Research On Leachate Treatment Technology Of Safe Landfill Based On Microalgae-based Wastewater Treatment System

In order to explore the harmless treatment of safe landfill leachate and the feasibility of algae treatment of leachate,this paper selects Chlorella and Scenedesmus obliquus for the treatment of the leachate from one safe landfill in Wenzhoua.The effects of sterilization pretreatment of leachate,initial concentration of leachate,and added nutrients on the effect of pollutant removal and algae growth were studied,and the leachate was explored by using three-dimensional fluorescence spectroscopy technology and parallel factor analysis.The change characteristics of the dissolved organic matter（DOM）in the system were studied,and all the index factors were analyzed by the absolute principal component score-multiple linear regression analysis method（APCS-MLR）.The main research contents and conclusions are as follows:（1）Analysis of changes in conventional water quality indicators and algae growth indicators showed that:whether sterilization has little effect on the growth of Chlorella and Scenedesmus obliquus and the removal of pollutants in the leachate,sterilization treatment is not necessary for engineering applications;When the leachate is diluted to a concentration of 10%,the effect of algae growth and pollutant removal is the best.When the concentration reaches 30%and above,both algae cannot grow and reproduce normally.When 0.2g/L K₂HPO₄·3H₂O+0.06g/L ferric ammonium citrate were used as the nutrient,the growth of algae and the removal of pollutants are both high.The chlorophyll growth rates of Chlorella and Scenedesmus obliquus are 555.53%and 265.15%,and the removal rate of nitrogen is also the highest,reaching 59.51%and 56.69%.（2）The three-dimensional fluorescence spectrogram and the analysis of the changes in the fluorescence spectrum index showed that:whether sterilization has little effect on the DOM components such as humus-like substances and protein-like substances;there were always more new self-generating DOMs in the processing system,and the most of organic matter were newly produced;additional nutrients have little effect on the production and composition of DOM in the system,but ferric ammonium citrate is a photochemically sensitive substance that interferes with the measurement of three-dimensional fluorescence spectroscopy.（3）Using the parallel factor model to analyze the three-dimensional fluorescence spectrum matrix of the water samples,it is obtained:the common components of each group are mainly tyrosine and tryptophan proteins-like（Ex/Em=230-240/300-350nm）,Fulvicacid-like（Ex/Em=250-290nm/390-420nm）,Fulvic acid-like（Ex/Em=340/420nm）.（4）Absolute principal component score-multiple linear regression analysis obtained the corresponding models of each group of principal components-ammonia nitrogen and other factors-ammonia nitrogen.Based on this,the factors that are highly correlated with ammonia nitrogen can be divided into three categories:（1）Water quality physicochemical indexes（COD,TP,DON,p H）;（2）Algae growth index（OD680,Chla,Fv/Fm）;（3）Organic matter index（DOC）;The regression equation between the predicted value of ammonia nitrogen concentration and the measured value obtained by combining all the data:Y=35.23X+45.15（R²=0.877）,the model prediction ability is quite good and can be applied to follow-up research.