Study On Greenhouse Gas Emission From Slurry Storage Of Swine Farm

The continuous and rapid development of concentrated animal feeding operations (CAFOs) contributes greatly to sufficient animal product supply and facilitates the development of rural economy, but the concomitant animal wastes pose tremendous threats to the environment, especially waste water. Liquid manure storages (LMS) are widely used cost-effective facilities for the waste management in CAFOs in our country, LMS is considered to be an important source of greenhouse gas (GHG) emissions in agriculture sector. There is a lacking of information on the GHG emissions from LMS. The results of the study will provide some basic data for the estimation of GHG emissions from animal waste management, and be helpful to the development of mitigation practices.This study investigated the effects of temperature, chemical oxygen demand (COD), covering on the CO2, CH4, N2O emissions based on the laboratory experiments, and measured the quantities of CO2, CH4, and N2O emissions from LMS on a swine farm, the results were as following:1. The fluxes and cumulative emissions of CO2 and CH4 increased with COD concentrations. CH4 emissions were 0.12L, 0.28L, and 0.31L with each gram of COD removal from LMS with the COD ranges of 1000-3000mg/L,3000-5000mg/L and 5000-7000mg/L, respectively, the corresponding CO2 emissions were 0.47 L/g, 0.66 L/g, 1.90L/g.2. The inside temperature of LMS affected both the CO2 and CH4 emissions. The maximum fluxes and cumulative emissions of both CO2 and CH4 exhibited in 40℃, which were significantly higher than those in 25℃and 10℃, with the minimum values appearing in 25℃. When the inside temperature of LMS was 40℃, the CO2 and CH4 emissions were 1.19L and 0.59L for 1g COD reduction, and 0.99L and 0.49L for 1g VS reduction, respectively. The CO2 and CH4 emissions from the LMS of 25℃were similar to those from under the LMS of 10℃.3. No significant difference in the cumulative CO2 and CH4 emissions was observed between ceramisite and control. Corn stalk covering could significantly increase both the cumulative CO2 and CH4 emissions from LMS in comparison with ceramisite and non-covering control. The fluxes and cumulative emissions of CO2 and CH4 with corn stalk cover were 29.57 L and 10.49 L for 1g COD removal, and 37.06L and 13.14 L for per gram VS removal, respectively.4. No daily variation in the concentrations and fluxes of CO2 and CH4 were observed in winter, spring and summer. The N2O concentration was much lower than those of CO2 and CH4, it's negligible. The amount of CO2 and CH4 emissions were positively correlated with ambient temperature.5. The first septic tank contributed to 60.1%, 62.1%, and 43.4% GHG emissions in winter, spring and summer, respectively. Therefore it's very important to contain the GHG emissions from the first septic tank.6. The CO2 equivalent of CO2, CH4 and N2O emissions from the LMS accounted for 19%, 78% and 3% GHG emissions in winter, and 10%, 90%, 0% in spring, and about 5%, 95%, 0% in summer, respectively. CH4 was the leading GHG from LMS, and CO2 followed. Measurements should be taken to control the CH4 emission from LMS.7. N2O emission from LMS was negligible according to both the laboratory and field experiments.