| The effects of cationic polyacrylamide?CPAM?on the enhanced flocculation characteristics,and factors involving in separation efficiency such as temperature,pH and hydraulic conditions were studied by methods of UV-Vis spectrum.Influence of above pre-separation on downstream biological treatment about removing nitrogen and phosphorus was investigated.Results show that CPAM exhibited better efficiencies for particulates removal,and turbidity removal reached above 90%.It had a fairly good removal of organic matter,while it had poor removal efficiencies of nitrogen and phosphate,12%for TN and 15.86%for TP respectively when CPAM dose was 0.3mg·L-1.There was an optimum dosage of CPAM in the flocculation process.Significant improvement of organic removal was not observed with additional CPAM dosing beyond the optimum dose.CPAM could effectively remove organic with absorbance near UV250,which might enhance the biodegradability.Comparing to single biological treatment,preset enhanced flocculation showed remarkable improvement on denitrification and phosphate removal.The study of inorganic coagulant shows that PFS is the most effective to TN and DON.It was found that the best removal rate of TN?DON at pH=7.13,and the highest removal rate of TN?DON was 49.09%,56.62,respectively;Coagulation at low temperature will make the removal of TN?DON significantly worse.Fluorescence spectrum analysis found that coagulation has a significant removal of organic compounds in the ultraviolet region of fulvic acid.Compared with DOC coagulation,the removal effect of DON was more obvious.UV spectrum analysis showed that coagulation had obvious effect on removing amino acids in DON.Coagulation could reduce Ph/Pp value.The removal rate of humus is high,the sewage is easy to biodegrade,and the biodegradability of wastewater can be improved significantly,and the C/N ratio can be adjusted in the most suitable range,which is beneficial to the subsequent biological denitrification.PCFC is a composite polymer formed by hydrolysis of copper and ferric,and was characterized by removal efficiency and mechanism of nitrogen and organic matters during coagulation and biological treatment process in treating sanitary waste by PCFC were investigated compared to those by poly-ferric-chloride?PFC?.The results indicated that PCFC is similar coagulation performance with PFC:In 56mg·L-1,they gave the greatest turbidity and TP removal of 95%and 98%over the whole dosage range,respectively.The removal rate of COD was about 50%.TN,DON removal rate can reach 25%and 45%,respectively.When the dosage is 56mg·L-1,the copper ions are concentrated in the PCFC coagulation settling sediment,which can effectively inhibit microbial growth and slow down the release of organic matter.PCFC gave lower NH3-N and COD emission flux over the whole dosage range,respectively,in comparison with 1/6 and 1/4 by PAC.The residual Cu2+,in the dose range,promote the growth of nitrifier and shorten the aeration time,which is beneficial to biological nitrogen removal,and the effluent can meet the discharge standard. |
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