Start-Up Of Partial Nitrification-Anammox (Pn/A) Process Treating Piggery Wastewater

Nitrogen removal had become a major focus in piggery wastewater treatment since nitrogen was the nutrient causing eutrophication. Recently, partial nitrification-Anammox (PN/A) was a promising process for ammonia-rich wastewater. This study investigated the start-up and operation of PN/A process for nitrogen removal from piggery wastewater under oxygen-limited (0-0.2 mg/L). Firstly, the diluted piggery wastewater was used as the influent; results showed that excess of biodegradable organic carbon would threaten Anammox bacteria survive. Then, the anaerobic digestion of piggery wastewater with the gradient dilution was fed into the reactor, corresponding to gradually increasing the ratio of chemical oxygen demand (COD) to ammonia (COD/N) to 0.99, 1.37, and 1.61, the PN/A reactor could recover to good performance. And the ratio of COD removal value (CODremoved) to ammonia (CODremoved /N) closed to 0.17 averagely on phase III-V, which indicated that digested piggery wastewater which mainly consisted of refractory organics as the effluent did not affect the operation of the PN/A process. Using the high-throughput sequencing, the abundance of Candidatus Brocadiacese was decreased from 8.61% on day 125 to about 4.56% on day 173 and remained a stable proportion (3.41% on day 235). Our study provided a start-up strategy of the PN/A process for treating piggery wastewater.