Biofilm Attached Cultivation Of Scenedesmus Sp.for The Treatment Of Swine Wastewater,Biomass And Lipid Production

This research aimed to outline the efficacy of the microalgae Scenedesmus sp.firstly,onselected refractory pollutants that could mainly be found in swine wastewater for biomass productivity,secondly,to understand how Scenedesmus sp.could be used to treat swine wastewater.Thirdly,to study the effects of nitrogen source,nitrogen concentration and nitrogen feeding times?NFTs?on biomass and oil production from Scenedesmus sp.using biofilm attached cultivation method.Firstly,the growth of selected Scenedesmus sp.with biofilm attached culture in different concentrations of NH₄Cl,CuSO₄,tetracycline,norfloxacin and sulfadimidine were investigated.The highest biomass productivity of 6.2 g·m^-2·d^-1 was achieved by 50.0 mg·L^-1 of NH₄Cl,which was significantly different?P<0.05?from the values of BG 11?control?,500 mg·L^-1 and 2000mg·L^-1.The results also showed that 1.0 mg·L^-1 copper could accelerate the growth of Scenedesmus sp.,and the highest biomass was 57.2 g·m^-2 at day 8.Moreover,the biomass was the highest with the concentration of tetracycline 20.0 mg·L^-1,norfloxacin 100.0 mg·L^-1 and sulfadimidine 10.0 mg·L^-1,and the values were 59.5 gm^-2,57.1 g·m^-2 and 58.1 g·m^-2,respectively.The removal efficiency for ammonium nitrogen,copper,tetracycline,norfloxacin and sulfadimidine with Scenedesmus sp.at their optimal initial concentration by biofilm attached culture is 85.2%,64.6%,74.6%,71.2%,and 62.3%,respectively.This suggest that,some types of antibiotics,which are present in swine wastewater with a certain concentration could improve the growth of Scenedesmus sp.Secondly,the biofilm attached cultivation of Scenedesmus sp.with liquid suspension cultivation under identical conditions in BG11 medium and the growth,removal of nutrients and lipid production were investigated.The results showed that the biomass productivity of Scenedesmus sp.in BG 11 medium under biofilm attached culture was 6.15 g·m^-2·d^-1,which was significantly higher than that of 5.48 g·m^-2·d^-1 yielded by the algae using liquid suspension method.The nitrogen removal rate of biofilm attached culture was also higher than liquid suspension,which were 85.23%and 77.84%,respectively.The highest biomass productivity(8.09 g·m^-2·d^-1)of Scenedesmus sp.in swine wastewater was achieved at day 6 using the biofilm attached method which was significantly?P<0.05?higher than that of the BG11 medium(6.31 g·m^-2·d^-1)under the same cultivation conditions.The lipid content of algae cell under biofilm attached culture of swine wastewater was 34.6%,which was also similar with the BG 11 culture medium of 35.2%.Notably,Scenedesmus sp.with biofilm attached culture could treat swine wastewater efficiently,NH₄⁺-N,TP and COD were removed with an efficiency of 99.04%,73.06%and 72.32%,respectively.Thirdly,during the cultivation of the algae using different nitrogen sources,nitrogen concentrations,and nitrogen feeding times?NFTs?to help assess biomass and lipid productivity.Scenedesmus sp.grown well by adhering to the cellulose acetate membrane in five kinds of nitrogen medium:KNO₃,urea,NaNO₃,?NH₄?₂CO₃,and NH₄NO₃.Under the criteria of bio-productivity and lipid productivity,urea was the optimal nitrogen source.Among different urea concentrates,biomass productivity and lipid content of Scenedesmus sp.cultivated in 0.27 g·L^-1urea medium were optimized at 8.8 g·m^-2·d^-1 and 31.1%,respectively.These results showed that culturing Scenedesmus sp.using urea as sole nitrogen source by improving nitrogen uptake with biofilm attached cultivation is more efficient.Based on the results,a process combining algae-based wastewater treatment by biofilm attached cultivation and oil-rich microalgae production can be proposed as an effective way to treat agro-industrial and food processing wastewater as well as producing profitable byproducts.Also,findings from this thesis could be a step forward in developing or designing suitable microalgae biomass and lipid production for human and animal nutrition,cosmetics,and pharmaceuticals.