Abstract: A side-linebiologicaldenitrification filter combined carbon-based biological aerated filter (CBAF) was used to investigate the removal efficiency of organic matter and total nitrogen in reverse osmosis (RO) concentrated wastewater produced in the process of refinery wastewater reuse,and the change of organic matter in the treatment process was analyzed. The results showed that the combined process could effectively remove the total nitrogen in the RO concentrated water (the average removal rate 51.25%) and reduce chemical oxygen demand (COD) by 59.44%. The main pollutants in the ROconcentrated wastewater are humic acids and dissolved microbial metabolites, and the fluorescence intensity of the main pollutants in the wastewater was significantly decreasedafter the treatment with CBAF. The concentrations of hydrophilic organic carbons such as low molecular weight acids substances, building block,low molecular weight neutralsubstances, humic and biopolymer were reduced by 81.65%, 68.58%, 63.85%, 60.83% and 49.3%, respectively. At the same time, due to the adsorption of the carrier, the CBAF reactor has a high removal rate of both hydrophilic and hydrophobic organic carbon (64.2% and 74.58%, respectively).

Key words: carbon-based biological aerated filter, reverse osmosis concentrated water, excitation-emission-matrix spectra, hydrophilic organic carbons, humic acid substances