基于吸附-生化解吸实现低浓度氨氮废水的亚硝化

Stable Nitritation for Low-strength Ammonium Wastewater Based on Adsorption and Biological Desorption

探究了基于沸石生物固定床反应器(ZBFB)的吸附-生化解吸实现低浓度氨氮废水稳定亚硝化的可行性。当进水NH_4^+-N为50 mg/L左右时,ZBFB在吸附-生化解吸循环操作后的吸附出水NH_4^+-N都可稳定低于5 mg/L;当解吸温度为27℃时,ZBFB在前34个周期内的亚硝化生化解吸显著,出水亚硝化率(NAR)大于90%,但从第35个周期起,因硝酸盐氧化菌(NOB)对低游离氨(FA)的逐步适应,亚硝化生化解吸被破坏;逐步提升生化解吸温度可迅速恢复ZBFB的亚硝化生化解吸,并在生化解吸温度稳定在36℃时,ZBFB生化解吸出水NO_2^--N和NO_3^--N浓度分别稳定在259. 0～281. 2 mg/L和3. 2～12. 1 mg/L,对应的NAR保持在95. 5%～98. 8%,表现出稳定的NO_2^--N积累效果,实现了稳定亚硝化生化解吸。QPCR分析表明,相比于未升温条件下的生化解吸,控制生化解吸温度为36℃时ZBFB的amoA表达量明显大于Nitrobacter sp. 16S和Nitrospira sp. 16S的表达量,进一步验证了通过吸附床层升温恢复和实现ZBFB稳定亚硝化生化解吸的可行性。

The feasibility of stable nitritation for low-strength ammonium wastewater by adsorption and biological desorption in zeolite biological fixed bed reactor ( ZBFB) was investigated. Wastewater with 50 mg/L NH4^+- N was firstly adsorbed by ZBFB and the effluent NH4^+- N concentration could be lower than 5 mg/L during the whole experiment. Then biological desorption was carried out after each adsorption for ammonium transformation and zeolite recovery. With biological desoqition temperature of 27 ℃,significant nitritation performance occurred in ZBFB during 34 operational cycles with nitrite accumulation ratio (NAR) higher than 90%. However, due to the gradual adaption of nitrate oxidizing bacteria ( NOB) to low free ammonia ( FA), biological desorption was destroyed from the 35th cycle. Dramatically, increasing biological desorption temperature could restore nitritation biological desorption of ZBFB rapidly. With biological desorption temperature of 36℃, it was found that desorption effluent NO2^-- N and NO3^-- N stayed in the range of 259. 0 - 281.2 mg/L and 3.2-12.1 mg/L, respectively, leading to the NAR of 95. 5%- 98. 8%. The results revealed that increasing biological temperature to 36 could maintain stable nitrite accumulation and nitritation biological desorption in ZBFB. QPCR results showed that, compared with those of ZBFB without biological desorption temperature increase, amoA gene expression was obviously higher than that of Nitrobacter sp. 16S and Nitrospira sp. 16S with biological desoiption temperature of 36 ℃, respectively, which further demonstrated the feasibility of increasing operational temperature in recovering nitritation and keeping stable nitrite accumulation performance for biological desorption of ZBFB.