Evaluation of Biogas Production Potential from Waste Coconut Water

Abstract

Coconut oil production is the eminent agro based industries in Tamil Nadu. The matured coconut water was considered as a waste. Coconut oil industries discharge considerable amount of waste coconut water having very high values of Biochemical Oxygen Demand (BOD) to the extent of 29,000 mgl-1, the wash water about 3,000 mg. and Total Solids (TS) of 5.45 ± 0.35%. Coconut water contains most nutrients required for microbial growth. The pH of coconut water is 6.1. The Total Suspended Solids in coconut water is found out as 0.0028 g/ml. The Total Dissolved Solids is 0.8014 g/ml, Total Solids is 0.8042 g/ml and Volatile Soluble Solids is 99.5 %. A laboratory scale batch type anaerobic digester (Air tight 2 litre plastic bottles) was set up for the experimental purpose for a retention time of 35 days. Coconut water, water and cow dung were mixed in different proportions (5 treatments). Each treatment was replicated 3 times. Biogas volume and biogas composition were measured at 5:30 pm every day. Remarkable volume of biogas production was noticed between 12th and 16th days. Maximum biogas volume of 976. 67 ml was noticed for the combination of 1:1 (Cow dung: Coconut water) with methane content of 53 %. For the combination of 2:1:1 (Cow dung: Coconut water: Water) the maximum volume of biogas production is 833.3ml with methane content of 31 %. For the combination of 1:1 (water: Cow Dung) the maximum volume of biogas produced is 133.3 ml with methane content of 48 %.  The biogas produced from different ratios was tested for its flammability. It was seen that blue flame is produced and the flame is last for few seconds for all ratios but the maximum amount of flame was produced from the sample which contains maximum amount of Coconut water than other samples.