| Water pollution in china is serious, and there is dynamic balance of material exchange between the sediment and its overlying water; the study of sediment characteristics is of great significance for improving quality of water body; sediment dredging is often used in governance of water, but how to dispose dredged sediment is a problem. In this study,12surface sediment and5cylindrical sediment sampling points were set up in South Lake of Wuhan city, contents of organic matter, nutrients, heavy metals and other indicators in sediment of every sampling point were measured to analysis the pollution characteristics of sediment in South Lake; batch and semi-continuous anaerobic digestion test were conducted with sediment to study the feasibility of energy production; influence of land application of original sediment and anaerobic digestion residue on plant growth and soil properties and feasibility of land application were analyzed. The conclusions are as follows:(1) For the surface sediment, these characteristics were found:organic matter (OM) and total nitrogen (TN), OM and total phosphorus (TP) were significantly related; the TN and TP, the various forms of nitrogen were significantly related too. From point of view of TOC/TN, there was similar influence from external source and internal source pollution on sediment. OM and most of the heavy metals were significantly related. There was strong variability of spatial distribution of various pollutants.(2) For the stanchion form sediment:the contents of pollutants decrease along depth. OM and TN, OM and TP were significantly related; TN and TP weren't significant related. There were strong or moderate variability of vertical distribution of various pollutants.(3) By comparing the contents of pollutants of pore water and overlying water, nitrogen may be released from sediments to overlying water but phosphorus may be not. There were certain correlation of nitrogen or phosphorus among overlying water, pore water and sediment.(4) The organic pollution status of sediment in Nanhu Lake were evaluated by organic nitrogen evaluation and organic index evaluation, results showed that the organic pollution of sediment in Nanhu Lake is serious. Two assessment methods were used to assess the pollution degree of heavy metals of sediment in Nanhu Lake, which were Index of Geoaccumulation and Potential Ecological Risk Index. The results showed that for cadmium the pollution degree was moderate; for mercury, arsenic, copper, lead, chromium, zinc, the pollution degree were slight; and potential ecology risk of all element were slight.(5) The orthogonal experiment of batch anaerobic digestion was conducted, the results showed that:gas yield was significantly impacted by temperature, carbon and nitrogen ratio (C/N), the solid concentration; and were affected indistinctively by Inoculum-Substrate ratio (ISR). The influence order of the four factors on biogas yield are temperature> C/N> solid concentration>ISR. The best optimum anaerobic digestion conditions are the temperature is55℃, the C/N value is12.5:1, solid concentration is10%and ISR is1:1.(6) Semi-continuous anaerobic digestion experiment was conducted on mesophilic condition, the reactor was operating normally. Volume load had influence on biogas yield, VS/TS of discharged sludge and percentage of methane in biogas, the best digestion efficiency is in the condition of1.96gVS/(L·d). The anaerobic digestion kinetics model has been deduced that theoretical gas yield was278.6ml/gVS and the reaction rate constant was0.166d-1(7) when applying sediments and anaerobic digestion residue from Nanhu Lake on red soil, the results showed that:bulk density and porosity were within the normal range of soil, pH was increased; crop growth was promoted, heavy metals contents in crop did not exceed the relevant standards of agricultural products and food; nutrient contents of soil were significantly increased; content of Cd in soil were also increased but did not overturn the soil environmental quality standards; after fly ash or pig manure was added, activation of Cd was decreased, available content of Cd in soil and absorption of Cd for crop were reduced; soil porosity increased; therefore fly ash and pig manure can play a supporting role in land application of sediment.(8) From view of bulk density, porosity, nutrients, heavy metals, cation exchange capacity and potassium, sediments of Nanhu Lake are suitable for agriculture or greening application. However, if the sediments are used to plant edible agricultural products, application amount should be controlled, especially under acidic or neutral soil conditions.
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