerobic packed-bed reactor) for acid mine drainage treatment, yielding near-complete metal precipitation (~ 100–99%, respectively). The PbS and PbS/TiO2 composites obtained using sulphide generated in batch have an average particle size ranging from 17 to 25 nm and 15 to 20 nm, respectively, while in bioreactor, both PbS and PbS/TiO2 particles have a similar size range from 20 to 50 nm. All the produced particles presented crystalline cubic structure. The specific surface area of TiO2 and PbS/TiO2 was estimated to be 46.559 m2/g and 38.005 m2/g, respectively. Chloramphenicol removal by photolysis was about 61% after 60 min of Hg irradiation and 36% under sunlight exposition. Chloramphenicol photodegradation using PbS/TiO2 as catalyst was successfully performed in a photoreactor (Hg medium pressure, 450 W) and under solar exposition with a high drug removal efficiency of 96% and 93% after 60 min and 240 min irradiation, respectively. Using TiO2 as a catalyst for photodegradation achieved 98% removal for both Hg and sunlight irradiation (UV index ranging 7–8) after 60 min and 240 min, respectively. Paracetamol removal by photolysis was about 18%. Drug’s photocatalytic degradation using PbS/TiO2 was successfully performed under sunlight exposition with a high removal efficiency of 93%, while in the presence of TiO2, the removal was complete, after 235 min irradiation.

Antimony removal from wastewater by sulfate-reducing bacteria in a bench-scale upflow anaerobic packed-bed reactor

The objective of this research was to study the precipitation of Sb and the stability of Sb2S3 during treatment of synthetic Sb(V) wastewater by sulfate-reducing bacteria (SRB). We investigated the transformation and precipitation of Sb, as well as the re-dissolution of Sb2S3 under different pH and carbon sources. The results showed that the precipitation of aqueous Sb and the re-dissolution of Sb2S3 depend on the conversion between Sb(III)-S(-II) complexes and Sb2S3 precipitates. These processes were highly pH-dependent, and a decrease in pH enhanced reduction of Sb(V) and precipitation of Sb2S3 were observed. The newly formed Sb2S3 was found to be unstable and could re-dissolve through complexation with H2S due to the increase in pH. When pH decreased to approximately 6.5, Sb was almost completely transformed into Sb2S3 precipitates, and the Sb2S3 precipitates were relatively stable. Compared with lactate as a carbon source, ethanol resulted in a comparable H2S yield and a relatively low pH and was, therefore, more conducive to the removal of Sb(V). The results of this study suggest that when removing Sb(V) in wastewater by SRB, it is important to control the pH at a relatively low level.

Integrated bio-chemo degradation of Mordant Yellow 10 using upflow anaerobic packed bed reactor (UAPBR) and tray type photo-Fenton reactor (TPFR)

Feasibility of the two stage anaerobic/photo-Fenton process to mineralize a mono-azo dye, Mordant Yellow 10 (MY10) in continuous mode of operation was demonstrated using an upflow anaerobic packed bed reactor (UAPBR) and a novelly-designed tray type photo-Fenton reactor (TPFR). The halotolerant Pseudomonas aeroginosa BRPO3 strain used in the UAPBR system demonstrated stable dye decolorization with almost 99% of dye removal efficiency up to 220 mg/L of dye concentration supported by glucose as co-substrate operated at 24 h retention time. Maximum dye removal rate was observed to be 933 ± 8 mg/day at 200 mg/L of dye concentration. The amines formed in the UAPBR were degraded almost completely (99%) using hydrogen peroxide (340 mM) in TPFR packed with iron shavings as the catalyst. Ecogenotoxicity studies with earthworm Eisenia fetida using alkaline comet assay revealed that the untreated and bio-treated dye water induced DNA damage in coelomocytes of earthworm whereas sequentially treated solution did not induce damage even after 72 h of exposure. This is probably the first study to investigate the detoxification efficiency of sequential treatment systems operated in continuous mode.

