Ambient temperature SNAD process treating anaerobic digester liquor of swine wastewater

In present study, effluent from anaerobic digestion of swine wastewater was treated by the simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) process using a lab scale 5 L sequencing batch reactor (SBR) under ambient temperature. The fluctuation of anaerobic digester liquor quality (COD, 387 ± 145 mg/L; TKN, 662 ± 190 mg/L; NH4+-N, 519 ± 134 mg/L) and temperature created difficulties to develop a stable SNAD process in the SBR (days 1–285). Fed batch feeding strategy was adopted to have a stable condition in the reactor and overcome the negative effects of organic nitrogen. The average total nitrogen, NH4+-N and COD removal efficiencies in the SBR under steady state conditions (days 485–523) were 80%, 96% and 76%, respectively. The results showed that presence of organic nitrogen, mode of feeding and reactor temperature affects the SNAD process.

► SNAD process was used to treat the anaerobic digester liquor of swine wastewater.
► High NH4+-N removal efficiency (96%) was achieved under steady state conditions.
► Average COD removal efficiency of 76% was achieved under steady state conditions.
► Organic nitrogen negatively affects the performance of SNAD process.
► Fed batch feeding strategy facilitated to have stable SNAD process.