Leachate from mature landfills is typically characterized by high ammonium (NH4+) content, low biodegradability (low BOD5/COD ratio) and high fraction of refractory and large organic molecules such as humic and fulvic acids. Mature leachate effluents are known to contain recalcitrant and/or non-biodegradable organic substances and biological processes are not efficient in these cases. A promising alternative to complete oxidation of biorecalcitrant leachate is the use of ultrasonic process as pre-treatment to convert initially biorecalcitrant compounds to more readily biodegradable intermediates, followed by biological oxidation of these intermediates to biomass and water. The objectives of this study are to investigate the effect of son catalysts process on biodegradability improvement. Results showed that when applied as relatively brief pre-treatment systems, the sonocatalysis processes induce several modifications of the matrix, which results in significant enhancement of its biodegradability. For this reason, the integrated chemical–biological systems proposed here represent a suitable solution for the treatment of landfill leachate samples with an efficient remediation of the relevant parameters (COD, TOC).
Background and purpose: Fluoride is one of the fundamental and required components in human body. The current study intends to survey the status of fluoride in drinking water supplies (underground water source and drinking water) in Qaemshahr city from 2006 (march/21) to 2012(march/19) and comparison with universal standards, national and climatic conditions. Materials and Methods: This is a descriptive and sectional study. Samples were experimented in Qaemshahr water and wastewater department laboratory. Fluoride concentration in samples has been measured by DR 2800 and SPADNS Fluoride Reagent Solution. Results were analyzed with Excel software. The medium of maximum temperature in different seasons has been obtained from meteorology department. Then fluoride levels in several years have been compared to each other and to universal, national and climatic standards. Results: Comparing to standards National standards of IRAN and according to climatic conditions, proper levels of fluoride were in underground water sources respectively (9 %-0.9 %) in spring, (17 %-6.5 %) in summer and, (13 %-0.00 %) in autumn and in winter. Also in Urban water distribution network were respectively (3.2 %-3.2 %) in spring, (12.5 %-5 %) in summer, (8.3 %-0.00 %) in autumn and, (0.00 %-0.00 %) in winter. The Fluoride levels in 100% of samples were lower than standards (MCLG and MCL= 4 mg/l). Conclusion: No significant relation was observed between fluoride concentrations obtained in different seasons and in different years. In most cases the Fluoride levels in studied city were lower than universal standards, national and climatic conditions. It is recommended that adding fluoride to food chain of the studied citizens should be noticed by the relevant authorities.
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