DO浓度和pH对沼液废水短程硝化反应的影响

Effect of DO and p H on Short-cut Nitrification for Biogas Slurry Wastewater

目的]研究溶解氧(DO)浓度和p H对沼液废水短程硝化反应的影响。[方法]采用自制的SBR反应器,针对DO浓度和p H 2个影响因子进行单因素试验,考察其对亚硝酸盐积累的影响。[结果]在温度(25±2)℃,进水氨氮(NH_4^+-N)浓度550~600 mg/L、化学需氧量(COD)1 600~1 700 mg/L、p H 7.5,水力停留时间(HRT)为1 d的条件下,DO浓度在1.1~1.5 mg/L时,出水亚硝氮(NO_2^--N)/总硝氮(NO_x^--N)可达到0.85,NO_2^--N/NH_4^+-N接近于1。在温度为(25±2)℃、DO为1.3 mg/L和进水NH_4^+-N浓度为600 mg/L时,将p H控制在7.3~7.8,亚硝酸菌整体活性最高。[结论]DO浓度会显著影响亚硝酸盐的积累和转化,p H直接影响亚硝酸菌的生长,过高的p H会导致高NH_4^+-N沼液废水中游离氨的浓度升高,从而抑制亚硝酸菌的活性。

Objective]To study the effect of DO concentration and p H on short-cut nitrification of biogas wastewater.[Method]A single factor experiment was conducted to investigate the effects of two factors,DO and p H,on nitrite accumulation in a SBR reactor.[Result]The NO_2^--N/NO_x^--N could reach 0.85 in effluent and NO_2^--N/NH_4^+-N was close to 1 under the following conditions:(25±2)℃,the concentration of NH_4^+-N and COD in influent was 550-600 and 1 600-1 700 mg/L,p H was 7.0-7.5,HRT was 1 d,and the concentration of DO was 1.1-1.5 mg/L.It has the highest activity of nitrosomas under the control of p H within 7.3-7.8 with the following conditions:(25±2)℃,the concentration of NH_4^+-N in influent was 600 mg/L,and the p H was controlled within 7.3-7.8.[Conclusion]The concentration of DO significantly affects the accumulation and transformation of nitrite,and the level of p H will directly affect the growth of nitrite bacteria.The excessive p H will lead to the increase of ammonia concentration in the biogas slurry wasterwater with high ammonia nitrogen,thus inhibiting the activity of nitrosomas.