RESUMEN
Basic principles of Integrated Solid Waste Management [ISWM] are: Reduction, Reuse, Recycling and Recovery [411s]. Composting as an element of ISWM strategy that can be applied to separately collected or mixed wastes, is a controlled aerobic process carried out by successive microbial populations com-bining both mesophilic and thermophilic activities and leading to the production of carbon dioxide, water, minerals and stabilized organic matter. In this research, comparing between windrow and pit co-composting methods was studied in the city of Damghan, Iran. Waste proportioning was done based on C/N ratio [about 25:1] and moisture content [about 55%]. Mixed wastes were located in windrow and pit with natural aeration tunnel. Sufficient oxygen supply was provided in the piles of compostable materials in two systems through frequent turning of the piles in 7 d intervals during the first month. Temperature reached to maximum level in 10-15 d and then depleted [days: 20-25]. It reached to the safety level [about 60°C] based on U.S.EPA and WHO recommendations. Finally, compost was produced with pll=7.7, dark brown color and 30- 35% moisture content. N, P, K, organic matter and organic carbon were measured by standard methods. Results were compared with WHO and U.S.EPA recommendations showing suitable conditions Also it was indicated that pit method was better for maintaining temperature, nitrogen, organic C and organic matter