The potential of a low cost EPAD system in the treatment of textile mill effluents

Abstract

Anaerobic treatment is feasible for raw textile mill effluents under tropical conditions. This possibility offers textile industries an opportunity to cost effectively treat their effluents. This study evaluates the biodegradability of raw textile mill effluents and subsequently the technical feasibility of a combined cost effective Enhanced Pre-treatment (EP) followed by anaerobic digestion (AD). The enhanced pre-treatment consisted of a coagulant (AlCl3) and a polyelectrolyte organic flocculant (Calflock 2900) to remove the suspended solids. The combined EPAD system was operated semi-continuously under laboratory conditions for 1680 hours with the anaerobic batch reactor operating at a Bv of 2.6 g COD/L.d and HRT of 12 hours. The EP process on average achieved respectively 53% and 68% COD and colour removal efficiencies. The combined EPAD system on average achieved 72% and 87% COD and colour removal efficiencies respectively however the reactor produced a low amount of biogas. The batch anaerobic reactor operated without the need to discharge regularly the biological excess of sludge produced. The implementation of the combined EPAD system can lower the chemical cost to less than Kshs 2.4 per kg COD removed. A new approach for the treatment of textile wastewater is thus proposed.