Study On The Conversion Efficiency Of Four Common Green Algae In The Purification Of Food Wastewater And The Enhancement Of Hydrolysis Pretreatment

The treatment of food wastewater is an important part of urban wastewater treatment.Using microalgae to purify food wastewater can achieve "recycling" and "economy" at the same time,which can remove pollutants and obtain high-value biomass.This article evaluated the growth and purification effects of several common green algae in food wastewater.Performed different pretreatments on food waste and examined the growth and removing pollutants ability of microalgae in food wastewater pretreatment liquid.To study the effects of food waste pretreatment on the growth,cell volume and purification capacity of four green algae.It can be found that food wastewater can be used as a medium to support microalgal growth after analysing the growth and removal of pollutants of four common green algae in food wastewater and changes in p H of algae liquid.The microalgae could be used for the purification of food wastewater and the cell volume of microalgae increased.Chlorella sp.HQ had the strongest growth ability in the food wastewater.Its highest algae cell density could reach 69 times the initial inoculation density,and the relative growth rate could reach 0.61 d-1.Its removal effect on TN and TP was also better,reaching 73.89% and 95.77%,respectively.The pretreatment method of food waste was selected,and it was found that the growth capacity of microalgae was higher in the food wastewater pretreated by enzymatic hydrolysis than the untreated food wastewater and acid hydrolysate and alkaline hydrolysate.When the complex enzyme consisted of acid protease(enzyme activity 10,000 U·g^-1),?-amylase(enzymatic activity 20,000 U·g^-1),glucoamylase(enzymatic activity 50,000 U·g^-1)and cellulase(enzymatic activity 50,000 U·g^-1),the enzyme ratio was acid protease: ?-amylase: glucoamylase: cellulase = 50: 1: 10: 1,and the dilution factor of sewage was 10 times,the microalgae had a stronger ability to grow in its hydrolysate.The highest algal cell density can reached 60.7 times the initial inoculation densityEnzymatic hydrolysis pretreatment was beneficial to the growth of four green algae in food waste.The density of algae cells of the four kinds of green algae in the food waste enzyme hydrolysate was higher than that in the food waste raw solution.The highest algal cell density of Scenedesmus obliquus in the food waste enzyme hydrolysate was 2.66 times that in the original solution.The cell volume of most microalgae also increased.After the food waste was pretreated by enzymatic hydrolysis,it had different effects on the pollutant removal ability of microalgae,which improved the COD removal ability of four kinds of green algae and the absorption of TP by three kinds of green algae and reduced the TN removal ability of some microalgae.In the enzyme hydrolysate,the change of p H of the algae liquid was similar to that of the original liquid.The p H of the algae liquid of Scenedesmus obliquus,Chlorella vulgaris and Chlorella sp.HQ was stabilized at alkaline,and the p H of the algae liquid of Scenedesmus sp.LX1 was acidic.Through research,we could see that four kinds of green algae could grow rapidly in food wastewater and purify wastewater while obtaining biomass.Enzymatic hydrolysis was more suitable for pretreatment of food waste.In the hydrolysate,the growth rate of the four green algae was further accelerated,the cell volume was increased and the ability to remove pollutants had also changed,especially for the improvement of the COD removal rate.This article provided guidance for the treatment of food wastewater and microalgae purification wastewater coupling resource utilization technology.