Lipid-rich bacterial biomass production using refinery wastewater in a bubble column bioreactor for bio-oil conversion by hydrothermal liquefaction. (October 2020)

• Record Type: Journal Article
• Authors: Paul, Tanushree; Sinharoy, Arindam; Pakshirajan, Kannan; Pugazhenthi, G.
• Is Part Of: Journal of water process engineering. Volume 37(2020)
• Publication Date: 2020-10
• Subjects: Refinery wastewater -- Bubble column reactor -- R. opacus -- Hydrothermal liquefaction -- Bio-oil -- Bio-char; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2020.101462
• Languages: English
• ISSNs: 2214-7144

Abstract

Graphical abstract: Highlights: Bio-oil production from refinery wastewater is reported. Bubble column reactor is suited for maximum wastewater utilization and biomass growth. The bioreactor performance depended on hydraulic retention time of wastewater. Bio-oil with complex hydrocarbon was obtained in pure form. The bio-char obtained is a value added product obtained in this process. Abstract: In this study, a bubble column reactor (BCR) was evaluated for producing lipid rich biomass of Rhodococcus opacus using refinery wastewater as the substrate. The biomass obtained was used for bio-oil production by hydrothermal liquefaction (HTL) process. Initially, the effect of three media constituents viz. NH4 Cl, KH2 PO4, and Na2 HPO4 and three physicochemical parameters i.e., pH, agitation and temperature on refinery wastewater treatment by R. opacus was studied employing Placket Burman experimental design. From the results, it was observed that variation in the levels of these parameters does not have any significant effect on the wastewater treatment efficiency indicating the robust nature of R. opacus in treating refinery wastewater. During the continuous wastewater treatment using BCR, a very high chemical oxygen demand (COD) removal efficiency of 97 % was obtained along with 2.4 g L −1 of biomass and 1.33 g L −1 lipid yield. The lipid rich bacterial biomass was later subjected to HTL treatment which resulted in production of bio-oil with 26.5 % yield on biomass. Detailed characterization of the bio-oil revealed that it primarily contains different complex organic hydrocarbons. Characterization of solid residue (bio-char) obtained as a byproduct of HTL process contained a high amount of carbon (41.8 %) of large porosity and many active groups over its surface indicating its potential high application value. Overall, this study serves as an excellent example of zero waste strategy for recovering energy in the form of bio-oil from industrial wastewater.