Decomposition of Phosphorus Pollution and Microorganism Analysis Using Novel CW-MFCs under Different Influence Factors

A constructed wetland (CW)-coupled microbial fuel cell (MFC) system was constructed to treat wastewater and generate electricity. The total phosphorus in the simulated domestic sewage was used as the treatment target, and the optimal phosphorus removal effect and electricity generation were determined by comparing the changes in substrates, hydraulic retention times, and microorganisms. The mechanism underlying phosphorus removal was also analyzed. By using magnesia and garnet as substrates, the best removal efficiencies of two CW-MFC systems reached 80.3% and 92.4%. Phosphorus removal by the garnet matrix mainly depends on a complex adsorption process, whereas the magnesia system relies on ion exchange reactions. The maximum output voltage and stabilization voltage of the garnet system were higher than those of the magnesia system. Microorganisms in the wetland sediments and electrode also changed considerably. It indicates that the mechanism of phosphorus removal by the substrate in the CW-MFC system is adsorption and chemical reaction between ions to generate precipitation. The population structure of proteobacteria and other microorganisms has an impact on both power generation and phosphorus removal. Combining the advantages of constructed wetlands and microbial fuel cells also improved phosphorus removal in coupled system. Therefore, when studying a CW-MFC system, the selection of electrode materials, matrix, and system structure should be taken into account to find a method that will improve the power generation capacity of the system and remove phosphorus

Mechanism of sand body prediction in a continental rift basin by coupling paleogeomorphic elements under the control of base level

In view of the complex sandbody distribution in continental rift basins, a sandbody prediction method is proposed based on the coupling of three core paleogeomorphic elements, provenance system, channel system, and slope break system, which composes the process of “provenance-transport-sedimentation” controlled by base level. The sand body prediction method takes the base level as the lever, the equilibrium position near the lake basin edge as the supporting point, and the core paleogeomorphic elements as study objects, lays stress on the fact that dynamic factors controlling static factors, and takes full consideration of flow state conversion and sandbody genesis. The core paleogeomorphic elements have eight types of theoretical coupling modes, corresponding to coupling deposition effect from the worst to the optimal. During fluctuations of base level, the coupling modes of the core paleogeomorphic elements in continental rift basins change under the “seesaw effect”, as a result, the migration pattern, sedimentary environment, and genesis of sand body change significantly, which control sand body distribution in turn. The sand body development regularity of the Gaoyou Sag in Northern Jiangsu Basin and the Weixinan Sag in Beibu Gulf Basin has been analyzed based on this sand control mechanism and a good prediction result of sand body is achieved, which confirms the validity and practicality of the sand control mechanism. Key words: continental rift basin, base level, ancient landform, coupling mode, sand control mechanism, Northern Jiangsu Basin, Beibu Gulf Basi