Recent and expected developments in sewage treatment all over Europe have had profound effects on sludge production. Changes in environmental legislation coupled with difficulties in establishing and maintaining sustainable sludge management methods, make sludge disposal a complex problem. This puts authorities involved in wastewater treatment under pressure, which may lead to the adoption of environmentally inappropriate practices. It is well recognised that current sludge disposal practices in Southern Europe (where landfill and/or uncontrolled agricultural use dominates) are not sustainable in the medium and/or long term and other alternatives must be investigated.
The aim of this technology transfer project was to demonstrate in three pilot sites in Southern Europe, two in Greece, (Lamia and Rethimnon) and one in Spain or Portugal, that sludge management options where domestic sewage sludge treatment with the addition of quicklime (CaO) in ratios that provide pH values over 12 for over 3 months, can create the background for agricultural valorisation.
The pilot locations were typical Southern Europe medium size towns with tourist activities in balance with agricultural activities. It was anticipated that other communities in Europe, facing similar problems with sludge disposal could benefit by the experience gained and the innovative approach.
The short-term objectives included:
- high quality sludge products prior to agricultural land application, in terms of odours and nutrient content.
- sludge product management without health risks from pathogens (during storage, spreading).
- toxic compound monitoring on sludge and agricultural soil.
- financial benefits from technology application and sludge product marketing.
With regards to the longer term objectives, the project aimed to demonstrate how a combination of technical, organisational, managerial and training measures can lead to a sustainable sludge management system and beneficial use in agriculture.