Study On The Effect Of Optimization Of Chlorella Immobilization On Nitrogen And Phosphorus Removal In Sewage

In the 1950 s,some scholars proposed the use of algae to remove nutrients such as nitrogen and phosphorus from wastewater,which was gradually valued by scholars at home and abroad who studied algae decommissioning and phosphorus removal.The algae for immobilization treatment is a high efficiency,high recovery rate of the use of methods,for wastewater denitrification and phosphorus removal has a good effect,in the conventional immobilization materials to add auxiliary materials have also become a research hotspot,auxiliary materials are cheap,simple operation,can greatly enhance the stability of immobilization,immobilization methods,optimization of internal conditions and the addition of auxiliary materials will improve the removal effect of nitrogen and phosphorus.In this project,the immobilized chlorella and auxiliary materials were immobilized and separated from the water,and the effect of nitrogen and phosphorus removal of chlorella on domestic sewage after immobilization was explored,and the growth status and sedimentation effect of chlorella after separation were explored.This test firstly optimize the chlorella immobilization methods,to cultivate the experimental effects of ball,the logarithmic phase of chlorella mixed with different concentrations of sodium alginate,using different concentrations of calcium chloride to fixed immobilized chlorella rubber ball,put it in manual monitoring the efficacy of nitrogen and phosphorus in wastewater,the results show that 3% sodium alginate 2% CACl2 group effect is best,The removal rates of ammonia nitrogen,total phosphorus and COD reached 68%,84.6%and 78.66%,respectively.Through optimize the chlorella immobilized internal conditions,the algal cell density and fixed rubber ball diameter size of immobilized chlorella denitrification and phosphorus removal effect,the influence of the research shows that when the density of algal cells in the higher level will weaken the effects of nitrogen and phosphorus,algal cell density,the greater the strength of the light shielding effect between cells,and will affect the structure stability of algin ball;At the same time,the increase of particle size is beneficial to the absorption of nitrogen and phosphorus in wastewater by algal glue pellets.Within the range of 2mm to 3mm,the absorption effect of nitrogen and phosphorus by algal glue pellets fixed with 3mm particle size is the best.The results showed that the removal rates of ammonia nitrogen,total phosphorus and COD reached 79.93%,94.4% and 78.65%,respectively,when the density of algae cells was 10×106 per ball and the particle size was 3mm.The effects of different concentrations of activated carbon and PVA on nitrogen and phosphorus removal of chlorella immobilization were studied by optimizing the immobilized auxiliary materials.Selection of different concentrations of active carbon and PVA as auxiliary materials to join in immobilized material joint fixed chlorella,determination of immobilized algae glue ball effect on the absorption of nitrogen and phosphorus,the results showed that low concentration of activated carbon,help algin ball absorption of nitrogen and phosphorus,but as the reaction time extended,activated carbon adsorption capacity gradually saturated,algin ball of denitrification and phosphorus removal efficiency also decreases;Increasing the concentration of PVA in a small range can help strengthen the mass transfer process of algal pellets.The algal pellets formed by combined fixation have good biocompatibility,which can ensure the growth rate of Chlorella while stable embedding.The results showed that the removal rates of ammonia nitrogen,total phosphorus and COD reached 85.36%,96.4% and79.21% in 1.5%PVA group.The effect of immobilized Chlorella on sewage treatment and sedimentation was studied.Compared with the artificial wastewater,the effect of nitrogen and phosphorus removal of the actual wastewater treated by the immobilized CHLOrellococcus colloids is slightly worse.The removal rates of ammonia nitrogen,total phosphorus and COD reach 90.87%,93.14% and73.99%,respectively,meeting the first-class A discharge standard of Pollutants in Urban Sewage Treatment Plant(GB18918-2002).The cell density of isolated chlorella increased,but the growth was slower than the standard growth.The immobilization could prolong the decay time of Chlorella,which was beneficial to maintain its growth state.At the same time,the SS concentration of effluent was measured in the range of 8.5～9.3mg/L,and it was found that the immobilized substances would be slightly separated.