Immobilization Of Different Chlorella Species And Its Utilization Of Nitrogen And Phosphorus From Municipal Wastewater

Algae can take advantage of a variety of inorganic and organic nitrogen compounds as nitrogen source, Inorganic phosphorus are used as Phosphorus source in the form of H2PO4-and HPO42-So, microalgae systems provides a good solution of effectively removing the nitrogen, phosphorus compounds whice cause eutrophication problem and Wastewater tertiary treatment.In this immobilization experiment, we use Chlorella as experimental material, combined with relevant literature, sodium alginate (SA) and polyvinyl alcohol (PVA) was used as immobilized carrier It improve the traditional single immobilized Chlorella method, remove the nitrogen and phosphorus of wastewater.In this research, sodium alginate, polyvinyl chloride, calcium chloride, boric acid, are respectively use to the chlorella immobilization reaction. By Qualitative Analysis of the mechanical strength of the fixed rubber ball, adhesive degree and the speed of Forming into a ball, The optimum immobilization concentration of sodium alginate and calcium chloride is found(2%).Using nitrogen and phosphorus removal rate as an indicator, with the orthogonal experiment, the result are concluded as follows:The affect sequence is sorted by vinyl alcohol (PVA) concentration, boric acid concentration, Activated Carbon, immobilization timeThe optimal immobilization conditions was1.5%of PVA,4%of boric acid,4%of activated carbon,3h。Contrast removal rates of nitrogen and phosphorus by the immobilizeg and non immobilized, we indicate that studies on immobilization carrier screening has an important significance to immobilized biological purification of waste water.This optimization experiment was designed by using Response surface analysis methodology (RSM) as follows:the appropriate cell density and cell starvation time of immoblized Chlorella sp., ratio of nitrogen and phosphorus as well as the content of glucose in medium were selected as the independent variables, the removal rate of nitrogen and phosphorus from wastewater were determined as dependent variables for optimization experiments of the best combination of independent variable elements. The best combination conditions were observed as follws:immobilized cells were in the stable phase with cell density of3.20X106cell per immobilized bead, cell starvation time was51.84h, N/P ratio was about26.72:1and the content of glucose was0.47%in the medium. Under such optimal treatment conditions, the removal rate of nitrogen and phosphorus from wastewater were92.86%and97.32%, respectively. Meanwhile, the removal rate of nitrogen and phosphorus by using non-immoblized Chlorella sp. were86.77%and91.59%, respectively. This result shows that immobilized cells of Chlorella sp. have enhanced capability of removal rate of nitrogen and phosphorus from wastewater by response surface methodology optimization.