Assessment of Cow Urine as a Nutrient Medium for Indoor Cultivation of Spirulina sp.

Abstract

This study aims to explore the feasibility of utilizing cow urine as an economical alternative nutrient source for microalgae cultivation. By leveraging its mineral content and cost-effectiveness, this research investigates the potential to reduce production expenses associated with nutrient mediums, thus enhancing the value proposition of microalgae-derived products on a commercial scale. In order to assess its efficacy, cow urine was gathered, diluted, and introduced into our Spirulina-modified medium. This concoction was subjected to 8 hours of daily light exposure. Following an 18-day incubation period, we analysed the biomass quantity, specific growth rate, density, chlorophyll level, and total carotenoid content. In the Aquatic Biology laboratory at VNSGU, an experiment was conducted utilizing five distinct concentrations (0.2 ml, 1 ml, 2 ml, 3 ml, and 4 ml in 200 ml) over an 18-day period. The control flask (0 ml) did not contain cow urine. In our current investigation, Spirulina cultivated in a cow urine extract at a concentration of 0.2 ml/200 ml exhibited a dry weight of 0.034±0.0029 g, a specific growth rate of 0.0016±0.00015, and a carotenoid content of 4.683±0.015. The density of Spirulina peaked at 0.0052±0.00005 with a concentration of 1 ml/200 ml of cow urine extract. Across various concentrations of cow urine extract, including 2 ml/200 ml (8.022±0.016 mg/L), 0.2 ml/200 ml (2.191±0.021 mg/L), and 4 ml/200 ml (0.631±0.020 mg/L), Spirulina exhibited higher levels of chlorophyll a, b, and c compared to the control medium in indoor culture setups.