Isolation And Screening Of Microalgae And Its Application In The Treatment Of Vermicelli Wastewater

Different kinds of wastewater will be produced in the production process of food industry,among which the wastewater produced by vermicelli is highly concentrated organic wastewater,which has the characteristics of large yield and high concentration.If not handled effectively,it will cause serious harm to the environment.On the basis of traditional water treatment,research and development of efficient,green and sustainable water treatment technology is a measure to reduce carbon emissions and ensure carbon peak.Microalgae wastewater treatment technology is to use microalgae to reduce organic matter and nitrogen and phosphorus in water,provide carbon source,nitrogen source and phosphorus source for themselves,and produce valuable nutrients.Microalgae wastewater treatment is a double-benefit method to achieve sustainable development of resources.Wastewater from shandong zhaoyuan paper fans fans of a processing plant wastewater treatment station,through the fans wastewater separation and screening effects in the environment,and for fans of wastewater treatment,examining the fans waste water tolerance,optimization of micro algae for fans of the wastewater treatment condition of nitrogen and phosphorus,to explore the feasibility of micro algae fans wastewater treatment,screening the advantage of fans wastewater treatment effects.The main research contents are as follows:（1）Separate and purify microalgae from vermicellia vermicellia wastewater and its sludge by dilution and plate separation technology,and identify them by morphology and molecular biology.Three algal species,which are closely related to Chlorella sorokiniana,Monoraphidium sp.,and Chlorella sp.,were identified as NZ1,NZ4,and NZ6.After 12 days,the absorbance values of OD₆₈₀were 1.746,1.380 and 1.014,respectively,indicating that NZ1and NZ4 strains had strong growth capacity.Therefore,NZ1 and NZ4 strains were selected as the research objects of subsequent experiments.（2）The tolerance of microalgae to vermicelli wastewater was explored through experiments of vermicelli wastewater with different concentrations.At the initial screening,the concentration of vermiculture wastewater was diluted to 100%,75%,50%and 20%,and the appearance of algae plants turned white and microalgae could not grow.The concentrations were further diluted to 10%,5%,2.5%and 1.5%.The results showed that the biomass of the two microalgae in the 10%wastewater was relatively high.After 14 days of treatment,the absorbability value of OD₆₈₀was 1.063 and 0.974,and the chlorophyll A content was up to 5.86 mg/L and 3.51 mg/L.In this concentration of wastewater,the algae strains NZ1and NZ4 have relatively good purification effect on pollutants.The removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD of NZ1 are 58.35%,55.00%,49.50%and24.83%,respectively.The removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD of algae strain NZ4 were 46.42%,56.53%,44.45%and 21.16%.Comprehensive analysis showed that the growth and pollutant removal capacity of NZ1 strain was stronger than NZ4 strain.（3）To optimize the biomass,high-value biomass production and wastewater treatment efficiency of the microalgae in the viper wastewater,under 30℃,40μmol photons·m^-2·s^-1,and24 h light,Different NaNO₃concentrations（0 g/L,0.5 g/L,1 g/L,1.5 g/L and 2 g/L）were added for experimental study.The results showed that the microalgae of the two strains grew well in the treatment of 0.5 g/L vermiculture wastewater.After 14 days of treatment,the OD₆₈₀light absorption value was 2.356 and 1.739,and the chlorophyll A was 13.4 mg/L and 6.0mg/L.In the wastewater without additional nitrogen source,the oil content of algae NZ1 was the highest,up to 20.62%,and the oil yield was only 6.71 mg·（L·d）^-1.With the increase of nitrogen concentration,the oil content decreased,indicating that nitrogen restriction had a promotion effect on oil production.In the wastewater with NaNO₃dosage of 0.5 g/L,the two microalgae had the best removal effect on ammonia nitrogen,total phosphorus,total nitrogen and COD.The removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD of algae strain NZ1 were 65.12%,64.01%,61.87%and 34.15%,respectively.The removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD by NZ1 were 52.29%,60.46%,55.17%and 27.44%,respectively.（4）In NaNO₃dosage of 0.5 g/L fan wastewater,adding different concentrations of K₂HPO₄（0 mg/L,0.05 mg/L,0.1 mg/L,0.2 mg/L and 0.4 mg/L）for experimental study.The results showed that the growth of NZ1 and NZ4 strains in 0.1 mg/L K₂HPO₄wastewater was relatively good,the absorbance value of OD₆₈₀was 3.562 and 1.986,the content of chlorophyll A was 21.07 mg/L and 6.90 mg/L,and the content of oil was 24.08%and 18.26%,respectively.Under this concentration,the removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD by NZ1 were 78.13%,70.02%,77.21%and 38.44%,respectively,and the removal rates of ammonia nitrogen,total nitrogen,total phosphorus and COD by NZ4were 61.40%,63.34%,58.45%and 30.52%,respectively.The growth and wastewater treatment efficiency of NZ1 strain were better than NZ4 strain.Comparative analysis of the above experimental results showed that the biomass of NZ1strain was the best when the nitrogen dosage was 0.5 g/L and phosphorus dosage was 0.1mg/L,and the high value biomass such as chlorophyll A and oil could be accumulated well.The removal ability of pollutants in vermicelli wastewater is strong,and the dosage is suitable for the treatment of vermicelli wastewater by microalgae.This study provides technical support for microalgae treatment of high concentration organic wastewater.