Micro-electrolysis Research Articles

Iron-carbon microelectrolysis coordinated advanced N and P removal from municipal tailwater: Unexpected N conversion and microbial characteristic

The biochemical mechanisms that iron-carbon microelectrolysis (IC-ME) advanced and coordinated treating nitrogen (N) and phosphorus (P) from tailwater are not intensive. Depending on the optimal operating conditions of the iron carbon biofilter (ICBF), the interface P reaction, functional microbial community and characteristics were analyzed. Results demonstrated that iron (Fe) engaged in reaction with nitrate nitrogen (NO3−-N), facilitating the release of both nitrite nitrogen (NO2−-N) and ammonia nitrogen (NH4+-N) to 0.75 and 2.46 mg/L. Total nitrogen (TN) and total phosphorus (TP) were simultaneously removed lower than 10 and 0.3 mg/L under the optimum conditions i.e., gas water ratio of 15, empty bed contact time (EBCT) of 105 min, and backwashing cycle of 12 h. Microelectrolysis (ME) exhibited a robust capacity to degrade macromolecular pollutants, and P was predominantly eliminated via Fe3(PO4)2 and Fe4(PO4)3(OH)2 precipitation. Intriguingly, IC-ME did alter the microbial community composition, especially the Fe-containing microflora (Desulfuromonas, Azospira, Denitratisoma, Rhodobacter and Paludibaculum). The relatively high abundance of Gammaproteobacteria (29.67–38.3 %) promoted N transformation and the N cycle was mainly dominated by nitrogen respiration (1.95–3.39 %), nitrate reduction (2.06–3.45 %) and nitrate respiration (1.95–3.39 %). ME invigorated functional metabolism, thereby promoting organic carbon metabolism.

Effective reinforcement ozone oxidation degradation of N,N-dimethylformamide with cobalt doping micro electrolysis composite

Here we report a novel cobalt doping iron carbon micro electrolysis composite Fe-Co-AC (FCA) that exhibits excellent catalytic performance for the remove of N,N-Dimethylformamide (DMF). The catalytic effects of FCA micro electrolysis (ME), only ozone oxidation (O3), and micro electrolysis synergetic ozonation (ME-O3) on the degradation of DMF were carried out. The results proved that the ME-O3 could obtain high •OH radical yield, showing eminent catalytic efficiency. This is attributed that Co doping optimizes the electron transport path in the material, improves the micro electrolysis synergetic catalytic ozonation performance. Additionally, the relative contribution of reactive oxygen species (ROS) and related reactions were qualitatively evaluated, and the reaction mechanism of ROS generation and pollutant removal was explored. According to the conversion of organic nitrogen and the detection of intermediate, the possible degradation paths of DMF were speculated. The column experiments showed that the ME-O3 process has a certain potential in practical application.

Pretreatment of Rubber Additives Processing Wastewater by Aluminum–Carbon Micro-Electrolysis Process: Process Optimization and Mechanism Analysis

The pretreatment of rubber additives processing wastewater was performed by Al/AC micro-electrolysis (ME). The single-factor experiments for the removal of COD and chroma were investigated. The Box-Behnken Design (BBD) was also applied to optimize the experimental conditions, and the fitted response surface model supplied highly significant quadratic models for the process. The COD removal efficiency reached 51.6% at an initial pH of 9.8, Al scrap dosage of 98.6 g L−1, Al/AC mass ratio of 0.26, and reaction time of 176 min, which was reasonably consistent with the predicated value of 51.9%. Moreover, we proposed a reaction mechanism of the process for the degradation of organic contaminants, and found that the removal of COD and chroma were mainly ascribed to the combination of active hydrogen [H] with strong chemical reactivity and flocculation of aluminum hydroxide. All these results showed that Al/AC ME is a promising pretreatment technique for this wastewater.

Enhanced degradation of reactive brilliant red X-3B by photocatalysis integrated with micro-electrolysis.

