Experimental Study On Purification Of Aquatic Plants In Different Seasons

The ability to purify nitrogen and phosphorus of six kinds of aquatic plants were investigated in static water environment in summer and winter,including Pontederia cordata,Canna glauca,Iris pseudacorus,Ruellia brittoniana,Sagittaria trifolia,Thalia dealbata.We implemented a field pilot project in the winter to assess the effects of the selected aquatic plant on nitrogen and phosphorus purification and provide reference for the purification of nitrogen and phosphorus polluted water by aquatic plants.The summer hydrostatic test has run from July 2016 to October 2016,a total of 82 days.Six kinds of aquatic plants have a certain ability to purify nitrogen and phosphorus.Comprehensive comparison found that the purification effect of iris and canna is better than other aquatic plants,the removal rate of TN and TP by iris was 84.3%and 80.7%.The Fe/Al-P in the sediments decreased by 55 mg/kg.The winter hydrostatic test has run from November 2016 to February 2017,a total of 84 days.Compared to the summer,the ability to purify nitrogen and phosphorus of six kinds of aquatic plants in the stable period has decreased.Comprehensive comparison found that the purification effect of iris and thalia is better than other aquatic plants,the removal rate of TN?TP and NH3-N by iris was 63.6%?78.2%and 41.4%.The Fe/Al-P in the sediments decreased by 19 mg/kg.In addition,seedlings of six plants were planted in static water environment in winter,which the seedlings of iris and ruellia have grown in the winter and have better ability to adapt and better effect of purification.The removal rate of TN?TP and NH3-N by iris was 43.7%.43.7%and 35.5%,but the efficiency of Iris seedling was lower than that of iris in stable period.We built a field pilot project base of iris in the tributary of the DongYaxi River in Sanyuan District of Sanming City from November 2016 to March 2017,where the concentration of TP is 0.3mg/L-0.35mg/L;the concentration of TN is 0.7mg/L-2.7 mg/L;the water retention time is 1d;the water content of the test is 10 m3/d,and the plant density is 9 plants/m2.The results showed that the removal rate of TP reached 67%and the removal rate of TN reached 61%.And in the system the load removal rate of TP and TN is 17mg/(m2.d)?135mg/(m2.d),which is lower than the standard of ? class waterquality,reducing the nitrogen and phosphorus load effectively.In the hydrostatic simulation test and the pilot project,the iris showed a better effect of purifying nitrogen and phosphorus,which is suitable for promotion and application.According to the goal of water purification,We can match with thalia?ruellia and canna to improve the efficiency of removal.