Biological powdered activated carbon (BPAC) microfiltration for wastewater reclamation and reuse

Abstract

The experiment was conducted to evaluate a biological powdered activated carbon (BPAC) microfiltration (MF) system as an alternative for wastewater reclamation and reuse. A synthetic secondary sewage effluent contains refractory organic compounds such as humin, tannin, lignin, protein and high molecular carbohydrates as well as coliphage Qß as a model virus. The system performance was investigated at the activated carbon concentration of 20 g/1, water temperature 25°C and transmembrane pressure of 55 kPa. It was noted that organic removal occurred mainly at the membrane module. This was caused by the accumulation of the powdered activated carbon in the membrane module. The average organic removal efficiency was 83%, resulting in an effluent TOC concentration of 1–2 mg/1. The performance of the process did not deteriorate at water temperature of 15°C, showing an organic removal efficiency of 89.6%. It was estimated that the higher removal efficiency at lower water temperature was mainly due to the less self-degradation of microorganisms because the permeate flux of the membrane was maintained at the same level by increasing the transmembrane pressure up to 80 kPa. The removal of virus by the BPAC-MF system was significant. From the mass balance at steady state, 99.9997% of fed coliphage Qß was removed from the system. Especially coliphage Qß showed a strong adsorbability on powdered activated carbon (PAC). For 1 h contact with PAC, the removal of Qß was 99.999% even at PAC concentrations of 0.55 g/l. It was obvious that the virus removed was inactivated in the system.