Research On The Breeding And Characteristics Of Tolerance Microalgae For Dairy Cattle Breeding Wastewater

With the rapid development of dairy cattle farming industry,there is a dramatic increase in the cattle breeding wastewater,which has brought serious reverse effect to the ecological environment and the health of local residents.In order to promote sustainable development of the industry,it is necessary to achieve harmless disposal,resource utilization and reduction of dairy farming wastewater.The emergence of sewage treatment based on microalgae culture technology provides the great possibility of achieving this goal,but how to reduce the cost of microalgae cultivation should clearly be at the top of the priority list.Sewage treatment technology,which combines water purification with high value biomass production,has achieved the treatment process transfer to the production process.However,the screening of algae species and the construction of culture system are keys to succeed in implementing of this technology.In this paper,21 isolates were separated from natural water and cow aquaculture wastewater in Shijiazhuang city by using BG11 medium.A microalgae strain,named Z4-3,which could grow fast in the cattle farming wastewater and produce high biomass was obtained through domesticating and screening by using wastewater.Then the Z4-3 was identified as Chlorella sp.according to morphological and molecular biological identification.The optimal growth conditions of Z4-3 are as follows: temperature 27±2?,light intensity 2500 Lux,initial p H=7,illumination time 20?4(light? dark,h),inoculum 6%(v/v).Modificating the concentration of Na NO3 to 17.6mmol/L,K2HPO4 to 0.18mmol/L on the basis of BG11 medium,the biomass of Z4-3 could reach to 3.21g/L.Preliminarily studied the growth of the Z4-3 in cattle farm wastewater,as well as the change of p H,Chemical oxygen demand(COD),Total nitrogen(TN)and Total phosphorus(TP)in the wastewater.The results show that the strain Z4-3 can grow in cattle farm wastewater which was diluted 10 times,the biomass can reach 6.2g/L(10d).While little effect on growth and metabolism of algae strains Z4-3 p H of waste water,the chemical oxygen demand,total nitrogen and total phosphorus removal rate can reach about 59.22%(16d),59.25%(16d),54.24%(16d).The ARTP mutagenesis was carried out and lethal rate was up to 95% at 30 s.A dominant strain with a biomass of 7.91g/L was found,which biomass about 1.41 times higher than Z4-3.