Title: Analysis of Water Quality Improvement of Ceratophyllum demersum under Laboratory Condition - by Nutrients Removal Efficiency
Abstract: To evaluate the ability of the submerged plant, Ceratophyllum demersum's (C.demersum) to remove nutrients and to inhibit growth of cyanobacteria, a total of 6 mesocosms were conducted in a batch reactor for 9 days.From the 84 hr of the experiment, C. demersum was stabilized and showed daily cycle trends according to changes in pH and DO levels.The concentration of nutrients, NH3 + , NO3-and PO4 3 continuously decreased until 9 days of the experiment, with the rapid decrease in nutrient concentration for the first 24 hours.High correlation coefficient (r 2 ≥ 0.96, p < 0.001) between the amount of C. demersum's biomass per unit area and the nutrients removal level were derived, and greater C. demersum's biomass per unit area showed higher removal efficiency of nutrients.However, there were differences in the C. demersum's activity level between batch reactors with higher and similar density of the C. demersum, but nonetheless water purification effect appears to have a significant influence due to attached algae and microorganisms.The growth rate of harmful cyanobacteria, Microcystis aeruginosa (M.aeruginosa) with C. demersum's density of 2,500 g fw/m 2 (100% of cover degree) was 0.31 /day, compared to the growth rate of 0.47 /day for the control group (0% of cover degree).In terms of number of cells, the control group had 1.7 times higher number of cells than the experimental group, proving that C. demersum has the ability to inhibit the growth of harmful cyanobacteria.