| The main ways of phosphorus removal in constructed wetland systems are direct absorption and assimilation of plant growth,adsorption of phosphorus by substrates,and metabolic transformation of microorganisms.This paper mainly compares the phosphorus removal performance of the chemical modification matrix and the enhanced biological phosphorus removal treatment and the stability of the system during operation,and makes a brief technical and economic evaluation of the two treatment processes,with a view to providing a new type of artificial wetland reference.(1)In order to obtain high performance new fillers,natural zeolites were thermally modified by Na Cl+Fe Cl3.Changes in physicochemical properties before and after modification were investigated,and the phosphorus removal ability and mechanism of phosphorus removal were compared and analyzed.The experimental results show that the modified natural zeolite surface is more rough,and the Fe content and the total amount of water-soluble salts are increased to a certain extent,with a higher potential for phosphorus removal;combined with isothermal adsorption experiments,adsorption kinetics and thermodynamic test results It can be seen that the saturated adsorption capacity of the filler on phosphorus has been significantly improved compared with that before the modification,and the adsorption method is mainly based on chemical adsorption;in the dynamic adsorption test,the system has been operating stably for 120 days,and the modified zeolite has changed the retention of phosphorus.The value of 0.045 mg·g-1 before sex increased to 3.469 mg·g-1,and the main phosphorus retained was mainly Fe-P.(2)Considering the high cost of modification,an attempt was made to construct a bio-pumped constructed wetland to study the biological phosphorus removal efficiency of the system and the stability of the bio-pumping stage.Set the system water intake into two tidal flows.The experimental results are as follows: The tidal currents of the two influent waters are conducive to the enrichment of PAOs,which promotes the action of microorganisms as the main way for the removal of phosphorus in the wetland system.The contribution rate of the microorganisms to the phosphorus removal in the enhanced phosphorus storage phase is as high as 96.04%;The phosphorus removal operation of the carbon source of the supplementary carbon source not only avoided the excessive accumulation of phosphorus in the system,but also promoted the utilization of the carbon source to 98.22%.TFCW has been operating steadily and efficiently for 90 cycles throughout the test cycle.(3)In order to explore the effect of organic carbon source replenishment on the system performance during the phosphorus removal operation,three sets of tests were conducted using the TFCW as the test device.The optimization of organic carbon source supplementation increased the abundance and activity of PAOs,induced sufficient release of phosphorus from PAOs,and increased the synthesis of intracellular PHB.During the period of typical biological phosphorus storage/phosphorus removal,the phosphorus removal rate of the system reached(91.4±2.1)% in the process of biological phosphorus storage,and the phosphorus release of PAOs was(1563.72±127.84)mg during the system phosphorus removal operation.The synthesis amount of intracellular PHB was(4.52±0.39)mmol-C·g-1·VSS-1,and the utilization rate of supplemental carbon source was(97.3±1.6)%.Based on the above findings,the effect of the two enhanced treatment methods on phosphorus removal is very good,but each has its own advantages in practical applications.From the aspect of applicability,the applicable range of the modified matrix in the constructed wetland is wider,and the difficulty in operation and management is also lower;but in terms of the stability of the operation,the bio-powdered constructed wetland is discharged through the periodical enrichment of phosphorus.The sludge avoids blockage in the wetlands and ensures long-term efficient operation of the system. |
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