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Polyaromatic hydrocarbons (PAHs) are uncharged, non-polar molecules generated from natural and anthropogenic activities, where the emissions from anthropogenic activities predominate. Chrysene is a high molecular weight PAH, which is found to be highly recalcitrant and mutagenic in nature. The aim of this study was to isolate chrysene-degrading microorganisms from oil-contaminated water and to enhance their degradative conditions using design expert. From the various samples collected, 19 bacterial strains were obtained through enrichment culture and the one which showed highest activity was identified by 16S rRNA sequencing as Bacillus halotolerans. Under optimum conditions of 100 mg/L chrysene concentration, 1,000 mg/L nitrogen source, and pH 6, B. halotolerans exhibited 90% chrysene degradation on sixth day. Positive results for the enzymes laccase and catechol 1,2 dioxygenase confirmed the ability for chrysene degradation by the isolated strain. Major metabolic intermediate determined in gas chromatography-mass spectrometry (GCMS) analysis was diisooctyl phthalate. Hence it can be concluded that B. halotolerans can be a promising candidate for the removal of high molecular weight (HMW) hydrocarbons from contaminated environments. HIGHLIGHTS Bacterial strain capable of degrading chrysene was isolated and sequenced.; Operational conditions like carbon source, nitrogen, pH and incubation period were optimized using design expert software to ensure maximum degradation.; It has been demonstrated that Bacillus halotolerans can mineralize chrysene to fewer toxic forms like catechol and phthalic acid derivatives.

Anthraquinone dyes are tough to degrade compared to azo dyes, due to the resonance in the anthracene structure that leads to more difficulty in the removal and challenges the possibility of an effective decolouration/degradation process. The purpose of this study was to examine the effect of copper and aluminium electrodes in electrocoagulation process for the elimination of an anthraquinone based aqueous solution of Red BFL dye. The efficiency of the electrodes in the dye removal was studied using X-Ray Photoelectron Spectroscopy of the collected sludge, in terms of the respective M(OH)n formation which contributes in coagulation of the dispersed dye molecules and the results indicated that Al formed four types of hydroxides and Cu only one type. The maximum removal of the dye solution obtained with Al was 99.17% at the optimum conditions: pH 8, contact time 15 min, current density 40 A m−2, and 91.88% with Cu: pH 9, contact time 25 min and current density 60 A m−2. Phytotoxicity and ecotoxicity studies with Vigna radiata and Artemia salina was done to investigate the toxicity of intermediate products in the treated Red BFL dye solution, results showed that the Al used Red BFL dye solution was less toxic in comparison to copper. Abbreviation: EC: Electrocoagulation; AQ: Anthraquinone; CD: Current density; CT: Contact time; ECE%: Efficiency in Colour Elimination percentage; HPLC: High-performance liquid chromatography; XPS: X-ray photoelectron spectroscopy; V. radiata: Vigna radiata; A. salina: Artemia salina

The world is facing rapid exhaustion of the available nonrenewable energy resources and compelled toward searching for various possible alternatives to meet the increasing energy requirements. The energy requirements across the globe are helping the energy and mineral ore processing industries in searching for a transformational leap forward toward new fuel sources. Nanotechnology is a growing field which will contribute effectively to the biofuel production industry. Nanotechnologies are part of the aspirational era for the biofuel of the future and have applications in different fields. Nanotechnology has applications in an increasing number of number of industries, but its current use in enhancing the production of power and heat from biomass is limited. This chapter explores the possible impact of basic science on bioenergy production. In addition, it covers the liquid biofuels, biofuels market at the global fuel level, nanotechnologies and processes used in the bioenergy industry, problems associated with those technologies and processes, and potential nanotechnology solutions to those problems.