Experimental production and quality evaluation of compost derived from different watse streams

Abstract

Solid waste management forms one of the biggest environmental challenges as a consequence of the significantly increasing population and the process of urbanization. Conditions of composting were applied in the present study and animal manure (A), municipal bio-waste (M) and cafeteria food leftovers (C) were composted in glass jars under aerobic conditions. Forced aeration was provided with the use of vacuum air pump. Three jars for each substrate and one containing distilled water were incubated at 50oC for 22 days. Samples were taken at day 0 and every 3 days for analyses of moisture content, pH, electrical conductivity (EC), seed germination and bacterial colony forming units C.F.U. pH and EC of A and M substrates showed an increasing trend at the first 2 weeks of the composting process and then a slight decrease at the last week of the cycle whereas C substrate showed a continuous increase in pH and EC values throughout the process. Moisture content decreased in the 3 substrates. A considerable increase in seed germination index was observed among both substrates M and A while phyto-toxic effect was accounted in substrate C. abundance of thermophilic bacteria at the first 2 weeks and the recolonization of mesophilic bacteria at the last week was observed among all the samples. Significant reduction in Coliform count was observed in all samples at the end of the composting process. Cellulolytic and amylolytic bacteria were found to have their highest activity during the first 2 weeks of the process during the active composting stage in all the substrates. Controlled composting under forced aeration and 50oC incubation temperature appeared effective and promising in terms of reducing pathogenic bacteria count as well as producing a good quality organic stable compost that can escalate the agricultural output, where the seed germination indexes were 192.5% and 171.5% for the composted substrates A and M respectively at the end of the 22 composting cycle.