Optimizing Temperature & C/N Ratios of Newspaper and Green Vegetable Waste for Methane Yield through MANUAL Optimization and Response Surface Methodology /

Abstract

Newspaper and green vegetable waste can be a noteworthy energy source for the production of renewable energy in the form of bio-methane. This research is focused on the optimization of temperature and carbon to nitrogen (C/N) ratio to enhance bio-methane yield from anaerobic co-digestion of newspaper and green vegetable waste. Manual optimization through hit and trial method and response surface methodology (RSM) using central composite design (CCD) were carried out in order to determine the optimum conditions of temperature and carbon to nitrogen (C/N) ratio for bio-methane yield. Both manual and CCD experiments were performed at organic loading of 10gVSL-1 and volatile solid (VS) substrate to inoculum ratio of 1:1. Results from the CCD experiments revealed that maximum specific bio-methane yield, 342 L/kgVS, is 12.87% more than the predicted value, obtained from reactor CCD-7 having C/N 30:1 and temperature 30.86 oC, while results from manual optimization experiments illustrated that maximum specific biomethane yield 401.8L/kgVS was obtained from rector MR3 having 48.3 % more than methane content than thermophilic reactor TR3 operated at C/N ratio of 30 and temperature 37oC having 93.45% green vegetable waste and 6.54 % of newspaper waste. A significant synergistic effect in co-digestion of newspaper and green vegetable waste was observed at mesophilic temperature rather than thermophilic. Verification experiments confirmed that temperature and C/N ratio have influential effect on bio-methane yield.