Stratification of microbial communities throughout a biological sulphate reducing up-flow anaerobic packed bed reactor, revealed through 16S metagenomics

Biological sulphate reduction (BSR) is a promising low-cost treatment of acid rock drainage effluents. In this paper, the system performance and microbial ecology of a lactate supplemented BSR up-flow anaerobic packed bed reactor (UAPBR) are evaluated across reactor height and compared to a continuous stirred tank reactor (CSTR). The biomass concentrations of planktonic and biofilm communities were quantified and subsequently characterised by 16S rRNA gene amplicon sequencing. The defined microbial communities were shown to correlate with differing availability of lactate, volatile fatty acids produced from lactate degradation and sulphate concentration. The UAPBR was able to achieve near complete sulphate conversion at a 4-day hydraulic residence time (HRT) at a sulphate feed concentration of 10.41 mM (1 g/L). The high volumetric sulphate reduction rate of 0.184 mM/L.h achieved in the first third of the reactor was attributed to OTUs present in the planktonic and biofilm communities. While the scavenging of sulphate within the final third of the UAPBR was attributed to an acetate oxidising genus of SRB which was not detected in the lactate-fed CSTR. The detailed analyses of the microbial communities throughout the UAPBR and CSTR contribute to the growing understanding of the impact of the microbial communities of BSR reactors on system performance.

Comparative Analysis of the Sulfate-Reducing Performance and Microbial Colonisation of Three Continuous Reactor Configurations with Varying Degrees of Biomass Retention

Biological sulfate reduction represents an alternative and sustainable option to reduce the high sulfate load, precipitate heavy metals and neutralise the acidity associated with acid rock drainage (ARD). Sulfate-reducing enrichment cultures have been developed on simple and complex electron donors from several environmental samples and used to inoculate three reactor configurations, namely a continuous stirred tank bioreactor, up-flow anaerobic packed bed reactor and a linear flow channel reactor, with varying degrees of biomass retention provided by carbon microfibres and polyurethane foam. These matrices are included to enhance microbial attachment and colonisation, allowing for the decoupling of hydraulic retention time and biomass retention time. The bioreactor systems are operated under increasingly stringent conditions through the reduction in the hydraulic residence time. The biological sulfate reduction performance and the biomass concentration of planktonic, matrix-attached and matrix-associated communities are routinely monitored. This investigation makes use of biomass quantification of the planktonic community and, following detachment, the matrix-associated community to investigate the resultant microbial communities in these reactor systems. Evaluation of these mixed microbial communities, and their link to process performance, provides an opportunity to impact the design and operation of pilot- and industrial-scale bioprocesses.

Fermentative hydrogen production in an up-flow anaerobic biofilm reactor inoculated with a co-culture of Clostridium acetobutylicum and Desulfovibrio vulgaris

Dark fermentation systems often show low H2 yields and unstable H2 production, as the result of the variability of microbial dynamics and metabolic pathways. Recent batch investigations have demonstrated that an artificial consortium of two anaerobic bacteria, Clostridium acetobutylicum and Desulfovibrio vulgaris Hildenborough, may redirect metabolic fluxes and improve H2 yields. This study aimed at evaluating the scale-up from batch to continuous H2 production in an up-flow anaerobic packed-bed reactor (APBR) continuously fed with a glucose-medium. The effects of various parameters, including void hydraulic retention time (HRTv), pH, and alkalinity, on H2 production performances and metabolic pathways were investigated. The results demonstrated that a stable H2 production was reached after 3–4days of operation. H2 production rates increased significantly with decreasing HRTv from 4 to 2h. Instead, H2 yields remained almost stable despite the change in HRTv, indicating that the decrease in HRTv did not affect the global metabolism.

Heavy Metal Removal Using Sulfate-Reducing Biomass Obtained from a Lab-Scale Upflow Anaerobic-Packed Bed Reactor

AbstractBiological sulfate reduction is an alternative and emerging technique to treat metal containing sulfate-rich wastewater. In this study, the potential of anaerobic biomass from three different wastewater treating systems was evaluated for heavy metal removal under sulfate-reducing conditions. Among the three different biomass sources tested in the study, the biomass from a lab-scale upflow anaerobic-packed bed reactor (UFAR) showed maximum sulfate reduction (>90%) within 96 h with a maximum wastewater chemical oxygen demand (COD) removal of up to 92.8%. The heavy metal removal efficacy was in the order Cu>Fe>Ni>Pb>Cd>Zn. Metal removal by the biomass was further established due to its precipitation with sulfide formed by the sulfate-reducing bacteria. The field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) of the metal-loaded biomass showed that the precipitates formed during the process consist of mainly the metal sulfides. The transmission electron mi...

