Study On The Nitrogen And Phosphporus Removal Of Anaerobic Digested Wastewater By Cycling Process And Characteristics Variations Of The Substance

The difficulty of treating anaerobic digested wastewater is its characteristics on the imbalance of carbon and nitrogen, serious lack of carbon source, lack of basicity, and no good biochemical quality. Aiming at solving the problem, study proposes using a combination recirculating system of hydrolyze-acidification and biological contact oxidation process to treat digested wastewater. Basis on these, study recurs to some advanced instruments such as ion chromatograph, fluorescence spectroscope and ultraviolet spectrometer to detect the changes of organic matter and nitrogen in different condition around the reaction process.The operating conditions and operating parameters of optimal process were studied on the denitrification cycling process combination with hydrolysis & acidification and biological contact oxidation to treat with anaerobic fermentation of digested wastewater. Results showed that hydraulic retention time with 24h, the recycling ratio with 1:3, DO concentration with 2-3mg/L and organic loading with 3g/L were the best running conditions, and then effluent clear and no objectional odor. The combination recirculating system was used to treat digested piggery wastewater for more than three months; the pollutants removal efficiency was continuously stable.Micromolecule organic acid results showed that during hydrolysis and acidification process, organic was degraded to be methanoic acid, acetic acid and propanoic acid. At the beginning of hydrolysis and acidification process, the total organic acid concentration reached maximum, and than reduced, at last it stayed relatively constant. Organic acids were not detected in aerobic reactor. Fluorescence spectroscope showed that organi matter was main protein-like fluorescence, the fluorescence intensity increased gradually in hydrolyze and acidification reactor. However, in aerobic reactor, fluorescence peak of DOM appeared fulic-like fluorescence, and the fluorescence intensity strengthened gradually.Ultraviolet spectrometer results showed that there is a absorption platform in 280nm in ultraviolet spectrum chart, along with the reacting time, it was a little increase arounding in hydrolysis process, but opposited in aerobic phase, both are not obvious. SUVA254 and E253/E203 increased respectively from 1.5 and 0.28 to 1.4 and 0.3 during the hydrolyze reaction, which suggested that aromatic and unsaturated compounds slightly increase and the stability of aromatic compounds weaken. It was declined, and easily degradable organic matter have been degraded rapidly in aerobic reactor.It was produced most organic acid and get a best effect in denitrification in the condition of recycling ratio with 1:3. The concentration of COD was significantly correlated with the concentration of organic acids, acetic acid and propanoic acid in hydrolyze and acidification reactor. A mass of organic matter and nitrogen in effluent were restrain removaling phosphorus, and it exists the competition mechanism of glycogen-accumulating organisms and phosphate-accumulating organisms, causing phosphate accumulating organisms can't grow greatly, then affected the phosphorous removal effect.