Evaluation of bacteriological and chemical quality of dialysis water and fluid in Isfahan, central Iran

Background: Chemical and microbial quality of water used in hemodialysis play key roles in a number of dialysisrelated complications. In order to avoid the complications and to guarantee safety and health of patients therefore, vigorous control of water quality is essential. The objective of present study was to investigate the chemical and bacteriological characteristics of water used in dialysis centers of five hospitals in Isfahan, central Iran. Methods: A total of 30 water samples from the input of dialysis purification system and dialysis water were analyzed for chemical parameters. Heterotrophic plate count and endotoxin concentration of drinking water, dialysis water and dialysis fluid of 40 machines were also monitored over a 5-month period in 2011-2012. Results: Concentration of the determined chemicals (copper, zinc, sulfate, fluoride, chloramines and free chlorine) did not exceed the recommended concentration by the Association for the Advancement of Medical Instrumentation (AAMI) exclude lead, nitrate, aluminum and calcium. Furthermore, the magnesium; cadmium and chromium concentration exceeded the maximum level in some centers. No contamination with heterotrophic bacteria was observed in all samples, while the AMMI standard for endotoxin level in dialysis fluid (<2 EU/ml) was achieved in 95 of samples. Conclusion: Dialysis water and fluid failed to meet the all chemical and bacteriological requirements for hemodialysis. To minimize the risk of contaminants for hemodialysis patients therefore, a water quality management program including monitoring, maintenance and development of water treatment system in hemodialysis centers is extremely important. In addition, an appropriate disinfection program is needed to guarantee better control of bacterial growth and biofilm formation. © 2016, Iranian Journal of Public Health. All rights reserved

Effect of dissolved oxygen and chemical oxygen demand to nitrogen ratios on the partial nitrification/denitrification process in moving bed biofilm reactors

Partial nitrification was reported to be technically feasible and economically favorable, especially for wastewater with high ammonium concentration or low C/N ratio. In this study, the effect of dissolved oxygen (DO) and influent ratio of chemical oxygen demand to nitrogen (COD/N) ratio on biological nitrogen removal from synthetic wastewater was investigated. Experiments were conducted in moving bed biofilm reactors (MBBRs) on partial nitrification process in pilot-plant configuration for 300 days. DO levels were changed from 0.04 to 0.12 and 0.42 to 3.4 mg/l in the anoxic (R1) and aerobic (R2) reactors, respectively. The optimum DO for partial nitrification was between 1-1.5 mg/l in the aerobic reactor (R2). Influent COD/N ratios between 20 and 2 g COD/g-N were tested by changing the nitrogen loading rate (NLR) supplied to the pilot plant. During operational conditions when the DO concentration in aerobic reactor was above 1 mg/l, near complete organic carbon removal occurred in the total MBBRs system. The effluent total nitrogen concentration in the operational conditions (1.7-2.1 mg O2/l and NH+ 4-N=35.7 mg N/l) was obtained in the range of 0.85-2 mg/l. The highest nitrite accumulation (50%- 52%) took place at the DO concentration of 1-1.5 mg/l and increased with decreasing COD/N ratio in aerobic reactor (R2). This study showed that the average nitrification rate at various COD/N ratios is about 0.96 gN/m2 per day while the maximum nitrification rate is about 2 gN/m2 per day at COD/N ratios lower than 6. The experimental COD/N ratio for denitrification was close to complete sum of NO2 - and NO3 - (NOx) removal efficiency (about 99%) at COD/N ratio equal 14 in the operational conditions in the anoxic reactor (R1)

Effectiveness of chitosan as natural coagulant aid in removal of turbidity and bacteria from turbid waters

