Effect of Turning ,covering Techniques and Season on Trough Composting

The trough composting experiments were carried out in the summer and winter in different turning frequency and covering condition respectively.The aim of present work was to determine the impact of turning and covering on the composting process and find the best composting technologys . By taking various kinds of indexes test and statistical analysis, The results were as follows:The results of summer composting showed that: all the 6 treatments in different turning frequency and covering conditions achieved the standards of harmless generally, and the high temperature phase which above 50℃lasted for more than 11days.The EC were under 2.14 m?·cm-1 ,The GI were over 52.27% in the end.The turning action could reduce the volume of compost, promote TOC to degradate significantly,speed up the rotten process,shorten the composting time,and increased the GI of compost products observably , reduce the toxic to the plants.But turning also improve nitrogen loss significantly because of NH3 emissions.There was no significant difference between turning and non-turning in dry weight,moisture content and EC . The covering could decrease the NH3 emissions, nitrogen losses remarkably , but it could also decrease TOC degradation and GI, slow down the decomposition course , and the covering had not play a prominent part in moisture content, material dry weight,volume, pH and EC.The results of winter composting showed that: the 6 treatments in different turning frequency and covering conditions were all achieved the standards of harmless basically, and the high temperature phase which above 50℃lasted for more than 26days, The EC were under 1.77 m?·cm-1 ,The GI were over 65.60% in the end. The turning action could enhance material decreasing, TOC degradating and GI remarkably,it also reduced the the moisture content in high temperature phase and decreased EC significantly. GI was the highest when turning 1time/1week. But turning also improved nitrogen loss significantly because of NH3 emissions,TN losses achieved maximum when turning 1time/1week. There was no significant difference between turning and not turning in pH. The covering could decrease the NH3 emissions, nitrogen losses remarkably,and it had not play a prominent part in moisture content, material decreasing pH,EC,TOC and GI . Based on the economic and environmental factors, uncovering with turning 1time/1week was the optimum scheme of summer trough composting,and covering with turning 1time/1week was the optimum scheme of winter trough composting.Compare winter composting with summer,The material decreasing of winter coposting was more obvious than the sunmmer.Dry weight and volume reduction were higher than summer 6.90 %,3.91 % respectively.The high temperature phase of winter composting was 37 days long,which was longer than summer 33 days.TOC degradation rate of winter composting was higher because of longer high temperature phase. TN losses of summer composting was more than winter because of more frequent turning and lots of NH3 emissions.The average GI of summer composting was higher than winter.