The microwave electrodeless lamp UV photocatalysis (MWUV) integrated with iron carbon micro-electrolysis (ME) was applied to degrade reactive brilliant red X-3B. In the present study, the removal rate of X-3B by MWUV/ME was 95%, which was significantly higher than 56% of MWUV and 62% of ME system. The experiment results demonstrated a synergistic effect in MWUV/ME system, wherein the ME system played an important role in color removal and the formation of ·OH in photocatalysis contributed most for the mineralization of X-3B and its intermediates. The removal efficiency of TOC was 32%, 7.5%, and 59.5% under MWUV, ME, and MWUV/ME processes at the end of the reaction, respectively. The Fe3+ existed in the system was an enhancer of producing ·OH via self-generation of ·OH by UV irradiation or improving the separation of electron-hole in photocatalysis by capturing the electrons. Therefore, the combined treatment of MWUV and ME system has the potential of synergistic effect compared to the separate process. Lowering the initial solution pH and increasing the iron filing dosage and dissolved oxygen were beneficial for the enhancement of degradation efficiency. The inorganic anions showed a diversity influencing the degradation of X-3B. NO3-, CO32-, and SO42- (at higher concentration) promoted the degradation reaction, while Cl- had non-significant effect.

Influence characteristics and mechanism of organic carbon on denitrification, N2O emission and NO2− accumulation in the iron [Fe(0)]-oxidizing supported autotrophic denitrification process

Abstract Iron [Fe(0)]-oxidizing supported autotrophic denitrification [Fe(0)-AD] is a promising process for low-carbon water treatment. Organic-carbon (OC) has been a common pollutant associated with nitrogen pollution. However, its interaction with Fe(0)-AD remains unclear. In this study, influence characteristics and mechanism of OC on Fe(0)-AD were investigated. Fe(0)-AD was established based on iron-scraps (ISs) and iron-carbon micro-electrolysis (ME) (ME-ISs-AD). The results showed that the OC-free ME-ISs-AD obtained denitrification load of 0.191 ± 0.028 kgN/(m3·d), which shifted to 0.445 ± 0.011 kgN/(m3·d) at OC-dosage of 1.0 mgCOD/mgTN. N2O (1.52 ± 0.16 mgN/L) and NO2− (6.86 ± 1.11 mgN/L) accumulated markedly in Fe(0)-AD and were reduced to 0.03 ± 0.01 mgN/L and 0.31 ± 0.20 mgN/L at OC-dosage of 1.0 mgCOD/mgTN, respectively. XRD analysis demonstrated that OC could reduce the Fe(0)-passivation, accelerating biological transformation and storage of iron-compounds, enhancing H2 (from 0.06 ± 0.01 to 0.22 ± 0.04 mg/L) and Fe2+ (from 7.4 ± 1.0 to 13.9 ± 1.5 mg/L) production. High-throughput sequencing revealed the enrichment of iron-oxidizing bacteria (e.g. Sphaerotilus and Ferriphaselus) and autotrophic denitrifiers (e.g. Hydrogenophaga and Hyphomicrobium). Real-time qPCR and enzyme activity analysis indicated that the nosZ-encoded NosZ and nirK-encoded NIR controlled N2O and NO2− accumulation in OC-dosed Fe(0)-AD, respectively. Overdose of OC (≥1.5 mgCOD/mgTN) accelerated the bio-organics-Fe complexes (BioFe) production and blocked the H2/Fe2+ transfer. NaAC was more efficient and cost-effective than Glucose and EtOH for Fe(0)-AD enhancement. The utilization of ISs under the enhancement of ME reduced the cost of Fe(0)-AD by 3.87-times comparing to the in-situ ZVI-AD process, and the dose of OC further improved the denitrification load by 1.33-times. This study provided an in-depth understanding of the influence of OC on Fe(0)-AD and could contribute to the application, optimization and secondary pollutants control of Fe(0)-AD process in low-carbon water treatment.

Treatment Performance and Degradation Process of Contaminants in Vitamin B12 Wastewater

Abstract Vitamin B12 wastewater, as a pharmaceutical wastewater, is difficult to treat due to its high concentrations of bioresistant organic matters, salinity, chromaticity, and poor biodegradability. A laboratory-scale microelectrolysis (ME) process with aeration device was designed to treat this wastewater. Our results suggested that, under obtained optimal condition of hydraulic retention time of 80 min, initial pH of 3, and air/water ratio of 100:1, the removal efficiency of chemical oxygen demand, ammonia nitrogen (NH3—N), and chromaticity in the wastewater by ME process was achieved by 43.9%, 7.9%, and 82.6%, respectively. Organic matter with benzene ring was largely removed or degraded and, therefore, C = C and C = O bonds were destroyed, and substituents of aromatic rings contained more aliphatic chains after treatment by ME process. All wastewater samples were divided into three parallel factor analysis components: one protein-like (component 1 [C1]) and two humic-like components (component 2 [C...

