Influences of environmental factors on arsenate adsorption, accumulation and biotransformation in biofilms using the Taguchi experimental design

Faced with the threat of arsenic (As) pollution to human and environmental health, biofilms offer potential for As bioremediation in polluted aquatic environments through adsorption, accumulation and transformation. This study investigated the As(V) bioremediation potential of natural biofilms using a Taguchi experimental design to explore the influence and optimal conditions of environmental factors such as light intensity (LI), salinity, phosphorus (P), and pH. Results showed that all environmental factors significantly regulated As(V) bioremediation processes of biofilms. Specifically, pH primarily affected As adsorption, LI was crucial for As accumulation, and P was a key factor for As(V) reduction in biofilms. Optimal conditions for maximum adsorption and accumulation in biofilms were found with low LI (15 μmol m −2 s −1 ), high salinity (5.00 ‰), high P (1.00 mg L −1 ), and high pH (9.0) levels. Under this condition, the bacteria/eukaryotes ratio and the absolute abundance of the genus Luteolibacter significantly increased. Interestingly, under low LI, high P levels unexpectedly enhanced As intracellular accumulation, challenging the conventional understanding of competitive uptake mechanisms. Moreover, low LI and high P levels were found to inhibit As(V) reduction to the more toxic As(III), in which high P levels mainly inhibited As(V) reduction by competing uptake with As(V). This study demonstrated how environmental factors regulate As adsorption, accumulation, and transformation, providing a scientific basis for optimizing biofilms bioremediation of As pollution. • The Taguchi method was used to design the experiments. • The solution pH is the most influential factor for As adsorption. • Light intensity is the crucial factor for As accumulation. • Phosphorous primarily affected As(V) reduction in biofilms. • High phosphorous promotes As accumulation under low light intensity.