Suspended solids from industrial and municipal origins

The origins of suspended solids are the effluents of municipal and industri al wastewater treatment plants and storm sewage treatment. This paper deals with the sources of industrial and municipal wastewater treatment and the single treatment of side streams. An overview of the common treatment proce sses is given and the main sinks for suspended solids are named and describ ed. The food industry is based on the processing of organic matter (fruits, etc.). During the single processing steps three main fractions occur, inor ganic material (e.g., from the washing step), organic residues (e.g., the p eel), and suspended solids (SS) in the wastewater. Today higher rates of re cycling (water and raw materials) can be found in all kinds of industrial p rocesses. The principle is that avoidance should take precedence over utili zation which should take precedence over disposal. Numerous possibilities o f production-integrated measures exist, e.g., conveyance of production circ uits, product recovery, and stepped cleaning. Despite and/or due to these e fforts, huge amounts of residues occur. They are the main sink for suspende d solids. Only seldom is landfilling used to treat these residues. Usually utilization as animal nourishment or biological (aerobic or anaerobic) or t hermal (incineration) treatment methods are used. Huge capacities for a cod igestion of agroindustrial residues (substrates) and wastewater sludge can be found in municipal digesters. As most of the food processing factories a re indirect dischargers, the largest amount of the SS fraction in the waste water is led to municipal wastewater treatment plants. Rarely, a connection between the SS concentrations in the influent and those in the effluent ca n be observed in conventional wastewater treatment. As a polishing step, fi ltration methods gain more and more importance with regard to suspended sol ids removal. (C) 2001 International Life Sciences Institute.