Landfill leachate treatment in Lithuania

Abstract

Around 6 million tons of nonhazardous waste and some 1 301 70 000 tons of hazardous waste is generated in Lithuania every year. Most of non-hazardous wastes are organic (2. 1 millions tons) or domestic ( 1 . 7 million ton). Since no general waste incineration is used in Lithuania, the overall used method of waste disposal is landfilling. Most of the landfills are not designed or located properly. They pose a threat for both surface and groundwater in Lithuania. The Lithuanian government has made environmental protection a priority concern in recent years. Bilateral and multilateral donors have made funding available for environmental projects. Until 1 998 no landfill in Lithuania had a landfill leachate treatment plant. Leachate was kept in the special storage places in the landfill, or collected and recirculated. In Vilnius, the capital of Lithuania, part of the landfill leachate is taken to the city s waste water treatment plant and part of it is recirculated. Competition for the landfill leachate plant was announced and hopefully in the near future Vilnius will have a real project for the landfill leachate treatment. Recirculation was carried out in Kaunas Lapes landfill too till the leachate treatment plant was built. Leachate is collected and kept in the ditches in the other three biggest cities of Lithuania Klaipeda, Siauliai and Panevezys. Klaipeda, as all other cities, is looking for a cost effective solution for the leachate treatment and Panevezys is thinking to clean the leachate in the city s waste water treatment plant. Biological leachate treatment is the idea of Siauliai municipality. Lina Gelaziene, Lithuania 347 https://doi.org/10.15626/Eco-Tech.1999.039 ECOLOGICAL TECHNOLOGY AND MANAGEMENT KALMAR, SWEDEN, September 22-24, 1 999 LEACHATE TREATMENT IN KAUNAS LANDFILL Kaunas is the second largest city in Lithuania, having a population of approx. 430 000 inhabitants. Since the year 1 973 all municipal solid waste has been directed to the Lapes landfill, located I 9 km outside Kaunas. The total landfill area is approx. 32. 7 ha. The area of existing landfill is 12 .5 ha and the area of the new under construction is 5 . 5 ha. Old part of the landfill is not provided with the bottom liner and drainage system for collection of leachate. It is estimated that during 25 years 2 .4 min. tons of municipal solid waste has been accumulated in the landfill. In 1 99 1 a hydromonitoring program was started in Kaunas landfill. Results have shown that both groundwater and open water sources are very polluted in the surroundings. Because of that reason Kaunas Municipality started to implement landfill reconstruction program, which covers gas extraction and recultivation questions in the old part of the landfill. A new part of the landfill, constructed with bottom clay layer, plastic membrane and drainage system for collection of leachate, will start to operate in very near future. Very important part of this program is landfill leachate treatment. Leachate treatment plant was designed and built with the help of Danish governmental institutions. Joint stock company Pramprojektas has worked together with Danish company COW! Consult. This plant is the first landfill leachate treatment plant in Lithuania. Construction job was finished in October 1 998. Total cost of the plant was 2 .5 min. Lt. Average daily amount of the leachate in Kaunas landfill is around 801 00 m3 It is rich with organic materials and metals: • N,tmg/1 P,tmg/1 BOD Cd, mg/I Cr, mg/I Pb, mg/I Fe, mg/I 1 500 I 5000 0.00 1 0.0 1 1 .2 0.03-0.3 0.46-64 0.0026 Amount of leachate depends on the weather conditions. Biological treatment with the special filtration fields was selected for the landfill leachate treatment plant in Kaunas. Plant was designed based on average daily amount of the leachate, which in Kaunas landfill is around 82 m3 • The unit works on sequence batch reactor (SBR) principle, aeration, biological nitrification and denitrification. Concentration of the sludge is 4.0 kg SS/m3 For the second stage of the treatment is used sand filter and the last stage is peat filter • (Leca/myr). Talking about removal of orgnic pollutants, projected efficiency of the leachate treatment plant is 99.5%. LEACHATE TREATMENT EXPERIMENT IN SIAULIAI LANDFILL Another example from Lithuania is leachate irrigation pilot project in Kairiai landfill in Siauliai . Project was prepared by ECAT-Lithuania, which is helping the municipality with technical and financial aid. The landfill in Siauliai municipality was started in 1 965. Since the start there has been no treatment of the leachate. Leachate has been caught in enlarged ditches and basins around the landfill. This stored leachate is highly concentrated in regards of chloride, nitrogen, phosphorous Lina Gelaziene, Lithuania 348 ECOLOGICAL TECHNOLOGY AND MANAGEMENT KALMAR, SWEDEN, September 22-24, 1 999 and metals . Since the leachate is too strong to be treated efficiently in an ordinary municipal waste water treatment plant, some kind of local treatment is necessary. It was agreed with Siauliai municipality to select a cost effective biological method for the landfill leachate treatment. It was decided to install four experimental plots ( lOx l 0 meters) and to plant them with Salix. The first experimental plot with clay layer and drain system was installed and planted in the spring 1 998.