Effects of activated carbon on the growth of Chlorella vulgaris in an aqueous solution

Abstract

Algal blooms, if left unmanaged, can negatively impact lake ecosystems. An unexplored method of removing excess nutrients from lakes, and therefore reducing algal blooms, is through the use of biochar. We hypothesize that due to the adsorptive characteristics of pyrolyzed material such as biochar and activated carbon, its presence would reduce the nutrient availability within aqueous solutions, therefore reducing algal growth. This experiment was conducted in an aqueous solution containing COMBO growth medium with and without the presence of activated carbon, studied under four conditions: 5 mg/L, 10 mg/L, 20 mg/L, and 50 mg/L phosphorous. We applied these treatments to an aqueous solution containing algae and measured fluorometer readings of the algae growth over a period of 12 days. An analysis of covariance followed by a Tukey’s HSD test demonstrated a significant difference between the means of samples containing activated carbon compared to samples without (p < 0.0001). Further, nutrient readings taken of each sample demonstrate a lower concentration of both phosphorus and nitrogen in samples containing activated carbon compared to those without. Our study demonstrates that activated carbon has the capacity to be used for the adsorption of phosphorous. This suggests that both activated carbon, as well as its more adsorptive counterpart, biochar, have the potential to be used in mitigating algal blooms and, more importantly, reducing the effects of anthropogenic eutrophication in aqueous environments.