A lab-scale flat sheet membrane bioreactor (MBR) system was used for the treatment of piggery wastewater to produce an effluent with the appropriate ratio of nitrite:ammonia (1:1 to 1:) as a pre-treatment for the anammox process. The feed wastewater, which was the effluent of a biogas digester, contained 253±49 (n=60) as COD, 231±18 as N-ammonia, 223±19 as total Kjeldalh nitrogen (TKN), alkalinity of 1433±153 as CaCO3 , and pH=±. This study aimed to determine the suitable hydraulic retention time (HRT) and alkalinity to yield the appropriate influent for the annamox process. The results showed that the suitable effluent of the partial nitrification with ratio of nitrite:ammonia at HRT of 7h30, equivalent to total nitrogen loading of kgNm-3d-1. The nitrite accumulation rate (NAR) was 82% at HRT of 7h30, whereas NAR were 11 and 63% at HRT of 12h30 and 8h45, respectively, due to the high growth of nitrite oxidation bacteria (NOB) at long HRTs. As increasing alkalinity of up to 1600 and pH of at HRT of 8h45, NAR was increased from 63 to 73%, ratio of ammonia:nitrite reduced from to and free ammonia concentration reached to nitrogen. This shows that the increase of alkalinity inhibited strongly NOB. | Partial nitrification of piggery wastewater as pre-treatment for anammox process using flat sheet membrane bioreactor
