Physical pretreatments of wastewater algae to reduce ash content and improve thermal decomposition characteristics

Wan-Ting Chen; Junchao Ma; Yuanhui Zhang; Chao Gai; Wanyi Qian

doi:10.1016/j.biortech.2014.07.076

Physical pretreatments of wastewater algae to reduce ash content and improve thermal decomposition characteristics

Bioresour Technol. 2014 Oct:169:816-820. doi: 10.1016/j.biortech.2014.07.076. Epub 2014 Jul 28.

Authors

Wan-Ting Chen¹, Junchao Ma², Yuanhui Zhang³, Chao Gai⁴, Wanyi Qian¹

Affiliations

¹ Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
² Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310027, China.
³ Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Electronic address: yzhang1@illinois.edu.
⁴ Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Mechanical Engineering, Shandong University, Jinan 250061, China.

PMID: 25123982
DOI: 10.1016/j.biortech.2014.07.076

Abstract

Previous study showed high ash content in wastewater algae (WA) has a negative effect on bio-crude oil formation in hydrothermal liquefaction (HTL). This study explored the effect of different pretreatments on ash reduction and the thermal decomposition of WA. Single-stage (e.g. centrifugation) and two-stage pretreatments (e.g. centrifugation followed by ultrasonication, C+U) were used. The apparent activation energy of the thermal decomposition (E(a)) of pretreated algae was determined. HTL was conducted to study how different pretreatments may impact on bio-crude oil formation. Compared to untreated samples, the ash content of algae with centrifugation was reduced from 28.6% to 18.6%. With C+U pretreatments, E(a) was decreased from 50.2 kJ/mol to 35.9 kJ/mol and the bio-crude oil yield was increased from 30% to 55%. These results demonstrate that pretreatments of C+U can improve the thermal decomposition behavior of WA and enhance the bio-crude oil conversion efficiency.

Keywords: Activation energy; Algae; Hydrothermal liquefaction (HTL); Physical pretreatment; Wastewater.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomass
Biotechnology / methods*
Centrifugation
Eukaryota / metabolism*
Temperature*
Thermogravimetry
Wastewater / chemistry*
Water

Substances

Waste Water
Water