Effect of Gypsum on Carbon Sequestration of Organic Matter in Anaerobic Decomposition
This paper investigated the affect of gypsum on methane emission and organic matter mineralization in anaerobic biochemical system by using beef extract peptone as the nutrient source. To explore the effect and mechanism of gypsum on suppressing the activity of methane-producing bacteria (MPB), three kinds of chemical and physical indexes were tested: 1) TOC, TIC, SO42-, sulfide and pH values of the aqueous phase; 2) volume of CO2, CH4 and H2S emissions in the gas phase, and 3) SEM, EDS and XRD analyses of the solid phase. Our results showed that addition of gypsum could effectively reduce methane emission by more than 40 ％. However, no apparent impact on the release of CO2 was observed during this process. Furthermore, the content of carbonate minerals in solid phase increased dramatically compared with the control group. These data further suggested that the major role of gypsum in this anaerobic system is represented in the following aspects: 1) the continuous dissolution of gypsum, one of the slightly soluble minerals, played an important role in controlled release of SO42- during its sustained reduction; 2) sulfatereducing bacteria (SRB) were promoted to be the dominant microorganism under the conditions of stable SO42- concentration and sufficient electron acceptors generated by slow dissolution of gypsum, and its competition of substrates and electrons further suppressed the methane production of MPB; 3) the consumption of organic carbon by SRB accelerated mineralization of organic matter, by which the carbonate generated could combine with Ca2+ in gypsum to form CaCO3. In this way, gypsum plays a crucial role in carbon sequestration by efficiently improving the rate of organic carbon mineralization.
国家科技期刊平台
NSTL
万方数据
维普
