A new approach to sewage treatment which involves rapid clarification of raw sewage with fine magnetite particles is described. The process, which is essentially a greatly accelerated chemical coagulation, provides a quick separation of the sewage into two liquid streams, one clarified, the other highly concentrated. Development of the process up to and including operation of a fully continuous pilot is outlined and potential advantages and disadvantages identified.

Clostridium perfringens enterotoxin (CPE) is an important cause of food poisoning with no significant homology to other enterotoxins and its mechanism of action remains uncertain. Although CPE has recently been shown to complex with tight junction proteins, we have previously demonstrated that CPE increases ionic permeability in single Caco-2 cells using the whole-cell patch-clamp technique, thereby excluding any paracellular permeability. In this paper we demonstrate that CPE forms pores in synthetic phospholipid membranes in the absence of receptor proteins. The properties of the pores are consistent with CPE-induced permeability changes in Caco-2 cells suggesting that CPE has innate pore-forming ability.

Efforts to understand and predict the role of different organic fractions in the fouling of low-pressure membranes are presented. Preliminary experiments with an experimental apparatus that incorporates automatic backwashing and filtration over several days has shown that microfiltration of the hydrophilic fractions leads to rapid flux decline and the formation of a cake or gel layer, while the hydrophobic fractions show a steady flux decline and no obvious formation of a gel or cake layer. The addition of calcium to the weakly hydrophobic acid (WHA) fraction led to the formation of a gel layer from associations between components of the WHA. The dominant foulants were found to be the neutral and charged hydrophilic compounds, with hydrophobic and small pore size membranes being the most readily fouled. The findings suggest that surface analyses such as FTIR will preferentially identify hydrophilic compounds as the main foulants, as these components form a gel layer on the surface while the hydrophobic compounds adsorb within the membrane pores.Furthermore, coagulation pre-treatment is also likely to reduce fouling by reducing pore constriction rather than the formation of a gel layer, as coagulants remove the hydrophobic compounds to a large extent and very little of the hydrophilic neutral components.

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14To help understand and predict the role of natural organic matter (NOM) in the fouling of low-15 pressure membranes, experiments were carried out with an apparatus that incorporates automatic 16 backwashing and long filtration runs. Three hollow fibre membranes of varying character were 17 included in the study, and the filtration of two different surface waters was compared. The 18 hydrophilic membrane had greater flux recovery after backwashing than the hydrophobic 19 membranes, but the efficiency of backwashing decreased at extended filtration times. NOM 20 concentration of these waters (7.9 and 9.1 mg/L) had little effect on the flux of the membranes at 21 extended filtration times, as backwashing of the membrane restored the flux to similar values 22 regardless of the NOM concentration. The solution pH also had little effect at extended filtration 23 times. The backwashing efficiency of the hydrophilic membrane was dramatically different for the 24 two waters, and the presence of colloid NOM alone could not explain these differences. It is 25proposed that colloidal NOM forms a filter cake on the surface of the membranes and that small 26 molecular weight organics that have an adsorption peak at 220 nm but not 254 nm were responsible 27 for "gluing" the colloids to the membrane surface. Alum coagulation improved membrane 28 performance in all instances, and this was suggested to be because coagulation reduced the 29 concentration of "glue" that holds the organic colloids to the membrane surface. 30 31