Abstract
Reactive dyes have been problematic compounds in textileeffluents as they are water soluble. Textile effluents also have a high organicload in the scouring and desizing processes. However, textile wastewater isnearly complete decolorization under anaerobic conditions. Therefore, thisresearch investigates the decolorization and kinetics of reactive dye (C.I.Reactive Red 120) in different carbon sources by partially granulated anaerobicmixed culture. Three sizing agents, namely acrylic size (AS), polyvinyl alcohol(PVA) and modified starch (MS) were used as carbon sources which the CODconcentration of 1200 mg/l. Batch test experiments were employed by mixing the1.8 g MLVSS/l of mixed microorganisms in the solution containing each carbonsource and dye and then incubated in incubator at 371 C for 324 hours.Results revealed that two steps of decolorization was found when used AS andPVA as carbon sources. The first step showed high rate of decolorization, whilethe second step showed low rate of decolorization. The maximum decolorizationfor AS, PVA and MS as carbon sources were 89.25, 88.74 and 93.97 %,respectively when the dye concentration of 60 mg/l were applied. The k valuesand color removal rate of decolorization with MS was higher than AS and PVA ascarbon sources, respectively. This is because, the MS as carbon source wassimple structure compared to AS and PVA. Additional experiments on the effectof dye concentration, using MS as the carbon source, revealed that degradationof RR 120 followed first-order kinetic. The decolorization rates increased withthe decreasing dye concentrations of RR 120. On the other hand, the zero-orderkinetic of decolorization respect to AS as carbon source, and then thezero-order kinetic of decolorization respect to PVA as carbon source in lowestdye concentration of 20 mg/l. In conclusion, the anaerobic biodegradation oftextile wastewater containing MS can be achieved, and that enhancement of azoreduction through addition of MS (electron acceptor) carbon source.
Keywords - Anaerobic treatment; Decolorization; Kinetics;Reactive dye
About the Authors:
Sunantha Laowansiri and Soydoa Vinitnantharat are associatedwith Division of Environmental Technology, School of Energy and Materials, KingMongkuts University of Technology Thonburi, Thungkru, Bangkok, 10140, Thailand.
Pawinee Chaiprasert is associated with Division ofBiotechnology, School of Bioresources and Technology, King Mongkuts University of Technology Thonburi, Thakam, Bangkhuntien, Bangkok, 10150, Thailand.
Sung-Ryong Ha is associated with Department of UrbanEngineering, Chungbuk National University, Keshindong Heudukgu Cheongju, Chungbuk,361-763, Republic of Korea.
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