Treatment of coking wastewater by a novel electric assisted micro-electrolysis filter

A newly designed electric assisted micro-electrolysis filter (E-ME) was developed to investigate its degradation efficiency for coking wastewater and correlated characteristics. The performance of the E-ME system was compared with separate electrolysis (SE) and micro-electrolysis (ME) systems. The results showed a prominent synergistic effect on COD removal in E-ME systems. Gas chromatography/mass spectrometry (GC–MS) analysis confirmed that the applied electric field enhanced the degradation of phenolic compounds. Meanwhile, more biodegradable oxygen-bearing compounds were detected. SEM images of granular activated carbon (GAC) showed that inactivation and blocking were inhibited during the E-ME process. The effects of applied voltage and initial pH in E-ME systems were also studied. The best voltage value was 1V, but synergistic effects existed even with lower applied voltage. E-ME systems exhibited some pH buffering capacity and attained the best efficiency in neutral media, which means that there is no need to adjust pH prior to or during the treatment process. Therefore, E-ME systems were confirmed as a promising technology for treatment of coking wastewater and other refractory wastewater.

Process design of high-concentration benzimidazole wastewater treatment based on the molecular structure of contaminants

ABSTRACTBenzimidazole is an important intermediate in industry and it is usually difficult to be degraded by many treatment technologies. Looking for a highly effective, environment-friendly degradation process for benzimidazole wastewater is of great significance to reduce pollution. Based on the structure of contaminants, the micro-electrolysis (ME) coupled with the Fenton technique was chosen to degrade the industrial benzimidazole wastewater. Special feeding was applied to maintain the suitable hydrogen peroxide (H2O2) concentration to produce the hydroxyl radicals (•OH) as much as possible and protect •OH from being quenched by excess H2O2 according to the reaction mechanism. The results showed that this combined technique was highly efficient to decompose benzimidazole compounds. More chemical oxygen demand (COD) could be reduced when flow control was used, compared to the flow not being controlled. The COD removal rate could reach 85.2% at optimal parameters. Then the effluent of this process was combined with the existing biochemical system for further degradation. The studies of Ultraviolet Spectrophotometry, Fourier Transform Infrared Spectroscopy and Liquid Chromatography Mass Spectrometry showed that both 2-(a-Hydroxyethyl) benzimidazole and 2-Acetylbenzimidazole were decomposed to the isopropanolamine and aniline after the ME treatment; then the intermediates were oxidized into oxalic acid after the Fenton reaction.

Performance of a coupled micro-electrolysis, anaerobic and aerobic system for oxytetracycline (OTC) production wastewater treatment

BACKGROUND The environmental and health effects caused by oxytetracycline (OTC) contamination of aquatic systems are a serious problem throughout the world. The OTC-contaminated wastewater cannot be treated effectively by conventional anaerobic and aerobic biological treatments. Few studies have investigated the systematic treatment of OTC-contaminated wastewater. RESULTS A system including micro-electrolysis (ME), an expanded granular sludge bed (EGSB) and an anoxic/oxic activated sludge process (A/O) could treat OTC production wastewater effectively. First, a ME reactor packed with new ceramic-corrosion-cell fillers, serving as a pretreatment step, was effective in removing residual OTC and enhancing biodegradability of the wastewater. Second, EGSB and A/O reactors played the main role in removing chemical oxygen demand (COD), ammonium nitrogen (NH3-N) and chroma (color of the wastewater). After reaching steady state, the coupled ME-EGSB-A/O system removed more than 95.0% of COD, 90.0% of NH3-N and 80.0% of color, and the final effluent met the requirements of the national discharge standard (COD ≤ 500 mg L−1, NH3-N ≤ 45 mg L−1 and chroma ≤ 70; CJ 343–2010, China). CONCLUSION The coupled ME-EGSB-A/O system could treat the OTC production wastewater effectively. These findings have significant implications for a cost-efficient system in OTC production systematic treatment. © 2015 Society of Chemical Industry

