Electrochemical treatment of coffee pulping wastewater using aluminum electrodes

Coffee processing involves large volume of water and wastewater. Coffee grown in many regions is processed using the wet method in order to be commercialized as green coffee. The coffee pulping wastewater from source-1 was characterised by low pH which varying between 3.92 to 4.99 and high COD between 8,320 mg/L to 10,400 mg/L, BOD 160 mg/L, total solids concentration was 5,000 mg/L, phosphorus varying between 60 mg/L to 94 mg/L, nitrate nitrogen varying between 32 mg/L to 52 mg/L, and ammonia nitrogen concentration was in the range of 50 mg/L to 84 mg/L. For wastewater to be easily treated in biological reactor the BOD5 / COD should be 0.5 or greater i.e., the waste is considered to be easily treatable by biological treatment. Since the BOD5 / COD ratio of coffee pulping wastewater was considerably less than 0.5 electrochemical treatment was tried to improve the BOD5 / COD ratio using aluminium electrode. The studies done for treating the raw coffee pulping wastewater by electrochemical method resulted in 93 %, 83 % and 90 % removal efficiency of COD, phosphorus and nitrate nitrogen respectively.