A Performance Comparison of Anaerobic and an Integrated Anaerobic-Aerobic Biological Reactor System for the Effective Treatment of Textile Wastewater (original) (raw)
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Anaerobic Treatment of Synthetic Textile Wastewater Containing a Reactive Azo Dye
Journal of Environmental Engineering, 2003
In this study, anaerobic treatment of synthetic textile wastewater containing a reactive azo dye, namely, Remazol Brilliant Violet 5R, was investigated. A fluidized bed reactor ͑FBR͒ was used in the study. Before the operation period, start-up of the FBR was completed in 128 days with an immobilized microorganism level of 0.069 g volatile suspended solids per g support material ͑pumice͒. Anaerobic treatment of synthetic textile wastewater revealed that 300 mg/L dye was removed in the FBR system. Chemical oxygen demand ͑COD͒ and color reduction in the system were approximately 60 and 94%, respectively. Under anaerobic conditions, formation of two sulfonated aromatic amines ͑SAAs͒ was detected due to anaerobic reduction of the dye. The SAAs were not degraded under anaerobic conditions. In addition to the anaerobic treatment, the effectiveness of aerobic treatment was investigated in order to further reduce the COD after the anaerobic treatment.
Separation and Purification Technology, 2011
The treatment of synthetic wastewater containing azo dyes found in textile industry wastewater was carried out by anaerobic biological method and chemical oxidation. The main target of this study was to compare different treatment methods and to evaluate the effect of different parameters on treatment effectiveness. In the microbial process, the results have shown that increasing the residence time, the amount of yeast extract and the addition of microorganisms originally growing on forest residues had positive effects on the dye removal. In the catalytic wet peroxide oxidation process, CWPO, the reaction conditions were optimized at 0.5 g/L activated carbon loading with 2 mL H 2 O 2 /300 mL solution (35 wt%), at 80 • C, in 2 h with pH = 3. At the optimum conditions, approximately 93% of the dye was removed. At these optimized conditions, the CWPO process was tested with real textile industry wastewater. The percentage of dye removal with this wastewater was 50%. The adsorption effect of the activated carbon was also investigated. At pH = 7, the removal by just adsorption was around 15%. But in acidic conditions (pH = 3) and at higher temperatures the adsorption effect of activated carbon increased. Adsorption and oxidation performances were compatible at 80 • C, however, at lower temperatures the adsorption effect was more considerable than the oxidation. It can be concluded that, generally the decolorization was accomplished by 60% adsorption and by 40% oxidation.
Anaerobic decolorisation of simulated textile wastewater containing azo dyes
Bioresource Technology, 2002
This study deals with the decolorization of the commercially important azo dyes, Orange II (C.I. Acid Orange 7) and Reactive Black 3HN (C.I. Reactive Black 8) under anaerobic conditions in wastewater. Laboratory scale semicontinuous studies were conducted using simulated cotton dyeing wastewater at ambient temperatures (24±28°C) by maintaining a HRT of 10 days. The dye concentration in wastewater was maintained at 100 mg/l. The reactors were operated for 58 days and Orange II and Black 3HN were easily decolorized under the experimental conditions employed. The performance of the bioreactors was evaluated by monitoring oxidation±reduction potential (ORP) in the reactor, color and Chemical oxygen demand (COD) removal. Color removal of >99% was achieved in both the dye-containing reactors. COD removals of up to 95%, 92% and 94% were achieved in control, orange-and black dye-containing reactors, respectively. Eect of dyes and salts present in textile wastewater on methanogenesis was evaluated based on maximum methane production and methanogenic activity. Based on the maximum methane production data, no inhibition of methanogenesis was observed for dye concentrations of up to 400 mg/l for both the dyes. However from the methanogenic activity data, it was observed that the black dye concentration of 400 mg/l seemed to cause inhibition of methanogenesis.
