Arsenic toxicity to Chlorella pyrenoidosa and its phycoremediation

Abstract

Provision of clean drinking water remains a global requirement, so for arsenic-affected areas where various physico-chemical methods are used. These methods require regeneration of media requiring non-stop arsenic checking and it requires skilled operation. Otherwise arsenic contaminated water has to be discarded into the environment. This study examined the probability of using living microalgae Chlorella pyrenoidosa for phycoremediation of arsenic contaminated water (either As(III) or As(V). DO and pH cycles in presence of arsenic (either As(III) or As(V)) ions in the culture did not significantly differ from the control (pure media) indicating that the algae were still growing and photosynthesizing in presence of arsenic ions. As(V) was more noxious than As(III), particularly at pH7.0, but it was opposite at pH9.0. Phycoremediation efficiency of As(V) at pH9.0 by algal cells was greater than that As(III). Monod model has been employed for demonstrating growth kinetics of microalgae in pure media containing various concentrations of nitrate ions. Maximum specific growth rate and saturation constant have been found to be 0.146 d−1 and 8.29E–4g/L, respectively. With the increase in concentration of phosphate in growth medium the growth of microalgae increased. Media with 1.0g/L NaCl indicated the highest algal growth. Addition of NaHCO3 (1g/L) resulted in higher maximum biomass concentration.