The use of bio-carriers and zeolite in a lab-scale MBR for membrane fouling mitigation

Abstract

The Membrane Bio-Reactor (MBR) technology offers a series of environmentally-friendly advantages, such as high quality effluent, pathogens removal capacity and avoided use of chemicals for disinfection, allowing it to be regarded as an environmentally friendly technology, when applied for wastewater treatment. However, membrane fouling still remains a major drawback, preventing its widespread application for municipal or industrial wastewater treatment. The use of additives (i.e. adsorbents, bio-carriers etc.) is considered to be among the major strategies implemented for membrane fouling control over the last few years. The present work examines the influence of bio-carriers addition, as well as of zeolite powder on the reversible and irreversible membrane fouling of a lab-scale MBR. High-strength synthetic municipal wastewater (with BOD5 around 1000 mg/L) was fed as the substrate for the activated sludge process and a flat-sheet microfiltration membrane was operated for solids (biomass) - liquid separation at the flux of 17 L/m2h. The obtained results showed that the addition of zeolite contributed mainly to the alleviation of irreversible fouling, leaving the reversible fouling practically unaffected, while the addition of bio-carriers had quite the opposite effect. In addition, it was shown that the lab-scale MBR system operated successfully, treating a high-strength synthetic municipal wastewater, as high removals were observed in terms of both organics and especially of ammonium removal (over 98%).