Activate sludge treatment of leachates from väätsa landfill, Estonia

Abstract

Vfilitsa Landfill is the first sanitary landfill in Estonia that meets the requirements of the
EU landfill directive. The landfill is dimensioned to serve about 130 000 inhabitants.
The first stage of landfill (out of seven) was accomplished in 2000. Disposal of wastes
was started in November 2000. By now, the landfill contains: one hectare large disposal
site for domestic waste, composting area for organic waste and storage site for
construction wastes. In Estonia, the collection of recyclables has not jet developed. In
Vfilitsa landfill, however, waste paper, glass and plastic are sorted. Organic waste is not
separated on-site, and this is the reason why the organic content (nutritive waste) of
garbage is high. Currently, the landfill serves approximately 40 000 inhabitants.
According to the requirements of the client, Veemaailm INC designed and built a twophase activated sludge leachate treatment plant. First phase of the treatment, extended
aeration, takes place in a container. In order to adjust the concentrations of biogenesis,
Ortho Phosphorus Acid is added to the leachate. During the first phase, concentrations of
pollutants are decreased approximately by 1/3. The second phase of purification takes
place in oxidation lagoon.
The leachate treatment plant worked effectively throughout the first year, both during the
summer with high temperatures, and winter with low temperatures. During the first
operating year, the main expenses were: energy for blowers, phosphorus acid for nutrient
adjustment, and exchange oil for blowers. The analysis of the first operating year shows
that BOD has decreased more than 95%, COD approximately 90% and N on an average
60 %. The activated sludge process also reduced the concentrations of some heavy
metals.