Treatment of milk wastewater using up-flow anaerobic packed bed reactor

Abstract An up-flow anaerobic packed bed (UAPB) bioreactor has been designed on a laboratory-scale and used for treatment of domestic milk wastewater (MWW). The UAPB bioreactor was operated under mesophilic temperature (37-45°C) and reactor performance evaluated at various organic loading rates of MWW effluent at hydraulic retention times (HRT) of 1, 2, and 3 d based on the removal of organic matter COD, BOD, SS, pH changes and biogas production. The kinetic parameters were estimated using the experimental data to develop a reactor model. Empirical relations were generated for the characteristics like COD, BOD, and SS using modeling equations. This study proved that the UAPB reactor performance is excellent for treating domestic MWW and easily biodegradable dairy wastewater influent. Hence, this system can operate at low costs, making it suited for use in the developing countries and rural areas.

High organic loading rate on thermophilic hydrogen production and metagenomic study at an anaerobic packed-bed reactor treating a residual liquid stream of a Brazilian biorefinery

This study evaluated the influence of a high organic loading rate (OLR) on thermophilic hydrogen production at an up-flow anaerobic packed-bed reactor (APBR) treating a residual liquid stream of a Brazilian biorefinery. The APBR, filled with low-density polyethylene, was operated at an OLR of 84.2kg-CODm−3d−1. This value was determined in a previous study. The maximum values of hydrogen production and yield were 5,252.6mL-H2d−1 and 3.7mol-H2mol−1total carbohydrates, respectively. However, whereas the OLR remained constant, the specific organic load rate (sOLR) decreased throughout operation from 1.38 to 0.72g-Total carbohydratesg-VS−1h−1, this decrease negatively affected hydrogen production. A sOLR of 0.98g-Total carbohydratesg-VS−1h−1 was optimal for hydrogen production. The microbial community was studied using 454-pyrosequencing analysis. Organisms belonging to the genera Caloramator, Clostridium, Megasphaera, Oxobacter, Thermoanaerobacterium, and Thermohydrogenium were detected in samples taken from the reactor at operation days 30 and 60, suggesting that these organisms contribute to hydrogen production.

The anaerobic treatment of pharmaceutical industry wastewater in an anaerobic batch and upflow packed-bed reactor

The pharmaceutical industry constitutes an important place in terms of health and environment, both in our country and throughout the world. Various complex organic chemicals are present in the wastewater generated by pharmaceutical industries. The accumulation of toxic and persistent organic substances in wastewater is a serious problem for the environment. Therefore, it is important that pharmaceutical industry wastewater is treated before being discharged into receiving waters. Today, anaerobic treatment systems are commonly used for wastewater-containing high organic matter. The first stage of this study statistically investigates the optimization of anaerobic treatment conditions of pharmaceutical industry wastewater in a batch study. In the second stage, continuous treatment processes were planned using data obtained as a result of the batch study. For processing, an upflow anaerobic packed-bed reactor was used for treating substrate mixtures containing 10–100% pharmaceutical industry wastewater. The effects of operating parameters on the chemical oxygen demand (COD) removal efficiency and the methane production rate were evaluated. COD removal efficiencies of 93–97% were obtained for the pharmaceutical industry wastewater using a 2.5–4 d hydraulic retention time and a 0.6–2.2g COD d−1 organic loading rate. The overall results suggested that the mixed bacterial and archaeal biomass was able to efficiently treat pharmaceutical industry wastewater under determined anaerobic conditions.

Effect of organic loading rate on hydrogen production from sugarcane vinasse in thermophilic acidogenic packed bed reactors

This study evaluated the effect of organic loading rate (OLR) on hydrogen production in up-flow anaerobic packed bed reactors (APBR) continuously fed with sugarcane vinasse. Four thermophilic up-flow APBR were operated in parallel at different ORL. Continuous hydrogen production was detected. The optimum OLR of 84.2 kg-COD m−3 d−1 was assessed by polynomial adjustment, which predicted a maximum Volumetric Hydrogen Production (VHP) and hydrogen yield (YH2) of 1117.2 mL-H2 d−1 L−1reactor and 2.4 mol-H2 mol−1total carbohydrates, respectively. The microbial composition was monitored using 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and quantification of Fe-hydrogenase gene by real-time PCR which was affected by the OLR. The number of the Fe-hydrogenase genes was proportional to the monitored hydrogen production and yield. Hydrogen-producing strains were isolated, and the 16S rRNA gene sequences were highly homologous to those of Thermoanaerobacterium thermosaccarolyticum. The ability of vinasse as substrate for hydrogen production was confirmed for both strains.

Impact of organic loading rate on biohydrogen production in an up-flow anaerobic packed bed reactor (UAnPBR).

