Ballast weight review of capsule husk Jatropha curcas Linn. on acid fermentation first stage in two phase anaerobic digestion

Increasing biogas production through the use of dried capsule husk - jatropha curcas linn. (dh-jcl) as raw materials study was conducted at pt bumimas ekapersada experiment field,in bekasi,west java,indonesia from september 2013 to march 2014. four hdpe pipes with 5 l volume used as first stage-hydrolysis digester,while an hdpe (high-density polyethylene) drum with working volume 80 l was used as second phase - methanogenesis digester. dh-jcl at the first stage was pressed by a 1 800 g ballast,which was to be compared to a 900 g ballast pressed,diluted in water with volume ratio of 1:8. one third of the second stage digester was filled by immobilized growth of random packing system on special plastic design. organic loading rate was predetermied at 3 000 cc · d–1 with hydrolic retention time of 4 wk. this study was repeated three times and conclusion was made using t test as inferential statistics. the test concluded that 900 g ballast produced the best result. dh-jcl biogas productivity is increased,by two phase system,as much as 163 % when compared to semi continuous single phase system. furthermore,the set up produces methane content higher (90 % to 91 %) than semi continuous single phase system (83.15 %). vfa average decrease of 16 %,and average alkalinity decreased by 11 %. average ratio of vfa/ alkalinity is 0.5 similar with semi continuous single phase system. © pakistan academy of sciences.