Preparation Of Modified Diatomite Algaecide And Algae Removal Performance& Safety Evaluation

At present,algae pollution is a major water environment problem in China.Although the traditional algaecide has good treatment effect,it also has significant side effects,which is not in line with the concept of green development in river management,so it is urgent to develop green and efficient algaecide.In this study,by analyzing the advantages and disadvantages of traditional algaecide,the modified diatomite green algaecide was prepared in weak acid solution with chitosan and PAC as modifier.The surface morphology and structure of algaecide were studied by means of scanning electron microscopy,X-ray diffraction analysis and other micro characterization techniques;the influence of environmental factors such as water temperature and salinity on algaecide removal effect was discussed;the mechanism of algaecide removal was analyzed by combining algaecide removal performance and floc morphology;the acute and chronic toxicity of algaecide was investigated by microbiological,plant and animal experiments.In this study,a pilot scale experiment was carried out to enhance the removal of algae from river water polluted by algae.The main research contents and results are as follows:The optimum preparation conditions of alginate remover modified by chitosan were obtained by orthogonal experiment.The removal rate of the algal density,chlorophyll a and turbidity of the algal bloom water can reach more than 90%.The algaecide is less sensitive to environmental factors such as water temperature and salinity.By comparing the zeta potential and algae removal rate of diatomite before and after modification,it is found that the zeta potential in diatomite water sample increased by 20-40 m V and the algae removal rate increased by more than 80%,which shows that the algae removal agent has the effect of electric neutralization,algae removal and destabilization settlement.It is found that there is a network structure between the flocs,which makes a large number of algal cells agglomerate,indicating that the algaecide has the function of net catching and sweeping.The acute toxicity of the algaecide was evaluated by the luminescent intensity of luminescent bacteria.The inhibition rate of luminescent intensity of the algaecide was less than 30%.According to the international standard ISO11348-1999,the toxicity grade of the algaecide was determined as grade I,which was a low toxicity risk.After the addition of the algaecide,the highest release of algal toxins in the water was0.405 μg/L,which was lower than the standard limit of 1.0 μg/L of microcystin-LR in the drinking water.The chronic toxicity of algaecide was evaluated by aquatic plants and fish.It was found that after 50 days of culture,the algaecide grew well without rotten roots and atrophic death.The actual water algae good test results,the dosage of the algaecide is 70 mg/L,the 1 h after natural sedimentation chlorophyll a,turbidity,TP,TN removal rate was86.4%,93.2%,61.42%,41.07%.In this study,the development of green algae algaecide not only efficient,and low toxicity,algae release toxins less,less impact on the ecology,in line with green concept.