EFFECT OF TEMPERATURE PRE-TREATMENT ON BIOGAS PRODUCTION FROM Calotropis procera (Aiton) LEAVES AND COW DUNG UNDER ANAEROBIC CONDITION

Abstract

Biogas is an alternative and renewable energy source produced through anaerobic digestion of organic matter. Low degradability of substrates is one of the factors that obstruct the production of biogas. With the aim of evaluating biogas yields from Calotropis procera (CP) leaves and cow dung (CD) a sequence of experiments were carried out under mesophilic conditions at 38ºC using batch digester operating for 21 days. The pre-treatments of biogas were done at 60 and 80ºC temperature. The parameters: total solids (TS), volatile solids (VS), organic carbon, and total nitrogen were measured. The experimental design, different combination ratios were adopted and employed for the five digesters. In this case, for the first digester 100% Calotropis procera, for the second one 75% Calotropis procera leaves and 25% cow dung were used. Moreover, for the third digester contained 1:1 ratio Calotropis procera leaves and cow dung, for the fourth one 25% of Calotropis procera leaves and 75% of cow dung, and for the fifth one 100% of cow dung were employed. Therefore, cumulative biogas production were TS and VS reductions from anaerobic digestion of both thermal temperature 60 and 80ºC pre-treated substrates were 17.65 in both parameters and 21.15 and 21.14 respectively. However, heat pre-treated at 60 and 80ºC were the highest cumulative biogas production observed in the same treatment (B) 75% of Calotropis procera leaves and 25% of cow dung. Finally overall results indicated for the biogas yield, Volatile solids (VS), total solids (TS), percent organic carbon, and percent total nitrogen reduction can be enhanced through thermal pretreatments to anaerobic digestion. The highest reduction of all parameters in treatment 75% of Calotropis procera leaves to 25% cow dung (B), it produced total amount of biogas 1267ml and 1511.33ml respectively. However, more biogas production at 80°C pretreated more than 60°C temperature.