Development Of A Rotating Hanging Membrane Photobioreactor For Microalgae Cultivation And Study On Pretreatment Of Swine Wastewater

The composition of nutrition of swine slurry was not balanced for algae cultivation,and has the characteristics of high ammonia nitrogen content.An artificial wetland system was developed for the pretreatment of swine slurry,and the effect of operating parameters of the wetland system was studied.Based on the needs for large scale,high density culture of microalgae and the sewage treatment,considering the issures of the current microalgal photobioreactor systems,a simple operation,higher light utilization efficiency,rotating hanging membrane microalgal photobioreactor system was also developed.A detailed description of the operating principle,components and their sturetures and interconnections was also given.Compared with results of' the traditional raceway pond photobioreactor.there were high microalgae biomass concentration in the novel photobioreactor,and different concentrations of swine slurry had effects on wastewater treatment and the lipid accumulation.The main conclusions were as follows:(1)Chlorella vulgaris couldn't survive in the swine slurry of 70%and 100%concentration,due to high ammonia concentration,in the third day a large number of precipitation appeared and microalgae turned yellow.At the concentration of 10%,30%and 50%of the swine slurry,Chlorella vulgaris could grow well,and the growth rate of Chlorella vulgaris was the best at the concentration of 30%group,where OD680 increased from 0.221 to 0.927.Chlorella growth rate on the 10%group is the worst,OD680 only increased from 0.221 to 0.593.The three groups were different in swine slurry nutrient removal of organic matter,nitrogen and phosphorus,and the microalgal oil contents were different from the three groups also,the concentration of oil in 10%group was the highest,reached 22%,the concentration of oil in 50%group was the lowest,about 15%.But in the low concentration of swine slurry,Chlorella cell density is low also,thereofre two-step culture method may be needed for high yield algae oil.(2)The effects of the water level,flow velocity and pollution loads on the slurry treatment in the constructed wetland system was studied.In each experiment,the effect on the nutrient removal was the best at the parameters of operating water level 25 cm,flow rate 5 mL/s,and swine slurry concentration of 30%,and the removal rate of COD,NH3-N,TN and TP in the wetland system reached 30.4%,35%,33.5%and 20.5%,respectively.(3)In the same culture condition,Chlorella vulgaris was cultured open in the rotating hanging membrane photobioreactor and raceway pond photobioreactor.On the 10 day experiment,the Chlorella biomass in the rotating hanging membrane photobioreactor increased from 0.068 mg/L to 0.34 mg/L,while the Chlorella biomass in the raceway pond photobioreactor only increased from 0.068 mg/L to 0.19 mg/L.In the novel photobioreactor,the growth rate had increased more than 2 times of that in the traditional raceway pond photobioreactor.Chlorella inoculation quantity had an effect on microalgae growth rate and oil accumulation.In the range of 5%to 15%of inoculation,the larger the inoculation amount,the faster the Chlorella growed and the higher the fat accumulated in the algae.