Effects Of Hydrogen Peroxide On The Growth And Damage Effects Of Microcystis Aeruginosa

The phenomenon of eutrophication has become more and more serious, and the outbreak of the "water boom" and "red tide" also has become increasingly frequent under the influence of social development and human activities, the ecological environment problems and the algae control problems arising from the algae have been praised by the world’s attention. At present, the algae removing technology mainly include chemical, physical and biological methods, these methods can not effectively large-scale application in actual water remove algae because of these methods have some shortcomings more or less. In recent years, it was found that a certain concentration of hydrogen peroxide can kill algae cells, and hydrogen peroxide contains only two elements hydrogen and oxygen, the environmental pollution is small, is a kind of potential environmental protection agent to remove algae.In this paper, in order to investigate the effects of hydrogen peroxide on the growth of Microcystis aeruginosa under the influence of single and complex environmental factors and algal cell itself, this study with Microcystis aeruginosa as experiment material that is characteristic of "water boom", and with the number of algal cells and the content of chlorophyll a as the experiment indicators, hope to provide a more comprehensive scientific basis for the management of cyanobacterial blooms and the technology of hydrogen peroxide remove algae. Then the author analyzed hydrogen peroxide on the damage effects of Microcystis aeruginosa from the oxidation and anti-oxidation of algal cells. With the level of total antioxidant capacity (T-AOC), the content of carotenoid and malondialdehyde (MDA) as the experiment indicators to research hydrogen peroxide on the oxidative damage mechanism of Microcystis aeruginosa, hope provide some theoretical reference for the mechanism of hydrogen peroxide remove algae. At the same time, this paper can provide a basis to a certain extent for the environment feasibility when applied the hydrogen peroxide remove algae in actual application through analyzing the content of hydrogen peroxide in culture medium to explore simple the effects in the aquatic environment after hydrogen peroxide remove algae. The main achievements of this paper are as follows:First, different concentrations of H2O2 treatment on algal cells produced different degrees of toxic, the greater the concentration of H2O2, the more toxic. After 24h, the decrease of the number of algal cells, the content of chlorophyll a and carotenoid and protein, and the level of T-AOC of Microcystis aeruginosa was very big, but the increase of MDA content is very obvious, the H2O2 content in culture medium at the same time also reduce rapidly; Toxic continued with the increase of processing time, and the H2O2 also consumed and decomposed gradually, each experiment index values fallen too low, at the same time, the content of MDA increased to the maximum, the damage effects of algal cells also achieve maximum; when the concentration of was 50 mg/L, H2O2 can remove algal cells effectively, and had a strong damage effect to physiological indexes and antioxidant capacity of algal cells; and after 72h, the medium of H2O2 content decreased by 98%, the residue is very low.The second, the pH of water solution, temperature, and light will affect the growth of Microcystis aeruginosa, and at the same time, it will affect to remove the algae of H2O2-The neutral and alkaline (pH7.5-8.5) environment is best to the growth of Microcystis aeruginosa, the effect of H2O2 remove algae and the decrease of chlorophyll a content is better in the neutral environment (pH6.5-7.5), and neutral and alkaline (pH7.5 ～9.5) environment more conducived to the consumption and decomposition of H2O2 in the culture medium. In the 20～30℃ temperature range, H2O2 can effectively remove cells of Microcystis aeruginosa, the influence of temperature on H2O2 remove algae was not big. The light conditions of 25001x-45001x were suitable for growth of Microcystis aeruginosa, with 35001x, it reached the maximum increment; in a short time, the low light intensity was conducive to H2O2 remove Microcystis aeruginosa algae, but the influence of the light effect is not obvious with the increase of time; at the same time, the greater of light intensity, the lower of residues of H2O2 in the culture medium.Third, the orthogonal experiment results show that the four factors affecting of the removal rate of algae cells is in turn:H2O2 concentration> pH> light> temperature; H2O2 concentration had the greatest influence on the removing of chlorophyll a concentration, minimal impact is pH; and the order of the effects on H2O2 residues in medium is:H2O2 concentration light> pH> temperature. Combined with the orthogonal experiment and the actual situation, the best condition of H2O2 remove algae is that light intensity is 15001x, H2O2 concentration is 50mg/L, pH is 7.5 and temperature is25℃.Fourth, the Microcystis aeruginosa itself factors will produce certain effect to H2O2 remove algae. The initial algal cell number of algae fluid had a little effect on H2O2 remove algae when 50 mg/L H2O2 treatment. Within 72h, the influence of the initial number of algal cells on H2O2 remove algae was bot big when the initial number of algal cells froml×106 cells/ml tol×107cells/ml, but when the initial number of algal cells more than 2×107 cells/ml, the effect of H2O2 remove algae was slightly decreased in the same concentration of H2O2. The effects of H2O2 on the growth and damage effect of different growth period can be used to kill were difference, the removal effect of algal cells is different also. The damage effect of H2O2 on decline phase of algal cells was the biggest, and the removal efficiency is the best, followed by the adaptation of algal cells, the difference of damage effect of H2O2 on stabilization and logarithmic phase was not significant.H2O2 is a kind of potential agent to remove algae, the decomposition makes only water and oxygen, the environmental pollution was free, H2O2 can be used to kill Microcystis aeruginosa in water body, it has great significance for the governance of cyanobacteria bloom. The dosage of H2O2 is the key, and also give full consideration to the influence of illumination, pH and temperature when apply the hydrogen peroxide remove algae in actual application, at the same time, we can also apply the appropriate adjustment of H2O2 content according to the extent of the outbreak of "water bloom". This was of great importance to guide the H2O2 remove algae in practical application.