Economic importance and application options of some industrial sludge conditioned by different treatment methods

Industrial sludge was obtained from four industries: aluminium extrusion, brewery, pharmaceutical and textile processing factory and treated by aerobic, anaerobic, physicochemical, combined aerobic/physicochemical and combined anaerobic/physicochemical methods. The results showed that the final destination of the sludge would determine the type and degree of treatment required for the sludge. Physicochemical method generally increases the quantity of sludge solids, thus making the sludge suitable for land reclamation; also, the firmer and denser floe characteristics of the physicochemically treated sludge makes the methods a better alternative if conditioned sludge are to be used to reinforce cement for brick making. Biological treatment methods (aerobic and anaerobic) can be used to reduce the quantity of sludge before disposal. Solids destruction is closely related to biogas production. If using sludge as a source of fuel is the focus, the anaerobic biological system may be the best option. Aerobic biological method and the combined aerobic/physicochemical methods are good options for ammonia reduction. Anaerobic biological method is best for improving the nitrogen content and hence the protein content of sludge so as to use the waste sludge as feeds for poultry birds and livestock. Economic values, application and disposal options of the various sludge are discussed.