Fate of Environmental Pollutants in Algal Cells

Conventional wastewater treatment methods based on physicochemical processes and activated sludge exhibit limited efficiency in removing trace metals, dissolved nutrients, and light hydrocarbon fractions, allowing these contaminants to persist in receiving ecosystems. In this context, the photoautotrophic physiology of microalgae has emerged as a promising tool for capturing and transforming such pollutant loads. However, their precise role as “living filters” depends on a rigorous understanding of the pathways each contaminant follows through the algal cell wall. Accordingly, this chapter explores how microalgae integrate negatively charged surface biosorption with intracellular ion transport mediated by P-type ATPases and ZIP (Zrt/Irt-like protein) channels, forming a continuous uptake pathway that mitigates effluent toxicity. Drawing on recent transcriptomic and metabolomic evidence, this chapter details how parameters such as pH, ionic strength, the nitrogen-to-phosphorus ratio (N:P), and light intensity influence contaminant capture and transformation dynamics across various taxa cultivated in urban, industrial, and agricultural wastewater matrices. In addition, it examines posttreatment biomass valorization pathways, including microbial carbonates for low-carbon biocement production, phosphate-based fertilizers derived from intracellular polyphosphate reserves, and lipid-rich oils targeted for biofuel generation. In doing so, this chapter presents the cellular mechanisms, operational frameworks, and valorization strategies essential for integrating algal bioremediation into advanced wastewater treatment schemes.