Single step production of activated carbon from microalgae cultivated with urban wastewater

Abstract

The production of activated carbon using as precursor a microalgae biomass produced in a wastewater treatment plant, consisting of an Upflow Anaerobic Sludge Blanket (UASB) reactor, followed by high-rate aerobic ponds, was studied. The harvest of microalgae biomass was carried out through coagulation with Tanfloc®, flocculation and settling. Activated carbon (AC) production was tested at 650 °C and 800 °C, with carbonization and activation performed in a single step, by the physical method with water vapor in different proportions of water mass relative to the sample mass. The specific surface area ranged from 10 to 177 m2·g−1 in samples produced at 650 °C and from 602 to 630 m2·g−1 in the ones produced at 800 °C. It is concluded that the harvested microalgae biomass can be used as a precursor of activated carbon. The best condition tested for the production of AC was carbonization at 800 °C and activation with water vapor in the ratio of 4 gwater/gsample. The results prove that the process of carbonization and physical activation can be done with water vapor in a single step and that activated carbons obtained under the highest temperature (>800 °C) are predominantly micro and mesoporous, with a predominantly aromatic structure.