Experimental Study On Biohydrogen Production By Anaerobic Fermentation Of Food Waste

Currently, the production of food waste in China grows at a high speed, with anincreasing proportion in urban domestic garbage. Kitchen waste has high moisturecontent, rich nutrients, and is highly perishable. Without proper disposal, it willhazard people’s health and urban ecological environment. On the other hand, energyshortage has long been a key factor that restricts the sustainable development ofChina’s society and economy. The supply of traditional fossil fuels is tight, and theircombustion brings a lot of gas that is harmful to the environment. Meanwhile,hydrogen is considered as the cleanest alternative energy. Therefore, producinghydrogen by anaerobic fermentation of food waste is a double-benefit tactics, andgains great significance in solving energy crisis and preventing the pollution ofkitchen garbage.In the experiment, food waste is used to generate hydrogen by anaerobicdigestion at medium temperature. The continuous flow test in the CSTR explores theoperating modes, including the system’s startup, the sludge’s cultivation anddomestication, the acidified sludge’s recovery, the reactors’ second startup after apause in the run, and so on. It also inspects the following factors’ effects to hydrogenproduction characteristics, such as COD organic load, pretreatment of the seed sludge,and alkalinity in the influent. After214days’ cultivation and acclimation, the CSTRis successfully launched, and the continuous flow experiment proves that COD loadhas certain influences on hydrogen yield, hydrogen productivity, COD removal rate,liquid fermentation products, hydrogen production type, etc. The heated treated seedsludge has higher hydrogen productivity, and its hydrogen production type convertsfrom mixed acid type to butyric acid type in a shorter time with the rising of organicload. However, the seed sludge without heat treatment has a richer strain diversity,and better adaptability to the changes of environment. Under the condition of37±1℃, system pH6.0±0.1, and hydraulic retention time24hours, CSTR’s highesthydrogen productivity is84.49mL/gCOD among the organic load range from2.5kgCOD/(m3·d) to8.0kgCOD/(m3·d).With food waste as substrate and the activated sludge from the CSTR asinoculated sludge, batch hydrogen production experiment by anaerobic fermentationis conducted, studying operating parameters’ effects on hydrogen output, such as pH,substrate concentration, etc. The experiment also illustrates the process of microbialzymolysis and hydrogen yielding with dynamic model. The results of the experiment show that pH5.0and substrate concentration5.0gCOD/L is the best condition forbatch hydrogen production, and the highest hydrogen productivity is60.630mL/gCOD.