Evaluating of the disinfection and water quality effects on UV application in the primary stage of water treatment

Background: Irradiation of water by UV has been considered as an attractive alternative for disinfection because its low-impact, pathogen killing capacity shows tremendous promise for meeting today's drinking water regulatory requirements. This study has been performed with the objective of utilizing medium pressure lamp in the preliminary stage of municipal water treatment, namely prior to water clarification and filtration. Methods: Raw water samples were irradiated for 30 s in a lab-scale closed reactor. Disinfection results showed nearly 2 log reduction in HPC for all the samples without formation of nitrite in excess of its MCL. As in a few previous works the formation of nitrite as an objectionable DBP had been reported, this study was extended by preparing synthetic water samples having different amounts of nitrate and turbidities. Results: As far as the initial nitrate concentration dose not exceed 10 mg/L N-NO3, there would be no risk of nitrite increasing in excess of the MCL. Conclusion: Meeting the goal of at least 90 % disinfection for water samples with turbidity levels of as high as 750 NTU is possible by utilizing medium- pressure UV lamp

A Simple Method for Finding Optimal Paths of Hot and Cold Streams inside Shell and Tube Heat Exchangers to Reduce Pumping Cost in Heat Exchanger Network Problems

In this paper, a simple method is presented for the synthesis and retrofit of heat exchanger networks (HENs) by considering pressure drop as well as finding proper path of streams inside heat exchangers (HEs) to reduce the pumping cost of network. Generally, HEN problems lead to MINLP models which have convergence difficulties due to the existence of both continuous and integer variables. In this study, instead of solving these variables simultaneously, a combination of Genetic Algorithm (GA) with Quasi Linear Programming (QLP) and Integer Linear Programming (ILP) was used for solving the problem. GA was used to find optimal HENs structure and streams paths, whereas continuous variables were solved by QLP. For the retrofit of HENs, a modified ILP model was used. Results show that the proposed method has the ability to reduce the cost of annual pumping due to considering optimal paths for streams in the HEs compared to the literature. This work is licensed under a Creative Commons Attribution 4.0 International License

Study on Transpiration Rates of Vicia Villocea and Bromus Inermis Species

Ecohydrology is concerned with the interaction between the hydrological and plant processes. Some aspects of the hydrologic cycle, such as transpiration and interception have received little attention owing to difficulties in field measurements. Quantifying the components of water balance for a watershed is crucial for understanding the dominant hydrologic processes occurring in a basin (Flerchinger & Cooley, 2000). Water use by vegetation is controlled by the water uptake by roots, the transfer of liquid water through plants and vapour loss from the leaf surfaces by the opening and closure of the stomata (Roberts, 2000) i.e. transpiration. Comparison of transpiration of rangelands species is a prerequisite for improving range management. The present study is a preliminary comparison in transpiration between two important Iranian rangeland species, viz. the legume, Vicia villocea and the grass, Bromus inermis

Effect of pulsed power on particle matter in diesel engine exhaust using a DBD plasma reactor

Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides (NOX) and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17 kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests

Experimental investigation and design of a solar desalination unit which work with humidification-dehumidification process

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Solar desalination is an appropriate method for providing fresh water by using renewable solar energy. Solar desalination with humidification and dehumidification process is one of the most effective methods among solar desalination units. This technique presents several advantages such as flexibility in capacity, moderate installation and operating costs, simplicity, possibility of using low temperature energy (geothermal, solar, recovered energy or cogeneration), etc. Processes that are used in this method are the open water cycle- open air cycle, open water cycle- closed air cycle and closed water cycle- closed air cycle. Process used in this work is a open water-closed air cycle type, in which air is circulated in the unit by forced or natural draft between the humidifier and condenser. In this paper, the different effective parameters such as rate of water flow entering condenser, internal temperature to the humidifier, natural and forced air flow, etc were examined. With the temperature increase of water entering humidifier, the amount of produced steam and, as a result, fresh water was increased. However, for temperature increase of water which exits from collector the mass of salty water inflow should be decreased. This decrease of water flow causes reduction of desalinated water in the condenser section of the unit. Results show that there is an optimum rate of salty water flow entering to the unit. Besides, a considerable difference in production of present work with almost others were observed for natural and forced air flow.vk201

