| Microalgae are one of the primary producers of the earth,with high photosynthetic efficiency,high environmental adaptability,fast growth rate,and excellent carbon and phosphorus sequestration and removal capabilities.Algae cells are rich in proteins,carbohydrates and lipids and are widely used as feed additives in animal husbandry and open bait in aquaculture.Large-scale culture of microalgae requires large amounts of water and nutrients.It was found that it is feasible to use wastewater to cultivate microalgae.In this work,based on the analysis of the physicochemical properties of vinegar factory wastewater（winemaking wastewater,vinegar wastewater and pickle wastewater）and the feasibility of culturing microalgae,Chlorella vulgaris（UTEX-2714）was cultured using the above three wastewaters respectively,and by comparing the growth characteristics in the above three wastewaters,the wastewater suitable for culturing microalgae was selected as microalgae culture medium;Next,Chlorella sorokiniana（FACHB-275）,Chlorella vulgaris（UTEX-2714）,Chlorella pyrenoidosa and Scenedesmus obliquus（FACHB-417）were cultured in wastewater.The algal species were selected by comparing the growth characteristics of the four microalgae and their removal of total nitrogen（TN）,total phosphorus（TP）and chemical oxygen demand（COD）from the wastewater;then the culture process was optimized（including initial cell density,light time and light intensity）to increase the biomass of the microalgae;finally,the phosphorus limitation and phytohormones were added to the microalgae by adding Cu and Mo elements.Finally,we added Cu and Mo elements,phosphorus limitation and phytohormones to improve the biomass and nutrient removal rate of microalgae.The results of the study are as follows:（1）C.vulgaris was cultured in winemaking wastewater,vinegar wastewater and pickle wastewater for 7 d.The maximum biomass concentrations at the end of culture were 0.73,2.45 and 0.64 g/L,respectively,with specific growth rates（μ）of 1.26,1.41 and 1.18 d-1 and biomass productivity（P）of 173.21,568.79 and 144.98 mg/L/d,respectively.This indicates that vinegar wastewater is a suitable wastewater for microalgae cultivation.（2）C.sorokiniana,C.vulgaris,C.proteinacea and S.obliquus could grow well in the vinegar wastewater,and the biomass concentration of C.vulgaris at the end of the culture was2.21 g/L.The removal rates of total nitrogen,total phosphorus and chemical oxygen demand were 78.36,58.90 and 77.92%,respectively,which were significantly higher than those of the other three microalgae,indicating that C.vulgaris is a kind of algae with good growth capacity and the results showed that Chlorella vulgaris is a kind of algae with strong growth and nutrient removal ability.（3）The biomass productivity of C.vulgaris showed a characteristic of increasing and then decreasing with the increase of initial cell density,and the maximum biomass productivity was obtained when the initial cell density was 0.27 g/L.The initial cell density had a significant effect on the nutrient removal capacity of microalgae,but not on the chemical composition of algal cells.（4）The biomass productivity of C.vulgaris increased with the increase of light time,and the maximum biomass productivity（777.50 mg/L/d）was obtained at a light time of 24 h.The biomass concentration was 3.03 g/L.The biomass productivity of C.vulgaris increased and then decreased with the increase of light intensity.The optimum light intensity was 72.7μmol/m2/s.Both the nutrient removal rate and the chemical composition of algal cells varied significantly with the light duration and light intensity.（5）The addition of different concentrations of Cu and Mo to the vinegar wastewater did not reveal an increase in microalgal biomass and nutrient removal;therefore,Cu and Mo were not limiting elements for the growth and nutrient removal capacity of C.vulgaris.The removal of total phosphorus by C.vulgaris was significantly increased by phosphorus-limited pretreatment and addition of phytohormones. |
PDF Full Text Request