Utilization of micro-electrolysis, up-flow anaerobic sludge bed, anoxic/oxic-activated sludge process, and biological aerated filter in penicillin G wastewater treatment

System which included micro-electrolysis (ME), up-flow anaerobic sludge bed (UASB), anoxic/oxic (A/O) activated sludge process and biological aerated filter (BAF) were investigated in penicillin G-processing wastewater treatment. The main quality of the wastewater was shown as follows: chemical oxygen demand (CODcr) of 1,4507–1,5280 mg L−1, ammonium nitrogen (NH3–N) of 598–826 mg L−1, suspended solid of 1,850–2,190 mg L−1, and pH of 3.5–5.2. Moreover, penicillin G residue in the wastewater was 130–150 mg L−1. ME was utilized as the pretreatment method, UASB and A/O process were designed for the secondary treatment, and BAF was used as the advanced treatment. The results revealed that biodegradability of the wastewater could be effectively improved by ME, and most of CODcr and NH3–N in the wastewater could be removed by UASB and A/O process, and the residual COD and NH3–N could be removed by BAF. The average COD and NH3–N in final effluent was about 275.3 and 19.8 mg L−1, respectively, and the treated wastewater quality reached the requirement of the national discharge standards (wastewater quality standards for discharging into municipal sewer pipelines, China, COD ≤ 300 mg L−1, NH3–N ≤ 25 mg L−1 in C standard). Especially, about 80% of penicillin G residue in the wastewater could be removed or converted by ME reactor, and the wastewater could be effectively deposed in this system.

Contaminant removal performances on domestic sewage using modified anoxic/anaerobic/oxic process and micro-electrolysis

The objective of this study was to enhance removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) from domestic sewage in a sequencing batch reactor with added new materials. A modified anoxic/anaerobic/oxic (MAAO) process, integrating a micro-electrolysis (ME) bed in an anoxic tank, and complex biological media (CBM) in anoxic, anaerobic and oxic tanks to treat domestic sewage, and their performances were investigated. The MAAO system was operated at controlled hydraulic reTENTion time (HRT) of 8 h and mixed liquor recirculation (MLR) at 75%. The results showed that the MAAO system could effectively remove COD, TN and TP with average rates of 93%, 80% and 94%, respectively, in March, and 94%, 76% and 91%, respectively, in August. In this system, TP was primarily removed from the anoxic tank regardless of the operational conditions; removal contribution ratios to TP of the anoxic tank reached 56% both in March and August, indicating that the ME bed can effectively enhance phosphorus removal. TN was primarily removed from the anoxic and anaerobic tanks; removal contribution ratios to TN of anoxic and anaerobic tanks reached 36–38% and 37–38%, respectively. The oxic tank had the highest share of COD removal (56% both in March and August) in the removal of phosphorus. The outflow concentrations of COD, TN and TP were 3–46, 7–14 and 0.3–0.5 mg/L, respectively, in March, and 26–49, 9–15 and 0.04–0.1 mg/L, respectively, in August. COD and TN removal performances indicated that the innovative materials of the ME bed and CBM can effectively enhance COD and TN removal.

The Optimization of Pb(II),Cu(II),Zn(II) and Cd(II) Ions Removal by Micro-Electrolysis Using Response Surface Methodology

In this study, the Box–Behnken design matrix and response surface methodology (RSM) have been applied in the experiments to evaluate the interactive effects of four most important operating variables: pH (2.0–4.0), temperature (30–40°C )，iron/carbon ratio（1/2–3/2）and iron carbon amounts (2-4) on the removal of Pb (II), Cu(II)，Zn (II) and Cd (II) ions in acid mine drainage with micro-electrolysis (ME) . The total 29 experiments were conducted in the present study for the construction of a quadratic model. The independent variables have significant value 0.0001, which indicates the importance of these variables in the ME process. The values of “Prob > F” less than 0.0500 indicate that model terms are significant for the removal of Cr (VI), Ni (II) and Zn (II) ions. The regression equation coefficients were calculated and the data fitted to a second-order polynomial equation for removal of Pb (II), Cu(II)，Zn (II) and Cd (II) ions with ME.

