Effects of soybean curd wastewater on the growth and hydrocarbon production of Botryococcus braunii strain BOT-22

A laboratory study was conducted to evaluate the possibility of using wastewater from a soybean curd manufacturing plant as a growth promoter of Botryococcus braunii strain BOT-22. Soybean curd wastewater (SCW) were added to AF-6 medium to set the final concentration to 0% (control), 1%, 2%, 5%, and 10% (v/v). The growth and hydrocarbon production observed in the cultures with 1% and 2% SCW were significantly higher than that observed in the control. It was postulated that proteins and/or reducing sugars in SCW could enhance the growth. A major finding was a shift in the chemical composition of hydrocarbons from C34H58 to C32H54 in association with increased concentrations of SCW. Considering the inorganic ions in SCW, it was presumed that a mixture of nitrate, 1–2% SCW, and secondarily treated SCW can be applied for mass cultivation of Botryococcus.

► Soybean curd wastewater (SCW) can be used as a promoter of growth and hydrocarbon production of Botryococcus braunii.
► The highest biomass production was obtained from the cultures with 1% and 2% (v/v) SCW.
► With increased concentrations of SCW, the chemical composition of major hydrocarbons shifted from C34H58 to C32H52.
► A mixture of nitrate, 1–2% SCW and secondarily treated SCW can be applied for mass cultivation of Botryococcus.