Cultivation of an Arthrospira platensis with digested piggery wastewater

An Arthrospira platensis strain ZJWST-S1 was isolated in Jiaxing City, China, which proved able to proliferate quickly in undiluted digested piggery wastewater (DPW), and the protein content in the algal biomass was high. Single factor experiments showed that the strain was able to quickly grow in a Zarrouk medium as the dosage of sodium bicarbonate, nitrate-nitrogen and phosphate-phosphorus was not less than 4.0 mg·L^–1, 40 mg·L^–1 and 10 mg·L^–1, respectively. No growth inhibition was observed when the culturing medium contained nitrite nitrogen of 0–120 mg·L^–1 and ammonium nitrogen of below 20 mg·L^–1. Five runs of semi-continuous cultivation with DPW as the culturing medium in a 250 L raceway pond showed that the biomass yield in a 9-day semi-continuous culturing was up to 45.2–64.7 g·m^–2·d^–1, higher than the yields obtained by other researchers, and the crude protein content in biomass was over 50%, meeting the national animal feed grade standard. Total nitrogen (TN) and total phosphorus (TP) were removed from DPW at a rate of 10.9–14.0 mg·L^–1·d^–1 and 1.3–1.8 mg·L^–1·d^–1, respectively. The mass balance revealed that 80–93% of TN and 84–98% of TP reduced from DPW were converted to A. platensis biomass.