Experimental Research On Simultaneous Removal Of Turbidity And Organic Matter In Reservoir Water By Circulating Granulation Fluidized Bed

In recent years,the source water of our country was polluted largly due to the rapid development of the domestic economy,and had a tendency to deteriorate with high turbidity and high organic matter.The safety of drinking water directly affects human health.Therefore,the improvement of water quality of source water has been a research hotspot in recent years.The circulating granulation fluidized bed,as a new type,but effective technology for separating solids from liquids,was the characteristic of a high load of treatment and a strong adaptability to different water qualities.The micro-sand synergistic circulating granulation fluidized bed is used in conjunction with PAC.And the removal effect of the turbidity and organic matter in micro-polluted reservoir water was explored.Three-dimensional fluorescence?EEM?analysis,molecular weight distribution analysis,pore structure analysis and surface morphology?SEM?analysis were used to study the mechanism of organic matter removal.When the reservoir water in Xi'an was taking as the object of treatment,the results of optimizing the parameters of the circulating granulation fluidized bed was indicated that PACl,12 million APAM,and 300-mesh+charcoal were the best choices for the agent;when PAC1 and PAC were added simultaneously,the treatment effect of the water was the best.The experimental results of micro-sand synergistic circulating granulation fluidized bed were showed that 80-120 mesh and 120-160 mesh micro-sand were the best choice,and the maximum ascending velocity was 120 cm/min,and the minimum dosages of PACl and PAM were 10 mg/L,0.7 mg/L;the best stirring speed was 6?9 r/min.The experimental results of powder activated carbon enhanced circulating granulation fluidized bed were showed that the optimal dosages of PACl,PAM and PAC were 24 mg/L,1.2 mg/L and 30 mg/L when operated with 70-140 mesh micro-sand.At this time,the turbidity,UV₂₅₄,COD_Mn,and DOC were removed 96.45%,72.0%,71.66%and 60.97%,respectively;the optimal ascending velocity was 90cm/min.There was a phenomenon that the particle size of the agglomeration group was decreased gradually from bottom to top in the circulating granulation fluidized bed.The intermittent addition of PAC in the fluidized bed was showed beneficial to the removal of organic matter and the stable operation of circulation granulation fluidized bed.Through the three-dimensional fluorescence analysis of organic matters during the water inflow and outflow,it was noticed that,in this fluidized bed system and under the effect of coagulation and granulation,the FI of fulvic acid and humic acid during water outflow were lowered by 40.1%and 43.0%as against the water inflow,after PAC was put in of 30 mg/L,the FI of fulvic acid and humic acid during water outflow were lowered by 54.0%and 55.3%as against the water inflow.The molecular weight of the organic matters in the water of reservoirs lay chiefly between<1kDa and 10-30kDa.In the circulating granulation fluidized bed system,the effect of coagulation and granulation was intended to remove the large molecular weight organic matters,and the organic matters of<1kDa could be removed comparatively better due to the adsorption by adding PAC.The adsorption isotherm of agglomeration group particles in the fluidized bed of powdered carbon enhanced circulating granulation was closed to the type IV isotherm,and the hysteresis ring type was H3 type.The agglomeration group particles were contained a large number of pores with a pore size of 3.0?4.5 nm,and the pore size span was larger than the ordinary sludge.The surface of agglomeration group particles was showed a sheet-like structure similar to bentonite formed by micro-sand synergism,a clear pore structure was formed after PAC was added.