Abstract
Currently, nitrates are the most commonly used nitrogen source for microalgal cultivation, but most of them are explosive chemicals, posing safety risks and their use is restricted. Therefore, microalgae producers urgently need to find safer and more economical alternatives. This work systematically investigated the development of novel culture medium to improve safety and reduce costs during microalgal cultivation. Urea was screened out as the best nitrogen source, and the optimum nitrogen concentration was 265 mg/L. When waste shells were used as pH stabilizer and carbon supplement, the biomass and biomass productivity were increased to 1.26 g/L and 71.59 mg/(L<middle dot>d), respectively. Pilot-scale cultivation was carried out in 50-L flat plate photobioreactors, and the Logistic model fitted the growth curves well. Notably, economic analysis showed the new medium could save 29.09%-32.76% of the input cost. This work provided a new alternative culture medium for the largescale culture of Haematococcus pluvialis.