Study of compost quality from rural solid wastes (Babol, Iran)

Background and In spite of many studies on composting from municipal solid wastes, rural solid wastes have not been studied. A high percentages of rural solid wastes containing domestic, animal and agricultural solid waste is biodegradable. The objective of this research was to study the chemical and microbial quality of compost produced by mixed rural solid wastes and other composts. In this study, food wastes mixed with animal and agricultural wastes with a weight ratio of 2, 5 and 2 (with a final mixed weighting 150 kg) were studied. For investigation of chemical quality of these materials, some indexes such as carbon/ nitrogen ratio, percentage of carbon, phosphorus, potassium, lead, cadmium and zinc were measured. Microbial quality of these compost materials were defined by assessing the amounts of coliforms and parasite ova. The average amounts of some indices in mixed, household and animal composts were: C/N (14 ± 1.5; 20 ± 1.7; 17 ± 1.8), percentages of organic material (73 ± 3.9; 64 ± 3.8; 76 ± 2.5), carbon (32 ± 2.2; 40 ± 2.4; 37 ± 4.5), nitrogen (2.5 ± 0.5; 1.5 ± 0.6; 1.9 ± 0.3) and lead in mg/Kg (3.5 ± 0.7; 16 ± 2.9; 11 ± 1.9), cadmium (0.3 ± 0.05; 3 ± 0.9; 1.5 ± 0.4), respectively. The number of total fecal coliforms in compost produced by mixed solid materials was 643 ± 176; 131 ± 52 respectively in 10 g of solid materials and the number of parasite ova was less than 2 in 4 g solid materials. The compost quality of mixed materials was in agreement with class A of USEPA guidelines hence, usable for flower and plant culturing. Composting may be considered a method to manage the rural solid waste problem.