Study On The Application Of Slaked Lime In Chemical Crystallization Circulation Granulation Fluidized Bed For Softening And Phosphorus Removal

In this paper,a static beaker and a pilot test study the effect of hydrated lime in the chemical crystallization cycle granulation fluidized bed on the softening and phosphorus removal of groundwater and an industrial wastewater.The main conclusions are:(1)Use static experiments to study the softening effect of hydrated lime slurry and provide data support for pilot experiments.The results show that: 20% mass concentration of hydrated lime slurry has the best dispersibility and reaction efficiency in water,and the maximum removal rate of calcium hard is 77.50%;the comprehensive removal effect is the best when stirring for 2.5min and rotating speed350r/min;calcium after suction filtration The removal rate of hard and bicarbonate alkalinity can reach 86.25% and 100%,and the turbidity is as low as 0.6NTU;slaked lime has obvious advantages over sodium hydroxide in reducing water conductivity.(2)Use chemical crystallization circulation granulation fluidized bed system to study the crystallization softening effect of slaked lime.For the groundwater in Guodu Town,20% mass concentration of hydrated lime slurry has the highest reagent utilization rate in the system,and the highest calcium ion removal rate is 60.82%.Reducing the flow rate can increase the calcium ion removal rate,and the effluent conductivity is the lowest at 60m/h;The series fluidized bed can reduce the turbidity of the effluent under certain conditions;after increasing the bicarbonate alkalinity of the raw water by three times,the maximum removal rate of calcium hard reaches 73.2%.When sodium hydroxide is used as a mixed agent in different proportions,when the dosage is 300mg/L,the calcium removal rate is as high as 82.43%;the maximum removal rate after PAM 2mg/L is added to the effluent is 89.42%,and the total hard removal is 77.1%;PAC cannot Significantly improve the coagulation effect of the slaked lime slurry in the treatment of raw water,and when PAC40mg/L is added,the mixed agent method has a certain hardness removal effect;with slaked lime: flake caustic=1:1+PAM1mg/L+PAC40mg/L this The method of chemical dosing can maximize the quality of Guodu groundwater,and the removal rate of calcium,magnesium,and total hardness can reach more than 96%.Regarding the cost of medicament,there are different optimal dosing methods under different hardness removal rates.At 90% removal rate,the cheapest method is slaked lime plus PAM.The cost of medicament per ton of water is 0.37 yuan;the mixed medicament method can be less than the pure slaked lime method.The amount of mud produced is 56-66%,and the heterogeneous nucleation crystallization rate is greatly increased.For the mixed wastewater of a power plant,a fluidized bed softening pilot experiment was carried out with slaked lime 1600mg/L,flake soda 800mg/L,and sodium carbonate 300mg/L.The bicarbonate alkalinity in the effluent was 100%removed,and the calcium hard removal rate was 98.11%.The removal rate of magnesium hard is 98.39%,which meets the requirement of the plant’s effluent limit.(3)Using 20% mass concentration of slaked lime slurry to treat raw water with different phosphorus concentrations under different dosages,the average removal rate of phosphate in the effluent can be more than 95%;the mixed agent method can further reduce the dosage and reach or close to 100% Removal;adding PAM helps to improve the removal effect of calcium and total phosphorus.When the phosphorus is basically removed,the removal rate of calcium hard can reach 75.9%,and the removal rate of total hard can reach up to 70%;Calcium phosphate and calcium pyrophosphate.