Study On Adsorption Of Municipal Wastewater For Pollutants Removal Using Excess Sludge And Its Settling Characteristics

At present,most wastewater treatment plants have adopted the activated sludge process.In the technological system of activated sludge,the microorganism will degrade the organic pollutants,thus for purifying the wastewater.However,it has also led to a large quantity of excess activated sludge which will involve are result in high cost for treatment.Based on the adsorptive performance of the excess activated sludge,this paper will explore an adsorptive biological treatment technology to optimize the wastewater treatment process and then discuss.The influent water of the aeration tank in a Tianjin-based wastewater treatment plant will be chosen as the raw water for experiment.The recycled sludge has been used as the experimental sludge.At the temperature of 20 oC,different amounts of sludge have been added to the 1 L raw water.After going through the mixing for different period of time,it will be subject to the static settling for 20 minutes,thus and then separating sludge from water.The removal rates for the COD,SCOD,BOD5,turbidity,SS,NH4+-N,TN and TP in the water will be utilized as the evaluation criteria.The optimal dosage has been determined as 20 mL/L while the optimal mixing time is 20 minutes.Before the mixing of water and sludge,aeration regeneration in the activated sludge will be conducted to could improve its adsorptive performance of the activated sludge.However,it will the results varied with the seasons.According to the experimental result,the better regeneration effect can be achieved with dissolve oxygen(DO)at the concentration of 5 mg/L than 2mg/L in spring and summer,thus achieving the better efficiency of sludge absorption in the wastewater especially for the summer.In autumn and winter,the sludge will be regenerated with the different concentrations of DO.There is not an obvious difference in the removal rate of the pollutants in the wastewater.Hence,it is suggested that the concentration of 2 mg/L should be adopted to save the cost for aeration system.During the process of the sludge absorbing the pollutants in the wastewater,the cationic polyacrylamide(CPAM)and anionic polyacrylamide(APAM)can be added to improve the removal efficiency of the pollutants in the wastewater.Compared with APAM,CPAM can outperform the APAM has a better result,especially for the removal of the turbidity and suspended matter.With the cost and effect considered the cost and effect,the optimal scheme should be the addition of dosage for CPAM is 5 mg/L.