Abstract
In the present study, 23 isolates, dominated by bacterial genera (74%) were isolated from petroleum sludge at refinery wastewater plant, Jeddah, KSA, by means of selective enrichment in nutritionally optimized refinery wastewater (NORWW) and over twelve successive transfers. Efficiency of biodegradation on complex mixture of hydrocarbons present in refinery wastewater was evidenced by changes in both total viable counts (TVC) and COD content of cultivation broth. Out of the 23 isolates three most potent isolates named BDCC-TUSA-8, BDCC-TUSA-12 and BDCC-TUSA-18 were selected for their efficient COD removal and active growth. The three isolates were tested separately in Bushnell-Haas (BH) media for their capabilities to degrade n-Hexadecane, phenol and phenanthrene, representing the major types of hydrocarbon pollutants. The results strongly indicated that all three isolates showed multiple degradation potentials with remarkably fast reaction rates. Before being recommended for future work, the three isolates were fully characterized and identified employing culture-dependent techniques such as API 20E, API 20NE and API 50CHB, and further confirmed by partial 16S rRNA gene sequencing and phylogenetic analysis as Pantoea agglomerans, Acinetobacter lwoffii and Bacillus thuringiensis respectively. The obtained potent strains provide valuable candidates if assemblages of mixed fewer strains with overall broad and complementary enzymatic capacities are to be considered in order to bring the rate and extent of petroleum biodegradation further as a cost-effective process.
Highlights
The release of oily wastewaters into the environment is one of the major causes of environmental pollution
The results strongly indicated that all three isolates showed multiple degradation potentials with remarkably fast reaction rates
Growth of indigenous bacteria was enhanced many folds, and a total of twenty three microbial isolates with the ability to grow on complex mixture of hydrocarbons present in nutritionally optimized refinery wastewater (NORWW) as carbon and energy sources and representing different colony morphologies were obtained
Summary
The release of oily wastewaters into the environment is one of the major causes of environmental pollution. The toxic effects of refined petroleum oils, those with low boiling point alkenes, aromatic hydrocarbons including n-Hexadecane, phenol and phenanthrene are devastating. These include cancers, birth defects, endocrine disruptions, still births, nervous disorders, liver disease, depression and irregular heartbeats [2] [3]. Physical and chemical treatments of refinery wastewater have been carried out utilizing different techniques [5]-[7]. These technologies are expensive and can lead to incomplete decomposition of contaminants
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