Influence of Different Pretreatments on Anaerobically Digested Sludge Characteristics: Suitability for Final Disposal

The debate on sludge recycling and disposal has been recently a target of growing interest due to the expressed concern about the potential risks of its agricultural use on human health and the environment. This fact has led to revisions in government policy and regulations and many novel treatment processes have been proposed in order to make the recycling and reuse of sewage sludge sustainable. In this work, the use of some pretreatments (alkaline, thermal, and ozonation) combined with conventional anaerobic digestion has been assessed on digested sludge quality in terms of pathogens, dewatering properties, heavy metals, and organic pollutants. All pretreatments proved to be efficient to reach the requirements proposed in the Working Document on Sludge prepared by the European Commission (CEC, Council Directive of 27 April 2000 on Working Document on Sludge-third draft. Brussels: European Commission DG Environment.