Optimization of Biogas Production by Solid State Anaerobic Digestion (SS-AD) Method from Water Hyacinth with Response Surface Methodology (RSM)

Water hyacinth is one of the rapid growth rate water weed in Rawapening Lake. Water hyacinth contains high hemicellulose which can be used for biogas production. This research aims to know the optimum value of total solid (TS), C/N ratio and microbial consortium for the biogas production with SS -AD from water hyacinth. The variations used for TS are 15%, 27.5%, and 40%, for C/N ratio are 20, 35, and 50, for microbial consortium are 3%, 6%, 9%. Sixteen reactors of 2 litres volume used with the variations inside are determined by Central Composite Design in Statistica software. Results of the biogas production are then analysed using Response Surface Methodology for optimization. Based on the analysis, the optimum value of TS is in the range of 5%-10%, value of C/N ratio is 32.09, and microbial consortium is 7.26%. Reactor 10 with the TS 5.45%, C/N ratio 35, and microbial consortium 6% has the closest value to the optimum value. The production rate of reactor 10 then analysed using Polymath 6.0. The constant kinetics rate of biogas (U) production rate is 1.88mL/g TS day; maximum biogas production is 108.41 mL/g TS; the minimum time to form the biogas is 8.87 days.