Abstract:

Manure-free piggery wastewater is low in COD but high in concentration with a COD-to-TN (C/N) ratio less than 1. In order to removal nitrogen from the wastewater efficaciously, a wood-packed-bed A/O process with four compartments was constructed and its performance in pollutant removal was evaluated, especially the denitrification. The reactor was operated at HRT 18.7 h and 32℃ with an internal recycle ratio of 200% and DO 1.5 mg·L^-1 in the last compartment. The treatment process was started up with diluted raw wastewater in which COD/TN ratio was regulated to about 3.9. When the process performed steady, the dilution rate of the raw wastewater was decreased stage by stage, synchronizing with C/N ratio. When the process was steady in the last stage even feeding the raw wastewater with a high of about 307.7 mg·L^-1 and a COD/TN ratio as low as 0.47, the removal of COD, and TN was averaged out about 66.5%, 93.6% and 89.0%, respectively. A load removal of TN above 0.22 kg·m^-3·d^-1 was obtained. The four compartments had illustrated difference in pollutant removal with a total COD removal of about 78.3% in the front three anaerobic compartments and a TN removal of about 73.1% in the last aerobic compartment. TN removal in the reactor was mainly attributed to the shortcut nitrification-denitrification process with the packed wood as the internal carbon source.

Key words: piggery wastewater, low C/N ratio, fixed-bed, anaerobic, aeration, nitrogen removal, carbon source, shortcut nitrification

摘要：

针对干清粪式养猪废水 浓度高和低C/N比的特点构建了四格室木质填料床A/O处理系统,通过调控运行探讨其除氮效能和机制。结果表明,在HRT 18.7 h、32℃、硝化液回流比200%、好氧区DO 1.5 mg·L^-1等条件下,即便进水 高达307.7 mg·L^-1,COD/TN平均为0.47,系统对COD、 和TN的去除率仍能维持在66.5%、93.6%和89.0%左右,TN去除负荷达到0.22 kg·m^-3·d^-1以上。系统对COD和TN的去除表现出一定的空间分区特征,其中前三厌氧格室是去除COD主要功能区,末端好氧格室是脱氮功能区。系统的脱氮机制以短程硝化反硝化为主,枯木填料的腐解为反硝化提供了必要的碳源。

关键词: 养猪废水, 低C/N比, 固定床, 厌氧, 曝气, 脱氮, 碳源, 短程硝化