| Clogging of constructed wetland will happen when it operated longer time which resulted in reducing purifying capacity of wastewater.Litter decomposition was directly or indirectly influenced by animal.The effect of addition earthworms and loach to litter decomposition and reducing clogging of constructed wetland was researched in this thesis.The main results were shown as following:(1)Addition the earthworms and loach enhanced decomposition of cattails litter.Compared with the control(CK1),earthworms and loach decreased the dry weight of cattails leaves and root.Similarly,TN and TP content were increased;The organic carbon accumulation factor were decreased;Lignin content were decreased;(2)Earthworms and loach enhanced the enzyme activity of substrates.Compared with the average value of vertical flow constructed wetlands I and II,addition of earthworms in constructed wetland increased urease,sucrase and phosphatase activity of substrate by 12.72%,49.33%and 48.94%respectively.Similarly,loach increased urease,sucrase and phosphatase activity of substrates by were increased 80%,51.61%and 121.05%respectively.(3)Enzyme activity of substrate and litter decomposition would be inhibited flooding conditions.Compared with the up-flow pool in vertical flow constructed wetland I,urease,sucrase and phosphatase activity were increased by 62%,22.58%and 15.79%respectively.Similarly,the rest of the litter of leaf and root in down-flow pool were decreased by 56.67%and 40.72%respectively;TN were increased by 62.36%and 9.09%respectively.The accumulation coefficient of the organic carbon were decreased by26.74%and 3.91%respectively.The value of C/N and C/P were decreased.(4)Adjusting the water level and addition the loach enhanced decomposition of litter and increased content of carbon,nitrogen and phosphorus.Compared with the control(CK2),adjusting the water level increased TOC,TN,TP content by 59.24%,28.5%and 7.28%respectively.Loach activities increased the organic carbon,TN and TP content by 66.4%,75.45%and 13.44%respectively.(5)Loach reducing the clogging for wetland,and improved the purification capacity.Compared with the vertical flow wetland ii,loach increased the ratio of permeability coefficient by 5.75%;The average value of dissolved oxygen concentration were increased by 50.18%;The average efficiency of removal efficiency of TN were increased by 24.52%;The average efficiency of removal COD were increased by 2.3%. |
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