Effects Of COD/SO₄^2- On Characteristics Of Biogas Production And Nutrients Utilization During Anaerobic Digestion Using Kitchen Wastes As Substracts

The anaerobic fermentation of kitchen wastes can not only make the reduction, reducing pollution to the environment, but also produce clean energy biogas and high-quality organic fertilizer, which aroused people’s wide spread attention. But in the process of sulfate(SO₄^2-) reduction and methane production（CH₄）, the competitive inhibition of organic matter（COD） between the two kinds of bacteria often leads to the failure of anaerobic fermentation process. Which process coming into prominence was up to COD/SO₄^2-.This study using batch experiments probed into the effects of different COD/SO₄^2- on the gas production characteristics and nutrients utilization in fermentation acid production phase of anaerobic fermentation with food waste, on the basis of study on the characteristics of anaerobic fermentation with all kinds of kitchen wastes. The main results were as follows:1. The anaerobic fermentation period of vegetables, pasta, fruits, meat and mixed kitchen wastes were 15, 20, 25, 26 and 26 d respectively. Belong to the vegetables of radish, carrot, cabbage, Chinese cabbage, potato, the greatest potential for methane are respectively 157, 175, 165, 94, 267 L/K g VS; Belong to pasta of rice, noodles, bread, the greatest potential for methane are 224, 259, 296L/K g VS respectively. Belong to the fruits of banana peel, orange peel, apple, the greatest potential for methane are111, 34, 264L/Kg VS; Eggs, fish, meat and mixed kitchen wastes of the maximum methane production potential were 496, 420, 476, 412L/K g VS. Using the modified Gompertz formula, the dynamic parameters of anaerobic fermentation of the cumulative gas production were simulated and the results were in agreement with the experimental results.2. Due to the toxicity of long chain fatty acid inhibition,the daily gas production rate of Kitchen waste fermentation in the early and middle stage of fermentation（25 days before） had been kept at a low level, while 25 days of fermentation later, inhibition reduced or eliminated.3.The effect relationship of different COD/SO₄^2- on fermentation accumulation gas production with kitchen wastes was 12:1 ﹥ 6:1 ﹥ 3:1.When COD/SO₄^2- ratio was 6:1, the maximum methane potential Pmax and maximum methane production rate Rmax reached the maximum value.4. The law for the degradation of organic compounds in acid production was carbohydrate﹥TS﹥COD﹥protein.5. The COD hydrolysis rate of the acid production phase was roughly equivalent to that of the dissolved COD, and the relationship of hydrolysis rate constant Kh was COD K﹥carbohydrate Kh﹥ protein K h.6.The content relationship of refractory particulate organic matter in matrix particulate organic matter was COD Sn/Si﹥protein Sn/Si﹥carbohydrate Sn/Si.