Conditioning, thickening, and dewatering: research update/research needs

The production of sludges that are amenable to beneficial reuse (and thereby merit the term "biosolids") has become a high priority concern in wastewater treatment. Regulations in many countries have become stringent in this regard, and the production of suitable biosolids now influences the selection, design, and operation of upstream processes. Among these are the conditioning, thickening, and dewatering of sludges, This paper briefly reviews current technology trends in these process areas, placing them in the context of overall needs for improved biosolids management. It is foreseen that conditioning, thickening and dewatering processes will need to operate at higher performance and reliability levels to maintain disposal and reuse flexibility. The chemistry of conditioning must be more clearly determined since secondary interactions of the conditioning additives may be important in ways that are not currently recognized.