Experimental Study On Purification Of Nanhai Wetland By Artificial Floating Island Technology

In order to solve the problem of nutrient enrichment of nitrogen and phosphorus in the South China Sea wetland and improve the water quality of the South China Sea wetland,from July 2018 to September 2018,a artificial floating island consisting of three kinds of aquatic plants,either alone or in combination,was constructed in the wetland.And tracking and monitoring the water quality of the floating island.Observe and test the changes of TN,TP and COD_crr in 7 groups of floating islands at any time,plant growth and water transparency.The results are as follows:After 92 days of trial treatment,the plants grew well,and the three plants grew slowly in the early stage of the experiment.After the plants were adapted to the water,the three plants began to grow rapidly.Finally,the Cyperus alternifolius L has the best removal effect on TN,the removal rate is 34.9%,which can increase the TN concentration in the water to the surface water V standard;the Cyperus alternifolius L+Scirpus validus Vahl+Lythrum salicariato L has the best removal effect on TP,the removal rate For 41.6%,the TP concentration in the water can be raised from the surface water V standard to the IV standard;the best for COD_crr removal is the Cyperus alternifolius L+Scirpus validus Vahl+Lythrum salicariato L,the removal rate is 28.3%.The Cyperus alternifolius L with the best inhibitory effect on planktonic algae can effectively inhibit the filamentous algae.Mixed plant artificial floating islands have better effects on removing nitrogen,phosphorus and other organic matter than single artificial floating islands..Single plant floating islands and mixed plant floating islands can increase the transparency of water bodies.From the perspective of plant production status,the ability of plants to absorb organic matter such as nitrogen and phosphorus,and the inhibition of planktonic algae,Cyperus alternifolius L,Scirpus validus Vahl and Lythrum salicariato L can be used as floating island cultivated plants for eutrophication control of the South China Sea wetland.Promote the application.Through the static test in the laboratory,the three factors affecting the purification effect of the single plant Cyperus alternifolius L floating island were studied.The effects of hydraulic retention time,coverage and temperature on the water quality improvement of the floating island system were investigated.The test results show that the TN removal effect of the Cyperus alternifolius L floating island is the best when the hydraulic retention time is 4 days.When the hydraulic retention time is 3 days,the removal effect of TP and COD_crr on the Cyperus alternifolius L floating island is the best.For coverage,the greater the coverage,the better the removal of TN and TP,while the COD_crr removal rate does not change much under different coverage rates.For temperature,26°C is the optimum temperature for plant and microbial growth and removal of TN,TP.