leachate collection system/or municipal solid waste sanitary landfill (case study: babol sanitary landfill)

landfilling is an ultimate fate of any municipal solid waste management system, and it is a no alternative choice for disposal of municipal solid waste. the major environmental concerns associated with landfilling of wastes are related to the leachate generation and eventual discharge of leachate into the environment. leachate quality is formed due to aerobic and anaerobic processes taking place in landfill. during aerobic decomposition of wastes, which is short in period, organic matters are converted to co2, h20 and volatile acids. anaerobic decompositon of wastes takes place in three phases, and methane, carbon dioxid, ammonia, and hydrogen sulfide gases are generated. in order to prevent leachate from percolation to ground water, natural or synthetic liners must be constructed at the bottom of landfill. babol municipal landfill is located in angelsi region, 30 km southwest of babol with general slope of 14%. the total area of this site is 4 hectare. yearly average municipal soild waste generation of babol is 136 mertic tonne. so the life time of this site is estimated to be 4 years. generation rate of primary leachate in this landfill is about 11.8m3 per day, for waste field capacity of 0.6 cm/cm and moisture content of 70%. steress due to vehicle is negligible (0.001492 kg/cm). leachate management system in bobal municipal landfill is composed of three elements leachate trench with low permeability of k=10 cm/sec, comprised of sand with 16-32 mm in diametere and depth of 30cm. thus 10500m3 of sand is used to construct these trenches in 3.5 ha of use full area available for landfilling. leachate collection system is made of cement pipes with 15 cm in dimeter. these pipes are especially prepared for this purpose. and finally a liner made of local clay compacted in thickness of one meter, so the maximum conductivity of this liner was in the order of mangitude of 10 cm/sec.