نشریه علوم و مهندسی آب و فاضلاب
سال هشتم شماره 1 (بهار 1402)

It is predicted that by 2050, more than 48% of the world's population will face water shortages. Desalination of seawater as the best way to supply fresh water has been on the rise for the past three decades. Membrane desalination methods, especially reverse osmosis, have become more popular than other methods due to their lower energy consumption. Despite the success of this method in removing seawater salts, contaminants such as boron are still found in the produced water due to the presence of boron as boric acid in seawater, which due to its small molecular size, leaks into the produced water through membranes. The average concentration of boron in seawater is 4.6 mg/l, which comes from various natural sources such as volcanic activity as well as anthropogenic sources. High levels of boron are harmful to human health and agricultural products. Factors such as pH, temperature and ionic strength of feed water have a great impact on boron removal in membrane processes. By examining credible sources, while pointing to the importance of boron and its removal methods, this validity review article addresses the challenges of boron removal by reverse osmosis as the most common seawater desalination technology.

Nowadays, membranes are widely used in various industries due to their advantages such as high removal efficiency and the ease of operation. However, membrane clogging is an important limiting factor in this process which is related to the hydrophobicity of membrane materials. Although reverse osmosis and nanofiltration processes were used to purify water, the use of nanofiltration is more cost-effective as the nanofiltration process is conducted at a lower pressure and plays a major role in water treatment and desalination. Recently, many researches has reported the improvements in the ability of nanofiltration process to reject salts, dyes, and heavy metals and also to reduce the clogging of nanofiltration membranes. Membrane clogging is the largest and most challenging barrier to membrane processes, greatly reducing membrane performance and membrane life, and increasing operating cost. In this review article, different methods of nanofiltration membrane modification using nano-minerals, carbon as well as mineral / carbon composite materials has been investigated in order to improve the performance of nanofiltration membranes.

Nowadays, the contamination of water resources with antibiotics are known as one of the major pollutants in the environment due to their widespread use, toxicity, causing drug resistance, and lasting effects. This study was designed to evaluate the efficiency of the advanced oxidation process of sodium persulfate activated with steel industry slag in the presence of ultraviolet rays, solution temperature, and pH aimed at eliminating the Azithromycin antibiotic from aqueous and effluent media. In the present study, the effect of the variables, including pH, solution temperature, reaction time, initial concentration of antibiotics, sodium persulfate concentration, and UV ray intensity was examined on the process efficiency. A High-Performance Liquid Chromatography (HPLC) machine was also used to measure the concentration of the Azithromycin antibiotic. According to the study results, under optimal and certain conditions in which sodium persulfate: 2 mM, pH: 2, iron ions level in the steel industry slag: 0.4 g/l, UV intensity: 8 watts, and during 60 minutes, the elimination efficiency rates of Azithromycin antibiotic, COD, and TOC were obtained as 91%, 57/4%, and 43/8%, respectively with a mineralization level higher than 55%. The rate of Azithromycin antibiotic removal was directly related to the concentrations of iron ions, sodium persulfate, UV intensity, and the temperature. However, increase in the pH from 2 to 10 led to decrease in the process efficiency from 81% to 43%, and enhance in the initial concentration of Azithromycin antibiotic from 5 to 50 mg/l also reduced the removal rate of the antibiotic from 73% to 43%. The research revealed that the advanced oxidation process of sodium persulfate activated by steel industry slag in the presence of ultraviolet rays can be used as a proper method with high efficiency to eliminate the high concentration of antibiotics found in a real sewage sample.

In order to optimally manage the pressure and reduce the non-revenue water as much as possible, taking into account the costs of each activity, it is necessary to examine the priority of each solution by scientific methods and considering the costs, efficiency and duration of implementation. Therefore, in order to avoid cost wastage and efficient use of financial resources, it is necessary to use a comprehensive and systematic approach to identify different strategies that can be used to manage urban water pressure, the benefits and Compare their disadvantages. In the statistical population of this research, the knowledge and experience of 35 experts in the water and wastewater industry were used. Also in order to prioritize the proposed operations with the aim of reducing non-revenue water based on three criteria: the impact of the project, the duration of the project and the cost of the project, the integrated TOPSIS-VIKOR method has been used. Findings indicate that in the first priority, the installation of online data loggers pressure gauges, the second priority is the continuous updating of water maps and GIS network mapping, and in the third priority the completion of its information layers including pipe life, material and diameter, were located.

Providing good quality drinking water is one of the most important concerns of today's societies. Using a proper system for the fair distribution of potable water is very necessary and evidently the type of the system will lead to different amounts of water use per capita. Today, the dispute over good quality water resources in arid regions has escalated, Governments are forced to use separate drinking and sanitation water systems. Understanding the consumption of people in the form of per capita is a prerequisite for the proper design of drinking water distribution networks, the data of which are collected and analyzed in different ways. Quality of groundwater resources in Bajestan region, has led to the plan of separate drinking and sanitation water, with the establishment of government water collection stations since 2014. The purpose of this article is to estimate the per capita drinking consumption by query method by considering 378 samples and random sampling at certain distances from each station. The amount of per capita obtained is estimated at about 3 liters, but its amount has a different distribution in different city districts ranging from 2.5 to 4.5 liters. The highest amount is obtained for the new districts with villa texture and the lowest for the zones with more apartments. The results of the survey of the plan and the problems and consequences of its implementation showed that about 69.03% of people are using the water of these stations for drinking and tea, which is the criterion for determining per capita; The biggest problems of withdrawal stations are the numerous breakdowns of the stations and difficulty harvesting them, which requires the revision of some network operations.

This paper aims to investigate the role of internal marketing and social responsibility of the company on the intention to leave the job and the mediating role of organizational commitment in Isfahan Water and Sewerage Company. In terms of method, it is a descriptive-survey correlation with the nature of application and in terms of time it is cross-sectional. The statistical population of this study includes all employees of Isfahan Water and Sewerage Company from which 285 people were selected as the statistical sample using Cochran's formula. The research tools were four standard questionnaires for social responsibility, internal marketing, organizational commitment and intention to leave the job. To measure the validity of the questionnaires, the content method was applied. Also to determine its reliability, Cronbach's alpha was estimated which was 0.893. Data analysis was performed using Spss26 and Smart Pls3 software. Kolmogorov-Smirnov test was used to check the normality of the data and structural equation method was applied to test the hypotheses. The results showed that in Isfahan Water and Sewerage Company, social responsibility, internal marketing and organizational commitment have a significant effect on the intention to leave the job. But social responsibility and internal marketing do not affect organizational commitment; Also the results of the Sobel test showed that organizational commitment has no mediating role in the relationship between social responsibility and internal marketing with the intention to leave the job.