Isolation And Identification Of A Microalgae Strain Treating High Ammonia Swine Wastewater And A Study Of Its Properties

With the rapid development of pig husbandry,there is a dramatic increase in the swine wastewater.Anaerobic fermentation technology,with the advantages of high organic load,low processing cost and recyclability,has become a primary processing technology of swine wastewater treatment.However,the water still contains a high concentration of ammonia nitrogen and other pollutants.If disposed without sufficient treatment,the nutrients would adversely affect local ecological environmental quality as well as people's lives.Besides,the serious situation of energy deficiency has drawn a growing number of scholars' attention on microalgae biodiesel which is deemed as the third generation of biological energy.But the high cost for microalgal cultivation has put limits on the development in industrial production.In this context,using wastewater as a nutrient source to cultivate microalgae is regarded as one of the best biological treatments.This method could greatly reduce the cost of culture medium and meanwhile remove the nutrient of the wastewater.Reports show that only a handful of microalgae such as Chlorella sp.and Scenedesmus sp.can grow in AnATSW.Therefore,to screen and separate a kind of preponderant algae which has a high efficiency in swine wastewater treatment is the key to make the technology practical.In this study,a microalgae was isolated from a local pond near the pig farm,and it discussed about the microalgae's identification,physicochemical characteristics and the processing properties of AnATSW,which provided the information basis for the swine wastewater treatment technology based on the microalgal cultivation.With the help of morphology and molecular biology approaches,this microalgal was identified as the Coelastrella sp.and named as Coelastrella sp.QY01.The newly generated sequence was deposited in GenBank(accession number KU744518).Coelastrella sp.QY01 adapted rapidly after inoculation,and it had no obvious lag phase,just directly entered into the logarithmic phase in the BG11 medium,reaching its plateauing phase in 14 days.When Coelastrella sp.was cultured with BG11 medium,the specific growth rates,doubling times,and the maximum of biomass and productivity were 0.251 day-1,2.76 days,0.629 g L-1 and 33.90 mg L-1 day-1,respectively.After 10 days of culturing,the contents and productivities of lipid were 25.4%and 12.5 mg L-1 day-1,respectively,after 10 days cultured.The fatty acid compositions of Coelastrella sp.QY01 was found to be mainly consisted of palmitic acid(C16:0),linoleic acid(C18:2)and linolenic acid(C18:3),which composed 83.3%of the total fatty acid.Saturated fatty acids,monounsaturated fatty acids and polyunsaturated fatty acids were 23.8%,3.4%and 72.8%of the total fat content,respectively.Coelastrella sp.QY01 cells are mainly made up of protein,carbohydrate,lipid and cellulose,which occupied the main part of protein and lipid.Coelastrella sp.QY01 adapted quickly after inoculating in 20%,40%,60%,80%and 100%of AnATSW and it grew faster in all samples of piggery wastewater than in BG11 medium.Removal rates for NH3-N,TP and inorganic carbon in AnATSW at the various nutrient concentrations ranged from 90%to 100%,from 90%to 100%and from 74%to 78%,respectively.The lipid contents of Coelastrella sp.produced in all cultures within 10 days ranging from 22.4%to 25.5%.The fatty acid compositions of Coelastrella sp.QY01 was found to be mainly consisted of palmitic acid(C16:0),linoleic acid(C18:2)and linolenic acid(C18:3),and the unsaturated fatty acid methyl esters(contains C16:3,C18:2 and C18:3)cultivated with 20%,40%,60%,80%and 100%of AnATSW were predominant in the FAME profile.These features of high quality biodiesel are very favorable.The above results show that the Coelastrella sp.QY01can grow rapidly in the AnATSW,and it is able to efficiently remove the pollutants,thus it has a potential to be used as the raw materials for the biodiesel.It should be noted that 40%of AnATSW was optimal for QY01 cultivation,in which nutrient removal and productivity of biomass and lipid were maximized.