Abstract:

Nitrogen removal from manure-free piggery wastewater (MFPW) with high and low C/N ratio is a great challenge. A novel upflow microaerobic biofilm reactor (UMBR) was constructed to treat the MFPW in the present research. The reactor was operated at 27℃ and a hydraulic retention time of 8.0 h, in which the dissolved oxygen (DO) was less than 1.0 mg·L^-1 controlled by refluxing aerated effluent with the reflux ratio decreased from 45:1 to 30:1 by stages. During the 79-day operation, the effect of wastewater characteristics and DO concentration on the UMBR' performance was investigated. The results showed that the internal DO decreased from 0.70 to 0.23 mg·L^-1 following the decrease of reflux ratio from 45:1 to 30:1 by stages, and no negative impact on COD removal was found with a well NH₄^--N oxidation. But the anaerobic ammonium oxidation would be inhibited by a DO above 0.70 mg·L^-1, resulting in a decrease in TN removal. Fed with raw MFPW characterized by a COD,NH₄^--N and TN of 271, 336.7 and 337.4 mg·L^-1 with the DO 0.40 mg·L^-1 and the reflux ratio 35:1, the average pollutant removal load reached 0.60, 0.94 and 0.91 kg·m^-3·d^-1, respectively. Though the COD/TN in the feed averaged 0.8, a removal of NH₄^--N and TN as high as 93.1% and 89.9% was obtained, respectively. Obviously, the filler allowed more activated sludge to grow as biofilm in the UMBR and could construct suitable microenvironments for chemoheterotrophic bacteria, ammonia oxidizing bacteria, autotrophic and heterotrophic denitrifiers, separately. The diversity of physiological groups of bacteria laid the foundation for the excellent pollutant removal in the microaerabic process.

Key words: piggery wastewater, ammonium, total nitrogen, low C/N ratio, microaerobic, biofilm, nitrogen removal

摘要：

针对高氨氮低C/N比干清粪养猪废水处理面临的脱氮问题，制作并运行了一种升流式微氧生物膜反应器（UMBR），考察了废水水质和由出水回流比调控的溶解氧（DO）对系统处理效能的影响。结果表明，将系统内DO控制在0.23～0.70 mg·L^-1范围，不会对UMBR的COD去除率造成不良影响，而且能够保证NH₄^--N的氧化效能。但DO为0.70 mg·L^-1的微氧环境，会抑制厌氧氨氧化作用，降低系统的TN去除效能。在HRT 8 h、27℃和DO 0.40 mg·L^-1的条件下，UMBR对NH₄^--N和TN的去除负荷平均可达0.94和0.91 kg·m^-3·d^-1，COD去除负荷也能达到0.60 kg·m^-3·d^-1左右。分析认为，填料的布设及生物膜的着生，不仅保证了UMBR的微生物持有量，而且可为化能自养菌群、氨氮氧化菌群、自养反硝化菌群和异养反硝化菌群等微生物类群创造各自适宜的微环境，是系统保持污染物高效去除的生物学基础。

关键词: 养猪废水, 氨氮, 总氮, 低C/N比, 微氧, 生物膜, 脱氮