A Study of the Remediation of Wetland Waste Water by Spirodela punctata

A large amount of sewage containing nitrogen and phosphorus was directly discharged without treatment into natural water such as rivers and lakes,resulting in an increasing harsh situation of wetlands and an increasing degree of eutrophication of water bodies.So it was imminent to repair the polluted water and recover the environment.In this experiment,0 mL·L^-1,20 mL·L^-1,40 mL·L^-1,80 mL·L^-1,160 mL·L^-1 of Microcystis aeruginosa were co-cultured with 0,100,200,400 and 800 mg·m^-2 of Spirodela punctata in 1/5 Hoagland culture medium.The above-mentioned Microcystis aeruginosa and S.punctata were subjected to the two-factor orthogonal test.The results showed that the total nitrogen(TN) and phosphorus(TP) contents in the culture medium of all Microcystis aeruginosa concentration decreased in 0~15 days with the increase of time.Co-culture of M.aeruginosa and S.punctata had better repairing effect on polluted water than that in their respective cultures.After 15 days,the microcystin content in the culture was determined,which showed that the S.punctata was effective for absorbing the TN,TP and amicrocystin in the culture.To sum up,the concentration of S.punctata was 400 mg·m^-2,the growth reached its maximum value,removal rates(%) of TN,TP and microcystin in the culture medium were also up to the highest.Therefore,it was concluded that the low concentration of M.aeruginosa and 100% coverage of S.punctata had a potential effect on wetland water repairing.