About UNEP
United Nations Environment Programme
Division of Technology, Industry and Economics
top image
space space space
Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

7.3 Treatment (Topic c)

7.3.1 Current situation

Most of the transition countries are still facing major problems. Because of complications in the privatisation process, it is sometimes not clear who actually owns the water works and sewage systems, so reconstruction or modernisation is still postponed. The lack of experience and lack of effective institutional and legal structures affect the decentralisation process, particularly the financing of i.e. treatment facilities.

Many industrial establishments are connected to municipal treatment plants. Connected industries are required by law to use pre-treatment facilities. Nevertheless, many of the constructed or existing industrial wastewater plants are not used, or are not well maintained.

7.3.2 Wastewater treatment in the Accession countries

In the AC 10 approximately half of all generated municipal and industrial wastewater is treated to a certain extent (Table 7.7). Mechanical treatment (primary treatment) is a simple and quite inefficient form of treatment, involving the removal of large solids through screening and sludge production through sedimentation lagoons or tanks. According to UN/ECE IEDS in the AC 10 nearly half of all treated municipal and industrial wastewater is only mechanically treated. There is a slight downwards trend in the last years through the installation of new or reconstruction of existing biological or advanced treatment plants. According to EEA data, on average municipal wastewater from 12% of the population in the AC 10 receive mechanical treatment. This percentage is less than 6% in countries like Czech and Slovak Republics, Hungary, Bulgaria and Romania in favour for biological and advanced treatment.

Biological treatment involves, in addition to mechanical treatment, biological sand-filters and constructed reedbeds, which achieve microbiological degradation of organic matter and a considerable removal of nutrients. In the AC 10 about 40% of the treated municipal and industrial wastewater receive biological treatment. There is a slight downward trend in favour of an increased advanced treatment. Advanced treatment might have different stages like coagulation and flocculation, precipitation, etc. (chemical treatment), but can also include advanced nutrient removal through nitrification/denitrification and removal of phosphorus. Unfortunately, through the given data it is not clear which kind of advanced treatment is used in the individual countries. Advanced treatment is increasing in all AC 10 countries over the period 1990-1995 and later, even if the nutrient removal efficiency is varying between the countries (Table 7.8 and Figure 7.1).

Table 7.7: Municipal wastewater treatment (% of AC10 population in the early 1990s)



35 17 9 12 12 12 23 12 8 13
Mechanical 0 4 27 5 10 32 10 6 5 16
Biological 34 52 15 22 51 29 28 29 45 15
Advanced     22 6     4      
(ETC/IW, 1998)


Table 7.8: Different types of municipal and industrial wastewater treatment for 1990, 1995 and later (in %), (treated municipal and industrial wastewater = 100%)


Year Mechanical Biological Advanced
Bulgaria 1991 59 20 21
  1995 56 19 25
Czech Republic 1990 16 84  
  1993 16 84  
Estonia 1990 72 28  
  1995 54 24 22
Hungary 1990 62 31 7
  1995 58 34 8
Latvia 1993 22 77 1
  1995 9 45 46
Poland* 1990 52 40 8
  1995 40 49 11
  1997 39 44 17
Slovenia 1990 36 56 7
  1994 58 38 4
Other transition countries and CIS
Croatia 1990 83 10 7
  1995 84 9 7
  1997 81 6 13


1995 9 89 2
  1996 8 91 1
*Poland: data from the Polish Statistical Yearbook, 1998, advanced treatment includes chemical and high efficient biological and chemical treatment with increased reduction of N and P.

Special country information

In Lithuania, in 1996, 17% of the total wastewater was not treated at all. About 43% of all wastewater was insufficiently treated, that means only mechanical treatment or ineffective biological treatment. Treatment, which met Lithuanian quality standards, was achieved for 40% of the total wastewater. These percentages do not include wastewater which meets quality standards without treatment, i.e. cooling water (EPR, 1998).

Latvia has 1570 wastewater treatment plants, of which 1/3 have only mechanical treatment, the remaining have biological treatment. About 20 % of the latter work with activated sludge systems. Nearly all mechanical treatment plants are hydraulically overloaded or in poor condition. About 40% of the secondary treatment plants fail to comply with national BOD standards and EU discharge requirements. The "800+" programme has now started in Latvia to improve the operations of wastewater treatment facilities in small and medium-sized towns (EPR, 1998).

In Bulgaria, the decline in industrial activity is reflected by an improvement of water quality in the main river basins of the country. There are 4450 large enterprises registered as discharging effluents, of which 2442 have some kind of treatment and 712 are listed as needing treatment systems. Out of 97 towns greater than 10 000 inhabitants, only 24 have sewage treatment plants and 29 are building treatment facilities (EPR, 1996).

Figure 7.1: Annual average (in %) of different wastewater treatment types of seven Accession countries (see tab.C.2) in the period of 1990 and 1995.


Sludge in the AC10

According to the European Environmental Agency (EEA/ETC/IW1998) sludge production in the AC 10 in 1995 was taken as baseline to estimate the amount of sludge produced after implementation of the UWWTD. Estimates are based on sludge production of 60 g dry solids per person per day and the extent of sewage treatment.

In 1995, Poland was the country with the largest production of sludge (369,000,000 t dry solids), followed by Romania (163,000,000 t dry solids) and Czech Republic 120,000,000 t dry solids).

The following graphic shows how the estimated sludge production will increase from the baseline in 1995 with the implementation of the UWWTD, according to the scenarios mentioned in section 7.3.4.

As shown in Figure 7.2, there will be an increase of sludge production between scenario A and B because an increase in the population connected to sewers will produce more pollution load as shown in scenario B and C. There is no difference in sludge quantities between scenarios B and C because, although there will be a greater quantity of total sludge produced arising from the chemicals used to precipitate the nutrients, only the organic matter content of the sludge is being considered.

It is estimated that the sludge production of the EU 15 including Iceland, Liechtenstein and Norway will be 11.2 million tonnes dry solid in 2005. The AC 10 would increase this amount by about 10-15%.

Figure 7.2: Estimated total sewage sludge production in the AC 10, in 1995 and after the implementation of the UWWTD, according to the 3 scenarios

Source: EEA/ETC/IW, 1998


      Main Menu


  • Brochure
  • IETC Brochure

  • International Year of Forests
  • International Year of Forests

  • World Environment Day
  • ??????

  • UNEP Campaign
  • UNite to Combat Climate Change