There has been considerable interest in the development of natural coagulants such as chitosan. By using natural coagulants, considerable savings in chemicals and sludge handling cost may be achieved. Chitosan, a natural linear biopolyaminosaccharide, is obtained by alkaline deacetylation of chitin. Present study is aimed to examine the effects of aluminium sulfate (alum) as coagulant in conjunction with chitosan as coagulant aid on removal of turbidity and bacteria from turbid waters. These tests were carried out using artificial water and kaoline as model suspensions to represent the wide range of natural turbid waters. A conventional jar test apparatus was employed for the tests. After determining of optimum mixing intensity and duration, alum suspensions were added to the samples and after one minute, the desired doses of natural chitosan were added. In optimum condition, residual Al+3 in treated water was less than 0.2 mg/l and meets the EPA guidelines. Turbidity removal efficiency was 74.3- 98.2% by chitosan at a pH 7.0-7.5 for all turbidities. In addition, chitosan significantly reduced the required dosage of primary coagulant 50-87.5%. Bacteria reduction of 2-4 log units (99 - 99.99%) was obtained within the first 1 to 2 h of treatment. Overall results indicate that E.coli was removed better than S. faecalis. The main effects of coagulation by chitosan on bacteria are enmeshment and stack on the microbial cell surface. We demonstrated that optimal design method is an efficient approach for optimization of coagulation-flocculation process and appropriate for raw water treatment

Multi-Component Adsorption of Benzene, Toluene, Ethylbenzene, and Xylene from Aqueous Solutions by Montmorillonite Modified with Tetradecyl Trimethyl Ammonium Bromide

Multicomponent adsorption of benzene, toluene, ethylbenzene, and xylene (BTEX) was assessed in aqueous solutions by montmorillonite modified with tetradecyl trimethyl ammonium bromide (TTAB-Mt). Batch experiments were conducted to determine the influences of parameters including loading rates of surfactant, contact time, pH, adsorbate concentration, and temperature on the adsorption efficiency. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to determine the adsorbent properties. Results showed that the modification of the adsorbent via the surfactant causes structural changes of the adsorbent. It was found that the optimum adsorption condition achieves with the surfactant loading rate of 200 of the cation exchange capacity (CEC) of the adsorbent for a period of 24 h. The sorption of BTEX by TTAB-Mt was in the order of B < T < E < X . The experimental data were fitted by many kinetic and isotherm models. The results also showed that the pseudo-second-order kinetic model and Freundlich isotherm model could, respectively, be fitted to the experimental data better than other available kinetic and isotherm models. The thermodynamic study indicated that the sorption of BTEX with TTAB-Mt was achieved spontaneously and the adsorption process was endothermic as well as physical in nature. The regeneration results of the adsorbent also showed that the adsorption capacity of adsorbent after one use was 51 to 70 of original TTAB-Mt

An investigation on bio-aerosol concentrations in the different wards of hospitals of Isfahan University of medical sciences

Background: Bioaerosol is defined as airborne particles such as living organisms include bacteria, viruses, fungi and their related metabolites, such as endotoxin. The exposure to bioaerosols in the hospital may causes infection especially in immunocompromised patients. The purpose of this study was to investigate the Bioaerosol concentrations in air of various parts of three hospitals of Isfahan University of medical sciences, Iran. Methods: An Anderson biosampler was used for the bacterial and fungal collection. The effect of factors such as humidity, temperature and outdoor Bioaerosol concentrations were also evaluated. Findings: The lowest mean of fungal and bacterial concentration was observed in hospital operating rooms and the highest concentration was detected in infectious diseases ward of hospital 1 and 2 and surgery ward of hospital 3. Significantly, bacterial levels were found to be higher in hospital wards than outdoor; except hospital operating rooms. Conclusion: Our results show that bioaerosol concentrations in hospitals were relatively high and in particular, the higher levels of bacteria than outdoor might be related to the presence of patients, their activity, unsuitable ventilation and disinfection. Therefore, environmental control measures are needed to assure hospital environmental quality especially in wards with immunocompromised patients

Removal of benzene, toluene, ethylbenzene and xylene (BTEX) from aqueous solutions by montmorillonite modified with nonionic surfactant: Equilibrium, kinetic and thermodynamic study

