The Research On Removal Of N And P In Synthetic Wastewater By Immobilized Algae And Bacteria

Wastewater treatment by microalgae has been used to remove eutrophication pollution due to its low cost and effciency. Nannochloropsis oculata and Chlorella are unicellular microalgae, easy to cultivate and reproduce rapidly. The Nannochloropsis oculata is less studied on wastewater treatment. But in the immobilized algae system,the use of intenal environment is not effectively. Co-immobilized bacillus-algae overcame the shortcomings,the bacillus and algae can become mutually beneficial symbiosis, This can enhance the treatment of nitrogen and phosphorus. The present study analyzed nitrogen and phosphorus removal in different conditions by Nannochloropsis oculata C170 and Chlorella C95 and Paenibacillus polymyxa, accumulate data for biological immobilization technology in wastewater treatment. The results are summarized as follows:The removal of ammonium and phosphate by free Nannochloropsis oculata(Na) and free chlorella(Ch) show that: the free Nannochloropsis oculata had a higher ammonium and phosphate removal rate(33.01%, 30.5%) than free chlorella of ammonium and phosphate removal rate(25.4%, 23.3%), the free Nannochloropsis oculata cells grew faster than free chlorella cells in the sewage.The present study analyzed the removal of ammonium and phosphate by free Nannochloropsis oculata, immobilized Nannochloropsis oculata, controls(beads without cells), results show that: the immobilized Nannochloropsis oculata was superior to removal by the free Nannochloropsis oculata alone, reaching removal of up to 60.4% ammonium, 76.6% phosphate, compared to 30.5% ammonium, 33% phosphate by the free Nannochloropsis oculata alone. the process of immobilized did not cause permanent damage to algae cells. once adapted the environment the cellular would recover their activity rapidly.The study compared the Co-immobilized bacillus-algae, immobilized Nannochloropsis oculata and immobilized bacillus to remove ammonium and phosphate. Results show that: a significantly higher ammonium and phosphate reduction efficiency was found in Co-immobilized bacillus-algae(60.4%, 88.8%) than the immobilized Nannochloropsis oculata alone(49.5%, 76.4%), and the bacillus alone immobilized had a lower ammonium and phosphate efficiency(31.7%, 30%)than the immobilized Nannochloropsis oculata alone. From the growth situation, we can see the environment of Co-immobilized microorganisms significantly enhanced the growth of Nannochloropsis oculata. When the p H rises to the peak, the change of the p H value of the Co-immobilized microorganisms was the most stable. And the p H was in the optimum p H range of Nannochloropsis oculata.The study compared the Co-immobilized bacillus-algae with 1:1, 3:2, 2:3 mixing ratio to remove ammonium and phosphate. results show that: the removal rate to ammonium and phosphate of 1:1 was best, reaching removal of up to(60.4%, 88.8%). When the Nannochloropsis oculata and bacillus relative to each other the most, the cellular viability was the best, so the removal efficiency of ammonium and phosphate was good.