Evaluation of the impact of lime softening waste disposal in natural environments.

Drinking water treatment residues (WTR), generated from the lime softening processes, are commonly reused or disposed of in a number of applications; these include use as a soil amendment or a subsurface fill. Recently questions were posed by the Florida regulatory community on whether lime WTR that contained a small percentage of other treatment additives could appropriately be characterized as lime WTR, in terms of total element content and leachability. A study was done using a broad range of leaching tests, including a framework of tests recently adopted by the United States-Environmental Protection Agency (EPA) and tests that were modified to account for scenario specific conditions, such as the presence of natural organic matter (NOM). The results of these additional leaching tests demonstrated that certain applications, including disposal in a water body with NOM or in placement anaerobic environment, did result in increased leaching of elements such as Fe, and that a site specific assessment should be conducted prior to using WTR in these types of applications. This study illustrates the importance of leaching test selection when attempting to provide an estimation of release in practice. Although leaching tests are just one component in a beneficial use assessment and other factors including aquifer and soil properties play a significant role in the outcome, leaching tests should be tailored to most appropriately represent the scenario or reuse application being evaluated.

Effect of water treatment additives on lime softening residual trace chemical composition--implications for disposal and reuse.

Drinking water treatment residues (WTR) offer potential benefits when recycled through land application. The current guidance in Florida, US allows for unrestricted land application of lime softening WTR; alum and ferric WTR require additional evaluation of total and leachable concentrations of select trace metals prior to land application. In some cases a mixed WTR is produced when lime softening is accompanied by the addition of a coagulant or other treatment chemical; applicability of the current guidance is unclear. The objective of this research was to characterize the total and leachable chemical content of WTR from Florida facilities that utilize multiple treatment chemicals. Lime and mixed lime WTR samples were collected from 18 water treatment facilities in Florida. Total and leachable concentrations of the WTR were measured. To assess the potential for disposal of mixed WTR as clean fill below the water table, leaching tests were conducted at multiple liquid to solid ratios and under reducing conditions. The results were compared to risk-based soil and groundwater contamination thresholds. Total metal concentrations of WTR were found to be below Florida soil contaminant thresholds with Fe found in the highest abundance at a concentration of 3600 mg/kg-dry. Aluminum was the only element that exceeded the Florida groundwater contaminant thresholds using SPLP (95% UCL = 0.23 mg/L; risk threshold = 0.2 mg/L). Tests under reducing conditions showed elevated concentrations of Fe and Mn, ranging from 1 to 3 orders of magnitude higher than SPLP leachates. Mixed lime WTR concentrations (total and leachable) were lower than the ferric and alum WTR concentrations, supporting that mixed WTR are appropriately represented as lime WTR. Testing of WTR under reducing conditions demonstrated the potential for release of certain trace metals (Fe, Al, Mn) above applicable regulatory thresholds; additional evaluation is needed to assess management options where reducing conditions may develop.

Cross-reactivity of autoreactive T cells with MBP and viral antigens in patients with MS.

In this study, we detected the viral DNA of Human Herpes Virus 6 (HHV-6) in the sera and cell-free cerebrospinal fluid (CSF) of Chinese multiple sclerosis (MS) patients. The results revealed that the copy numbers of serum HHV-6 viral DNA were higher in MS than in normal subjects (NS) or in other neurologic diseases (OND). We also found that in the MS subjects, most T cells recognizing myelin basic protein (MBP) were cross-reactive and could be activated by a synthetic peptide corresponding to residues of HHV-6 or EBV. The estimated precursor frequency of these cross-reactive T cells recognizing both peptides, MBP and HHV-6 or EBV, was significantly elevated in MS compared with that in controls. More significant was the presence of CD8+ cytotoxic cross-reactive T cells, as they could directly induce injury to oligodendrocytes that are known to express both MBP and MHC class I molecules. The study provides important evidence for understanding the potential role of HHV-6 or EBV infection in the pathogenesis of MS.

Active Chinese mistletoe lectin-55 enhances colon cancer surveillance through regulating innate and adaptive immune responses.

AIM: To investigate the potential role of active Chinese mistletoe lectin-55 (ACML-55) in tumor immune surveillance. METHODS: In this study, an experimental model was established by hypodermic inoculating the colon cancer cell line CT26 (5 x 10(5) cells) into BALB/c mice. The experimental treatment was orally administered with ACML-55 or PBS, followed by the inoculation of colon cancer cell line CT26. Intracellular cytokine staining was used to detect IFN-gamma production by tumor antigen specific CD8+ T cells. FACS analysis was employed to profile composition and activation of CD4+, CD8+, gammadelta T and NK cells. RESULTS: Our results showed, compared to PBS treated mice, ACML-55 treatment significantly delayed colon cancer development in colon cancer-bearing Balb/c mice in vivo. Treatment with ACML-55 enhanced both Ag specific activation and proliferation of CD4+ and CD8+ T cells, and increased the number of tumor Ag specific CD8+ T cells. It was more important to increase the frequency of tumor Ag specific IFN-gamma producing-CD8+ T cells. Interestingly, ACML-55 treatment also showed increased cell number of NK, and gammadeltaT cells, indicating the role of ACML-55 in activation of innate lymphocytes. CONCLUSION: Our results demonstrate that ACML-55 therapy can enhance function in immune surveillance in colon cancer-bearing mice through regulating both innate and adaptive immune responses.