Pollutants Flux On The Sediments Multi-phase Interface In Drinking Water Reservoir And Pollution Controlling Technology

Endogenous pollution happening on the sediments multi-phase interface is the mostimportant problem of drinking water reservoir. For most drinking wter reservoirs, theirsediments multi-phase interface is usually under high hydrostatic pressure, aerobic, lowtemperature and oligotrophic conditions. Moreover, considering the health effect, thepollution controlling technology for drinking water reservoirs must be elaborately selected. Inthis study, the nitrogen and dissolved organic matter fluxes on the multi-phase interface andhydrostatic pressure effects on this course were researched by field investigation andlaboratory simulation. And the pollution controlling methods suitable for drinking waterreservoirs were also studied. The crucial results and conclusions are as follows:（1）Fe/Al-P in the sediments was the most importan source for PO₄^3-release. Andnitrogen release were mainly coming from the IEF-N, WAEF-N and SOEF-N forms insediments. SOEF-N was the preponderant form of transferable nitrogen and is followed byWAEF-N. IEF-N, which can released into overlying water most easily, covered the least oftransferable nitrogen. Aerobic and reductive condition can accelerate PO₄^3-release.（2）NH₄⁺, TN and DOC cumulated in large quantities in overlying water under aerobiccondition, which deteriorated the water quality badly. When the DO in multi-phase interfacewas2³mg/L, the DOC with molecular weights of500³200Da can be decomposeddrastically by the microorganisms in the sediments and the STN and SOC contents in thesediments can be reduced by7.27%and21.00%respectively. Different DO concentration inthe multi-phase interface will effect some enzymes activities, STN, and SOC in the sediments,thus the microbial community structures in the sediments shown by PLFAs were remarkablydifferent. being devoid of suitable carbon source was the most important limiting effect fordenitrification on the multi-phase interface. The gas products on the multi-phase interfacemainly included of CH₄, N₂, CO₂and H₂. Under low temperature, N₂covered91.73%of total gas volume and under room temperature N₂and CH₄each covered nearly half of total gasvolume. Low temperature can inhibit microorganisms decomposing organic matter andpromote microorganisms nitrification and denitrification.（3） Hydrostatic pressure was the most important effect factor to overlying water quality andmicrobial community structures in sediments. Under0.1MPa¹.0MPa, high hydrostaticpressure can promote nitrogen and organic matter release and deteriorate overlying waterquality. Furthermore, under high hydrostatic pressure, the polydispersity of DOMρreduced and DOC with low molecular weights were decomposed by microorganisms anddispersed in overlying water. Under different hydrostatic pressure, the microbial communitystructure in the sediments were different. The microbial community diversity under highhydrostatic pressure was much richer than under low hydrostatic pressure.（4）Water lifting aerator combined with chemical stabilization can inhibit PO₄^3-and Fe2+release effectively, and the inhibit efficiencies can reach63.2%and58.6%respectively. Thehigher the PAC concentration was, the better the inhibiting efficiency was, and PAM additioncan strengthen the inhibiting efficiency significantly. The mechanism was that thehydrolyzing products can combine with PO₄^3-and form Al-P. The active capping materialcovered by especially selectived biofilm was more effective than capping material orfunctional microbes was singled used. The zeolites in the capping layers can adsrob the NH₄⁺and the biofilm covering on the zeolites then decomposed them. Simultaneously the zeoliteswere renewed. Therefore the polluting load of STN and SOC in the sediments can bereduced.