Experimental Research On Removal Of Typical Pollutants In Urban Sewage And Third Section Of Railway Wastewater By Coagulation And Sedimentation

Coagulation and sedimentation technology is widely used in urban domestic sewage,printing and dyeing wastewater,oily wastewater,landfill leachate and other fields due to its low technical difficulty and low investment and operating costs.As a commonly used sewage treatment process,traditional coagulants exist The problems of large dosage,poor adaptability to water quality,poor coagulation effect,and large amount of remaining sludge have always restricted the coagulation and sedimentation technology in practical engineering applications.The new coagulant has factors such as difficulty in research and development technology and high price.Become the bottleneck of the development of coagulation and sedimentation technology.Based on the actual situation,this article selects the relatively cheap traditional coagulant and new coagulant as the research object,starting from the idea of compounding coagulant to enhance the treatment effect,the actual urban domestic sewage and the third-stage wastewater of the railway are carried out Research,main research content and results are as follows:1.The study of the dosage of coagulant on the removal of pollutants shows that:?1?When FeCl3 is administered alone,the dosage should be controlled at 60mg/L?90mg/L,and the average removal rates of COD,SS,TP,TN are close to 40%,81%,48%,24%,the removal rate of COD and TP reaches the maximum when the dosage of FeCl₃ is 100mg/L,which is 45.11%and 60%respectively;?2?The best dosage when Al₂?SO₄?₃ is added alone is80mg/L,the removal rates of COD,SS,TP,and TN are 38.20%,88.20%,32.10%,and 28%respectively;?3?The optimal dosage when PAC is added alone is 80mg/L,and the removal of COD,SS,TP,and TN The rates are 64.20%,90.11%,62.10%,27.10%;?4?The dosage required when PAM is administered alone is greatly reduced,the optimal dosage is 1.5mg/L,and the removal rates of COD,SS,TP,TN are:30%,84.2%,28.10%,22.2%;?5?Comparison found that when the coagulant is added alone,the removal effect of the pollutants and the saved dosage are:PAM>FeCl₃>Al₂?SO₄?₃.2.The study of PAM and other coagulation compound treatment of domestic sewage shows that:?1?The best dosage of PAM+FeCl₃ compound coagulant is PAM:1.6mg/L,FeCl3:50mg/L,for SS,COD,TP,TN The removal rate reached 99.21%,69.54%,63.58%,45.26%respectively;?2?PAM+Al₂?SO₄?₃ compound coagulant best dosage is PAM:2.0mg/L,Al2?SO4?3:60mg/L,The removal rate of SS,COD,TP,TN reached 97.55%,69.88%,63.34%,41.88%respectively;?3?The best dosage of PAM+PAC compound coagulant is PAM:1.2mg/L,PAC:70mg/L,the removal rates of SS,COD,TP,and TN reached 99.51%,72.56%,68.87%,and 47.53%,respectively;?4?Comparing the various coagulants,the removal effect of each pollution index in actual domestic sewage and The saved dosage is:PAM+PAC>PAM+FeCl₃>PAM+Al₂?SO₄?₃.3.The study of PH conditions on the treatment of sewage with compound coagulant shows that:?1?PAM+Fe Cl₃ compound has a certain tolerance to the acidity of the influent,and the PH value is between 5 and 7,which has a good effect on the removal of pollutants.The optimal PH value of the compound should be slightly less than 7,which is slightly acidic;?2?The optimal PH value of the PAM+Al₂?SO₄?₃ compound is greater than 7,which is slightly alkaline,and the application range of the PH value of the influent is narrow.Under acidic conditions,the The removal effect of pollutants is poor;?3?The optimal PH value of PAM+PAC compound is slightly more than 7,which is slightly alkaline.The compound coagulant has a wide range of PH value for influent water,and the PH value is between 5-9.The pollutants can achieve a very good treatment effect;?4?The scope of application of each compound coagulant to the PH value of influent water is:PAM+PAC>PAM+FeCl3>PAM+Al₂?SO₄?₃.4.The use of PAC–PAM coagulant to treat actual railway construction wastewater shows that:PAC–PAM coagulant has a good removal effect on the main pollutants in the wastewater,When the optimal dosage of PAC-PAM coagulant is 40mg/L,the remaining SS,oil and COD are 68.55mg/L,3.42mg/L,75.61mg/L,which can reach one of China's Comprehensive Wastewater Discharge Standards Standard?GB 8978–1996?5.Using different PAC:PAM mass ratios to actual railway oily wastewater treatment results shows that the best ratio is when the PAM:PAC mass ratio is 1:130,and the removal rates of SS,grease,and COD in sewage reach 95.28%,respectively,74.69%,74.15%,which can reach the first-level standard?GB 8978–1996?in China's Comprehensive Wastewater Discharge Standard.