Influence of pipe length and flow rate on nano-particle deposition in laminar circular pipe flows

The Lagrangian particle tracking provides an effective method for simulating the deposition of nano-particles as well as micro-particles as it accounts for the particle inertia effect as well as the Brownian excitation. However, using the Lagrangian approach for simulating ultrafine particles has been limited due to computational cost and numerical difficulties. The aim of this paper is to study the deposition of nano-particles in cylindrical tubes under laminar condition using the Lagrangian particle tracking method. The commercial Fluent software is used to simulate the fluid flow in the pipes and to study the deposition and dispersion of nano-particles. Different particle diameters as well as different pipe lengths and flow rates are examined. The results show good agreement between the calculated deposition efficiency and different analytic correlations in the literature. Furthermore, for the nano-particles with higher diameters and when the effect of inertia has a higher importance, the calculated deposition efficiency by the Lagrangian method is less than the analytic correlations based on Eulerian method due to statistical error or the inertia effect

Performance evaluation of non-thermal plasma on particulate matter, ozone and CO2 correlation for diesel exhaust emission reduction

This study is seeking to investigate the effect of non-thermal plasma technology in the abatement of particulate matter (PM) from the actual diesel exhaust. Ozone (O3) strongly promotes PM oxidation, the main product of which is carbon dioxide (CO2). PM oxidation into the less harmful product (CO2) is the main objective whiles the correlation between PM, O3 and CO2 is considered. A dielectric barrier discharge reactor has been designed with pulsed power technology to produce plasma inside the diesel exhaust. To characterise the system under varied conditions, a range of applied voltages from 11 kVPP to 21kVPP at repetition rates of 2.5, 5, 7.5 and 10 kHz, have been experimentally investigated. The results show that by increasing the applied voltage and repetition rate, higher discharge power and CO2 dissociation can be achieved. The PM removal efficiency of more than 50% has been obtained during the experiments and high concentrations of ozone on the order of a few hundreds of ppm have been observed at high discharge powers. Furthermore, O3, CO2 and PM concentrations at different plasma states have been analysed for time dependence. Based on this analysis, an inverse relationship between ozone concentration and PM removal has been found and the role of ozone in PM removal in plasma treatment of diesel exhaust has been highlighted

The relationship between maternal awareness, socioeconomic situation of families and metabolic control in children with type 1 diabetes miletus in an Iranian population

Background: Type 1 diabetes mellitus (T1DM) is one of the most common chronic pediatric conditions, with potentially life-threatening sequels. However, good metabolic control can protect the patients against sequels. Objectives: The aim of this study was to examine the relationship between awareness of the mothers about this disease on improving diabetic children metabolic control and also, to examine the relationship between socioeconomic situations of families and control of diabetes in this group of patients. Patients and Methods: This is a cross-sectional descriptive analytic study on 80 diabetic children and their mothers, who were registered in the diabetes association of Iran, for outpatient control of disease. Diabetes knowledge was measured by Michigan diabetes knowledge test and glycemic control was assessed by glycosylated hemoglobin (HbA1c). To assess the socio-economic status of a diabetic child's family, educational level, occupational and marital status of parents were asked and the socioeconomic status (SES) was evaluated with Hollingshed four-factor index of SES. Results: Mothers' mean knowledge score was 17.72, children's mean HbA1c was 7.77 and mean of SES was 27.89. There was no significant correlation between children's HbA1c and mother's SES. Also, there was an inverse linear relationship between mothers' knowledge score and children's HbA1c and there was a direct linear relationship between the mothers' knowledge score and SES. Conclusions: Finally, based on the results obtained in this study, it can be concluded that the awareness of mothers of T1DM children has a good impact on blood sugar control, whereas the SES of families has no direct effect on blood sugar control. Additionally, SES can indirectly impact on the consciousness of mothers and lead to the reduction of HbA1c. © 2015, Iranian Society of Pediatrics