A study on start-up operation of fixed-bed Biofilm Sequencing batch reactor (FbSBR) for piggery wastewater treatment

The purpose of this work was to access the feasibility and stability of nitrogen and organic matters removal from piggery wastewater in Fixed-bed Biofilm Sequencing Batch Reactor (FbSBR) through the changes of hydraulic retention time (HRT) and substrate concentrations. At steady-state, 80 % total inorganic nitrogen was removed at its applied load of 0.16 kg N/m(3)/d, while total CODCr removal efficiency was 85 % when its load was at 0.8 kg COD/m(3)/d. The temporary accumulation of nitrite in the effluent is mostly due to limitation of DO in the inner-layer of biofilm. In the cyclic work on day 61, the occurrence of ORP and DO breakpoints mostly matched to the breakpoint-like of nitrogenous compounds profiles, especially, of NOx trendlines. It would be further utilized for online monitoring to determine operational modes during each steady-state period. The CODCr profiles in cyclic work showed that most biodegradable organic compounds were consumed by facultative bacteria in anoxic phase and only non-biodegradable part was remained during rest of cycle time.