Research On Test Of Nitrogen And Phosphor Removal From Sewage By Subsurface Flow Constructed Wetlands

Subsurface flow constructed wetlands(SSFW) has imponderable advantages in removal of nitrogen and phosphorus by contrast of traditional secondary treatment. However it was influenced by area obviously, the study on influence factors of nitrogen and phosphorus removal from sewage by SSEW in Jiangxi Province was seldom, for example, hydraulic loading rate, pollution loading rate, plants selection, seasonal variation etc, and there was no dynamic equation parameters can be referenced. Based on such factors as hydraulic loading rate, pollution loading rate, plants selection, seasonal variation influence, the experiment analysysed the effect of CODcr, NH3-N, TN and TP removal and effulent and established dynamic equation.The following results can be concluded:(1) Hydraulic loading rate was the important factor of CODcr, NH3-N, TN and TP removal and effulent,with the hydraulic loading decreasing, removal rate of pollutants increases and effluents improve. The removal rate and effluent is good when hydraulic loading is 166.7mm/d: the removal rates of CODcr, NH3-N, TN and TP can reach 95.99%, 37.24%, 56.09% and 76.00%; effluent quality of CODcr meets the case-Ⅳwaters of surface water quality(GB3838-2002)standard, effluent quality of NH3-N and TP meets the secondary class criteria specified in GB 18918-2002, effluent quality of TN meets the first class A criteria specified in GB 18918-2002.(2) Pollution loading rate was the important factor of CODcr, NH3-N, TN and TP removal and effulent, removal loading of CODcr, NH3-N, TN and TP increases with pollution loading increasing, and removal loading was linear with pollution loading. When pollution loading rate of CODcr is 2.8~26.3g/m2·d, NH3-N is 0.3g/m2·d, TN is 0.8~1.7g/m2·d, TP is 0.028g/m2·d, effluent quality of all constructed wetlands meets the first class A criteria specified in GB 18918-2002. When pollution loading rate of CODcr is 40.2g/m2·d, NH3-N is 0.8~2.2g/m2·d, TN is 2.4~4.8g/m2·d, TP is 0.169~0.882g/m2·d, effluent quality of NH3-N and TP meets the secondary class criteria specified in GB 18918-2002, effluent quality of CODcr, NH3-N, TN and TP meets the secondary class criteria specified in GB 18918-2002(3) Plant has great influence on removal rate and effulent. Removal rate for CODcr was 85.41%~95.99%, varied greatly with different plants, the ordes is Canna> Cyperus alternifolius>Zizania>Coix lacryma-jobi, effluent of Canna and Cyperus alternifolius wentlands meets the case-Ⅰwaters of surface water quality(GB3838-2002)standard, effluent of Zizania wentlands meets the case-Ⅲwaters, effluent of Coix lacryma-jobi meets the case- Ⅳwaters. When removal rate for NH3-N is 27.07%~37.24%, the orde is Canna >Zizania>Coix lacryma-jobi>Cyperus alternifolius, effluent of four wetlands meets the secondary class criteria specified in GB 18918-2002. When removal rate for TN is 44.89%~56.09%, the ordes is Canna >Cyperus alternifolius >Coix lacryma-jobi>Zizania, effluent of four wetlands meets the first class A criteria specified in GB 18918-2002. When removal rate for TP is 47.50%~76.00%, the orde is Zizania>Canna >Cyperus alternifolius >Coix lacryma-jobi, effluent of Zizania wetlands meets the first class B criteria specified in GB 18918-2002 and the other wetlands meets the secondary class criteria specified in GB 18918-2002.(4) Season hasd great influence on removal rate and effulent. Effluent in summer was better than in winner. There is good removal rate in winner in Jiangxi. When removal rate of CODcr reaches 91.79%, effulent meets the case-Ⅳwaters of surface water quality (GB3838-2002) standard. When removal rate of NH3-N reaches 44.90%, effulent meets the first class B criteria specified in GB 18918-2002. When removal rate of TN reaches 40.77%, effulent meets the first class A criteria specified in GB 18918-2002. When removal rate of TP reaches 49.50%, effulent meets the secondary class criteria specified in GB 18918-2002.(5) This experiment shows: First order kinetic equation can well simulate removal law of CODcr, NH3-N, TN and TP for domestic sewage in Jiangxi Province. It has a certain referent value for design of subsurface flow constructed wetlands in Jiangxi Province. Degradation constant k of CODcr, NH3-N, TN and TP in Canna wetlands is 0.3677, 0.1652, 0.1889, 0.2760. Degradation constant k of CODcr, NH3-N, TN and TP in Coix lacryma-jobi wetlands is 0.5172, 0.1227, 0.1637, 0.1833. Degradation constant k of CODcr, NH3-N, TN and TP in Zizania wetlands is 0.3994, 0.2236, 0.1227, 0.4479. Degradation constant k of CODcr, NH3-N, TN and TP in Cyperus alternifolius wetlands is 0.2748, 0.1724, 0.2657, 0.2172.The conclusion of positive research means that using subsurface flow constructed wetlands in Jiangxi can reach better effect for nitrogen and phosphorus. This research paper draws the law of hydraulic loading rate, pollution loading rate, plants selection, seasonal variation on nitrogen and phosphorus removal and the first order kinetic equation of nitrogen and phosphorus can be the basis of subsurface flow constructed wetlands in Jiangxi Province.