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BACKGROUND Improper disposal of crude oil sludge poses a public health risk due to the toxic nature of components of the waste, especially polycyclic aromatic hydrocarbons (PAHs). Such toxic wastes can be treated by bioremediation of the polluted sites with composting, an eco‐friendly technique that is gaining acceptance. Crude oil sludge was composted for four months during which surfactants were introduced. Fungi and bacteria were isolated from the compost using basic culture techniques. Residual concentrations of PAH components of the sludge during the composting period was monitored with gas chromatography – mass spectrometry (GC‐MS). RESULTS Molecular characterization of the internal transcribed spacer (ITS) genes of fungal isolates classified fungi in the compost into different genera including Aspergillus, Bionectria, Doratomyces, Exophiala, Fusarium, Galactomyces, Geotrichum, Mucor, Penicillium, Trichoderma and Trichurus. The bacterial isolates were classified into Stenotrophomonas, Pseudomonas, Bordetella, Brucella, Bacillus, Achromobacter, Advenella, Klebsiella, Mesorhizobium, Mycobacterium, Ochrobactrum, Pusillimonas and Raoultella. Results from analysis of residual PAH concentrations of composted samples showed higher degradation efficiency of the higher molecular weight (HMW) PAHs resulting in their complete degradation, whereas the lower molecular weight PAHs were not degraded completely. CONCLUSIONS Compost bioremediation is a sustainable waste management technique for hazardous wastes such as crude oil sludge. Inclusion of surfactants at different concentrations did not constantly improve the bioavailability of PAH compounds in the crude oil sludge but it promoted fungal growth in the treatments. © 2020 Society of Chemical Industry

The presence of geosmin in drinking water imparts a musty odour which leads to consumer complaints. Geosmin and other unwanted organics can be treated using photocatalysis. However, the intermediates formed during the photocatalytic degradation process and their degradation pathways have not previously been described. In this study, the degradation profile, as well as the intermediates formed during the photocatalytic degradation of geosmin was monitored in an effort to obtain a better understanding of the degradation kinetics and pathway. Photocatalytic degradation of geosmin in the presence of radical scavengers was shown to be inhibited, as evidenced by the reduction in reaction rate coefficient (k') from 0.055 to 0.038 min -1 . The hydroxyl radical reaction was thus shown to be the predominant process over direct photolysis by incident UV energy. Results from mass spectrum analysis of degradation intermediates indicate rapid fission of sp 3 ─sp 3 (C─C) bonds resulting in ring opening of the cyclic geosmin structure. Bicyclic compounds that could be expected from dehydration and dehydrogenation of geosmin's ringed structure were not found among the detected intermediate products.Intermediates identified consisted of acyclic unsaturated alkenes, carbonyl compounds and some organic acids. Although the identified degradation products are not seen to be directly harmful, chlorine disinfection of water containing these compounds could produce potentially harmful halogenated hydrocarbons.

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