This study assesses the impact of organic loading rate on biohydrogen production from glucose in an up-flow anaerobic packed bed reactor (UAnPBR). Two mesophilic UAPBRs (UAnPBR1 and 2) were tested at organic loading rates (OLRs) ranging from 6.5 to 51.4 g COD L(-1)d(-1). To overcome biomass washout, design modifications were made in the UAnPBR2 to include a settling zone to capture the detached biomass. The design modifications in UAnPBR2 increased the average hydrogen yield from 0.98 to 2.0 mol-H2 mol(-1)-glucose at an OLR of 25.7 g COD L(-1)d(-1). Although, a maximum hydrogen production rate of 23.4 ± 0.9 L H2 L(-1)d(-1) was achieved in the UAnPBR2 at an OLR of 51.4 g COD L(-1)d(-1), the hydrogen yield dropped by 50% to around 1 mol-H2 mol(-1)-glucose. The microbiological analysis (PCR/DGGE) showed that the biohydrogen production was due to the presence of the hydrogen and volatile acid producers such as Clostridium beijerinckii, Clostridium butyricum, Megasphaera elsdenii and Propionispira arboris.

The Effect of Biomass Immobilization Support Material and Bed Porosity on Hydrogen Production in an Upflow Anaerobic Packed-Bed Bioreactor

The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H₂ mol(-1) sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation, which resulted in a decreasing working volume.

Hydrogen production in an upflow anaerobic packed bed reactor used to treat cheese whey

In this work, an upflow anaerobic packed bed reactor configuration to produce hydrogen using cheese whey as the substrate was tested. The microbiological composition was linked to the reactor operation.Three different organic loading rates of 22, 33, and 37gCOD/L-d were used at a fixed hydraulic retention time of 24h. The increase of the organic loading rate from the initial value of 22gCOD/L-d to a value of 37gCOD/L-d and the adjustment of the pH to values greater than 5 had a positive effect on the hydrogen production and values of up to 1LH2/L-d were achieved. The production of hydrogen was stable under all of the investigated conditions, and the problems frequently reported in this kind of reactors (bed clogging, methanogenesis and solvent production) were not observed during operation.The highest hydrogen yield was 1.1molH2/mol lactose far from the maximum theoretical value (8molH2/mol lactose), but similar to previous works using cheese whey as substrate. The microbiological analysis showed a mixed population with a low proportion of hydrogen-producing fermenters (Clostridium and Klebsiella) and other non-hydrogen-producing organisms.

Heavy metal removal by combining anaerobic upflow packed bed reactors with water hyacinth ponds

The removal of four selected heavy metals (Cu, Cd, Pb and Zn) has been assessed in an upflow anaerobic packed bed reactor filled with porous volcanic rock as an adsorbent and an attachment surface for bacterial growth. Two different feeding regimes were applied using low (5 mg L−1 of heavy metal each) and high (10 mg L−1 of heavy metal each) strength wastewater. After a start-up and acclimatization period of 44 days, each regime was operated for a period of 10 days with a hydraulic retention time of one day. Good removal efficiencies of at least 86% were achieved for both the low and high strength wastewater. A subsequent water hyacinth pond with a hydraulic retention time of one day removed an additional 61% Cd, 59% Cu, 49% Pb and 42% Zn, showing its importance as a polishing step. The water hyacinth plant in the post-treatment step accumulated heavy metals mainly in the root system. Overall metal removal efficiencies at the outlet of the integrated system were 98% for Cd, 99% for Cu, 98% for Pb and 84% for Zn. Therefore, the integrated system can be used as an alternative treatment system for metal-polluted wastewater, especially in developing countries.

Hydrogen production from soft-drink wastewater in an upflow anaerobic packed-bed reactor

The production of hydrogen from soft-drink wastewater in two upflow anaerobic packed-bed reactors was evaluated. The results show that soft-drink wastewater is a good source for hydrogen generation. Data from both reactors indicate that the reactor without medium containing macro- and micronutrients (R2) provided a higher hydrogen yield (3.5 mol H2 mol−1 of sucrose) as compared to the reactor (R1) with a nutrient-containing medium (3.3 mol H2 mol−1 of sucrose). Reactor R2 continuously produced hydrogen, whereas reactor R1 exhibited a short period of production and produced lower amounts of hydrogen. Better hydrogen production rates and percentages of biogas were also observed for reactor R2, which produced 0.4 L h−1 L−1 and 15.8% of H2, compared to reactor R1, which produced 0.2 L h−1 L−1 and 2.6% of H2. The difference in performance between the reactors was likely due to changes in the metabolic pathway for hydrogen production and decreases in bed porosity as a result of excessive biomass growth in reactor R1. Molecular biological analyses of samples from reactors R1 and R2 indicated the presence of several microorganisms, including Clostridium (91% similarity), Enterobacter (93% similarity) and Klebsiella (97% similarity).

