Tofu wastewater industry with urea fertilizer as a cultivation medium for the microalga Spirulina plantensis

Abstract

One of the limiting problem in fish larvae rearing is the availability of live feed such as zooplankton and phytoplankton. Spirulina platensis is a phytoplankton with important uses in fish larvae culture either as a live feed or an ingredient supplementation in the feed. However, its cultivation has high economic costs associated with the growth medium. One of the alternative medium that potentially reduce costs and environmentally friendly is tofu wastewater. The purpose of this research is to evaluate the combination of tofu wastewater with urea for the cultivation of S. platensis. We investigated the growth of S. platensis in tofu wastewater containing various concentrations of urea: 0 g (control), 10 g, 20 g, 30 g, or 40 g urea added to 3 L diluted (2:1) tofu wastewater. The S. platensis productivity parameters were measured are population density, specific growth rate, and doubling time. The population density growth was significantly different, while the specific growth rate and doubling time were not significantly different for the various urea concentrations. The optimum growth was observed with 10 g urea per 3 L medium. This combination of tofu wastewater with urea could be a cost-effective medium for the cultivation of S. platensis.