脂肪酶强化水解餐厨油脂促进厌氧消化

Study on the Enhanced Hydrolysis of Kitchen Grease and Promoted Anaerobic Digestion Performance by Lipase

采用批次实验研究了脂肪酶预处理对餐厨油脂水解及其对厌氧消化性能的影响。首先考察了酶用量、水油比、pH和温度等因素对餐厨油脂水解的影响,进而通过响应面分析确定了其最佳预处理条件;最后基于预处理条件下的餐厨废水(含油脂)的厌氧消化实验,分析了预处理对餐厨废水厌氧消化的重要影响。结果表明:餐厨油脂的最佳预处理条件为:酶用量质量分数1.15%、水油质量比0.9、pH 8.0、温度42.5℃,水解率预测值为86.6%,重复实验水解率为(88.1±2.2)%,与预测值较为接近,表明该响应面模型能够很好地预测上述4个反应条件对水解的影响。对实际餐厨废水进行脂肪酶预处理和厌氧消化研究发现,加酶组的累积甲烷产量为572.12mL/g·COD,较餐厨废水组(368.86 mL/g·COD)和含油废水组(499.47 mL/g·COD)分别提高了55.10%和14.56%,表明餐厨废水中的脂肪具有较大的产甲烷潜力,脂肪酶预处理能显著提高油脂的产甲烷效率。对不同预处理条件下厌氧反应过程的pH、挥发性脂肪酸(VFAs)及脱氢酶活性进行了对比分析,发现酶促预处理对系统pH的影响较小;其对VFAs及脱氢酶活性的影响主要体现在厌氧消化前期,表现为对VFA及脱氢酶活性的显著提高,说明预水解能够保证产甲烷过程的底物供给并提高产甲烷效率。

The effect of lipase pretreatment on kitchen grease hydrolysis and its anaerobic digestion performance were studied with batch experiments.Firstly,the influence of enzyme dosage,ratio of water to oil,pH and temperature on the kitchen grease hydrolysis were investigated.Then,the optimized pretreatment condition was determined by response surface analysis.Finally,anaerobic fermentation of the kitchen wastewater with grease were carried out to analyze the impact of lipase pretreatment on the kitche grease digestion.Results showed that the optimized hydrolysis conditions were determined as enzyme dosage 1.15%,ratio of water to oil 0.9,pH 8.0,temperature 42.5℃.Under these conditions,the hydrolysis rate was predicted at 86.6%and the repeated experimental result was(88.1±2.2)%,which showed that the response surface model could predict the influence of four factors on the hydrolysis reaction well.For the results from anaerobic fermentation,the cumulative methane yield of the enzyme pretreated kitchen wastewater with grease was the highest with the value of 572.12 mL/g·COD,showed 55.10%and 14.56%increase than the wastewater with grease group(499.47 mL/g·COD)and the actual kitchen wastewater group(368.86 mL/g·COD)respectively.This indicated that grease had high methane production potential,and lipase pretreatment could obviously improve the methanogenesis efficiency.Further investigation demonstrated that enzyme pretreatment had little effect on pH variation,which showed the significant increase in volatile fatty acids(VFAs)and dehydrogenase activity during the early stage of anaerobic digestion.This manifested that pre-hydrolysis could promote substrate supply for the methane production and improve the methane yield efficiency.