Electrochemical treatment of rice grain-based distillery effluent: chemical oxygen demand and colour removal

Abstract

The electrochemical (EC) treatment of rice grain-based distillery wastewater was carried out in a 1.5 dm³ electrolytic batch reactor using aluminium plate electrodes. With the four-plate configurations, a current density (j) of 89.3 A/m² and pH 8 was found to be optimal, obtaining a maximum chemical oxygen demand (COD) and colour removal of 93% and 87%, respectively. The chemical dissolution of aluminium was strongly influenced by initial pH (pH_i). At higher pH_i (pH 9.5) anode consumption decreased while energy consumption increased. At the optimal current density 89.3 A/m², the aluminium electrode consumption was 16.855 g/dm³ wastewater and energy consumption was 31.4 Wh/dm³ achieving a maximum COD removal of 87%. The settling and filterability characteristics of electrochemically treated sludge were also analysed at different pH. It was noted that treated slurry at pH_i 9.5 gave best settling characteristic, which decreased with increase in pH. EC-treated effluent at pH_i 8 had provided best filterability. Characteristics of scum and residues are also analysed at different pH.

Keywords:

• rice grain-based biodigester effluent
• chemical oxygen demand
• colour reduction
• energy consumption
• filterability

Acknowledgements

Authors gratefully acknowledge Chhattisgarh Council of Science and Technology (CGCOST), Raipur, India for providing research grants to support this work.