COMPOSTING OF DECIDUOUS TREES LEAVES AND CATTLE DUNG: EFFECT OF TURNING OPERATION IN PROCESS PERFORMANCE

The aim of this study was to evaluate the feasibility of composting fallen leaves and cattle dung and the effect of turning frequency on final compost quality. A bioreactor vessel was designed, manufactured, and situated on the roof of the Agricultural Engineering Department, Faculty of Agriculture, MansouraUniversity for rapid composting of admixture leaves and cattle dung from November 2008 until June 2010. This bioreactor vessel is conical in shape (right frustum of cone) and made of double layer of stainless steel sheet 1 mm thick with a net volume of 0.1094 m³. A series of experiments were executed to investigate some engineering factors affecting performance of composting process such as; size of fallen leaves and stirring or turning frequency. Laboratory tests were also carried out to assess and evaluate some physical and chemical properties of raw composting materials, fresh compost, and final compost after curing process. Two different particle sizes of fallen leaves (shredded leaves of 2.0-5.5 mm and complete leaves) and one aeration rate (0.007 m³/min) were functioned. Two different levels of manual stirring (without and with stirring once every six days) were used. The obtained results revealed that, to maximize the microbial activity and speed up the composting process of admixture materials, they would be aerated by a rate of 0.007 m³/min, stirred once every six days, and shredded fallen leaves to a smaller particles size. The obtained results also showed that, the final compost contented Nitrogen (N), Phosphorus (P), and potassium (K) of 3.181%, 0.318%, and 3.790%, respectively. They also revealed that, there were no weed seeds found in all treatment samples of fresh and final composts. Rising up the temperature of admixture materials and persisting from the first day until the end of fifth day during the thermophilic phase caused in destructed of pathogens and other organisms.