Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech Sedimentation rate-based screening of oleaginous microalgae for utilization as a direct combustion fuel Young Joon Sung a , Anil Kumar Patel a , Byung Sun Yu a , Hong Il Choi a , Jongrae Kim b , EonSeon Jin b , Sang Jun Sim a, ⁎ a Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea b Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea GRAPHICALABSTRACT ARTICLEINFO Keywords: Microalgae High-lipid content strain Sedimentation rate Direct combustion fuel ABSTRACT The co-combustion of microalgae biomass with coal has the potential to signifcantly reduce CO 2 emissions by eliminating expensive and carbon-emitting downstream processes. In this study, the utilization of microalgal biomass as a direct combustion fuel in co-fring industries and the screening of potential oleaginous strains of high calorifc value was investigated. High-lipid accumulating mutants were selected from mutant mixtures based on cell density using diferential sedimentation rates. Of the mutant strains obtained in the top phase of the separation medium, 72% showed a higher lipid content than the wild-type strain. One mutant strain ex- hibited a 57.3% enhanced lipid content and a 9.3% lower heating value (LHV), both indicators of direct com- bustion fuel performance, compared to the wild-type strain. Our fndings indicate that sedimentation rate-based strain selection allows for the easy and rapid screening of high-lipid content algal strains for the use of micro- algae as direct combustion fuels. 1. Introduction The continuous usage of fossil fuels has increased the level of at- mospheric CO 2 and resulted in serious global environmental issues, including climate change (Keeling, 1997) and rising sea levels (Mitchell et al., 2006; Foster and Rohling, 2013). To overcome these challenges, researchers have been undertaking continuous eforts to reduce the atmospheric CO 2 levels, wherein Carbon Capture Utilization and Sto- rage (CCUS) is the preferred method, allowing for the immediate uti- lization of captured CO 2 in various applications (Haszeldine et al., 2018). Among the carbon capture processes, the photosynthesis-based biological conversion of CO 2 has attracted much attention due to its https://doi.org/10.1016/j.biortech.2019.122045 Received 27 June 2019; Received in revised form 17 August 2019; Accepted 20 August 2019 ⁎ Corresponding author. E-mail address: simsj@korea.ac.kr (S.J. Sim). Bioresource Technology 293 (2019) 122045 Available online 21 August 2019 0960-8524/ © 2019 Elsevier Ltd. All rights reserved. T