Research On The Phosphate Removal Performance Of Runoff Water Used By Modified Demolition Grated Wasted Red Bricks

The rapid development of urbanization makes the non-point source pollution become more and more serious,which aggravates the eutrophication of water body and causes the black and smelly water body in the city.At the same time,a large number of construction demolition wastes are produced in the process of urbanization,which leads to serious environmental problems.This research through the study of the modification of grated wasted red bricks,select the appropriate modification methods,effect of phosphorus adsorption,adsorption isotherm simulation and dynamics simulation combining with the experiments of phosphorus removal mechanism of the adsorption mechanism,using a small device for dynamic adsorption experiment simulated the actual application.Its main conclusions are as follows:(1)The bricks with the size of 0.5-1mm were modified with three metal salt solutions of Fe,Al and Fe-Al,respectively.The results showed that Fe-Al modified bricks had the best effect.By comparing the single Fe-Al modified brick with Fe-Al modified brick,the brick had better adsorption effect at lower phosphorus concentration and higher phosphorus concentration.The optimum conditions for Fe-Al modification were: 1mol/L iron salt solution,0.75mol/L aluminum salt solution,1:3 solid-liquid ratio and 180 min modification time.The phosphorus adsorption experiment results showed that in the simulated rain water,the optimal dosage was 6g/L,and the adsorption equilibrium was reached after 20 h.The adsorption amount of each modified red brick increased with the increase of the initial concentration.pH has little effect on the adsorption of phosphorus and has a certain acid impact resistance.(2)Both the Langmuir isothermal equation and the Freundlich isothermal equation could simulate the experimental process,in which the Langmuir fitting parameters were above 0.9,and the theoretical maximum adsorption capacity of Fe-Al modified red brick was 98.43mg/g.The fitting effect of the second-order kinetic model is better than that of the first-order kinetic model,and the fitting parameters are above 0.94,indicating that the modified red brick particles are mainly affected by the chemical adsorption in the reaction kinetic process.The fitting effect of the liquid film diffusion model is better than that of theparticle internal diffusion model,and the fitting parameters are above 0.85,indicating that the process of phosphorus removal by ion diffusion is dominated by the diffusion at the solid-liquid interface,and the adsorption rate is mainly controlled by the membrane diffusion process.Elovich equation simulation found that the activation energy in the adsorption process changed greatly,and there were some multi-interface reaction processes.(3)The grade-by-stage extraction and desorption of the original red brick and the three modified bricks showed that,after modification,the physical adsorption capacity was improved to a certain extent,but the desorption rate was lower than 2%.In the process of phosphorus adsorption,the reversible surface adsorption proportion was very low,and the main adsorption process was chemical adsorption.Fe-Al modified red bricks were used as the filler to carry out practical application experiments in a small device.The data showed that Fe-Al modified red bricks had a good phosphorus removal effect as the filler,and the optimal height of the filler was 10 cm.After Fe-Al modified red bricks were added to the soil,the phosphorus removal effect of the device was improved,and the effect of drought interval was reduced.