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A pilot-scale powdered activated carbon (PAC) countercurrent four-stage adsorption–microfiltration (MF) hybrid process was developed to remove organics from reverse osmosis concentrate (ROC). The main focus of this study was to remove the organic matters and prepare qualified influent with lower turbidity and silt density index (SDI) to reverse osmosis (RO) system for further desalination. The results indicated effective removal of organic pollutants from ROC with effluent values that met the requirements for RO influent. The average values of turbidity and SDI in the effluent were 0.70 NTU and 2.52, respectively. The average dissolved organic carbon (DOC) removal rate was approximately 70% when the PAC dosage was between 0.35 and 0.45 g/L. Membrane fouling under two operational modes was analysed and compared, and membrane fouling was reduced in mode II operation. Mode II operation performed better in terms of a shorter hydraulic retention time and lower membrane fouling rate, resulting in more economical and effective operation. UV254and DOC were linearly correlated for both the influent and effluent, and the removal rate of the DOC and PAC dosage also exhibited linear correlation with a linear coefficient R2> 0.95, which can be used to adjust the PAC dosage during operation.

The wet oxidation (WO) regeneration of powdered activated carbon (PAC) used for reverse osmosis concentrate (ROC) treatment was studied. The exhausted PAC was regenerated at different temperatures and times. The experimental results indicated that the optimum regeneration condition could be achieved at a temperature of 200 °C for 60 min. The mass of carbon in the solid, gas and liquid phases before and after the PAC regeneration was balanced in different regeneration conditions. A molecular weight (MW) distribution of organic matter (OM) in the effluent treated by the PAC regenerated at optimum conditions was performed. [ABSTRACT FROM AUTHOR]