Hydrothermal liquefaction of Scenedesmus abundans biomass spent for sorption of petroleum residues from wastewater and studies on recycling of post hydrothermal liquefaction wastewater

• Published in: Bioresource technology 2019-07, Vol.283, p.36-44
• Main Authors: Sundar Rajan, Panneerselvam, Gopinath, Kannappan Panchamoorthy, Arun, Jayaseelan, Grace Pavithra, Kirubanandam
• Format: Article
• Language: English
• Subjects: Bio-char; Hydrocarbons; Hydrothermal liquefaction; Petroleum wastewater; Scenedesmus abundans
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2019.03.077

•Petroleum residues were effectively removed by Scenedemus abundans.•Spent sorbent was hydrothermally liquefied to yield bio-oil 43.4 wt%.•HTL wastewater recycle showed increase in bio-oil yield (47.91 wt%).•Bio-char possessed 86.5% removal efficiency towards nickel ion. In this study Scenedesmus abundans was used as a biosorbent material for removing hydrocarbons from simulated petroleum wastewater. Batch experiments resulted in the removal of 92.16% of hydrocarbons from simulated wastewater within 60 min. The spent biosorbent was converted to bio-oil through hydrothermal liquefaction process (HTL) at temperature range from 220 to 320 °C with 1 h holding time. Liquid hydrocarbons (bio-oil) yield was 43.4 wt% at 300 °C with 15 g of spent sorbent loading and possessed HHV of 39.10 MJ/Kg. Additionally the HTL wastewater (aqueous phase) was recycled as reaction medium and studied for its effects on bio-oil yield which increased till second cycle (47.91 wt%). HTL bio-char was employed as adsorbent to remove heavy metals from wastewater. It showed greater removal efficiency of 86.5% to Ni(II) ions. From the results it was concluded that the petroleum residues can be effectively recycled back into liquid hydrocarbons with simple waste management pathway.