A study of a bacterial immobilization substratum for use in the bioremediation of crude oil in asaltwater system

An immobilization matrix, Drizit, was examined for use in the bioremediation of oil in asaltwater system. The support was examined by scanning electron microscopy, cell‐loadingcapacity, absorption of Ekofisk crude oil, the effect on cell recoverability of dryingDrizit‐immobilized cells at room temperature, 55°C or freeze drying and storage for up to 3months, and the capability of immobilized Pseudomonas fluorescens to enhance biodegradation ofpetrol (Slovene diesel) in a saltwater system. Results showed that Drizit is an ideal immobilizationsubstratum for use in bioremediation, and the substratum was found to have a good cell‐loadingcapacity (3·75 mg protein g −1 substratum) and a high absorbency of oil(7·49 g Ekofisk g −1 substratum). After drying the immobilized cells at roomtemperature, 55°C or freeze drying and subsequent storage, cells were not recoverable after 2weeks, 1 week or 2 months, respectively, and a significant decrease was seen in the number ofcells recovered after drying and 1 week’s storage in all cases. Enhanced biodegradation of C 13 –C 18 pristane and phytane, in petrol (Slovene diesel) occurred with theimmobilization of Ps. fluorescens to Drizit. An average degradation of 73·8%occurred in the immobilized system in comparison with the free system which resulted in anaverage degradation of 39·8%. When the two systems were supplemented with nitrates andphosphates, degradation in the free supplemented system increased to an average of 72·4%.However, no significant difference in biodegradation was found between the immobilized systemand the immobilized system supplemented with nitrates and phosphates which achieved anaverage degradation of 74.15%.