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<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

7.5 Disposal (Topic e)

According to the EU Directive on Urban Waste Water Treatment (UWWTD) Member States (EU 15) have to ensure the disposal of sludge from urban wastewater treatment plants. Sludge disposal is subject to general rules or registration or authorisation in order to minimise the adverse effects on the environment. The disposal of sludge to surface waters had to be phased out by 31/12/1998 for EU 15. The implementation of the UWWT Directive in the AC 10 will considerably increase the quantity of contaminated sludge generated by the treatment processes. The sludge will require further action, which might have negative impact on the environment.

Sludge treatment and disposal accounts for about half the total costs of sewage treatment. The resulting benefits are an improved surface water quality, a decline in costs for drinking water treatment and general public health benefits, as well as use as fertiliser for agriculture.

Especially in the CIS, the disposal of untreated sludge is carried out on huge sludge fields. Sludge management is hampered by a lack of dehydration technologies. On sludge fields, the sludge is drying out naturally, which creates problems in the dry period of the year through dust and smell trouble for the surrounding population, as well as in the wet period of the year through washing out the sludge into water bodies and /or groundwater. Most sludge field capacities are exhausted, they are overloaded, and there is not much space to build new ones, except in Russia. Sludge fields are not always monitored, ground water and soil contamination are common.

Incineration of sludge is rarely used, because of the costs of proper instalment of air pollution abatement technology. The dumping of wastewater sludge into the Black and Baltic seas is decreasing because of the commitments related mainly to the HELCOM and Black Sea Conventions as well as to other marine protecting conventions or agreements, signed by the adjacent countries.

According to Rojanschi, 1999, in Romania nearly all sewage sludge is disposed on drying platforms. A small amount of sludge is also discharged into the Black Sea, mostly out of the bathing season. The equipment of the drying beds is quite often old, and maintenance is often not adequate. That leads to infiltration into the ground, contaminating the groundwater and soil. Filled drying beds were abandoned, without any further care, and new ones were created. Under the new political and social circumstances, in which a restitution of the land to the former owners has taken place or is going to take place, disposing sludge on drying beds must be radically reviewed. That solution was valid and justified under the circumstances of the state ownership on land, where the cost of the land were not significant. Today, more economic solutions have to be found like de-hydration, composting, or incineration. Currently, the implementation of these methods is intensively studied and proposed as solutions to upgrade some of the wastewater treatment plants in Romania.

In the future the picture has to change, because of new environmental laws against water and soil pollution, as well new ownership arrangements for land and treatment plants. It is becoming too expensive to use large areas for often uncontrolled and leaking drying beds and landfills which stay contaminated.

Municipalities have to find economic solutions suitable for public and environmental health, which might include the use of treated sludge for agricultural purposes. Incineration facilities for sludge are still limited in nearly all transition countries.

Treated or untreated wastewater is usually disposed to watercourses eventually finding its way to rivers and lakes. Examples of the rate of wastewater disposal are given below.

Pollution load of Lithuania

According to the EPR, 1998, wastewater discharges from urban settlements particularly along rivers represent a significant pollution source. Discharges from the seven largest cities, or 44% of the population, produce about 67% of all wastewater discharges. In terms of BOD7 this is 74%, nitrogen discharges are 64% of the national total and phosphorus discharges are 60%. Pollution caused by industry has decreased over the recent years as result of reduced economic activity in certain key sectors.

The wastewater discharge which meets national quality standards without treatment, is mainly cooling water from the energy sector. Cooling water discharge increased by about 69% in the period 1992-1996. In 1996 it delivered up to 95% of the total wastewater discharge and was directly released into surface water. The remaining 5% wastewater requires treatment. This amount of wastewater decreased by about 31% in the period 1992-1996. Out of the wastewater requiring treatment, 40% is actually treated to meet national quality standards, 43% is insufficiently treated (not meeting standards) and 17% remains untreated. In 1997, out of the 787 wastewater treatment plants, 6% were only mechanical treatment plants and 85% biological treatment plants. Seven towns (Vilnius, Marijampole, Lazdijai, Silale, Raseiniai, Pakruojis, Moletai) remove both, phosphorus and nitrogen in their treatment plants, with a total capacity of more than 6 million m3 per year. The general removal efficiency of biological treatment plants in terms of BOD vary between 93 and 97%, for nitrogen between 62 and 80% and between 37 and 80% of phosphorus. The table 7.9 shows the decreasing trend of the main pollutants discharged into Lithuanian surface water in the period 1992-1996.

Table 7.9: Trends in pollutants discharged into Lithuanian surface water in the period 1992 - 1996 (1992=100%)

Pollutant 1995 1996

BOD5

66 52
Suspended solids 70 49
Oil products 65 47
Phosphorus 82 67
Nitrogen 72 61
Heavy metals 47 28
Source: EPR, 1998

Public health impacts

Microbial contamination of drinking water and food is often related to insufficient or untreated wastewater, inadequate sanitation and hygiene or to the natural occurrence of microorganisms in water. That might be associated with a relatively high incidence of outbreaks and isolated cases of dysentery, hepatitis A, typhoid, Salmonella and other enteric infections.

For example, Lithuania and Latvia are countries with an incidence of viral Hepatitis, which is about 10 times higher than the EU average, but still less than in other CIS countries (EPRs, 1998). The most affected countries are Ukraine and the Central Asian States of the CIS. Outbreaks of Cholera are reported in Ukraine (1994-95), in Moldova (1995) and in Romania (1991-93) and in Albania (1994), (WHO/EURO, 1999).

Ameobic dysentery is another disease which can contaminate surface water through sewage effluents. The number of cases reported from countries that maintain records is generally low. Outbreaks were reported, according to the EEA/WHO questionnaire, from Slovenia in 1991, from Hungary and Lithuania (WHO/EURO, 1999). Shigella species, causing bacillary dysentery, can occur if drinking water is contaminated with sewage. Large outbreaks of this disease were recorded in Romania in 1995, and in the 3 Baltic states with an especially severe outbreaks in Lithuania in 1996 (about 70,000 people), furthermore in Moldova and Albania, all in 1996.

Giardiasis outbreaks have been reported in Slovenia, of which 40% of these cases were linked to drinking water contamination. There were also outbreaks reported from Estonia, Lithuania , Hungary and Slovakia in 1996.

According to the available data from the EEA/WHO questionnaire of 1997, the occurrence and incidence of some water related diseases like bacillary dysentery, giardiasis, hepatitis A and typhoid, where insufficiently treated sewage might be a major contamination source, was more frequently found in the European transition countries than in Western Europe (WHO/EURO, 1999). In Central and Eastern Europe, a general decline in acute intestinal diseases is reported. Some reasons might be the drop in economy, because of a decrease in collective food distribution, (individually grown food has less chances to become contaminated) and lower density in schools and kindergartens, because of fewer children being born.

Political instability, like that found in parts of the Balkan or in the Caucasian region, leads to mass movements of refugees, not having access to adequate water supply and sanitation, which can have severe impact on human health. Sanitation in refugee camps is limited, will be discharged directly into nature and is normally not covered by statistics.

 

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