Phosphorus Removal Performance Of Modified Constructed Wetland Filler For Rural Dispersed Sewage

With the improvement of rural residents' requirements for the quality of life,the amount of water used in rural areas is also increasing,and the amount of sewage is also increasing.Due to the imperfect treatment system in rural areas and the backwardness of economy and talent management relative to cities,this study chose an artificial wetland system with low simulation cost,simple operation,and long operating life to treat decentralized rural sewage.In this paper,three kinds of fillers with low price,wide source and good adsorption performance are selected from limestone,zeolite and fly ash ceramsite.For the problems of too little adsorption capacity and low phosphorus removal efficiency,we choose appropriate Method to modify it to obtain a modified filler with better phosphorus removal effect.It is expected that the wetland phosphorus removal system will be more widely used in rural decentralized sewage treatment projects.In this experiment,chemical reagents such as sodium hydroxide,hydrochloric acid,ferric chloride,polyaluminum chloride,and calcium chloride were used for single modification and combination modification to obtain the best combination modification scheme for a single filler.Subsequently,the effects of various factors on the phosphorus removal effect of the mixed filler layers with different arrangement sequences and different proportions of the three fillers were further studied.The effects of the temperature of the mixed packing layer in the adsorption column,the initial concentration of phosphorus,and the flow velocity of the water on the adsorption and removal of phosphorus in the dynamic experiment were investigated.In this experiment,the adsorption characteristics of combined modified mixed fillers were studied using adsorption kinetics and adsorption isotherms.And the SEM characterization method was used to explore the structural characteristics of the modified filler.The specific conclusions are as follows:(1)In the beginning of this experiment,the effects of the reaction time of a single filler,the p H of the solution,the particle size of the adsorbent,and the amount of dosing on the adsorption effect were studied.Under the condition that the initial phosphorus concentration of the phosphorus-containing wastewater is 10 mg / L and the ambient temperature is 25 ° C,the phosphorus removal rates of the modified limestone,modified zeolite,and modified fly ash ceramsite are increased by 46.04% and 24.06% and 73.03% respectively compared with those before the modification.(2)SEM scanning electron microscopy showed that acid and alkali can widen the inner corridor of the filler,aluminum salt can change the crystal structure of the filler,and the modified filler has larger pores,more attachments,and better adsorption of phosphate.(3)The dynamic experimental results of the combined fillers show that at an ambient temperature of 25?,an inlet water flow rate of 4 m L / min,and an initial phosphorus concentration of 10 mg / L,the volume ratio of fly ash ceramic particles: limestone: zeolite = 2: 1: 3: The ratio combination method has the best removal effect of phosphorus in sewage.At this time,the phosphorus removal rate is 80.02%.The arrangement order of the matrix has almost no effect on the phosphorus removal effect in the wastewater,which can be ignored.(4)The quasi-first-order adsorption kinetics and quasi-second-order adsorption kinetics simulations of the best combination method in(3)were performed,and the correlation coefficients were all above 0.9,which corresponded to the quasi-first-order and quasi-second-order adsorption kinetics.