1. Sludge problems

All treatment processes produce waste. This waste is collected :

• Pre-treatment: screenings, waste from degreasing and grit removal;

• primary, secondary and tertiary decanters: sludge.

In terms of both volume and nuisance, sludge is the main waste to be treated at a wastewater treatment plant. Indeed, the water laws promulgated by European parliaments and expressed in French law by Decree no. 94-469 of June 3, 1994 (and supported by Directive 2000/60/EC of the European Parliament and of the Council, which established a framework for Community action in the field of water policy) result simultaneously in a densification of water treatment and a high level of purification (see Regulations [Doc. C 5 221]...