The adsorption characteristics of benzene, toluene, ethylbenzene and xylene (BTEX) from aqueous solutions by montmorillonite (Mt) modified with poly ethylene glycol (PEG-Mt) were investigated. The batch adsorption technique was used to assess the influence of various parameters such as loading rates of the surfactant, contact time, pH, adsorbate concentration, solution ion strength and temperature on the BTEX sorption capacity by PEG-Mt. The raw and modified Mt was specified with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The XRD results showed that the interlayer spacing of the raw montmorillonite (12.10 angstrom) was increased by PEG surfactant modification (17.48 angstrom). The adsorption capacity of the PEG-Mt was increased by increasing the surfactant loading until 200 cation exchange capacity (CEC) of the clay. The equilibrium was achieved at the contact time of 24 h. The adsorption capacity of the adsorbent was in order of B < T < E < X. The experimental data were analyzed by Langmuir, Freundlich and D-R isotherm models. The results indicated that the data were best fitted with the Freundlich isotherm. The D-R isotherm model also showed that the adsorptive behavior of these compounds has physical nature. The obtained data for BTEX adsorption onto the PEG-Mt were also fitted through the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The correlation coefficients values (R-2) showed that the adsorption kinetic described well by the pseudo-second-order model. The thermodynamic study also indicated that the uptake of BTEX by the adsorbent was spontaneous, endothermic and favorable at higher temperatures. (c) 2012 Elsevier B.V. All rights reserved

Evaluation of QIAamp DNA mini kit for removing of inhibitors in detection of Cryptosporidium parvum oocysts in water samples by a nested PCR assay

In recent years, there has been a dramatic increase in the occurrence of waterborne disease outbreaks caused by the Cryptosporidium parvum , and presence of this protozoan parasite in drinking water is a significant health problem faced by the water industry. A new strategy for detection of Cryptosporidium oocysts in water samples is PCR based techniques. In this study a nested PCR assay was designed for the specific amplification of a 199 bp DNA fragment of the gene encoding the heat shock protein (hsp70) of Cryptosporidium parvum oocysts. In order to prevent the inhibition of PCR amplification by substances contained in water samples, three DNA purification methods including QIAamp DNA mini kit, InstaGene Matrix, MagExtractor Genome were compared in concentrates of tap water samples spiked with the oocysts. After it was found that the QIAamp is only efficient purification technique, the efficiency of QIAamp and immunomagnetic separation for nested PCR assay of various water samples was compared. The results show that QIAamp provide a useful and rapid tool for removing of PCR inhibitors. It seems that QIAamp purification-nested PCR assay is a sensitive, rapid and cost effective method for detection of Cryptosporidium parvum oocysts in clean water samples with turbidity < 2 nephelometric turbidity unit (NTU)

Rapid Monitoring Of Indicator Coliforms In Drinking Water By An Enzymatic Assay

Coliform group has been extensively used as an indicator of drinking water quality and historically led to the public health protection concept. Multiple tube fermentation technique has been currently used for assessment of the microbial quality of drinking water. This method, however, has limitations. Enzymatic assay constitute an alternative approach for detecting indicator bacteria, namely total coliforms and Escherichiacoli   in various aquatic environments. This study compared the performance of LMX® broth as an enzymatic assay with the standard methods multiple tube fermentation technique and presence–absence test, for the detection of indicator coliforms in drinking water samples. In addition, the potential effect of water quality on the microbial detection method was assayed through measurement of some physicochemical parameters. From the 50 drinking water samples tested, 8 (16%) and 7 (14%) contained total coliforms and E.coli as indicated by all three techniques. Although on average the LMX recovered more total coliforms and E.Coli numbers comparing to multiple tube fermentation, but there was no significant difference. A significant difference existed between the level of residual chlorine for positive and negative samples. In conclusion, enzymatic assay showed a rapid and less labor method, allowing the simultaneous detection of total coliforms and E.coli. The method is particularly useful in the early warning of fecal pollution of drinking water