Effect Of Purifying Nitrogen And Phosphorus In Livestock Wastewater By Embedded Anabaena Aquae And Activated Carbon

In this study, polyvinyl alcohols (PVA) and Sodium alginate (SA) were applied to immobilize Anabaena aquae and activated carbon as embedding medium. Removal efficiency of Anabaena aquae in embedding state for NH4+-N was compared with adsorption and suspended state. Influence of immobilizing on the growth of Anabaena aquae was also investigated. The orthogonal test was used to investigate the optimum embedded conditions. The mass of SA, power activated carbon (PAC) and Anabaena aquae were selected as three orthogonal design elements. And the embedded particle was evaluated by its size, hydropHilism, dilatability, transfer efficiency, removal efficiency of NH4+-N, total pHospHorus (TP) and residual quantity of microcystin (MC) in wastewater. Also, the purification of particles was investigated to remove TN and TP in the high concentration synthetic wastewater through four kinds of factors by N/P, intensity of illumination, sewage quantity and pH. At last, their Nitrogen and PHospHorus removal performance was evaluated by adopting to purify the water from livestock farm. The results were as follows:In the gel process, alkaline environment was more conducive to maintain activity of Anabaena aquae, reduce adhesion among particles and improve strength of particles. The excessive boric acid could inhibit growth of Anabaena. Activity of Anabaena would be recovered after soaking in pHysiological saline of0.7%.Embedded Anabaena showed a higher removal efficiency of NH4+-N when comparing to adsorbed and suspended ones. Moreover, embedded mixture of Anabaena and PAC together had better removal efficiency of NH4+-N than embedded Anabaena and PAC respectively. Adding PAC in embedding particles can not only improve its adsorption capacity, but also keep adsorption steadily in long-term.According to the orthogonal test, Anabaena has no significant influence on size, hydropHilism, dilatability and transfer efficiency, while the influence of SA and PAC were significant. Different mass ratios of SA, PAC and Anabaena had significant influence on eliminating total Nitrogen (TN), TP and residual quantity of MC in wastewater. When PVA accounted for8%, the optimal parameters of embedding mixture were0.5%SA,0.5%PAC and0.2%Anabaena aquae respectively. And the concentration of MC in effluent was trace amount and far below the United Nations criterion of1ug/LAccording to the single factor test, the best operating conditions of removing N and P by embedded particles were found as follows:N/P is5,intensity of illumination is50001ux,ratio of sewage and particles quantity is15:1and pH is8, temperature is25℃, light dark ratio is12:12, the starving time was3days long and the work time of shaker is8h/d.After continuous degradation of actual livestock wastewater for five days, the TN, TP, TOC and COD removal rate were79.40%、95.12%、47.06%and50.43%, repectively. And the residual quantity of MC in effluent was0.0387ug/L. Thus, embedded Anabaena and PAC show excellent ability to remove N, P and organic pollutants. Furthermore, secondary pollution of MC can be avoided as well. This study offered guidance to take advantage of algal which produced MC.