Changes in physical, chemical, microbial and enzymatic parameters were monitored during the composting of organic fraction of municipal solid wastes under compost plant normal operating conditions (CPNOC) (pile size, moisture and turning were not adjusted) and compost plant adjusted conditions (CPAC) (pile size (1.5 m height and 3.0 m width), then moisture (40-60%) and turning (twice a week)).The results showed that the temperature reached its maximum (71.5 and 65.5 oC) after 26 and 19 days in the CPNOC and CPAC, respectively; then decreased. The final compost is odourless and dark brown, especially in case of CPAC. Marked changes in pH were found. Organic matter (OM) and organic carbon (OC) decreased, whereas ash, nitrogen (N), phosphorus (P) and potassium (K) increased and consequently C/N, C/P and C/K ratios decreased with time. The decrease was higher in case of CPAC. Also, Microbial populations (bacteria and fungi) were higher in the CPAC and bacteria were many. Activity of enzymes was higher in the CPAC. The maximum activity was at the beginning for a-amylase, after 40 days for carboxymethylcellulase (CMCase) and after 30 days for xylanase. The current study proves that CPNOC is not suitable for composting, whereas CPAC provides a favourable environment for microorganisms and their enzymatic activities thereby, making the final compost reached its full maturity. Generally, changes in microbial populations and enzymatic activities during composting could be used as suitable indicators to characterize the composting process and the compost maturity when combined with some physical and chemical parameters. Therefore, composting could be an appropriate technology to produce a useful product (compost) if optimum conditions are performed.
Organic fraction of municipal solid wastes, Composting, Evaluation parameters
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