Cultivation Of Filamentous Microalgae Tribonema Sp.for Nutrients Recycling,and High Value-added Biomass Production

The demand of microalgae biomass has been increased due to its valuable components and utilization in a multiple consumer product.Being a source of higher valued end products,microalgae have wide range of applications.Hence,various microalgae cultural techniques are required to meet its increasing demand in utilization in pharmaceutical,energy and food industry.Cultivation of microalgae in wastewater not only reduces the wastewater treatment cost but also eliminate the harmful substances from the wastewater.Moreover,with the production of useful products,microalgae provide the alternative solutions to environmental issues.To achieve optimize biomass and lipid productivity as well as reduction of nutrients,the present studies was employed.The resultant achievements obtained from the present studies are summarized as follow.1.To investigate specific light intensity ideal for microalgae in generation of optimum biomass and removal of nutrients,various light intensities were provided to the culture,with intensities of 1000Lux,1200Lux,1400Lux,1600Lux,1800Lux and 2000Lux.It was found Tribonema sp.was grown best at 1200Lux intensity,maximum biomass was obtained at the intensity along with efficient reduction of COD,TP and TN.At 1200Lux highest biomass 1.64(g/L)and chlorophyll content was 94(mg/L)found,the COD 92.96%,TP 36.11%,and TN 86.14%were removed during the cultivation.In the culture under 1800Lux,biomass and chlorophyll content were 1.48(g/L)and 0.80(mg/L)obtained respectively,whereas COD,TP and TN declined were 70.42%,8.33%and 77%respectively.It was investigated the growth and nutrient removal were not directly proportional to light intensity.2.The present study was performed to investigate the influence of bacterial presence on microalgae closed and open culture meanwhile their influence on biomass,lipid and fatty acids production.The Tribonema sp.grew better in closed cultural condition rather than in open cultivation.In closed cultural condition it obtained 5.33 g/L along with 43.5%total lipid contents,and higher saturated fatty acids content was found with 24.09%.In open culture 5.11 g/L biomass was harvested with 34%total lipid content,and polyunsaturated fatty acid content was higher with 8.02%.The presence of Bacterial species Rhizobium rosettiformans,Hydrogenophaga intermedia,Sphingopyxis terrae,Sphingopyxis ummariensis have effect on growth,total lipid and fatty acid production.In the further investigation to find the effect of Sphingopyxis ummariensis,Hydrogenophaga intermedia,Rhizobium rosettiformans bacteria on Tribonema sp.culture,it was found that Tribonema sp.grew well in the absence of these bacteria.In control culture condition highest biomass was 4.79(g/L).Highest total lipid content of 53%was obtained in the Rhizobium rosettiformans bacteria cultural.There was highest nutrient removal of total phosphorous and total nitrogen was found in control culture condition with removal of 98.34%,94.64%,respectively.Higher amount of saturated fatty acids 45.35%also found in the control culture.Monounsaturated fatty acids 37.95%were highest in mix culture of three bacteria.While the Tribonema sp.culture with Hydrogenopohaga intermedia bacteria obtained the highest amount of 12.54%polyunsaturated fatty acids.3.The sterilization effect of media to be utilized for microalgae the Chlorella sp.and Tribonema sp.cultivation and nutrient removal has been investigated.The sterilized wastewater,as compared to unsterilized wastewater,had potentially generated higher microalgae biomass along with the removal the nutrients from wastewater.Both of the species performed well in sterilized condition rather than unsterilized.In sterilized conditions,Tribonema sp.grew well in industrial nitrifying wastewater,attained biomass and total carotenoids contents of 4.58(g/L)and 6.48(mg/L),respectively.In the nutrient's reduction of COD,TP,NH₃-N were 96%,99%,99%were found respectively,by Tribonema sp.in nitrifying wastewater under the sterilized condition.Whereas,under unsterilized conditions Chlorella sp.attained maximum biomass of 2.78(g/L)with total carotenoids contents of 7.36(mg/L)with the reduction of COD,TP,NH₃-N 86%,97%,98%in raw wastewater,respectively.Consequently,it was found that media sterilization had a significant effect in microalgae growth and nutrient removal.4.In co-culture technique of two microalgae species the Chlorella sp.and Tribonema sp.had presented better results in both ways,the maximum biomass generation and nutrient removal along with lipid production.Mix culture of both species the Tribonema sp.and Chlorella sp.found to be more effective in achieving required results.The single cultures of both species cultivated separately,had not produced desired results.Maximum biomass was obtained in co-culture with 2.78(g/L)along with better reduction of COD,NH₃-N,TP 18%,48%,63%respectively,and the lipid content was 43%found to be highest at the same culture with at the end of culture.In the single culture of Chlorella sp.maximum biomass was 1.69(g/L)whereas reduction of COD 31%,NH₃-N 15.78%,TP 63.88%respectively,and the lipid content was 42%.In the single culture of Tribonema sp.maximum biomass was 1.13(g/L)COD,NH₃-N,TP 9.8%33.36%,54.05%respectively,and the lipid content was 37.67%.Hence,co-culture performed better during the culture in removal nutrients and lipid production.Therefore,certain cultural techniques to gain optimum microalgae biomass,lipid contents so that increasing demand of microalgae can be meet along with nutrient reduction as a double objective by utilizing various kind of wastewaters and applying various cultural techniques have been studied.It was investigated that removal rate of nutrients e.g.Nitrogen and Phosphorus can be enhanced by using a specific intensity of light,culture and media condition.In this way not only,maximum undesired nutrients can be eliminated but also maximum biomass can be obtained.