Study of the effect of periphyton nutrient removal on eutrophic lake water quality

To study the effect of periphyton on water quality, we chose to start our experiment in the summer, when microorganisms are active. In this study, we constructed six experimental groups to simulate eutrophic lakes and used polyurethane sponges as artificial substrates to support periphyton. We systematically studied the effect of periphyton on water quality and nutrient removal by monitoring water quality indexes, including total nitrogen (TN) and total phosphorus (TP), and established two required attachment area equations of periphyton for TN and TP to calculate the attachment area of periphyton required to decrease the concentration of TN and TP, which can provide effective reference for practical engineering decisions. The results show that periphyton can effectively degrade nutrients in eutrophic lakes. The maximum nutrient degradation that can be achieved is Delta TN = 4.93 mg/L and Delta TP = 2.92 mg/L, which can inhibit harmful algae growth compared with the control group; the highest rate of Chl-a degradation was 85.8%. The coefficients of the required attachment area equation of periphyton under the TN condition are as follows: k(1-TN) is 0.1843, k(2-TN) is 0.0002, and the nutrient removal capacity per unit area of periphyton is alpha(TN) = 1.23 x 10(-5) g/m(2).day. Under the TP condition, the parameters are as follows: k(1-TP) is 0.0910, k(2-TP) is 0.0004, and the nutrient removal capacity per unit area of periphyton is alpha(TP) = 2.46 x 10(-5) g/m(2).day. In summary, periphyton is a potential microorganism for in situ lacustrine remediation; its positive impact cannot be ignored during the treatment of eutrophic lakes. However, considering the effects of season, climate and latitude on the harmful algae blooms and periphyton growth, the above equation is only applicable to the subtropical monsoon climate in the summer. Its practicability in other places and seasons remains to be verified.