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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.
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.
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%)
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,
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.
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.