Activate sludge treatment of leachates from väätsa landfill, Estonia

Vfilitsa Landfill is the first sanitary landfill in Estonia that meets the requirements of theEU 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 wasteswas started in November 2000. By now, the landfill contains: one hectare large disposalsite for domestic waste, composting area for organic waste and storage site forconstruction wastes. In Estonia, the collection of recyclables has not jet developed. InVfilitsa landfill, however, waste paper, glass and plastic are sorted. Organic waste is notseparated on-site, and this is the reason why the organic content (nutritive waste) ofgarbage 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, extendedaeration, 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 ofpollutants are decreased approximately by 1/3. The second phase of purification takesplace in oxidation lagoon.The leachate treatment plant worked effectively throughout the first year, both during thesummer with high temperatures, and winter with low temperatures. During the firstoperating year, the main expenses were: energy for blowers, phosphorus acid for nutrientadjustment, and exchange oil for blowers. The analysis of the first operating year showsthat BOD has decreased more than 95%, COD approximately 90% and N on an average60 %. The activated sludge process also reduced the concentrations of some heavymetals.