Anaerobic decolorization of textile wastewater containing reactive azo dyes
1997
In this study, the ability of anaerobic system to decolorize different reactive azo dyes were investigated Three reactive azo dyes were used in this study including CI-198 (Remazol Red RB), CI-141 (Reactive Red) and CI-5 (Remazol Black B). Most of the study on reactive azo dyes degradation used parent dyes (commercial dyes without any teatrrent), but it was known that mostly of the dyes ended up in the waste stream as a hydrolyzed form. Thus, the decolorization of parent and hydrolyzed fomt dyes were also compared in this study. The standard assay conditions for measurement of dye decolorization were adopted from Carliell et al. (1995). Experimen8 were performed in senrm bottles with the temperature was maintained at37"C and an initial dye concentration of 100 mg/L. This study shows that the Earent and hydrolyzed form dyes had the same decolorization behavior. It also shows that the decolorization of CI-198 and CI-141 in anaerobic system was found to be fust order with respect to dye concentration. However, decolorization of CI-5 was much more complex.
Anaerobic/aerobic treatment of selected azo dyes in wastewater
Waste Management, 1994
Azo dyes represent the largest class of dyes in use today. Current environmental concern with these dyes revolves around the potential carcinogenic health risk presented by these dyes or their intermediate biodegradation products when exposed to microflora in the human digestive tract. These dyes may build up in the environment, since many wastewater treatment plants allow these dyes to pass through the system virtually untreated. The initial step in the degradation of these dyes is the cleavage of the Azo bond. This cleavage is often impossible under aerobic conditions, but has been readily demonstrated under anaerobic conditions. The focus of the study was to determine the feasibility of using an anaerobic fluidized-bed reactor to accomplish this cleavage. The effects of typical process variables such as hydraulic retention time (HRT), influent dye concentration levels, and degree of bed fluidization on removal efficiencies were also studied. The four dyes selected for this study were Acid-Orange 7, Acid-Orange 8, Acid-Orange 10, and Acid-Red 14. The effectiveness of using a bench-scale-activated sludge reactor as a sequenced second stage was also examined. Results indicate that nearly complete cleavage of the Azo bond is easily accomplished for each of the four dyes under hydraulic retention times of either 12 or 24 h. Initial results indicate, though, that aromatic amine by-products remain. The sequenced second stage was able to remove the remaining Chemical Oxygen Demand (COD) load to acceptable levels. Work is presently underway to determine the fate of the anaerobic by-products in the aerobic second stage.
International Biodeterioration & Biodegradation, 2011
In the present study the performance of anaerobiceaerobic one and two stage processes for the biological treatment of synthetic wastewaters containing Reactive Black 5 (RB5) were studied and compared with each other. In both processes the majority of colour removal by biodegradation occurred under anaerobic environment. The colour change under aerobic conditions was correlated with extent of anaerobic decolourisation in the preceding phase/stage of the process. Partial mineralisation of the anaerobic dye metabolites, roughly to the same extent, was achieved aerobically in both one stage and two stage processes. The majority of COD was removed in the anaerobic stage for two stage processes and aerobic stage in one stage processes. In one stage processes, the exposure of anaerobic sludge to alternating anaerobiceaerobic environment decreased anaerobic decolourisation efficiency and COD removal; when employing activated sludge, the same exposure enhanced anaerobic substrate utilisation whereas the effect on the anaerobic decolourisation efficiency depended on RB5 concentration. The comparative performance of one and two stage processes in terms of overall dye decolourisation depended on RB5 concentration. Both types of processes brought about similar overall COD removal. Increase in RB5 concentration, in the range studied, resulted in decrease in overall COD removal for both processes.
Decolorization of Synthetic Azo Dyes under Anaerobic Condition in A Continuous Stirred Tank Reactor
Journal of Pure and Applied Microbiology, 2021
Biological treatment for textile wastewater always has a limitation in term of time of reaction and uncertainty along the process. This study focused on the decolorization of synthetic azo dyes in batch reactors with controlled thermotolerant anaerobic conditions. Less-volatile digested sludge collected from a palm oil biogas reactor was used as the organic biodegradation agent for azo dyes. Digested sludge contains high amounts of microbes with uncertain species viable for decolorization purposes. Sodium acetate trihydrate (C2H9NaO5) was used as carbon source and mixed with a specific composition of minimum salt media (MSM) in batch reactors as an additional nutrient. Digested sludge both in mesophilic (35°C) and thermophilic (55°C) conditions were found to be capable of decolorizing 100, 200 and 300 ppm of three types of azo dyes: Reactive Green 19 (45.56%, 69.73%; 63%, 73.49%; 70.02%, 75.92%), Reactive Orange 16 (46.08%, 78.4%; 64.21%, 85.52%; 74.95%, 85.91%) and Reactive Red 120...