Recovery of UAPB from high organic load during startup for phenolic wastewater treatment

Biodegradation of synthetic wastewater containing phenol by upflow anaerobic packed bed reactor (UAPB) was studied in this work. The reactor was operated at a hydraulic retention time (HRT) of 24 h and under mesophilic (30?1?C) conditions. The startup operation was conducted for 150 days; split into 4 phases. The phenol concentration was stepwise increased. The concentration of phenol in phases 1, 2, 3 and 4 were 100, 400, 700 and 1000 mg/l, respectively. In phase 1, the reactor reached steady state conditions on the 8th day with a phenol removal efficiency and biogas production rate of 96.8% and 1.42 l/d, respectively. For an increase of the initial phenol concentration in phase 2, a slight decrease in phenol removal efficiency was observed. Similar trends were observed in phases 3 and 4 of startup. Due to the high phenol concentration a sudden decrease in removal efficiency and biogas production was observed. The surviving microorganisms were gradually adapted and acclimated to high phenol concentrations. In phases 3 and 4, the phenol removal efficiency at steady state conditions were 98.4 and 98%, respectively. The maximum biogas production was observed at day 130 with a value of 3.57 l/d that corresponds to phenol concentration of 1000 mg/l.

Batch treatment of saline wastewater by Halanaerobium lacusrosei in an anaerobic packed bed reactor

AbstractBACKGROUND: This study considers batch treatment of saline wastewater in an upflow anaerobic packed bed reactor by salt tolerant anaerobic organisms Halanaerobium lacusrosei.RESULTS: The effects of initial chemical oxygen demand (COD) concentration (COD0 = 1880–9570 mg L−1), salt concentration ([NaCl] = 30–100 g L−1) and liquid upflow velocity (Vup = 1.0–8.5 m h−1) on COD removal from salt (NaCl)‐containing synthetic wastewater were investigated. The results indicated that initial COD concentration significantly affects the effluent COD concentration and removal efficiency. COD removal was around 87% at about COD0 = 1880 mg L−1, and efficiency decreased to 43% on increasing COD0 to 9570 mg L−1 at 20 g L−1 salt concentration. COD removal was in the range 50–60% for [NaCl] = 30–60 g L−1 at COD0 = 5200 ± .100 mg L−1. However, removal efficiency dropped to 10% when salt concentration was increased to 100 g L−1. Increasing liquid upflow velocity from Vup = 1.0 m h−1 to 8.5 m h−1 provided a substantial improvement in COD removal. COD concentration decreased from 4343 mg L−1 to 321 mg L−1 at Vup = 8.5 m h−1, resulting in over 92% COD removal at 30 g L−1 salt‐containing synthetic wastewater.CONCLUSION: The experimental results showed that anaerobic treatment of saline wastewater is possible and could result in efficient COD removal by the utilization of halophilic anaerobic bacteria. Copyright © 2008 Society of Chemical Industry

Anaerobic treatment of saline wastewater by Halanaerobium lacusrosei

An upflow anaerobic packed bed reactor was operated continuously with synthetic saline wastewater at different initial COD concentrations (COD 0 = 1900–6300 mg/L), salt concentrations (0–5%, w/v) and hydraulic retention times ( θ H = 11–30 h) to investigate the effect of those operating parameters on COD removal from saline synthetic wastewater. Anaerobic salt tolerant bacteria, Halanaerobium lacusrosei, were used as dominant microbial culture in the process. The percent COD removal reached up to 94% at COD 0 = 1900 mg/L, 19 h hydraulic retention time and 3% salt concentration. No substrate inhibition effect was observed at high feed CODs. Increasing hydraulic retention time from 11 h to 30 h resulted in a substantial improvement in the COD removal from 60% to 84% at around COD 0 = 3400 mg/L and 3% salt concentration. Salt inhibition effect on COD utilization was observed at above 3% salt concentration. Modified Stover–Kincannon model was applied to the experimental data to determine the biokinetic coefficients. Saturation value constant, and maximum utilization rate constant of Stover–Kincannon model for COD were determined as K B = 5.3 g/L day, U max = 7.05 g/L day, respectively.