Abstract: In this study，a biological removal process using a combination recirculating system of hydrolyze–acidification was used to treat digested piggery wastewater. The transformation of volatile fatty acids（VFAs）and nitrogen under different cycle ratio conditions for this recirculating system were investigated. The results showed that formic acid，acetic acid and propionic acid give main contribution of VFAs in hydrolysis process. The concentration of formic acid was very low or undetected，and the proportion of acetic acid and propionic acid in organic acids were high. The species and concentrations of organic acids on 1/3 cycle ratio were higher than these under other two conditions. The relationship between COD and organic acids contents，COD and acetic acid，COD and propionic acid were linear. The good efficiency for nitrogen removal was obtained at 1/3 cycle ratio with the lowest NH₃-N and NO₃^--N concentrations in treated effluent of 3.57 mg/L and 48.60 mg/L，respectively.

Key words: digested piggery wastewater, cycle ratio, organic acids, hydrolysis acidification, nitrification and denitrification

摘要： 采用水解酸化工艺处理厌氧发酵液，研究了不同循环比条件下，水解过程挥发性脂肪酸和氮元素转化规律。结果表明：水解过程产生的挥发性脂肪酸主要有甲酸、乙酸和丙酸，仅有少量样品检测出甲酸，乙酸和丙酸占有机酸总量比例较大。在循环比为1/3条件下产生的有机酸的种类、总量比其它两个条件要多。处理后出水中COD浓度与有机酸总量、乙酸、丙酸浓度均呈线性关系。循环比1/3条件下，处理后出水中氨氮和硝态氮浓度最低（分别为3.57 mg/L和48.60 mg/L），脱氮效果最好。

关键词: 发酵液, 循环比, 有机酸, 水解酸化, 硝化反硝化