Waste Water Management in the Danube region
In 2017 an expert team of Umweltbundesamt and International Office for Water (IOW) conducted a study to assess the results of the implementation of the Urban Waste Water Treatment Directive (UWWTD, 91/271/EEC) in the Danube Region, taking into account environmental, economic, sustainability and affordability aspects. The specific geographic focus of the study is on the 8 EU Member States of DRB in central, east, and southeast Europe, namely: Austria, Bulgaria, Croatia, the Czech Republic, Hungary, Romania, Slovakia, and Slovenia. Most of these countries are still in the process of implementing the UWWTD. The study was commissioned by the World Bank and the International Association of Water Supply Companies through their Danube Water Program (DWP).
The main findings of the study can be summarized as follows:
- On water quality aspects four compounds are targeted by the UWWTD: Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) representing organic pollution, as well as total nitrogen (Ntot) and total phosphorus (Ptot) representing nutrient pollution. The observed trend of these four compounds in surface waters is predominantly downward in most countries, reaching up to 70% for some cases. The decreasing surface water pollution can clearly be linked to improved wastewater treatment and decreasing emissions from urban point sources.
- The key emitters of organic pollution into the aquatic environment are point sources. Because emissions from agglomerations represent the majority of point sources (compared to industrial and agricultural point sources), the implementation of the UWWTD is significantly contributing to improved surface water quality.
- With regard to nutrient pollution, the source apportionment model MONERIS has revealed that, among point sources, urban wastewater management is partially responsible for the discharge of Ntot and Ptot emissions into the Danube. The implementation of the UWWTD is contributing to the improvement of surface water quality. However, other emission sources, in particular diffuse sources, have a major role in the emission and discharge of nutrients into the aquatic environment and also need to be considered in the assessment of impacts on surface water quality. Agriculture has a prominent role in this by using a large share of the soil in the basin.
- At the time of the study (2017), the link between the implementation of the UWWTD and the improvement of water status in surface water bodies according to the WFD could not be well investigated: Any assessment of the change of surface water body status is only possible by comparing the results of the 1st and the 2nd river basin management plans under the WFD. As these data from the 2nd river basin management plans were not available in 2017, this evaluation was not possible within the study.
- On financial sustainability, the lack of comparable financial data is a major weakness for planning, analysing and reporting. The available data shows that the costs of operation, maintenance and reinvestment are currently not covered by service revenues in many MSs assessed. In the case insufficient revenues are mobilised by wastewater utilities, they might not be able to undertake the necessary maintenance and renewal of infrastructure. This could possibly lead to poor quality wastewater effluent and to deterioration of water quality and ecology of the receiving aquatic environment but also to financial consequences, including fines due to non-compliance to the EU legislation.
- On the economic assessment the implementation of the Directive has so far been poorly linked to economic justifications. The study observed a lack of organised and publically available quantitative and monetised datasets as regards the environmental, social and health benefits of the implementation of wastewater management. Based on the data sources explored in the study the costs of UWWTD-implementation cannot currently be justified from an economic benefits perspective. However, the overall economic benefits may be more pronounced than in the indicative calculated figures documented in this study.
- A set of recommendations is presented based on the assessment conducted: improve the availability of biophysical and financial data; build additional wastewater infrastructure; use wastewater as a resource; rely on less centralised and less resource-intensive solutions such as nature near wastewater treatment or IAS; better address nutrient management including other economic sectors; train administration and water utilities staff; improve financial viability by focussing on key aspects such as financial framework, tariff setting, tax adaptation; develop value transfer function to anticipate and plan cost benefits of systems and speed up the development of ecosystem services valuation to support the cost benefit analyses.
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