Date of Award

Fall 2019

Document Type


Degree Name

Master of Science (MS)


Civil & Environmental Engineering


Environmental Engineering

Committee Director

Sandeep Kumar

Committee Member

Mujde Erten-Unal

Committee Member

James W. Lee


Ash is inherent in algae biomass and it causes operational difficulties, equipment failure, and disposal issues during biomass conversion to biofuels and bioproducts. The objectives of this study are to (i) investigate the use of the biodegradable chelating agent for reducing ash content of algae and (ii) evaluate the potential of regeneration and recycle of the chelating agent for multiple uses. Conventionally, ethylenediamine-tetraacetic acid (EDTA) has been studied extensively to remove ash from biomass. However, EDTA is non-biodegradable and causes environmental issues at the disposal.

Nitrilotriacetic acid (NTA) is a biodegradable chelating agent and was used in this study for removing ash from algae. The algae samples were first treated with deionized water (DI) followed by NTA and DI wash at 130℃ for 2 hours. Ash analyses were conducted on the raw and treated algae samples. It was observed that the use of NTA reduced the ash content of algae from 15.2 wt.% to 3.8 wt% which implies to 85.1wt% of ash removal both NTA and DI wash. The NTA liquor saturated with ash was regenerated by the use of Na₂S with Ca (OH)₂. The proposed regeneration method caused inorganic (ash) contents of the saturated NTA liquor to precipitate. The top/clear portion of the solution was decanted and recycled for the next cycle of ash removal from algae. The precipitate/bottom portion was stored for composition analysis. The results of this study provide an environmentally benign method of ash removal from algae biomass feedstock.