نشریه علوم و مهندسی آب و فاضلاب
سال چهارم شماره 3 (پاییز 1398)

The purpose of this study is to determine the effect of utilitarian and hedonic motivation on organizational knowledge sharing through social networks in the Southwest Water and Sewage Company of Tehran Province. This is an applied research method from the objective point of view and a descriptive survey from the point of view of the data collection method. The statistical population of the research is the managers and employees of the Southwest Water and Sewage Company of Tehran Province with 515 people. Sampling method, class and sample size are determined by the Cochran formula 220. A standard questionnaire is used to collect data. Validity of the questionnaire is confirmed by the opinion of the organization's experts and its reliability by Cronbach's alpha. In order to analyze the collected data, Smart PLS software, which is a second-generation software for structural equations, has been used. The results indicated that utilitarian and hedonic motivation is needed to share external and internal knowledge through organizational social networks. Also, to share the internal knowledge of knowledge, functional motivation is proposed.

Groundwater nitrate pollution is nowadays one of the most important environmental issues with significant effect on human and environment health. Due to the importance of this vital water source, methods have been developed for purifying the groundwater contaminated with nitrate. One of the effective and long-lasting purification methods for groundwater contaminated with agricultural drains is the in-situ method of denitrification wall. The general concept of this technology is placing a denitrification wall with carbon material across the nitrate-contaminated groundwater pathway so that it can block the nitrate pollution as nitrate masses pass through the wall due to the groundwater natural hydraulic gradient. Despite widespread acceptance, there are still many unresolved issues regarding the long-term performance of denitrification walls which requires more understanding on the behavior, principles of design and construction methods of such walls. Accordingly the aim of this study was to fully investigate the technology and implementation of denitrification walls in all aspects. The method of this study was library type and the content, explored in simple expressions in different sections, is based on a descriptive-analytical approach to experimental and scientific experiences of this method on contaminated sites. Results showed that denitrification wall can be drilled underground either in form of funnel and gate or continuous configuration and the choice depends on the hydrological characteristics of the site and the cost of materials used in the wall. Also, when water flow contaminated with nitrate passes through the denitrification wall, nitrate pollution is treated with either adsorption or biological removal mechanisms or a combination of them. The right application of the denitrification wall can be economically efficient and the success of the system depends on the use of appropriate tools and solutions for accurate formulation of the problem in the real aquifer environment with its large dimensions and complexity. In this regard, numerical modeling and laboratory studies can help to achieve a detailed understanding of the problem in a real environment.

This research aims at studying the key indicators of success in knowledge management (KM) in urban water and sewage companies. The authors’ proposed model for implementing KM was based on the investigating the current state of the population under study. First, through literature review, nine factors which included a total of 62 components were chosen as the main factors from many key factors in KM's success. A confirmatory factor analysis was used to identify the key factors of success. The results of the performed tests indicated that the experts in the water and wastewater industry confirmed that the indicators considered in this study, can play a key role in the success of the implementation of KM in urban water and wastewater companies. Having the related indices confirmed by industry experts, a questionnaire was distributed among experts for ranking and determining the relationships between the components. Using DEMATEL approach, causal relationships between the factors were mapped out by the interaction-effect diagram. Analysis of the results showed that among the factors studied, the strategies and goals have the greatest effect on the success of implementing KM in urban water and wastewater companies. This research provided valuable information which can help the effectiveness of KM in this business sector. It also provided a solution for the effective step by step development of knowledge management.

The loss of water due to evaporation from reservoirs’ free surface is an important problem in water resource management and accordingly conserving water in storage facilities became a big challenge for water managers and researchers. This has led to developing physical and chemical methods in form of new technologies to save water. In this study applying shade balls as a physical method has been compared with using octadecanol and hegzadecanol alcohols as a chemical method. Three evaporation pans were used to assess the evaporation in three scenarios. Results revealed that both physical and chemical methods have significant effect in evaporation reduction while the shade balls method showed better efficiency. However considering wind effect, oxygen transfer and water quality, shade balls method could be considered as an appropriate method in small scales. Also, for large scale applications, the economic analysis should of course be regarded.

Due to role of water consumption management as a main part in demand management, installing the retrofit accessories for the house fixtures, on the technical side of water consumption management, can have a significant impact on reducing urban water consumption. There is a question, however, on how Water and Wastewater Companies (WWC) can implement such approach and equip households with retrofit accessories. This article presents an optimal plan which includes the kind of accessories, target community and the way of implementation. The study hired the data for Isfahan city customers’ water consumption and prices in Iranian year 1396. According to the cost-benefit diagram for 6 packs of accessories, the optimal pack included 3 aerators, 1 shower head and 1 flush tank. Due to cost and impact of this pack on reduction of water consumption, the target community was selected from customers who have high consumptions over 2 times of consumption authorized pattern. Among 3 ways to implement this plan, distributing accessories by WWC and paying the cost by customers in installment showed shorter payback period and more feasibility in implementing the plan.

About 95 billion m3 of water is used all over the country every year, 1.8% of which is consumed in industrial sector. Sugar factories are among consumers with high water demands. In Iranian sugar factories, between 22 and 27 m3 of water is used per ton of sugarcane which is much higher than the world’s average which is about 11 m3 per sugarcane ton. Besides, the organic load in the wastewater of these factories is high. Therefore wastewater treatment and water reuse are essential for such factories. Water reuse is an effective solution to reduce the consumption of freshwater entry and prevent the environmental consequences. This study introduced a process of sugar production from sugarcane and analyzed the water consumption and feasibility of water reuse in different sections of the production process. Four main methods for reducing water consumption and wastewater production are: rainwater harvesting, using the humidity of sugarcane, water recycle and wastewater treatment and water reuse which are studied and important parameter in each case are introduced. In case of wastewater treatment, application of new methods of treatment such as aerobic granulation will be most efficient.