初始碱度和温度对养猪废水厌氧发酵过程的影响特征

EFFECTS OF INITIAL ALKALINITY AND TEMPERATURE ON ANAEROBIC FERMENTATION PROCESS OF PIGGERY WASTEWATER

采用序批式实验研究了不同初始碱度(3503,5500,7500 mg/L,以CaCO_(3)计)和温度(20℃、35℃和50℃)下养猪废水的厌氧发酵过程,考察其对发酵液pH、挥发性脂肪酸、产气量、沼液养分、重金属含量、抗生素和抗性基因的影响特征。结果表明:初始碱度调控会延缓水解酸化阶段的启动,强化产酸过程,提高总产酸量;高碱度对发酵液pH的维持能力最高;初始碱度调控适用于以产酸为目的的中温(35℃)和高温(50℃)厌氧发酵。35℃和50℃有利于沼液中养分的释放,50℃时养分浓度最高,为(1365.14±124.38)~(1471.71±135.29)mg/L。50℃厌氧发酵更有利于沼液中水溶态重金属(Cu、Zn)的削减,消减比例分别为(81.53±9.51)~(86.04±7.72)%和(96.48±8.73)~(97.81±10.29)%。厌氧发酵对沼液中抗生素(土霉素和诺氟沙星)具有削减作用,50℃时的削减比例最高,比20℃和35℃分别高(14.61±1.39)~(56.26±5.24)%和(23.83±3.21)~(85.84±17.35)%。50℃和适量初始碱度调控能够降低抗性基因的相对丰度。该研究结果可为畜禽养殖废水厌氧发酵的工艺优化提供参考。

The anaerobic fermentation process of piggery wastewater at different initial alkalinity levels(3503,5500,7500 mg/L,as CaCO_(3))and temperature(20,35,50℃)was studied by sequential batch experiment.The characteristics of its influences on pH,volatile fatty acids,gas production,biogas slurry nutrients,heavy metal content,antibiotics and resistance genes were investigated.The results revealed that the initial alkalinity adjustment could delay the initiation of the hydrolysis and acidification stage of anaerobic fermentation,strengthen the process of acid production and increase total acid production.The highest pH maintenance ability was presented with the operation of the highest level of alkalinity.The initial alkalinity regulation was suitable for anaerobic fermentation at moderate and high temperature with the purpose of producing acid.35℃and 50℃was conducive to releasing nutrients from fermentation substrates,and the highest nutrient concentration was(1365.14±124.38)~(1471.71±135.29)mg/L at 50℃.Anaerobic fermentation at 50℃was more conducive to the reduction of soluble heavy metals(Cu,Zn)in biogas slurry,and the reduction ratios were(81.53±9.51)~(86.04±7.72)%and(96.48±8.73)~(97.81±10.29)%,respectively.Anaerobic fermentation could reduce the concentrations of antibiotics(oxytetracycline and norfloxacin)in biogas slurry,and the highest reduction rate was(14.61±1.39)~(56.26±5.24)%and(23.83±3.21)~(85.84±17.35)%at 50℃compared with 20℃and 35℃,respectively.The relative abundance of resistance genes were decreased at 50℃and appropriate initial alkalinity regulation effectively.The results of this research could provide a reference for the optimization of the anaerobic fermentation process of livestock wastewater.