Study On The Feasibility Of Cultivating Spirulina By Aquaculture Wastewater

Spirulina cultivated in wastewater could be used as feed and feed additives.Also Spirulina lives in the wastewater has the ability of purifiing wastewater.So several Spirulina strains-Spirulina subsalsa 351,Spirulina maxima 438,Arthrospira indica TJSD,Spirulina platensis 834 and Arthrospira NMG were cultivated in different media respectively-reclaimed water,fresh aquaculture wastewater,marine aquaculture wastewater,industrial wastewater.In order to evaluate water quality and guide the subsequent nutrition demand of each strain,several important indexes-total nitrogen(TN),ammonia(NH4+-N),total phosphorus(TP),phosphate phosphorus(PO43--P)and chemical oxygen demand(COD)-were measured.The suitability of wastewater for cultivating Spirulina was examined by OD560 and filament color.The results showed that Spirulina subsalsa 351 cultivated in fresh aquaculture wastewater was better.And the OD560 values and filaments color were even more better with adding sodium nitrate in the wastewater.Measures of pretreatment were done by adding additional nutrients.Found that cultivate Spirulina by fresh aquaculture wastewater need to add baking soda to adjust pH and provide carbon,and sodium nitrate as nitrogen resources.Single factor experiments were taken to study baking soda,sodium nitrate,inoculum size,light intensity and temperature on the growth of Spirulina subsalsa 351.The indicators were algae powder yield and protein content.The results showed that: in fresh aquaculture wastewater when add baking soda 3.0-13.6g / L,temperature 25-40 ?,light intensity 6000-12000 lx,the Spirulina subsalsa 351 grows fastly.When with baking soda9.0g / L,sodium 1.0g/ L,light intensity 10000 lx,temperature 32?contitions,got dried algae powder yield of 3.15 g / L;illumination 9000 lx,temperature 25 ? got the protein content of 31.7 %.Based on the single factor experiments,using the L16(45)orthogonal experiment to study how the protein content of Spirulina powder can reach the national feed standards(crude protein(%)?50).The results showed that adding sodium baking soda 9.0g/L,sodium nitrate1.5g/L,light intensity 6000 lx,temperature 40 ? made the protein content of algae reached 50.894 %,while the protein content of several other groups up to ? 42.362%.The orthogonal experimental results were analyzed by SPSS software.Results showed that Spirulina subsalsa 351 cultured in baking soda 9.0g/L,tempreture 25-35?,light intensity6000-9000 lx,sodium nitrate 1.0-1.5g/L turned out to be dark green and protein contein up to 40%.Therefore,the use of appropriate waste water tocultivate Spirulina subsalsa 351 is feasible.Several of the indexes were tested which provided the content of protein up to50.894 %.And results showed that total nitrogen reducted 98.88%,ammonia nitrogen reducted 52.63%,found no total phosphorus and phosphate phosphorus,COD reducted39.97%.So,Spirulina subsalsa351 can reduce pollutants in waste water and also get feed-grade algae.Cultivation of Spirulina in seawater directly was not satisfied,then domasticated the salt-tolerant species from the 5 species;got acclimated species which can tolerance 30 ‰NaCl: Spirulina maxima 438 and Spirulina platensis 834.However,ion in seawater maybe too complexity to culture Spirulina maxima 438 and Spirulina platensis 834,during the process,precipitation occurred to paste to the bottom,affected the growth and OD values.Therefore,use of marine aquaculture wastewater cultivating Spirulina.need further study.