The Advanced Treatment Technology And Engineering Application To Terminal Wastewater Of The Sewage Station

As the development on economy and society of our country,the industrial wastewater emissions are increasing,which causing serious threat to water environment protection of our country.Therefore,reducing COD and ammonia concentration in wastewater is of great significance to environmental protection.In this paper,we used Fenton oxidation for advanced removal of COD in wastewater.We also adopt methods like magnesium ammonium phosphate(MAP)precipitation,fold point chloride and cyclic activated sludge system(CASS)for advanced treatment of ammonia nitrogen wastewater.(1)For a stream of wastewater treated by biochemical method which COD content is 610mg/L,we found the optimum technological conditions of Fenton reaction through the single factor experiment.When the dosage of H2O2 and FeSO4 is 0.05 wt%of the wastewater,pH of reaction system is 3 to 4,the reaction time is 2h,the COD of wastewater can be reduced to 200mg/L in a Fenton oxidation process.And the.COD removal rate reached 67.21%.(2)We got a simulative ammonia nitrogen wastewater by mixing ammonium chloride wastewater with three-acid wastewater in a ratio of 1:10,which concentration is 818 mg/L.And we found the optimal bleaching conditions of MAP through the single factor tests.When the ratio of magnesium and nitrogen to phosphorus is 1:1:1,the pH,temperature and time of reaction is 8.5,25? and 30min,the ammonia nitrogen removal rate of MAP method can reach 80%.(3)For low-concentration ammonia nitrogen wastewater which concentration is 101 mg/L and 88mg/L,the ammonia nitrogen removal and dosing proportion is approximately linearly related in a fold point chlorination treatment.And the reaction equilibrium can be achieved in 30min.In addition,the COD concentration will have a significant change only when the dosing ratio reaches more than 5‰ before and after the reaction.(4)In the advanced treatment experiments about ammonia nitrogen wastewater that using CASS method,for the first time,we saw the effects on ammonia nitrogen removal efficiency of related factors,by adjusting the dissolved oxygen,temperature and aeration time.The experimental results showed that,?when the DO>7mg/L,T<31?,aeration time>ld,ammonia nitrogen removal rate can reach 100%.?Even if the DO=0.96mg/L,when the aeration time=48h,the removal rate can also reach 100%.So we can enhance aeration effect of aerobic and CASS pond by extending aeration time and appropriately increasing the DO content,and achieving the goal of improving ammonia nitrogen removal rate.(5)In engineering applications,1)The Fenton oxidation method was applied to biochemical treatment to reduce COD and improve the biodegradability of wastewater.The total water inflow of Fenton process was 5599 t/d.The COD of water inflow was 565 mg/L.The COD content in average daily water inflow was 3.16t.The pH of Fenton pool water inflow was adjusted to 3.0-4.0 by adding acid.The dosage of H2O2 and FeSO4 was respectively 0.04 wt%and 0.05 wt%of the average daily total water inflow.The COD of water outflow was 308 mg/L,and the average COD removal rate was 44.45%.2)The MAP method was applied to the removal of ammonia nitrogen with high concentration in fermentation plant wastewater.Average process parameters in the practical processing were as follows.The inflow of fermentation plant wastewater was 400t/d.The concentration of Mg2+,NH4+ and PO43-was respectively 1050,1102 and 4236mg/L.The complement addition amount of Na2HPO4 was 150 kg/d.The concentration of NH4+-N in water outflow was 258mg/L and ammonia nitrogen removal rate was 76.59%.The effluent will be mixed with the remaining wastewater of high concentration,and the residual ammonia nitrogen will be further processed in the subsequent process.3)The method of fold point chlorination was applied to the removal of ammonia nitrogen,which in water outflow of sewage station's radial sedimentation tank(total discharge)in that exceeding environmental standards.The mean process parameters of the actual process in the early part of a month were as follows.The total water outflow was 220m3/h.The average concentration of ammonia was 85mg/L and the environmental standard was 35mg/L.The dosage of sodium hypochlorite was 860.9L/h.4)The aerobic and CASS pool improved the removal efficiency of ammonia nitrogen in water inflow by changing the conditions like dissolved oxygen(DO)and aeration time.The process parameters of the actual operation of aerobic pool were as follows.When the concentration of ammonia nitrogen in water inlet was 123mg/L,the aeration time equaled to 28h and the concentration of dissolved oxygen was 6.88 mg/L,the removal rate of ammonia nitrogen can reach 100%.The process parameters of the actual operation of CASS pond were as follows.When the concentration of ammonia nitrogen in water inlet was 85mg/L,the aeration time equaled to 6h and the concentration of dissolved oxygen was 6.56 mg/L,the removal rate of ammonia nitrogen was 100%.