氨胁迫对猪粪厌氧消化性能的影响

Effects of Ammonia Stresses on Anaerobic Digestion of Swine Manure

以猪粪为原料,采用批式试验方法,研究不同氨氮添加量(0、400、800、1600、2400、3200、4000 mg·L-1)对厌氧消化产气效果的影响。结果表明:随着氨氮添加量的增加,总产气量和CH4产率均呈现先升高后降低的变化趋势,氨氮添加量≥2400 mg·L-1时,厌氧消化过程受到显著抑制;不同处理中猪粪挥发性固体(VS)的CH4产率分别为328.5、338.1、323.2、304.9、276.2、124.9、56.1 m L·g-1。氨氮添加量为0~800 mg·L-1时,最大VS产CH4速率分别为18.3、18.4、17.1 m L·g-1·d-1;氨氮添加量为2400 mg·L-1时,产气高峰推迟,产CH4速率明显降低;氨氮添加量≥400 mg·L-1时,厌氧消化30 d底物的生物转化产CH4效率随氨氮添加量的增加逐渐降低,分别为56.7%、54.5%、52.4%、30.6%、1.6%和1.3%;氨氮添加量为400~2400 mg·L-1时,乙酸利用型产甲烷菌Methanosaeta的相对丰度总体随氨氮质量浓度的增加而降低,而氢利用型产甲烷菌Methanosarcina和Methanococcus具有相反的变化规律。

Anaerobic digestion is a commonly used technique for treating livestock manure and producing biogas. However, ammonia gener-ated during the digestion may reduce the efficiency of an anaerobic digestion system. Here a batch experiment was carried out to investigate the effect of ammonia on anaerobic digestion of swine manure by adding ammonia at 0, 400, 800, 1600, 2400, 3200 mg·L-1 and 4000 mg·L-1 under mesophilic conditions(35℃). Cumulative biogas production had no obvious differences at 0~800 mg·L-1 of ammonia concentrations. However, the lag phase appeared and cumulative biogas decreased when ammonia was higher than 2400 mg·L-1. Yields of CH4 were 328.5, 338.1, 323.2, 304.9, 276.2, 124.9 mL·g-1 and 56.1 mL·g-1 VS for 0, 400, 800, 1600, 2400, 3200 mg N·L-1 and 4000 mg N·L-1, respective-ly. The maximum CH4 yield rates were 18.3, 18.4, 17.1 mL·g-1·d-1 at 0, 400 mg N·L-1, and 800 mg N·L-1 of ammonia added, respectively. Increasing ammonia from 3200 mg·L-1 to 4000 mg·L-1 sharply decreased the CH4 yield rates and greatly delayed the peaks. The biodegrad-ability(BAD)of VS at 30 d was 55.6%, 56.7%, 54.5%, 52.4%, 30.6%, 1.6%and 1.3%for 0, 400, 800, 1600, 2400, 3200 mg N·L-1 and 4000 mg N·L-1, respectively. The results from terminal-restriction fragment length polymorphism(T-RFLP)and clone library showed that the relative abundance of acetate-utilizing Methanosaeta decreased with increases in ammonia concentrations, but the abundance of hydro-gen-utilizing Methanosarcina and Methanococcus had an opposite tendency at ammonia range of 400~2400 mg·L-1.