Research Journal of Pharmaceutical, Biological and Chemical Sciences
Azo dyes constitute the largest class of synthetic dyes and represent the major chemical in textile industry wastewater. The remediation of textile industry wastewater before reaching the agricultural environment is of significance for the safety of the surrounding environment. However, the recalcitrant nature of these chemicals requires special technologies to remove and/or reduce the risks associated with their discharge. The bioremediation of these toxic synthetic dyes is among the approaches for remediation of textile industry wastewater. This study focuses on the isolation, screening and azo dye removal by bacteria isolated from dumping site of textile wastewater. Fourteen isolates were tested in this study. One of them was the most efficient in decolourization of RB dye. This isolate was identified by 16s DNA sequences to Pseudomonas aeruginosa strain OS4 (NCBI accession number: KC762943). Bioremediation of azo dyes was found to occur efficiently under two sequential phases; s...
Release of textile azo dyes to the environment is an issue of health concern while the use of microorganisms has proved to be the best option for remediation. Thus, in the present study, a bacterial consortium consisting of Providencia rettgeri strain HSL1 and Pseudomonas sp. SUK1 has been investigated for degradation and detoxification of structurally different azo dyes. The consortium showed 98-99 % decolorization of all the selected azo dyes viz. Reactive Black 5 (RB 5), Reactive Orange 16 (RO 16), Disperse Red 78 (DR 78) and Direct Red 81 (DR 81) within 12 to 30 h at 100 mg L -1 concentration at 30 ± 0.2 °C under microaerophilic, sequential aerobic/microaerophilic and microaerophilic/aerobic processes. However, decolorization under microaerophilic conditions viz. RB 5 (0.26 mM), RO 16 (0.18 mM), DR 78 (0.20 mM) and DR 81 (0.23 mM) and sequential aerobic/microaerophilic processes viz. RB 5 (0.08 mM), RO 16 (0.06 mM), DR 78 (0.07 mM) and DR 81 (0.09 mM) resulted into the formation of aromatic amines. In distinction, sequential microaerophilic/ aerobic process doesn't show the formation of amines. Additionally, 62-72 % reduction in total organic carbon content was observed in all the dyes decolorized broths under sequential microaerophilic/aerobic processes suggesting the efficacy of method in mineralization of dyes. Notable induction within the levels of azoreductase and NADH-DCIP reductase (97 and 229 % for RB 5, 55 and 160 % for RO 16, 63 and 196 % for DR 78, 108 and 258 % for DR 81) observed under sequential microaerophilic/aerobic processes suggested their critical involvements in the initial breakdown of azo bonds, whereas, a slight increase in the levels of laccase and veratryl alcohol oxidase confirmed subsequent oxidation of formed amines. Also, the acute toxicity assay with Daphnia magna revealed the nontoxic nature of the dye-degraded metabolites under sequential microaerophilic/aerobic processes. As biodegradation under sequential microaerophilic/aerobic process completely detoxified all the selected textile azo dyes, further 159 efforts should be made to implement such methods for large scale dye wastewater treatment technologies.
Destruction of azo dyes by anaerobic–aerobic sequential biological treatment: a review
International journal of Environmental Science and Technology
Dyes are synthetic organic compounds widely used in various industries such as, textile, leather, plastic, food, pharmaceutical, and paints manufacturing industries. Coloured effluents are highly toxic to the aquatic life and mutagenic to humans. Wastewater containing dyes has become an important issue demanding serious attention. Among the synthetic dyes, azo dyes are the largest and most widely used dyes and account for more than half of the annually produced dyes. The biodegradation of azo dyes is difficult due to their complex structure and synthetic nature. Several treatments have been proposed for efficient azo dye removal, most of them presenting some limitations such as generation of waste sludge, high operational costs, poor efficiency, and incomplete mineralization. Biological treatment is a cost-effective and eco-friendly process for dye degradation. Sequential anaerobic–aerobic biological treatment is considered as one of the most cost-effective methods for the complete ...