MBR sewage and wastewater treatment

UF membranes with a MWCO of 100,000 Da was highly effective in removing organic pollutants and suspended soHds prior to RO desalination [102], 

Case study I. In 2007, two of the largest MBR plants in the world for treating landfiU leachates were built in Istanbul, Turkey. The capacities are 1200 m /d (Plant A) and 2000 m /d (Plant E) [104]. The plants use external MBR systems (Norit X-flow UF) to treat waters with h h COD (20,000 mg/1), BOD (13,000 mg/1), TSS (1500 mg/1) 

The MBR effluent is treated with NF membranes to remove residual COD and heavy metals, thus making it possible to discharge the treated water into the Black Sea. The NF system water recovery is 90%. 

Case study III. The food processing plant in St Mary s, Ontario discharges to a municipal wastewater treatment works and must meet the limits for BOD (300 mg/1) and TSS (350 mg/1). The mean influent COD and BOD concentrations are 400 and 5500 mg/1, respectively. The wastewater also includes oil and grease [98]. 

The UF unit is designed for a flow rate of 45 m /h with a flux of 21.6 Imh (27.8 Imh max). The membrane TMP is 15 mbar with the mean permeability 1500 Imh/bar at 20°C. The MBR operating cycle is 8 m on /2 m relaxation. CIP is with NaOCl (6 g/1 solution) annually. The UF permeate is pumped to the RO system at 20—25°C. The RO unit is a three-stage (4 2 1) array with six elements per pressure vessel. The RO elements are spiral-wound 20 cm diameter (Toray SU-720). The membranes are brackish water polyamide membrane thin-fikn composite. The feed pressure is 11—14 bar g and the product water recovery is 85%. The RO permeate is poHshed by mixed-bed ion-exchange to provide boiler feed water. The plant meets the effluent concentration limits COD 51 mg/1, ( 97% removal), undetectable TSS and 5 mg/1 Total nitrogen. 

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