Non-ionic surfactants usually are often selected for use in surfactant flushing technology, which is a process that can be used as part of PAH-contaminated soil bioremediation. Phenanthrene (PHE) biodegradation in the presence of polyethoxylate lauryl ether (Brij 35) was studied in two soil/water systems. The natural soil organic matter content (SOM) and the present of Brij 35, both above the critical micelle concentration (CMC) and below the CMC, changed the rate of PHE biodegradation in the presence of Brij 35. PHE biodegradation is different in the two different soil/water systems: PHE > PHE-Brij 35-Micelle > PHE-Brij 35-Monomer in the clay/water system; PHE-Brij 35-Micelle > PHE-Brij 35-Monomer > PHE in the natural soil/water system. Among the free-living species associated with PHE-Brij 35 biodegradation, Brevundimonas diminuta, Caulobacter spp., Mycoplana bullata, Acidovorax spp. and Pseudomonas aeruginosa accounted for 90.72% to 99.90% of the bacteria present. Specific hydrolytic enzymes, including esterases, glycosol-hydrolases and phosphatases, are expressed during PHE biodegradation. The information presented here will help the engineering design of more effective PAH bioremediation systems that use Brij 35 series flushing technology. In particular, micelles of Brij 35 can be used to accelerate the rate of remediation of PAH-contaminated soil in natural soil/water systems.
The traditional process for enhanced biological phosphorus removal (EBPR) in wastewater treatment involves an anaerobic zone followed by an aerobic zone. Although there is no strict anaerobic zone in aerated-anoxic Orbal™ processes, phosphorus removal in excess of that required for cell growth does occur. The microbial ecology of polyphosphate accumulating organisms (PAO) in two full-scale Orbal™ wastewater treatment plants was investigated using flow cytometry to physically separate PAO from non-PAO and fluorescent in situ hybridization (FISH) to identify the main bacterial groups in the PAO subpopulation. Although organisms related to Rhodocyclus were present in these full-scale Orbal™ processes, they were not enriched in the PAO subpopulation, suggesting that the operational characteristics of aeratedanoxic processes select for a PAO community significantly different from that observed in traditional EBPR processes.
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