Heat treatment - drying of sludge at the central wastewater treatment plant

Scope of works

Construction works, delivery and installation of electric and machine equipment, commissioning, trial operation and training of client’s staff.


WWP: 55.000 PE, system for sludge treatment: 3.500 / year, 90% dryness
Waste management
Municipality of Novo mesto


The Novo mesto wastewater treatment plant has a capacity of 55,000 PE. The retrofit project included the construction of an additional building to dry out sludge with the associated infrastructure and was one of the first facilities of its kind in Slovenia and on the Balkan Peninsula. The project included the development of sludge drying technology using a temperature regime of 70-90°C, the construction of a combined heat and power plant (CHP) to generate electric energy and heat together with heat transfer, exhaust air and dry sludge storage systems.

The heat gained in this way is used in the sludge drying system via heat exchangers for hot air drying of the de-watered sewage sludge. The dry matter content in the de-watered sludge increases in the drying process from 23% to more than 90%.

The work was carried out while the existing wastewater treatment plant was in operation and was completed more than 30 days before the agreed contract term expired. This project was selected as the winning project by coordination of the Ministry of Environment and Spatial Planning among all projects that had applied for funding from the “EU project, my project” campaign for European cohesion projects in the previous financial period (2007 to 2015).