assessment of the variations in the composition of the leachate ‎generated in open dumps in three provinces of the caspian sea ‎region, iran

background: the municipal solid wastes (msws) are disposed in open dumps, which have no leachate collection and removal system, in the caspian region of iran. leachate readily reaches the nearby water resources such as streams, rivers, lakes, and sea. therefore, understanding the quality and quantity of open dump leachate is vital to the proper treatment of leachate. methods: the leachate samples from 18 open dumps were monitored and analyzed in terms of 21 different variables, namely ph, ec, temperature, ts, tss, tds, vss, cod, bod5, po43--p, so42-, nh4+-n, tkn, and no3--n based on the priority to analyze parameters as prescribed by accepted procedures outlined in “standard methods for examination of water and wastewater”. moreover, ca2+, mg2+, na+, k+, total fe, mn2+ and zn2+ elements were determined using a shimadzu flame atomic absorption spectrophotometer, model 67og. results: the mean values of parameters in the sites’ leachate samples of the three provinces were compared. the results of comparing the mean values of the parameters in the leachate samples from these provinces demonstrate that golestan province had a significantly higher concentration of the parameters than mazandaran and gilan provinces. conclusion: these results may be due to the warmer weather conditions in golestan province in comparison with other provinces. furthermore, relatively low ph (6.15-6.90), high cod concentration (2607-25307 mg/l), high bod5/cod ratio (0.56-0.87), and high heavy metal concentration indicated that the open dumps were representative of the acid phase and/or the end of the acid phase and the beginning of the methanogenic phase.