Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
It can be assumed
that there is little difference in total loading discharged between EU15
(European Union Member States) and the AC10. However, the use of water per
capita is considerably higher in AC10, while the quality of rain water that has
to be treated is often lower because of the presence of separated sewers (e.g.
Poland). Table 7.4 compares quantity (flow) and quality (concentration) of
wastewater from EU 15 and AC 10 (ETC/IW, 1998). It is supposed, that the
current lower wastewater concentrations in the AC 10 compared to the EU 15,
which originated in the economic regression, will increase in the coming years
through industrial and agricultural growth. Future treatment capacities in the
AC 10 will not completely cope with increasing wastewater quantity and
declining quality until the UWWTD and other directives are in full power.
In the early 1990s, the total
organic pollution load from urban wastewater treatment plants for the AC 10 was
for BOD5 about 1136 kilotonnes O2/year. The nutrient load
was at the same time for total P about 69 ktonnes P/year and for total N about
334 ktonnes N/year (ETC/IW, 1998). There is little information available
regarding the other transition countries.
In the European CIS
countries a high percentage of the population is connected to municipal
wastewater treatment plants (60-75%), but most villages discharge without
treatment. Municipal wastewater treatment plants are mostly designed to reach a
60-70% reduction in BOD. However, in the early 1990s only about 60% of the
installations were functioning and there is no indication that the situation
has improved since then.
Sometimes, the pollution
discharge standards of municipal wastewater are ignored. This is due to the
limited treatment capacity of most plants, causing overload, and the high
pollution load of the incoming wastewater. Due to poor maintenance and the poor
technical state of installations, overloading and even complete breakdown, the
reconstruction or extension of existing plants is unsatisfactory or has been
completely abandoned for the time being.
Many industrial enterprises
are connected to municipal treatment plants and most of them are required to
have pre-treatment facilities. However, industrial wastewater plants that were
constructed in past years are either not in use or not well maintained. The
absence of detoxifying pre-treatment of wastewater from i.e. metal finishing /
galvanising enterprises leads to an excess of heavy metals in municipal
treatment plants, undermining biological treatment. It is assumed, that the
situation has not greatly improved over the last few years, although the
continuing recession accounts for some reduction in industrial wastewater generation.
Furthermore, treatment efficiency and other investment–dependent indicators
have also deteriorated further.
In Croatia, the bulk
of generated wastewater is treated only mechanically (primary treatment) (81%);
which means poor performance yields, except for suspended solids, and a poor
effect on dissolved pollution. About 6% is biologically treated and 13% are
combined treated. There are no data available for the pollution load, despite
existing monitoring systems. The reduction in pollution load is estimated at
around 25% of what is treated. Since wastewater treatment has been a priority
for the past several years, many municipalities have built treatment
facilities, but their operation is fraught with difficulties. Most
municipalities which borrowed to finance 50% of the building costs, cannot
cover the loans and so cannot operate and maintain the plants properly. The
result is often, that they bypass their empty facilities and discharge their
wastewater untreated. At the same time, new projects are designed and partly
financed by the national water agency to equip urban settlements (EPR, 1999).