Research On The Effects Of Nitrogen And Phosphorus Removal From Wastewater By Microalgae Reaction System

Microalgae could purify wastewater by capturing and utilizing bicarbonate, nitrogen,phosphorus and other nutrient. Combining energy raw material production and sewage purification, contamination control and microalgae resources production could be reached simultaneously by microalgae reaction system. This paper took simulated secondary effluent as object. The microalgae reaction system was set up with auto-control light source and run coutinuously. The effects of nitrogen and phosphorus content in wastewater and lights with different wavelength on the nitrogen and phosphorus removal by microalgae were explored,which had a reference value to improve microalgae reactor and the technology of unifying microalgae production and wastewater treatment.The experiment results show that hpospnorus concentration,N/P,NH4+-N/NO3--N ratios could affect the growth of microalgae and the nitrogen and phosphorus removal. In the condition of TN/TP=10, NH4+-N/NO3--N=2/1, microalgae could effectively decline N and P concentration, no matter when the phosphorus content is below 6.0mg/L and even below 6.0mg/L. The removal rates of phosphorus and nitrogen content increased as P concentration increased. The phosphorus removal efficiency reached 98.3%. In the condition of same P content,the removal rates of NH4+-N content was higher than the removal rates of NO3--N.When TN/TP=11.4,The removal efficiency of TN was higher and over 95.0%, the removal efficiency of NO3--N could reach 74.8% higher than the other two experimental group. In the condition of NH4+-N/NI3--N=0.6-0.8,microalgae could effectively decline TN, NH4+-N,NO3--N and content.The effects of lights with six different wavelengths on the nitrogen and phosphorus removal by microalgae were explored with automation control of artificial LED light source.In a short time, Red and blue LED light could improve removal efficiency of nitrogen and phosphorus. In the condition of lights with different wavelength, the removal efficiency of TP in first 3 days were in this order: blue > white > red > yellow > purple > green. The removal efficiency of TN were in this order: red > white > blue ≈ yellow > purple > green. The microalgae biomass concentrations were in this order: red > white > yellow > blue > purple >green. The ratio between red LED light and blue LED light was considered. The results indicated that the removal efficiency of TN was highest and the removal rate of TP reached 0.96mg/L. The removal efficiency of TP was 72.7%。Average productivity of microalgae was up to 91.27mg/(L-d).The microalgae reactor wastewater treatment system was set up and run continuously.The results of daily run shows that the removal efficiency of TP、NN、NH4+-N were higher than 70%, the removal efficiency of NO3--N was lower in the microalgae reactor. The removal efficiency of TP、TN were over 70%,the removal efficiency of NH4+-N was over 90%, the removal efficiency of NO3--N was 50% in flat membrane reactor. The concentration of TP in influent was range from 1.80mg/L to 2.02mg/L in continuous run. The concentration of TP in effluent was below O.lOmg/L. The removal efficiency of TP was over 94.0%, which reached the standard sewage reuse. The removal efficiency of TN was over 92% stably. The concentration of NH4+-N in effluent was below 0.50mg/L. The system had NO3--N in wastewater removal to a certain extent. The removal efficiency of NO3--N was over 70%.