Membrane fouling and cleaning in microfiltration of activated sludge wastewater

The loss of membrane flux due to fouling is one of the main impediments in the development of membrane processes for use in drinking water treatment. The objective of this work was to determine the nature of nanofiltration membrane foulants for a pilot system fed conventionally treated Ohio River water for 15 months. The foulant responsible for flux loss was shown to be a film layer 20−80 μm thick with the greatest depth in the first of three elements in series. Heterotrophic plate count, phospholipid, and pyrolysis-GC/MS analyses showed the film layer had a strong biological signature. The inorganic contribution to the dried film layer was low (less than 15%). Both acid and alkaline/detergent cleaning yielded only short-term flux recovery, although they were independent of each other. Neither acid cleaning, alkaline/detergent cleaning, nor hydraulic flushing removed the thickness of the film layer, nor changed its organic characteristics. Only alkaline/detergent cleaning inactivated a large percentage of...

Nanofiltration Foulants from a Treated Surface Water

A membrane bioreactor (MBR) combines membrane separation and biological treatment, normally involving the activated sludge process, in municipal wastewater treatment. Despite excellent performance over years of full‐scale operation, the interactions between microbes and the membrane in the MBR process, which determine its design and operational criteria, remain unclear. This report reviewed research regarding how numerous process parameters impact biofouling rates and, in particular, the possible contribution of microbial products to biofouling. This study also characterized different fractions of microbial products and assessed their potential affect on membrane fouling.

M. W. Stupy

Papers

The dynamics of biofilms