Efficient cultivation of Porphyridium purpureum integrated with swine wastewater treatment to produce phycoerythrin and polysaccharide

In the present study swine wastewater diluted at the different percentages (10%, 20%, 60%, and 100%) was used to cultivate the red alga Porphyridium purpureum to evaluate microalgal growth, nutrient removal and the production of polysaccharide and phycoerythrin. The results showed the dilution level significantly affected algal growth and nutrient removal. The best growth was in the swine wastewater diluted at 60% resulting in the highest biomass concentration of 9.44 ± 0.44 g L −1 , and the corresponding removal efficiency of COD, total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH 4 + -N) reached up to 94.85 ± 0.08%, 92.69 ± 0.09%, 96.08 ± 0.02%, and 100 ± 0.00%, respectively. Moreover, the algal cells cultured in the wastewater produced high concentration of polysaccharide and phycoerythrin. Microalgae cultured in 10% swine wastewater produced the highest polysaccharide concentration of 2.16 ± 0.02 g L −1 . The highest phycoerythrin concentration of 54.45 ± 4.76 mg L −1 was observed in the 60% swine wastewater group. The results showed that P. purpureum has great potential in treating wastewater and producing high-value byproducts, which is conducive to the development of the bio-circular economy.