Anaerobic Biohydrogen Production From Food Waste: Effects Of Additives And Initial Conditions

With the improvement of living standard, the increasing food waste has great influence on environment, whichhas attracted people's attention. And hydrogen energy is one of the most potential renewable clean energy Energy production by wastes is an important measure to solve the problems of energy shortage and environmental pollution. It becomes hotspot of the research that how to ferment food origin waste anaerobically to produce hydrogen and achieve resource recycling in this process.In this paper, food waste as a substrate of biological hydrogen production, inoculated with anaerobic granular sludge and the aged refuse as food waste bio-hydrogen system additives. Using the aged refuse have porous structure and rich content of micro-organisms to improve hydrogen production. Major researched the mechanism and effects of agent additives and aged refuse. The effects of main influence factors (inoculation rate, moisture content, pH) and the reflux ratio on the hydrogen fermentation were studied. Results are as follows:(1) Alkaline agent XYF and aged refuse were demonstated to enhance biohydrogen fermentation from food origin waste. Adding aged refuse, alkaline agent XYF, and mixture of aged refuse and alkaline agent XYF to biohydrogen fermentation system, the hydrogen yield were 5.2mL/g food waste (wet weight),16.3mL/g food waste (wet weight), and 19.5mL/g food waste (wet weight),respectively.(2)Porous structure and abundunt microorganisms of aged refuse were helpful to promote hydrogen production. When the food wastes and aged refuse ratio froml:1.0 to 1:3.0, the hydrogen yield were 16.2 mLH2/g food waste (dry weight) increased to 65.4 mLH2/g food waste (dry weight), respectively.(3)The optimum process conditions were found by single factor experiments. The results showed that the maximum hydrogen yield 290.3mLH2/gVS was obtained at inoculation ratio 35%, the hydrogen yield was 37.6mLH2/gVS and 149.7mLH2/gVS at inoculation ratio 10% and 60%, repectively. Ferment material was in a fluffy state at moisture content 95%, which is good for fermentation. And the maximum potential of hydrogen production achieved at 424.3mL, which compared to 75% and 85% increased by 8.3 times and 1.9 times.Hydrogen yield reached 31.7 mLH2/g food waste (dry weight) at the initial pH 6.5, which was more suitable for the growth of microorganisms than other pH values.(4) Results of the several factors orthogonal experiments illustrated that sequential impact of three factors was listed as follow:moisture content> inoculum ratio>initial pH. Low inoculum ratio and low moisture content were not favourable to biohydrogen fermentation. However effects of different initial pH on hydrogen production were similar.(5)Effect of reflux ratio(mixing Fermentation liquor and food waste in different ratio) on biohydrogen fermentation was taken. Under reflux ratio 50% and 100%, the hydrogen production rate and hydrogen concentration were higher than that at reflux ratio 0%. The average hydrogen production rate and hydrogen concentration were 5.4L/d and 42.1% at reflux ratio 50%was.The average hydrogen production rate was 6.3L/d at 100% reflux ratio, and hydrogen concentration only increased by 1.0% compared to that at reflux ratio 50%.