جستجوی مقالات مرتبط با کلیدواژه "air stripping" در نشریات گروه "پزشکی"

The purpose of this study was to regenerate clinoptilolite natural zeolite by air stripping followed by removal of ammonium from aqueous solutions. The research was carried out in continuous system. The characteristics of graded clinoptilolite from Semnan (one of the central provinces in Iran) mines were determined and then regeneration tests were done by contacting of 1 N NaCl solution with given weights of ammonium saturated zeolite. Then the brine of column was transferred to the air stripping column for regeneration. The pH of brine solution before entrance to a stripping column was increased to 11. Air stripped ammonia from the brine was converted to the ammonium ion by using acid scrubber. The outlet effluent from stripping column was collected for reuse. The results showed that the cation exchange capacities were 17.31 to 18.38 mg NH4 of zeolite weight. Regeneration efficiency of zeolite by NaCl solution and air stripping was in the range of 92%-97% under various operational conditions. However, the efficiency of acid absorption of released ammonia in stripping process was 55% with a major rejection of the surplus ammonia to the atmosphere. It could be concluded that the method studied may be considered as an advanced and supplementary process for treating effluents of aqueous solution and fishponds in existing treatment plants.

The harmful substances, defined as trihalomethanes (THMs), were found to be formed during the disinfection of drinking water when chlorine was used as the disinfectant. In this research, the effectiveness of granular activated carbon (GAC) and air stripping (AS) packed column for the removal of chloroform (CHCl3) (as THMs basic indicator compound in many resources) in range of 50 to300µg/L, from drinking water was studied. Pilots of GAC and air stripping columns were designed and set up. The study was carried out for the two cases of deionized and chlorinated Tehran tap water. Also the effects of flow rate, chloroform and TDS concentrations were considered in both treatment systems. Gas chromatography (GC) with electron capture detector (ECD) was used for determination of chloroform concentration in inlet and outlet samples. The obtained data were analyzed by SPSS and non-parametric Kruskal–Wallis method. Results showed a positive correlation between the flow rate and chloroform concentration, and removal efficiencies. The average of variations of removal efficiencies for AS and GAC columns with deionized water samples were, 89.9%, 71.2% and for chlorinated Tehran tap water were 91.2% and 76.4%, respectively. The removal of feed residual chlorine in these columns with 0.5, 0.8 ppm was 100%, respectively and re-chlorination for finishing water was recommended. Results showed AS to be considered more effective in chloroform removal for conventional water treatment plants as a finishing process.