Bicarbonate trigger in mixed culture of algae increases carbohydrate content of biomass

Residual nitrogen and phosphorus from wastewater treatment plant effluents remains a key challenge as governments work to reduce the incidence of harmful algal blooms in surface waters. Permits for nitrogen and phosphorus release from municipal wastewater treatment plants are becoming increasingly common and strict in many areas of the US. Algal-based wastewater treatment technologies are uniquely situated to recover these nutrients to lower than current limits of technology and potentially produce valuable byproducts such as biofuels. A key barrier to financial viability is the sale of the biomass, the value of which could be increased by enriching the biomass in lipid and carbohydrates. Previous research has shown that adding sodium bicarbonate just before nutrient depletion can drastically increase the lipid content of algal biomass, but this has only been shown in pure cultures. The goal of this study is to test the effectiveness of a bicarbonate trigger for lipid and carbohydrate accumulation on a mixed culture of algae via lab-scale batch experimentation. This study found a 67.8% increase in volatile suspended solids concentration for the 50 mM bicarbonate addition condition versus a 18.6% increase for the 0 mM bicarbonate addition (control) condition. This increase was found to be mostly from carbohydrate accumulation with an increase in the carbohydrate to protein ratio of 3.1 fold and 9.6 fold for the 0 mM and 50 mM bicarbonate conditions, respectively. This increase in carbohydrates, rather than lipids is a unique result and is likely due the fact that a mixed community of algae was used with a low solids retention time. This could increase the revenue from both an increased mass of produced biomass due to the higher solids concentration and an increased value of the final product due to increased carbohydrate content. This increased biomass value could potentially offset some of the costs of algal-based wastewater treatment, making it more financially viable.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Environ Engr in Civil Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Avila, Nick

Contributors dc:contributor

• Guest, Jeremy S

• Environmental engineering

Statement dc:rights

• Copyright 2021 Nickolas Avila

Language dc:language

en, eng

Handle dc:identifier

http://hdl.handle.net/2142/113926

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F113926