Study On Ferric Enzymatic Activated Sludge For Biological Nitrogen&Phosphorus Removal

From1960’s, Water Eutrophication has focused by people all over the world,controling and treating nitrogen and phosphorus pollution is the essential way to cureit.While the present state of the nitrogen and phosphorus pollution was more andmore serious, research on the municipal wastewater treating technology for furthernitrogen and phosphorus removal was becoming urgent and essential. The paper wasemphasized on composite activated sludge in improving the usual nitrogen andphosphorus removal technology. Experiments and researches wer carried out onprocessing of town sewage by the composite ferric enzymatic activity sludge. At thesame time, the paper analyse the principle of ferric enzymatic activated sludgebiological nitrogen and phosphorus removal from the view points of the macroperspective, microbial activity and community metabolism to reveal its reactionmechanism of biological nitrogen and phosphorus removal, and compare the effect ofdifferent external carbon source.The results showed that:（1） the composite ferric activity sludge had the betterability to remove N, P and organic matter than the traditional activated sludge. Whentemperature is under12℃, the ammonia nitrogen, phosphate and organic materialremoval rate of the composite ferric activity sludge is higher than that of traditionalbiological nitrogen and phosphorus removal system, and the improve rate is19.1%、16.8%and12.6%respectively; Under the low-and-medium temperature （12²0℃）,its were increased by5.4%,9.9%and2.3%; Under the moderate temperature （20²5℃）, its were increased by3.5%,4.8%and5.8%.（2） Under different temperatureconditions, the nitrification ability of the composite ferric activity sludge is better thanthat of traditional biological nitrogen and phosphorus removal system, and thetemperature is lower, the difference is more obvious, especially in the lowtemperature （12℃）, the nitrification ability is2.0mgNH3-N/gMLSS·h, which is66%higher than that of traditional system, this conclusion plays an important role insolving low temperature nitrification.（3） Microbial activity of the composite ferricactivity sludge was substantially increased, formed large and dense floc structure, microbes were more abundant and bacteria types increased, there were not onlybrevibacterium and coccus, but also emerged few vibrios in the sludge. Compared tothe traditional activity sludge, the INT-ETS activity and TTC-ETS activity of thecomposite ferric activity sludge is higher, at the same time, the activity is higher, theeffect is better.（4） The composite ferric activity sludge makes better use of carbonsource than that of the traditional activity sludge. denitrification test research showsthat sodium acetate effectively time is45minutes, while the effect time of themethanol is30minutes; When dosing acetic acid sodium for external source ofcarbon, the denitrifying rate of the composite ferric activity sludge is2.96mgNO₃--N·g^-1VSS·h^-1, while the denitrifying rate of the composite ferric activity sludgeis1.98mg NO₃--N·g^-1VSS·h^-1, which is49.5%lower than that of composite ferricactivity sludge. When dosing methanol for external source of carbon, the denitrifyingrate of the composite ferric activity sludge is2.47mg NO₃--N·g^-1VSS·h^-1, while thedenitrifying rate of the composite ferric activity sludge is1.94mg NO₃--N·g^-1VSS·h^-1,which is27.3%lower than that of composite ferric activity sludge.（5） Dosingexogenous carbon sources, because of the improvement of microbial activity, thesecond stage denitrifying rate is also increased. When dosing acetic acid sodium forexternal source of carbon, this stage thedenitrifying rate of the composite ferricactivity sludge is1.03mg NO₃--N·g^-1VSS·h^-1, while the denitrifying rate of thecomposite ferric activity sludge is0.97mg NO₃--N·g^-1VSS·h^-1, which is6.2%lowerthan that of composite ferric activity sludge. When dosing methanol for externalsource of carbon, this stage the denitrifying rate of the composite ferric activity sludgeis1.02mg NO₃--N·g^-1VSS·h^-1, while the denitrifying rate of the composite ferricactivity sludge is0.85mg NO₃--N·g^-1VSS·h^-1, which is20.0%lower than that ofcomposite ferric activity sludge.