Cross-study analysis of factors affecting algae cultivation in recycled medium for biofuel production

Abstract

Current high costs of commercial-scale algal biofuel production prevent its widespread use as a renewable fuel source. One cost-saving approach is the reuse of algae cultivation water after biomass harvesting, which reduces water pumping and treatment costs. However, dissolved compounds, cell debris, and microorganisms remaining in the water could affect subsequent algae generations. Previous studies demonstrate a variety of effects of recycled medium on algae growth, yet their results have not been collectively analyzed. Here we integrate data across 86 studies to determine the relative importance of different factors influencing algae growth in recycled medium. We found that algae taxa can have the greatest influence, while the harvesting method is less influential on growth outcomes. This meta-analysis identifies favorable taxa and thus provides a tool for algae cultivation decision-making when medium reuse is an important driver. Results can also aid in estimating relative algae yield and growth rates for technoeconomic assessments that incorporate water recycling.

Reused Cultivation Water Accumulates Dissolved Organic Carbon and Uniquely Influences Different Marine Microalgae

“…Algae growth responses observed here are broadly consistent with the observation that growth success in reused medium is taxa-dependent, as shown in a meta-analysis (Loftus and Johnson, 2017). This genus-level specificity appears to be true even within major groups of algae, as within the diatoms Staurosira sp.…”

“…Previous studies have tested how reused medium affects algae growth using a variety of algae taxa, harvesting methods, and growth conditions. These studies revealed diverse growth responses ranging from inhibition to stimulation, though most experiments found no substantial effects caused by reused medium (Loftus and Johnson, 2017). One factor that accounted for the wide variety of growth responses was algae taxa.…”

Effects of Co-culture on Improved Productivity and Bioresource for Microalgal Biomass Using the Floc-Forming Bacteria Melaminivora Jejuensis

“…However, microorganisms are known to have preferred organic carbon sources, and different types of organic carbon are available depending on the environment (Brückner and Titgemeyer, 2002;Abreu et al, 2012). In addition, some studies suggest that the medium obtained by culturing certain microbial species can be recycled (Loftus and Johnson, 2017;Wang et al, 2018;Li et al, 2019). Therefore, it is expected that there has been no competition to impede growth in the use of organic carbon sources among species in conditions in which higher biomass could be produced (Loftus and Johnson, 2017;Wang et al, 2018;Li et al, 2019).…”

“…In addition, some studies suggest that the medium obtained by culturing certain microbial species can be recycled (Loftus and Johnson, 2017;Wang et al, 2018;Li et al, 2019). Therefore, it is expected that there has been no competition to impede growth in the use of organic carbon sources among species in conditions in which higher biomass could be produced (Loftus and Johnson, 2017;Wang et al, 2018;Li et al, 2019). Furthermore, improved lipid productivity may be related to lipid accumulation due to nutrient starvation (Chu et al, 2020;Poh et al, 2020).…”

Water reuse and growth inhibition mechanisms for cultivation of microalga Euglena gracilis

“…The effects of water reuse on algae growth are different across algae taxa [ 6 ]. The most researched taxa are green algae, diatoms, cyanobacteria, haptophytes, eustigmatophytes, chrysophytes, and xanthophytes [ 3 ].…”