Diversity Of Purification Of Polluted River Water Using Different Kinds Of Surface-subsurface Constructed Wetlands

Since ancient times,the rise and decline of a city was always related to rivers.A healthy river enviroment can not only provide a healthy and comfortable living enviromenr for mankind,but also promote the development of urban economy.With the development of the city,the pollution of urban river is becoming more serious,drawing more attention to prevention and control of it.Compared with the traditional sewage treatment technology,constructed wetlands is more suitable for pollution management and ecological restoration of polluted rivers because it has large processing capacity,low cost,good purification efficiency and other advantages.Each form of constructed weland has it's own features and application conditions.When putting different forms of constructed wetland together in a series to form a hybrid constructed wetland,it leads to a more efficient and stable treatment technology,which can also make up the disadvantages of singal form of constructed weland.Nowadays,most of the studies are focused on the efficiency and mechanism of hybrid constructed wetland,and there are few researches pay close attention to the diversities of efficiency and influent factors of different kind of hybrid constructed wetlands.Therefore,a surface-horizontal subsurface flow hybrid construated wetland(FWS-HF CWs)and a surface-vertical subsurface flow hybrid construated wetland(FWS-VF CWs)were built,using the polluted river water form Zao River as inflow,to study the difference of purification effect on two kings of hybrid constructed wetlands,and analyse the impact and diversity of factors such as plant absorption,temperature and load in two kings of hybrid constructed wetlands,with a view to seeking a more suitable kind of hybrid constructed wetland used in the north.The results show that:(1)Each kind of hybird constructed wetlands in this article can efficiently putiffy organic matter and suspended solid.The average removal rates of BOD5,CODCr,SS in FWS-HF CWs and FWS-VF CWs were 96.61%-95.62%,85.21%-85.21%,98.11%-95.46%,respectively.The purification effect of these three kinds of contaminant in both kinds of hybrid constucted wetlands can not be affected by temperature,and the removel process of three contaminants are mainly took place in the first stage-FWS CWs.Meanwhile,FWS-HF CWs had a better purification effect than FWS-VF CWs in removel of BOD5 and SS.(2)Each kind of hybird constructed wetlands in this article can efficiently putiffy phosphorus.The average removal rates of TP in FWS-HF CWs and FWS-VF CWs were82.73%-79.35%,respectively.The purification effect in both kinds of hybrid constucted wetlands can not be affected by temperature,and the removel of TP was complished by either the first stage-FWS CWs or the second stage-HF/VF CWs.Meanwhile,FWS-HF CWs had a better purification effect than FWS-VF CWs in removel of TP.(3)The average removal rates of TN,NH3-N in FWS-HF CWs and FWS-VF CWs were 63.63%-55.83%,68.13%-54.79%,respectively.The purification effect of both two kinds of contaminant in both kinds of hybrid constucted wetlands were stongly affected by temperature,the removel rate is decline with the temperature falls,and the removel of both TN,NH3-N were complished by either the first stage-FWS CWs or the second stage-HF/VF CWs.Meanwhile,FWS-HF CWs had a better purification effect than FWS-VF CWs in removel of TN and NH3-N.(4)The first-order kinetics model can not simulate the removel of contaminants in hybrid constructed wetlands well.During the simulations of both kinds of hybrid construted wetlands,the simulations of removel of TN and NH3-N show the best correlation,while he simulations of removel of BOD5 show the worst.