Treatment of highly acidic wastewater from a food processing industry

Abstract

Food processing is one of the most important industries around the world. The food processing industry uses a huge amount of water in the production process and consequently generates wastewater rich in inorganic and organic contaminants. The Wastewater generated needs to be treated before being released into the environment. This research aims to treat wastewater released from a food processing industry. This food processing industry processes spices including Garcinia (Goraka), pepper, turmeric, mustard, chili and fenugreek and other food items including noodles, soy products etc. The pH, temperature, TDS, conductivity, COD, and BOD5 of the wastewater were determined. The wastewater was unusually acidic with pH of 2.35. Its conductivity and TDS were 1240 μS and 477 ppm respectively. The average value for COD and BOD5 were 3667 and 871 ppm. The wastewater was highly acidic due to the presence of (-) hydroxycitric acid released during the processing of Garcinia. Thin layer and paper chromatographic studies showed Rf 0.36 and 0.24 respectively for the solvent system, n- butanol: acetic acid: water = 4:1:5 confirming the presence of (-) hydroxycitric acid in wastewater. Conventional treatment methods using poly aluminium chloride and alum as the coagulants followed by closed aeration were employed to treat the effluents. The Highest COD removal efficiency was observed when coagulation was carried out at pH 5 followed by neutralization to pH 7 using poly aluminium chloride as the coagulant. Under these conditions the COD removal efficiency was 88 % and BOD was reduced by 92 % in the treated wastewater.