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Colour removal and its mechanisms in textile wastewater treatment by UASB reactor system with anaerobic granular sludge
By Dewwanthi Karunarathna | January 18, 2008
Textile wastewaters generated from different stages of textile processing contain various toxicants or pollutants that are seriously harmful to natural aquatic environment when released without proper treatment. Although there are different methods, which can be adopted for the treatment of textile wastewater, biological approaches are considered as environmentally friendly, low cost and effective methods over other physico-chemical methods. In the present study, simulated textile wastewater (STW) prepared by mixing of three popular acid dyes (Acid blue 204, Acid red 131 and Acid yellow 79) in synthetic wastewater was studied for the decolourization and removal of degradable organic in the laboratory scale Upflow Anaerobic Sludge Blanket Reactor system with anaerobic granular sludge for about five months at different organic and dye loading rates. The colour removal mechanisms under anaerobic treatment were also examined since microbial colour removal occurs basically in two ways namely biological degradation, which is more important in textile wastewater treatment, and adsorption of dye molecules onto microbial biomass. Chemical oxygen demand (COD) removal of acid red 131 (AR131) containing STW was about 80% at 300 mg/l dye concentration and it was over 89% in acid yellow 79 (AY79) dye containing STW under studied conditions. Although acid blue 204 (AB204) showed a little inhibition over methanogenic consortia, about 93% of COD removal was observed at 100 mg/l dye concentration. Colour removal of AR131 dye containing STW was 95% and it was credited to biodegradation. Treatment of STW prepared using AY79 showed 95% colour removal owing to biodegradation while AB204 was quite resistant to biodegradation by anaerobic microorganisms. Observed colour removal was merely due to the adsorption of dyes onto microbial granules. Even though a little accumulation of volatile fatty acid (VFA) was observed in increased dye concentrations, the detected values of VFA, alkalinity and pH showed that those values were in the range of desirable limits of anaerobic process. It seems that AR131 and AY79 can be decolourized almost completely by UASB reactor system while AB204 cannot be decolourised since all colour removal attributed to adsorption of dye onto microbial granules. It can be concluded that anaerobic technology can be used for the treatment of textile wastewater containing different dyes as an alternative method over other methods. However, further study of UASB reactor for the treatment of real textile wastewater is suggested to find out matrix effect of other chemicals present in real textile wastewater before application to the real world situations.
W Somasiri, Li Xiufen, Wenquan Ruan and Jian Chen
Laboratory of Environmental Biotechnology, School of Biotechnology, Southern Yangtze University, Wuxi,
Jiangsu, PR China.
Topics: Pollution control, symposium 2006 |
June 1st, 2008 at 11:15 am
We also finding economical method of color removing. Whather we can try with a UASB pilot plant. Could you help us?
Thanks.