Feasibility Study of Indigenously Developed Fly Ash Membrane in Municipal Wastewater Treatment

Abstract

Afly ash membrane developed by The Energy and Resources Institute (TERI), New Delhi was studied for its applicability in municipal wastewater treatment. In particular, the effect of aeration on preventing membrane fouling was studied. The velocity field generated by aeration was studied to understand how the rising bubbles would efficiently scour the membrane filter and prevent fouling. Particle image velocimetry was used to monitor the air bubble movement along the membrane surface. The optimal reactor configuration (membrane module orientation) for which the aeration would impart maximum shear over the membrane was determined using potable water. This reactor configuration was later used for the biological treatment of synthetic wastewater. The second aspect of the study involved designing a support system to improve the strength of the membrane. Membrane modules without any internal support were able to withstand trans-membrane pressures (TMP) up to 270 mmHg. Two types of frames/seperators were used to increase membrane strength. In one type of the frame, support was unidirectional and in another, bidirectional. Bidirectionallysupported membranes were able to withstanda TMP of 760 mmHg for a period of 7 days. At a constant filtration rate, a membrane bioreactor with more than one membrane in parallel operation was able to delay the fouling process than in a single membrane system due to lesser pressure across the membranes. As expected, membrane fouling took longer time in the systems operated at higher air flowrate due to better scouring action of the air bubbles.