| In recent years, sudden arsenic pollution in surface water occurs frequently, and it has become one of the major social problems in the world. Currently, adsorption and precipitation are the common technologies for the treatment of sudden arsenic pollution. The precipitation could reduce the arsenic level from the contaminated water, but the formation of arsenic sediment would cause the secondary pollution to the environment and affect the quality of the overlying water. Compared to precipitation, adsorption can remove the arsenic from the contaminated water without any secondary pollution. Adsorption has great potential in the practical application for the emergency removal of arsenic.For the hydraulic characteristics of sudden arsenic pollution in lakes and reservoir-type water, activated alumina was selected as the adsorbent for the pilot experiments by the mobile adsorption equipment. The pilot experiments investigated the effect of operating parameters on the arsenic removal, and on this basis, the process run mathematical model for the arsenic emergency treatment in Lake and reservoir-type water is constructed. This study can provide some guidance when the mobile adsorption is used to removal the arsenic in the practical application.Two parts were involved in the study:①The effect of adsorption bag length (L), floating velocity (u), initial As (V) concentration (Co) and adsorbent dosage (M) on the arsenic removal were investigated.②ANSYS CFX—a Computational Fluid Dynamics (CFD) software was applied to simulate the fluid field characteristics in the mobile adsorption equipment under the total test conditions. The correlation between the residual arsenic concentration and the various operating parameters was analyzed by dimensional analysis. The process run mathematical model for the arsenic emergency treatment in Lake and reservoir-type water is constructed to get the semi-theoretical semi-empirical formula of the arsenic removal between the residual arsenic concentration and the effecting factors. The main findings of the study are as follows: (1) Two adsorption bag lengths (L=35cm,61.25cm) are selected to investigate the influence of adsorption bag length on arsenic removal. The results showed that higher arsenic removal efficiency is found with greater adsorption bag length.(2) The adsorption rate and removal efficiency of As (V) are both increased with the rising floating velocity (u=0.03,0.045and0.06m/s).(3) The adsorption rate of As (V) is increased with higher initial As (V) concentration (Co=0.1,0.5and1.0mg/L).(4) Under the following operating conditions, the residual arsenic concentration can be less than0.05mg/L after120h:①Co=0.1mg/L, υ≥0.03m/s;②Co=0.5mg/L, L=61.25cm, M=12kg, υ≥0.045m/s。(5) The formula between the residual As (V) concentration and various factors is(6) Under various operating conditions, the maximum velocity locates at the adsorption bag and its vicinity. On the water surface, the maximum velocity occurs on the opposite side wall, and the direction is opposite to the floating velocity.(7) The fluid field velocity at the same location point increases with the increased absorption bag length and floating velocity. |
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