Removal of uranium from contaminated groundwater using monorhamnolipids and ion flotation.

Mining of uranium for defense-related purposes has left a substantial legacy of pollution that threatens human and environmental health. Contaminated waters in the arid southwest are of particular concern, as water resource demand and water scarcity issues become more pronounced. The development of remediation strategies to treat uranium impacted waters will become increasingly vital to meet future water needs. Ion flotation is one technology with the potential to address legacy uranium contamination. The green biosurfactant rhamnolipid has been shown to bind uranium and act as an effective collector in ion flotation. In this study, uranium contaminated groundwater (∼440 µg L-1 U) from the Monument Valley processing site in northeast Arizona was used as a model solution to test the uranium removal efficacy of ion flotation with biosynthetic (bio-mRL) and three synthetic monorhamnolipids with varying hydrophobic chain lengths: Rha-C10-C10, Rha-C12-C12, and Rha-C14-C14. At the groundwater's native pH 8, and at an adjusted pH 7, no uranium was removed from solution by any collector. However, at pH 6.5 bio-mRL and Rha-C10-C10 removed 239.2 µg L-1 and 242.4 µg L-1 of uranium, respectively. By further decreasing the pH to 5.5, bio-mRL was able to reduce the uranium concentration to near or below the Environmental Protection Agency maximum contaminant level of 30 µg L-1. For the Rha-C12-C12 and Rha-C14-C14 collector ligands, decreasing the pH to 7 or below reduced the foam stability and quantity, such that these collectors were not suitable for treating this groundwater. To contextualize the results, a geochemical analysis of the groundwater was conducted, and a consideration of uranium speciation is described. Based on this study, the efficacy of monorhamnolipid-based ion flotation in real world groundwater has been demonstrated with suitable solution conditions and collectors identified.

Percutaneous Treatment of Herniated Lumbar Discs with Ozone: Investigation of the Mechanisms of Action.

PURPOSE: To elucidate the mechanism of action of intradiscal oxygen-ozone therapy for herniated intervertebral disc therapy. METHODS: Ozone's mechanism of action was investigated using 3 approaches: mathematical models of intervertebral disc space to explore the relationship between disc pressure and volume; ozonolysis experiments using glycosaminoglycans (GAGs) from a Chinese hamster ovary cell line that were similar in composition to GAGs found in human nucleus pulposus; and experiments in which live Yucatan miniature pigs received various concentrations of percutaneous, image-guided intradiscal oxygen-ozone treatment and were examined (after sacrifice) with histology and semiquantitative analysis of disc cytokine concentrations. RESULTS: Engineering calculations support observations that a small (6%) disc volume reduction can result in considerable (9.84%) intradiscal pressure reduction. Porcine disc histology and Chinese hamster ovary GAG ozonolysis results showed that administered ozone reacted with and fragmented disc proteoglycans, reducing disc volume through disc dehydration. Cytokine analysis of porcine discs found that each of 4 cytokines measured (interleukin [IL]-1ß, IL-6, IL-8, and tumor necrosis factor α) increased in concentration after 2 wt% ozone treatment. CONCLUSIONS: Oxygen-ozone therapy breaks down proteoglycan GAGs that maintain disc osmotic pressure, dehydrating the nucleus pulposus and reducing intervertebral disc volume. This is likely a primary mechanism by which ozone relieves nerve root compression and alleviates herniated disc-related pain. Additionally, 2 wt% ozone appears to interact with intradiscal cytokines, generating an antiinflammatory response that may contribute to symptom improvement.

Treatment of Contained Herniated Lumbar Discs With Ozone and Corticosteroid: A Pilot Clinical Study.

PURPOSE: The primary objective of this pilot study was to compare pain and function scores from patients before and after an ozone injection in combination with steroids and bupivacaine to treat herniated discs. A secondary objective was to correct some of the methodological weaknesses of some previously published ozone studies. METHODS: Fifty patients were enrolled; 1-3 mL of 2 wt% ozone in 98 wt% oxygen was delivered into the nucleus pulposus, and 7-9 mL into the adjacent paravertebral tissues. The oxygen/ozone treatment was followed by a periganglionic injection of corticosteroid and bupivacaine. All patients were evaluated 1 month after the treatment to quantify improvement in pain and function, and to monitor for potential adverse events. RESULTS: Forty-four patients had intradiscal injections and were included in the analysis. After 1 treatment, 75.0% showed significant improvement in pain based on the visual analog scale (improvement >1.8), 72.7% showed significant improvement in function based on the Oswestry disability index (improvement >15%), and 79.5% showed improvement based on the modified MacNab criteria. There were no adverse events associated with the treatment. CONCLUSIONS: Patients showed significant improvement in pain and function after receiving ozone injections in combination with steroids and bupivacaine for the treatment of herniated discs. Because of the lack of a control group and short follow-up times, conclusions about the safety and efficacy of ozone injections for the treatment of herniated discs are not warranted. However, the results provide sufficient evidence that the risk and expense of an additional randomized controlled study is merited.