Treatment of reverse osmosis concentrate by biological aerated filter

The aim of this study is to employ the biological aerated filter (BAF) in the treatment of reverse osmosis (RO) concentrate received from reuse of wastewater treatment plant. BAF is known as economic and efficient treatment method for the effluent standards. The result of the treatment of RO concentrate by BAF process was found to be efficient for biological oxygen demand (BOD) removal (95.86%). However, it was relatively less efficient in the chemical oxygen demand (COD) (88.95%) and suspended solids (SS) (81.12%) removal. A high BOD removal efficiency is due to the complete oxidation of organic matter which comes from low food to micro-organisms (F/M) ratio (0.049kg BOD/kg MLSSday) of the influent. The TN (total nitrogen) and NO3-N removal percent were found to be 81.42% and 76.70%, respectively. However, total phosphorous (TP) and PO4-P removal percent were obtained low with 67.66 and 61.42%, respectively. It is observed that decreasing the COD/N ratio caused to decrease the TP and PO4-P removal efficiency. However, the denitrification and nitrification rates were increased from 211.8 to 301.0mg/Lday and 87.7 to 109.4mg/Lday, respectively, for a change in COD/N ratio from 8.19 to 7.64. Therefore, in order to reuse the RO concentrate, BAF process could effectively treat the RO concentrate.