ENVIRONMENTAL MANAGEMENT OF THE SEWAGE SLUDGE: CASE STUDY - THE WASTEWATER TREATMENT PLANT OF TIMISOARA

When we talk about the sewage sludge, we refer to the excess of the sludge resulting from the wastewater treatment plants. The EEC Directive 91/271, referring to the Urban Waste Water Treatment, modified by the EEC Directive 98/15 is implemented in Romania also. This requires that until 31 December 2018, all localities with more than 2000 population equivalent (p. e.) must be served by sewerage networks and wastewater treatment plants where the resulting sludge should be managed ecologically. Therefore it is necessary to implement urgently an environmental management strategy of the sludge. The ecological studies on the sewage sludge management in short (2013), medium (2020) and long (2040) term were made in the EU in 2008 and in Romania in 2012. Both in the EU and in Romania the main option is to use the sludge on agricultural land as organic fertilizer but also to use the sludge as an energy source recovered by combustion. For an efficient management, in both cases there is a need for the sludge dewatering and drying. Thus the sludge volume will decrease, the transport and storage costs will be significantly reduced, and the lower heat value (u(t)) will increase. As a main conclusion one will support the idea that it is necessary to make a preliminary assessment of the thermodynamic energy content of the sewage sludge in order to depict and select the global vision of the process, assuring both the optimal energy development and environmental friendly treatment processes.