餐厨垃圾与污泥厌氧发酵产气动力学特性研究

Kinetics Characterization of Anaerobic Digestion of Food Waste and Sludge

对餐厨垃圾、污水厂污泥以及餐厨垃圾与污泥混合甲烷发酵的产气能力与动力学特性进行了实验分析,餐厨垃圾在中温和高温发酵的产甲烷潜能分别是400和426 m L CH_4·g VS-1,经过120℃、20 min蒸煮除油后的餐厨垃圾在中温和高温发酵的产甲烷潜能分别是418和531 m L CH4·g VS^(-1)。经Gompertz模型计算,除油后餐厨垃圾的最大产甲烷速率Rmax比除油前提高了49.8%(中温)和19.0%(高温),但餐厨垃圾中固体有机物的产甲烷速率变化不明显。在餐厨垃圾机械破碎匀浆过程中,部分固体有机物被液化,中、高温发酵产气过程的一级动力学呈现两阶段特征,液相有机物在中温发酵的产甲烷速率(速率常数k=0.195 5 d^(-1))略快于高温(k=0.154 3 d^(-1));而固体有机物在高温条件下的产甲烷速率(k=0.080 4 d^(-1))快于中温(k=0.038 8 d^(-1))。除油后餐厨垃圾中的固体有机物和污泥高温发酵的产甲烷速率也快于中温发酵,表明高温发酵有利于提高固体有机物的产气速率。污泥的产气潜能较低,产气速率慢,与餐厨垃圾共发酵有助于调节碱度和防止发酵体系的酸化。

The biogas production kinetics characterization of food waste, sludge and the mixture of food waste and sludge were investigated in mesophilic and thermophilic anaerobic digestion system. The methane potential of food waste were 400 and 426 m LCH_4·g VS^(-1) in mesophilic and thermophilic anaerobic system and then increased to 418 and 513 m LCH_4·g VS^(-1) after oil removing(boiling at 120 oC for 20 mins). The maximum of methane production, Rmax obtained from Gompertz model, was increase by 49.8% and 19.0% after oil removing, nevertheless, there were no significant increment of methane production rate of the solid fraction of oil removed food waste. Grinding of food waste partially liquefied food waste. The methane production was faster in mesophilic with constant k of first order kinetics of 0.195 5 d^(-1) than that in thermophilic with a k of 0.154 3 d^(-1). However, the methane production from solid fraction of food waste was faster in thermophilic(k of 0.080 4 d^(-1)) than that in mesophilic process(k of 0.038 8 d^(-1)), the same results were obtained for solid fraction of oil removed food waste and sludge. The sludge provide a lower gas production potential and lower production rate.