Membrane Bioreactor Technology for Wastewater Reclamation

RESPONDING to the water shortage in Egypt, the use of submerged membrane bioreactor (SMBR) for wastewater reclamation has been studied. The impact of hydraulic retention time (HRT), as the most influential operational parameter has been investigated. A bench-scale module was operated at three HRT: 6, 10 & 15hs. The results demonstrated that total COD and BOD removal rates were not affected by changing the HRT or by variations in raw wastewater strength. Average residual COD values in the membrane permeate ranged from 14 to 20.3 mg O2L-1. Corresponding residual BOD was below 3.0 mgL(-1). Nitrification capacity of the SMBR was high. HRT was found to be a key parameter for fouling. Decreasing the HRT enhances membrane fouling. At HRT of 6h, fouling happened after 6 days. Corresponding values for HRTs 10 and 15 were 13 day and more than 42 days, respectively. Total coliform bacteria counts in most of the MBR permeate samples were below the detection limit of 10 CFU/100 mL. All protozoan parasitic stages detected in raw wastewater were removed by the SMBR. At HRT of 15h, both human rotaviruses and adenoviruses genome copies were reduced by 2 to 3 log(10). This ratio was reduced by decreasing the HRT.