Simultaneous biodegradation of BTX by isolated degrading bacterial strains in a newly designed modulated bio-scrubber assisted to airlift parallel bioreactors

Hamed Nayyeri; Hossein Ghanavati; Hossein Mazaheri; Ali Hassani Joshaghani

doi:10.1007/s40201-021-00726-6

Simultaneous biodegradation of BTX by isolated degrading bacterial strains in a newly designed modulated bio-scrubber assisted to airlift parallel bioreactors

J Environ Health Sci Eng. 2022 Jan 7;20(1):11-27. doi: 10.1007/s40201-021-00726-6. eCollection 2022 Jun.

Authors

Hamed Nayyeri¹, Hossein Ghanavati², Hossein Mazaheri¹, Ali Hassani Joshaghani¹

Affiliations

¹ Department of Chemical Engineering, Arak Branch, Islamic Azad University, Arak, Iran.
² Microbial Biotechnology Department, Agricultural Research, Extension, and Education Organization (AREEO), Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran.

Abstract

A new approach in this present study, isolated bacteria from refinery sludge were used in a laboratory-scale bio-scrubber, connecting with two parallel airlift bioreactors to eliminate harmful and toxic fumes of BTX. One of the main features of this bio-scrubber is using porous mineral pumice fillers (Lava Rock) inside poly-urethane foam (PUF) module tower, connecting with agitator bio-phasic continuously stirred tank bio-reactor (CSTbR) to increase retention time and contact surface. The bio-scrubber and airlift plug flow bio-reactor (PFbR) were used in parallel with cooling flow to be more efficient in preservation of the corresponding heater and endothermic from removal reactions. Performance of bio-scrubber in removing BTX vapors with 10 % silicone oil and grade 350 poise as organic phase in the inlet concentration range of 180 ± 0.3 to 1950.5 ± 0.1 mg /m³ (ppmv) for up to 6 months in two air flow rate's 2.5 and 3.5 (lit/min) that each treatment lasted about 2 months. The rate of biodegradation in this study was carried out by mixing 3 isolated bacteria, obtaining from refinery sludge, named DBIS-03, DTIS-12, and DXIS-09, which they had highest biodegradability than all the isolated strains. The results of BTX biodegradation at each EBRT (Empty Bed Retention Time) showed that the removal efficiency of BTX with isolated bacterial samples was able to grow and multiply on porous fillers and regenerate the growth medium of autotrophic bacterial strain with O₂ gas and micronutrients from contaminated air flow with minimum concentration. Benzene, toluene and xylene inputs maximum concentration over a period of 20 days loading, respectively: B :99.2 % (at 2.5 lit/min and 183.2 ± 0.2 mg /m³ (ppmv)), T: 98 % (at 2.5 lit/min and 327.1 ± 0.1 mg /m³ ( ppmv)) and X: 85.9 % (at 2.5 lit/min and 296.8 ± 0.8 mg /m³ (ppmv)) compared to 3.5 lit/min and so show the best performance in removing BTX from polluted air in period of 30 days.

Keywords: Benzene; Bio-phasic bioreactor; Bio-scrubber; Biodegradation; Isolated bacteria; Mineral pumice; Toluene and Xylene (BTX).