Colour and nutrient removal from textile waste water using an enhanced fluidised bed bioreactor

Abstract

Textile waste water contains an array of chemicals with different biodegradation characteristics that often presents chronic colour and nutrient removal problems. Conventional and advanced methods commonly applied to treat textile wastewater are normally costly and require substantial investment costs. Enhanced anaerobic digestion (E.A.D) of textile wastewater, in comparison with other processes, seems to be most promising since it drastically reduces the organic and colour load of the wastewater at substantially minimised costs. This possibility offers textile industries an opportunity to cost effectively treat their effluents. This study evaluated colour and COD removal from raw textile waste water by means of an enhanced fluidised bed bioreactor. The enhancement of the bioreactor entailed pretreatment of the raw waste water using a coagulant (AlCl3) and a polyelectrolyte organic flocculant (Calflock 2900) to remove the suspended solids. The enhanced system was operated semi-continuously under laboratory conditions for 1680 hours. The fluidised bed anaerobic bioreactor was operated at a Bv of 2.6g COD/L.d and HRT of 12 hours. The enhancement process on average achieved respectively 40 ± 13 per cent and 68 per cent COD and colour removal efficiencies. The combined system on average achieved 72 ± 7per cent and 87 ± 4 per cent COD and colour removal efficiencies respectively however the bioreactor produced a low amount of biogas. The bioreactor operated without the need to discharge regularly the biological excess of sludge produced. The implementation of the combined system proved to be quite promising thus a new approach for the treatment of textile wastewater is thus proposed.