餐厨垃圾生化产甲烷潜力的数学模拟

Mathematical simulations biochemical methane potential of food waste

为资源化回收利用餐厨垃圾,采用BMP实验对其产甲烷潜力进行了研究,测定了不同厌氧消化时间内的沼气产量及COD、VFA浓度,并在此基础上对餐厨垃圾产甲烷潜力进行了数学模拟。结果表明,混合液COD浓度变化曲线呈逐渐下降的趋势,VFA出现短暂积累,应调控厌氧消化系统的碱度。餐厨垃圾经40 d厌氧消化后,实际生物化学产沼气及产甲烷潜力分别可达559.1、349.7 m L·g^(-1)VS,第20天后累积产气量增加不显著。数学模拟结果表明,餐厨垃圾最初7 d的平均水解常数为0.244 d^(-1),模拟产沼气及甲烷潜力分别可达578.36和363.72 m L·g^(-1)VS,实际产沼气及甲烷潜力分别占模拟产沼气及甲烷潜力的96.7%、96.1%,采用固体停留时间为25~30 d进行厌氧消化较为合理。

In regard to food waste recycling,a BMP test for methane production potential of food waste was conducted. Biogas production and concentrations of COD and VFA were determined during anaerobic digestion,and based on the BMP test results,a mathematical simulation of methane production potential of food waste anaerobic digestion was performed. The results showed that the COD concentration in the mixed liquor declined gradually,and the VFA concentration briefly accumulated; therefore,the alkalinity of an anaerobic digestion system should be controlled to avoid acidification. The biogas and methane production yields of the food waste were 559. 1 and 349. 7 mL·g^-1VS,respectively,after 40 d of anaerobic digestion. Meanwhile,cumulative biogas production after 20 d of anaerobic digestion increased insignificantly. The mathematical simulation results indicated that the average hydrolysis rate constant of food waste during the first 7 days was 0. 244 d^-1,and the simulated biogas and methane production potentials of food waste reached 578. 36 and 363. 72 mL·g^-1VS,respectively,of which biogas and methane production yields accounted for 96. 7% and 96. 1%. Therefore,it is suitable to use a solid retention time between 25 d and 30 d to digest food waste.