Removal of colour and organic matter from textile wastewaters using two anaerobic processes

Abstract

In this study, textile wastewater containing dye was treated using two anaerobic processes and then the dye degradation was studied. Textile wastewater was treated using a two-stage anaerobic system that included an anaerobic fermenter and a methane reactor. After a hydraulic retention time (HRT) of 3 d in the fermentation reactor, the maximum colour removal was 86% in the wastewater with the most colour (355 as Pt-Co). After the methane reactor, this value was 74%. When the removal of organic matter at different HRTs was examined, it was noted that 20%–30% of the removal occurs in the fermentation reactor. This is because the organic matter in the fermentation reactor was transformed by anaerobic bacteria into different organics (volatile fatty acids, alcohol, amines, etc.). However, as the HRT in the methane reactor increased, the removal of organic matter is increase to 95%. When the HRT in the methane reactor was 3 d, the chemical oxygen demand removal efficiency was around 84%. Therefore, 3 d was accepted as the optimum HRT in the anaerobic hybrid up-flow anaerobic sludge bed and was also found to be the optimum HRT in the fermentation reactor.