BOD5之去除率於鹽水入侵後，2％鹽度系統即大幅下降，僅為對照組之24.6％，至於B、C系統亦會下降，惟期過程較為緩慢，約5~7週可降至最低，其後BOD5去除率可漸與對照組相仿。至於其反應速率常數K20則顯示皆有下降趨勢。另者，就氨氮與硝酸鹽氮之去除率並未明顯受鹽度影響，僅發現於SSF單元之K20隨鹽度增加而降低。至於含磷污染物之降解並未受溫度變化之影響，僅受鹽度影響而導致去除率下降。 This research mainly investigated the degradation characteristics of the tidal freshwater constructed wetland. In order to understand the change of degradation efficacy in different conditions of salinity, this research was operated by the artificial wetland systems of 0.5%、1.0% and 2.0% in salinity at the same time and has a control system of fresh water. Every group system included a surface-flow wetland and a subsurface-flow wetland which planted separately of the cattail and reed. The types of pollutant in this research are mainly dissolvent pollutants of organics、nitrogen and phosphorus.
In order to precisely understand the characteristic of the whole constructed wetland, each system carries on a hydraulic characteristics test before starting. The results show that the difference in temperature of in flows causes the FWS unit presented a completely mixed state, and the effective volume ratio is up to 0.99. The constructed wetland that had been operated for 8 months represented the rise in the density of plant and could cause effective volume ratio dropped to 0.56~0.66. The characteristic of completely mixed state reduced. After the systematic characteristic of every artificial wetland was steady in this research；The inflow sewage was spiked with sodium chloride to simulate the saline environment. On the system, of 2% salinity the cattail had withered within two weeks, thereafter the reed also showed a similar phenomenon. But, the response of the other salt systems was comparatively gentle and less in quantity in death of plant. Through analyzing the content of C , N , H , S , Cl of these deathful plant, it was found that the sulphur and the chlorine of the root increased largely, and then caused the death of the plant.
The rate of degradation of BOD5 in the system of 2.0% salinity became decreased largely after beening invaded by the salt water. It was only 24.6% of the control group. Also drop as for B and C system, only the course was comparatively slow. It dropped to the lowest about 5-7 weeks. Thereafter the degradation rate became the control group. It shows that all there is a downward trend as for its K20. In addition, the degradation rate of the ammonia nitrogen and nitrate had not been obviously influenced by salinity the K20 of SSF unit increased as the salinity reduced. The degradation of pollutant contained the phosphorus had not influenced by temperature change. It only leaded the degradation rate dropped by salinity effect.