| The characteristics of low C / N generally exist in urban sewage of residents in China,which makes the sewage treatment plants face the problem of insufficient carbon source when treating urban sewage,resulting in the limitation of the ability of nitrogen and phosphorus removal of most sewage treatment plants in China.The integrated system used in this experiment is a combined process of flocculation adsorption process,hydrolysis acidification process and UCT（University of Capetown）process.Firstly,the domestic sewage completes the primary enhanced treatment through the adsorption of biological flocculation tank,stripping the macromolecular particles and colloids in the domestic sewage,and concentrating them for hydrolysis and acid production,the products of hydrolytic acidification can serve as supplementary carbon sources,after that,UCT process will further treat domestic sewage.The main research results are as follows:（1）The effect of the inside reflux ratio on the combined system’s nitrogen and phosphorus removal efficiency was explored.The results show that the inside reflux ratio has little effect on removing COD and ammonia nitrogen in the combined system.However,it has a specific effect on the removal of total nitrogen.The removal efficiency of total nitrogen generally increases with the increase of the inside reflux ratio.When r=200%,the removal rate of total nitrogen can reach 65.38%.The effect of different internal reflux ratios on phosphorus removal is indirect.When r=200%,the average value of total phosphorus concentration in the effluent is 0.52 mg/L,and the average removal rate of total phosphorus in raw sewage by the combined system is84.40%.（2）The effect of the external reflux ratio on the combined system’s nitrogen and phosphorus removal efficiency was studied.The experimental results show that with the continuous increase of external reflux ratio,the removal of COD and ammonia nitrogen is stably maintained at a high level.However,the efficiency of nitrogen removal is continuously improved.When r=80%,the average value of total nitrogen in the system’s effluent is 12.79 mg/L,and the average removal rate of total nitrogen is68.43%.At the same time,with the continuous increase of the external reflux ratio,the efficiency of phosphorus removal will gradually decline.When r=60%,the effect of phosphorus removal of the system is the best.The average value of total phosphorus in the effluent is 0.35 mg/L,and the average removal rate of phosphorus is 87.48%.（3）The pollutant removal effect of the combined system under the optimal conditions is studied.The average values of COD,ammonia nitrogen,total nitrogen,and total phosphorus in the influent are 217.77 mg/L,25.66 mg/L,39.38mg/L,and 3.45 mg/L respectively.The average values of COD,ammonia nitrogen,total nitrogen,and total phosphorus in the effluent of the combined system are 24.75 mg/L,0.47 mg/L,11.21 mg/L,and 0.46 mg/L,respectively.The average removal efficiency of COD,ammonia nitrogen,total nitrogen,and total phosphorus in the influent of the combined system is 88.63%,98.14%,71.53%,and 86.41%,respectively.The effect of sludge reduction in the combined system is explored.The apparent yield of sludge in the combined system is 0.21 g MLSS/g COD,and the efficiency is about 30% ～ 48%.（4）The effect of the dosage ratio of hydrolytic acidification solution on nitrogen and phosphorus removal in the combined system was explored.Three different dosing ratios of hydrolytic acidification liquid are set respectively:3.5 L/h hydrolytic acidification liquid is added to the anaerobic tank,and 1.5 L/h hydrolytic acidification liquid is added to the anoxic tank（condition 1）;Add 2.5 L/h hydrolytic acidification fluid（condition 2）to both anaerobic tank and anoxic tank;Add 3.5 L/h hydrolytic acidification liquid to the anoxic tank and 1.5 L/h hydrolytic acidification liquid to the anaerobic tank（condition 3）The results show that with the increase of the amount of carbon source added to the anoxic section,the performance of the combined system in nitrogen removal is improved as a whole.Under condition 3,the concentration of total nitrogen in the effluent is 10.50 mg/L,and the removal rate remains about 72.83%;With the decrease of the dosage in the anaerobic section,the performance of the combined system in phosphorus removal will decline.Under the working condition,the combined system has the best effect on removing total phosphorus.The total phosphorus concentration in the effluent is 0.32 mg/L,and the removal rate remains about 91.01%.Careful consideration,under condition 3,the combined system has the best nitrogen and phosphorus removal effect.Figure [34] table [4] reference [97]... |
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