[Study on the quality and comparing of the compost produced by Khomain and Tehran compost factories]

ABSTRACT

Over than 70% of solid wastes is consisted of food wastes with high putrecibility in Iran. Due to this regard, construction of composting factories for sanitary disposal or fertilizer production from solid wastes was very appreciated in our country. The objective of this research was to study on the quality and comparing of the compost produced by Khomain and Tehran compost factories. This study was accomplished on the compost produce from Khomain and Tehran compost factories about 9 months. For investigation of chemical qualities of these materials, some indexes such as percentage of organic materials, carbon, nitrogen, phosphorus, potash and heavy metals consists of lead, cadmium, mercury and chromium were measured. Microbial quality of these compost materials were defined by assessing of the amounts of coliforms bacteria, salmonella bacteria and parasites ova. The average amounts of some indexes in compost of Khomain and Tehran were been organic materials% [37.77, 29.80], carbon%[22.14, 18.12], nitrogen% [2.08, 1.6], lead [229.6, 59.44 ppm], and chromium [70.2, 19.75], respectively. The microbial quality of these compost samples were agreement with class B of USEPA guidelines. This study showed that quality of organic materials percent in Tehran's samples was better than Khomain's samples, but these indexes on these samples were lower than the grade No.2 of compost. The percentage of carbon, nitrogen and potash in these samples were desirable but, phosphorus amount were not in sufficient. The heavy metals especially lead and chromium in Tehran's samples were higher than Khomain's samples, but these samples were usually in agreement with guidelines of compost. Due to the defined microbial qualities, these samples could be used as well as amendment agents for poor soil