The effect of a semi-permeable membrane-covered composting system on greenhouse gas and ammonia emissions in the Tibetan Plateau

The Tibetan Plateau is a traditional pastoral area in the western part of China where animal husbandry is a local pillar. The cattle manure in this area accounts for 77% of the total amount of local livestock and poultry manure. To reduce the harmful side effects associated with cattle manure use in the Tibetan Plateau region of China, a highly-efficient semi-permeable membrane-covered compost system was used. Main physicochemical and gas indicators were measured to investigate the effects of this compost system. Overall, the composting temperature was above 50 °C for 34 days, which resulted in the moisture content and germination index of the final compost being 30 ± 1% and 84%, respectively. Additionally, the obstruction of semi-membrane, high oxygen and water concentrations under the semi-permeable membrane reduced the emission of greenhouse gases and ammonia, with cumulative emissions of CO2, CH4, N2O and NH3 outside the membrane being 73%, 96%, 80% and 65% lower than those inside the membrane, respectively. Moreover, the maximum cumulative concentrations of CO2, CH4, N2O and NH3 outside the membrane were 98%, 95%, 72% and 58% lower than those inside the membrane, respectively. This research demonstrated the advantages of using the semi-permeable membrane-covered composting system to reduce GHGs as well as ammonia production and emissions and the responsible mechanisms. The semi-permeable membrane-covered composting system could be a good choice for treatment of manure in the Tibetan Plateau region.