Phosphorus recovery from wastewater using Microalgae

INTRODUCTION

Phosphorus (P) is an essential macronutrient required for plant growth, crop productivity, and food security. It plays a critical role in energy transfer (ATP), genetic material (DNA, RNA), and membrane structure (phospholipids). However, the global phosphorus cycle is under severe stress due to two major challenges: the overexploitation of finite phosphate rock reserves and the excessive release of phosphorus into aquatic ecosystems through wastewater, agricultural runoff, and industrial discharges.

Among the innovative approaches, the use of microalgae has gained considerable attention. Microalgae are photosynthetic microorganisms capable of efficiently assimilating dissolved phosphorus and nitrogen from wastewater while simultaneously generating valuable biomass. This dual function makes microalgae-based systems not only effective for wastewater remediation but also sustainable for nutrient recycling. The recovered phosphorus, stored mainly in the form of polyphosphate within algal cells, can be harvested and transformed into biofertilizers, offering a renewable and circular solution to phosphorus management.

 Economically, microalgal phosphorus recovery reduces dependency on imported phosphate rock, stabilizes fertilizer markets, and creates opportunities for value-added bioproducts such as biofuels, animal feed, and nutraceuticals. Environmentally, it mitigates eutrophication, lowers greenhouse gas emissions compared to conventional wastewater treatment, and promotes a carbon-neutral circular economy. Agronomically, microalgae-derived fertilizers enhance soil fertility, improve nutrient-use efficiency, and provide slow-release phosphorus sources that align with sustainable agricultural practices.