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.

Pretreatment of coking wastewater by acid out, micro-electrolysis process with in situ electrochemical peroxidation reaction

The coking wastewater was pretreated by acid out, micro-electrolysis process with in situ electrochemical peroxidation (ECP) (approximately 0.013–0.015M H2O2) reaction to reduce the subsequent processing load. The results showed that the acidification process brought about changes not only in organic species of contaminants but also in decrease of COD, NH3N in wastewater through precipitation and some special reactions, resulting in 33% of COD and 9.7% of NH3N removal. Then Fe/C micro-electrolysis (ME) with in situ ECP reaction exhibited a stronger ability to remove the COD and NH3N than that with ex situ Fenton reaction, because at this stage, for the two reaction models, the total COD and NH3N removal were 65%, 26% and 43%, 25% in sequence, but in view of the contribution of only Fenton reaction to the whole COD and NH3N removal, they were 26%, 4.2% (the former was about six times as strong as the latter) and 9.3%, 8.1%, respectively. So it was reasonable to deduce that there was a prominent synergistic effect on COD removal between the dynamic Fe/C micro-electrolysis and the Fenton reaction; furthermore, the Fenton reaction in in situ ECP process was not only high-efficient but also low-cost. These advantages might mainly be attributed to the technique of dynamic Fe/C ME with in situ ECP reaction, as it was presumed that the technique might promote some favorable reactions involved, but inhibit those unfavorable ones. The major degradation mechanism of organic contaminants in effluent had been proposed.

Research on the treatment of phosphoric wastewater by ultrasound-assisted microelectrolysis method

In this research work, ultrasound was introduced to the microelectrolysis (ME) method to improve the treatment efficiency for phosphoric wastewater. The effects of treatment time, Fe/C ratio (v/v) and iron filings dosage on the efficiency of phosphorus removal from wastewater with different initial pH values were investigated. The results showed that the phosphorus removal efficiency by the ME method was significantly enhanced in the presence of ultrasound. The maximum removal rate of phosphorus (RRP) for the wastewater with an initial pH value of 4.0 was 92.4% after 60 min of treatment when the Fe/C and Fe/H2O volume ratio were 2/1 and 1/10, respectively. The reaction kinetics analysis indicated that the phosphorus degradation processes for the ultrasonic and ME methods as well as the ultrasonically assisted ME method (UME) were in accordance with the pseudo-first-order kinetic model. The synergetic effect of the combined ultrasound and ME method for phosphorus removal was also studied by reaction kinetics analysis.

The oxidative degradation by pyrolusite of p-nitrophenol wastewater after micro-electrolysis pretreatment

P-nitrophenol wastewater was pretreated with iron-carbon micro-electrolysis (ME) technology. After the pretreatment, pnitrophenol was degrade into p-aminophenol. The degradation ratio of p-nitrophenol could almost be up to 95% when pH value reached 2.0 and the quantity of added iron scrape was 2.0g/100mL. Through the experimental investigation, to identify the changes closely associated with treatment effect on wastewater containing nitrophenol, reaction time, pH, amount, particle size of pyrolusite and shaking speed were analzed. The p-nitrophenol were almost eliminated at a pH value of 3.5, shaking rate of 150 rpm, reaction time of 2h and pyrolusite amount of 1.0g/100mL, mineral grain size of 75-106μm. The removal ratio of COD is over 95% and TOC has been reduced by 89.0% at the same time. P-aminophenol was degraded into H2O and CO2 finally. The degradation mechanism of wastewater from pretreatment by pyrolusite has been further investigated based on previous work. International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 104-109

The oxidative degradation by pyrolusite of p-nitrophenol wastewater after micro-electrolysis pretreatment

