Influence of temperature variations on the cake resistance and EPS of MBR mixed liquor fractions

Abstract

A B S T R AC TFew studies have been carried out to correlate the infl uence of temperature on the fi lterability of different mixed liquor fractions, i.e. suspended solids, colloidal matter and soluble organic matter. It is known that temperature has a big impact on the fl ux in microfi ltration processes. The aim of this research was to fi gure out the impact of temperatures in the range of 10ºC to 40ºC on fouling, especially in terms of the release of particles and soluble microbial products (SMP). Results based on the contribution of each fraction, namely mixed liquor (>1 μm), supernatant (1 μm to 1 nm) and soluble (<1 nm), to fouling, suggest that the colloids present in the supernatant are affected by temperature changes. Low and high temperatures result in defl occulation and formation/release processes respectively, resulting in a release of submicron particles and were observed due to retention changes. Similar values of the cake resistance for all the fractions and for the range of temperatures studied, indicate that all submicron/colloidal particles within the range 0.05-0.4 μm have a similar infl uence in terms of fouling. No correlation was found between the concentration of EPS and the cake resistance, which indicates that (an)other foulant(s) could contribute to the cake resistance. Finally, low retentions of both polysaccharides and proteins were observed at 40ºC.

Changes in wastewater treatment performance and activated sludge properties of a membrane bioreactor at low temperature operation

“…Other factors may contribute to membrane fouling at low wastewater temperatures as well. These include increased sludge viscosity, reduced sludge stabilization or sludge deocculation, 26,49 reduced particle size of the mixed liquor, 50 and reduced mass transfer efficiency. 30 Whether the fouling of the MBR is correlated with sludge bulking at low wastewater temperature operation is, however, largely unknown.…”