نشریه علوم و مهندسی آب و فاضلاب
سال پنجم شماره 4 (زمستان 1399)

Water Distribution Networks (WDN) are amongst the six pillars of smart urban infrastructures which can be managed without or in connection with other smart grids. This research uses an adaptive study to review and compare the approaches and international experiences of smart WDNs. The comparative results initially verify that smart WDN can relatively reduce bursts, leakage, and the reaction time required for operation in comparison with SCADA. In addition, it improves asset management, social awareness about water consumption, the satisfaction of users, water quality, and the revenues of water companies. This study also outlines that smart WDN is a multidisciplinary issue and requires consecutive steps for implementation as described in the Spiral model. This conceptual model is more like a roadmap. It introduces a methodology for upgrading SCADA to smart WDNs and illuminates practical steps, in addition to the short and long term scopes, toward integrated supply and demand management of urban water. Here, the proposed methodology emphasizes pilot studies in different scales and conditions for the validation of integrated software-hardware system prior to any practice.

In recent years due to water resources scarcity and increase in water extraction costs, more attention has been given to water consumption; specifically, urban water consumption as a more sensitive and high priority demand with high costs of supplying. Accordingly the water and wastewater authorities are directed to modern water management methods including water demand management policies and water conservation. These practices and policies not only have widespread positive and negative effects in different aspects, but also by affecting the different components of the system, can make more severe and immense effects. Amongst the most important aspects related to such policies are the social aspect and the main stakeholders of the urban water management, i.e. households. Thus, the purpose of this paper is to address these different aspects by reviewing the requirements and obligations of the integrated framework in assessment of water demand management policies. To this end, firstly the importance and necessity of assessing the water demand management policies has been discussed. Then, different approaches for integrated environmental assessment and management have been introduced by demonstrating the main implications. Also, some illustrative examples are presented. Finally, the agent-based model is introduces as the integrated approach for investigating the micro-level social interaction and assessment of macro-level aggregated impacts.

Minimum Night Flow (MNF) analysis in District Metered Areas (DMAs) is the most important method for monitoring and estimating the leakage volume in Water Distribution Networks (WDNs). An estimation of night leakage in a DMA is calculated by deducting legitimate night consumption from MNF. Therefore, the amount of household night water consumption is a crucial parameter in determining the leakage level in WDNs. The household night water consumption may be different in various countries or even in different utilities within a country. Therefore, a precise estimation of household night water consumption and use appropriate techniques are required to determine the volume of physical losses using MNF analysis. The present paper provides a literature review on analysis methods for estimating household night water consumption in different countries, their estimated values, and the effective parameters on the per capita household night consumption. This review could be used by practitioners and researchers dealing with estimating leakage level in WDNs.

In the present paper, based on case study, risk measurement using failure mode effects analysis (FMEA1) methodology was performed in 4 chosen water and wastewater treatment plants in Mashhad. In this method, first the chlorination units were categorize to 6 classes including cylinders storage, chlorination room, gas cylinders, transportation of chlorine gas, joints of chlorination equipment, and educational systems of employee and management. The different potential modes of failures of these water and wastewater treatment units were listed and the severity rating, occurrence rating, and detectability rating were determined with interviewing the experts. According to these, risk priority number was calculated and the risk of mode of failure was prioritized in the parts of the water and water treatment plants. The results indicate that in general, the first priorities corresponded to the risks in terms of electrical and transportation; and using standard equipment and appropriate means of transport were suggested.

Construction of wastewater treatment plant, if energy and water resources are recovered, can justify some undesirable effects such as greenhouse gas emissions. sludge management and treatment is one of  the most complex and costly parts of  treatment  plants  that can cover  up  to  60%  of  initial capital  and  operation  costs of  a  wastewater  treatment  plant. Considering the importance of reducing energy consumption in wastewater treatment plants as an environmental  and  economic  point  of  view,  some investigations  have  done  to construct and modify wastewater plants worldwide in order to the self-sufficiency of energy supply recently year. This article is a practical study that the costs of capital and energy consumption were analyzed in comparison with other processes for MLE1 process with aerobic digestion in wastewater treatment plant in east of Mashhad with flow rate of 80000 m3/d. The results show that energy consumption in this system is about 2 times of similar wastewater treatment plants with optimal process. Also, however, the energy level will decrease from 1 kwh/m3 to 0.58 kwh/m3 with the change of aerobic digestion to anaerobic, but it is necessary to use of CHP system for decrease of energy consumption and recovery in comparison with constructed or optimized of wastewater treatment plants in worldwide. Therefore, it is necessary to pay more attention in selecting the process of liquid and sludge section in wastewater treatment plants under studying or optimizing wastewater treatment plants built in the country because of the numerous benefits of reducing energy consumption in wastewater treatment plants, in order to be self-sufficient in energy supply.

In the present paper, the HELP model was first introduced as a US EPA approved software to estimate the amount of leachate produced in landfills, and its implementation was described. Hydrological data were then prepared for the time of operation of the hypothetical landfill of waste produced in Urmia (as a case study) and 30 years after its closure at different conditions. According to the results, at the time of operation during the most severe rainfall conditions, due to incomplete final coverage, infiltrated leachate into the soil will increase to 8.282 m3/year, which can have a significant impact on soil and groundwater contamination. Also, using its outputs as baseline data in leachate calculations during the 30 years after landfill closure results in a 6.71% increase in the amount of leachate (this leachate is generally ignored in leachate design calculations). In other words, precipitation and hydrological conditions change the moisture contenet of the buried layers during the operation of the burial site, which, if approached by saturation conditions, will result in excess moisture form the leachate. In the long-term, increasing or decreasing precipitation will have a direct effect on leachate.