P-nitrophenol wastewater was pretreated with iron-carbon micro-electrolysis (ME) technology. After the pretreatment, pnitrophenol was degrade into p-aminophenol. The degradation ratio of p-nitrophenol could almost be up to 95% when pH value reached 2.0 and the quantity of added iron scrape was 2.0g/100mL. Through the experimental investigation, to identify the changes closely associated with treatment effect on wastewater containing nitrophenol, reaction time, pH, amount, particle size of pyrolusite and shaking speed were analzed. The p-nitrophenol were almost eliminated at a pH value of 3.5, shaking rate of 150 rpm, reaction time of 2h and pyrolusite amount of 1.0g/100mL, mineral grain size of 75-106μm. The removal ratio of COD is over 95% and TOC has been reduced by 89.0% at the same time. P-aminophenol was degraded into H 2 O and CO 2 finally. The degradation mechanism of wastewater from pretreatment by pyrolusite has been further investigated based on previous work. International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 104-109

Bioaugmentation Treatment of Bromoamine Acid Wastewater with <i>Sphingomonas</i> Sp. FL

One effective bromoamine acid (BAA) degrading strain FL was isolated previously with the ability to use BAA as the sole source of carbon and energy. The strain FL was applied in a combined process of microelectrolysis (ME) and biological aerated filter (BAF) to treat the bromoamine acid wastewater, and the treatment efficiency was investigated. It was shown that when the influent CODcr was lower than 1000 mg L-1, and the total hydrolytic retention time (HRT) was 37.7 h, the removal rate of chrominance and CODcr could reach 95.3% and 77.3% respectively. Most of the chrominance was removed by the ME treatment, while the removal of CODcr is mostly owned to the BAF treatment. After long-term contact with the BAA wastewater, the strain FL became one of the predominent species in BAF. When the system was subjected to hydraulic loading shock, the strain FL ensured the efficient removal of chrominance and BAA.

Treatment of oilfield produced water by anaerobic process coupled with micro-electrolysis

Treatment of oilfield produced water was investigated using an anaerobic process coupled with micro-electrolysis (ME), focusing on changes in chemical oxygen demand (COD) and biodegradability. Results showed that COD exhibited an abnormal change in the single anaerobic system in which it increased within the first 168 hr, but then decreased to 222 mg/L after 360 hr. The biological oxygen demand (five-day) (BOD 5)/COD ratio of the water increased from 0.05 to 0.15. Hydrocarbons in the wastewater, such as pectin, degraded to small molecules during the hydrolytic acidification process. Comparatively, the effect of ME was also investigated. The COD underwent a slight decrease and the BOD 5/COD ratio of the water improved from 0.05 to 0.17 after ME. Removal of COD was 38.3% under the idealized ME conditions (pH 6.0), using iron and active carbon (80 and 40 g/L, respectively). Coupling the anaerobic process with ME accelerated the COD removal ratio (average removal was 53.3%). Gas chromatography/mass spectrometry was used to analyze organic species conversion. This integrated system appeared to be a useful option for the treatment of water produced in oilfields.

Treatment of bromoamine acid wastewater using combined process of micro-electrolysis and biological aerobic filter

The wastewater originated from the production of bromoamine acid was treated in a sequential system of micro-electrolysis (ME) and biological aerobic filter (BAF). Decolorization and COD Cr removal rate of the proposed system was investigated with full consideration of the influence of two major controlling factors such as organic loading rate (OLR) and hydraulic retention time (HRT). The removal rate of COD Cr was 81.2% and that of chrominance could be up to 96.6% at an OLR of 0.56 kg m −3 d −1 when the total HRT was 43.4 h. Most of the chrominance was removed by the ME treatment, however, the BAF process was more effective for COD Cr removal. The GC–MS and HPLC–MS analysis of the contaminants revealed that 1-aminoanthraquinone, bromoamine acid and mono-sulfonated 1,2-dichlorobenzene were the main organic components in the wastewater. The reductive transformation of the anthraquinone derivatives in the ME reactor improved the biodegradability of the wastewater, and rendered the decolorization. After long-term of operation, it was observed that the predominant microorganisms immobilized on the BAF carriers were rod-shaped and globular. Four bacterial strains with apparent 16S rDNA fragments in the Denaturing Gradient Gel Electrophoresis (DGGE) profiles of BAF samples were identified as Variovorax sp., Sphingomonas sp., Mycobacterium sp., and Microbacterium sp.