Simultaneous nitrogen and phosphorus removal in sequencing batch reactor(SBR)with porous biomass carrier

Abstract

A theoretical as well as experimental investigation was made on porous biomass carrier sequencing batch reactor (PBCSBR) for simultaneous removal of nitrogen and phosphorus. This type of reactor is innovative and considered to be a hybrid of sequencing batch reactor(SBR) and porous biomass support systrem (PBSS). In this research, experiments were conducted over a range of organic loadings and operational modes on SBR with and without porous biomass carrier(PBC). To get more insight into the behavior of the organics, nitrogen and phosphorus during an operation cycle, chronological track studies were made at various operational conditions. The removal efficiencies of nitrogen and phosphorus in PBCSBR were far better than in SBR while the behavioural patterns of concerned matters were similar in both systems. In PBCSBR, biomass hold-up increased with the organic loading rate. Maximum biomass hold-up was about 20 g MLSS/l in volumetric concentration irrespective of media volumes in the reactors and the retained biomass was held in attached and entrapped conditions. Nitrogen was removed in SBR and PBCSBR by nitrification and denitrification while phosphorus was by biological phosphorus release and uptake. For the efficient simultaneous removal of nitrogen and phosphorus, sufficient organic matter and proper environmental conditions must be provided. The increased biomass and reduced oxidized nitrogen in PBCSBR caused by aerobic denitrification occurring in the inner part of the media enhanced simultaneous nitrogen and phosphorus removal. The mathematical model proposed in this research using the organic storage and simultaneous nitrification and denitrification concepts agreed well with experimental results assuming pH change was insignificant.