Water losses investigation and evaluation in water distribution system – the case of SA city in China

Faced with the severe leakage and chaotic water management situation in developing countries, this research is committed to provide an appropriate and practical water audit calculation method for most water companies so as to guide their leakage control management. It prepares a recommended basic standard terminology for calculation of real and apparent losses, which can be consistent with practice in China. Due to more detailed subdivision of unmetered water along with water component analysis, the water consumption of SA city can be calculated more accurately. The proportion of water loss in SA is 18.02%, while unbilled authorized consumption contributes no more than 1% to the total water consumption. Meanwhile, the “Neighbourhood Metering Area (NMA)” project in SA city also suggests that metering inaccuracies and leakage on service connections up to the point of customer metering can be prioritized for active leakage control in China.     

Using water consumption smart metering for water loss assessment in a DMA: a case study

ABSTRACT

In this study we analyse the benefits that may be gained from using a smart metering system to assess water losses at a district level with reference to a real case. Consumptions of all the users of this district metered area (DMA) were monitored at an hourly time step by means of electromagnetic meters. Assuming that information on water consumption was available for only a portion of users, we then estimated the water consumption of the entire DMA and calculated the error committed in this estimation as the number of available users varied. Finally, as the simultaneous hourly pattern of inflow into the DMA was also available, we used the water balance method to assess water losses. The results obtained show that monitoring even only 60% of users makes it possible to achieve an error of less than 2% in the estimation of daily consumption across the entire DMA.     

Performance analysis of the domestic water meter park in water supply network of Ibarra,Ecuador

Apparent losses are one of the most important components of non-revenue water and mainly caused by water meter under-registration. This paper studies the performance of a water meter park from a developing country water utility in Ibarra city, Ecuador. The study includes three major aspects: water meter error curve reconstruction with seven different flow rates; water meter evaluation as a function of class, manufacturer and totalized registered volume, use of two water consumption patterns for weighted error determination and their influence on water balance and performance indicators analysis. Results indicate that 44% of analyzed meters works at optimal conditions. Weighted error obtained by using two different consumption patterns indicates a 0.95% difference, which has an important impact on water balance and performance indicator results. This detailed analysis of water meters can help to develop a more efficient water meter replacement strategy and to estimate apparent water loss volume more accurately.     

Measures to control rising groundwater for construction on slightly permeable soils

The possibility is shown of controlling rising groundwater at sites composed of slightly permeable, silt-clay soils. Ways of decreasing water losses into the soil by reducing water consumption, monitoring consumption and diversion of water, removal of water-containing structures and networks to the surface, etc. are suggested. Construction of blanket drains in the base of structures is also recommended. Russian National Committee on Soil Mechanics and Foundations. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 21–23, March–April, 1994.     

Quantifying measuring errors of new residential water meters considering different customer consumption patterns

Water meter measuring errors vary depending on the water flow rate. The difference between water actually consumed and registered by a meter will differ depending on how water consumption is distributed by flow rates. Published studies assessing the performance of new residential meters have only analysed the error curves of the meters – without calculating the influence that consumption patterns have on their field performance. In most cases, research has been limited to analysing compliance with published standards. This work presents an evaluation of the actual commercial losses to be expected considering the consumption characteristic of domestic users. Several types of residential meters have been tested and the error curves obtained have been combined with measured consumption patterns of domestic users. As a result, this paper provides information about the order of magnitude of the initial measuring error as a function of the residential meter model and user characteristics.     

Drivers of non-revenue water: A cross-national analysis

Reducing water losses is seen as key to sustainable water management, but turns out to be challenging. This paper applies a panel data analysis with fixed effects to assess the major drivers of non-revenue water, some of which are under the control of utilities and some of which are not. The analysis finds that the most important drivers are population density per kilometer of network and type of distribution network, which are mostly resulting from urbanization patterns which are factors mostly out of the control of the utility. Yet, low opportunity costs of water losses and high repair costs of water losses have an important adverse effect on water loss reduction. We also found that the country environment in which the utility operates has an important impact on non-revenue water levels.     

The development of reference values for energy certification of buildings in Lithuania

The paper deals with the experience in the field of arrangement of the building certification system in Lithuania. The arranged document provides the energy consumption in a building to estimate according to the calculation results, including heat losses through the building envelope elements, due to the ventilation, air infiltration and domestic hot water. The reference U-values for the building elements representing the best 50% of the building stock are derived. The changes in the energy consumption and reference values in regard with building renovation development are discussed.     

A composite indicator for water meter replacement in an urban distribution network

In water supply management, volumetric water meter are typically used to measure users' consumption. With water meters, utilities can collect useful data for billing, assess the water balance of the system, and identify failures in the network, water theft and anomalous user behaviour. Despite their importance, these instruments are characterised by intrinsic errors that cause so-called apparent losses. The complexity of the physical phenomena associated with metering errors in aging water meters does not allow meter replacement to be guided by single parameters, such as the meter age or the total volume passed through the meter. This paper presents a meter replacement strategy based on a composite ‘Replacement Indicator’ (RI) that aims to reduce apparent losses. The performance of a meter during its operating life was analysed by means of this indicator, which signals when the meter needs to be replaced. To test the reliability and robustness of the proposed indicator, a Monte Carlo uncertainty analysis was performed. The methodology was applied to a real case study: a district metered area (DMA) in the Palermo city water distribution network (Italy). The analysis showed that ranking based on the composite indicator is better than common ranking procedures based on typical variables (e.g., the meter error curve or the meter age): the proposed indicator can better select the meters to be replaced and favourably affect the associated costs.     

同程与异程采暖系统在节能方面的比较

利用对比沿程水头损失及局部水头损失的方法,分析了同程系统和异程系统的总体能耗,得到同程系统的能耗小于异程系统的结论,并进一步推广同程系统的使用,以达到节能的目的。     

Estimation of the benefits yielded by pressure management in water distribution systems

The occurrence of water losses in Water Distribution Systems is inevitable. Knowing that most of the real losses take place in distribution mains and in service connections, the methodology proposed in this paper is based on several leakage-assessment approaches from literature and on water distribution network modeling. This allows assessment of the benefits that can be achieved by pressure management in Water Distribution Systems, particularly in terms of water production reduction. Moreover, this approach can be useful for cost benefit analysis to help establish the level after which there is no more economic interest in reducing water losses (Economic Level of Leakage). Finally, the results from hypothetical case studies are presented and discussed, assuming the installation of Pressure Reducing Valves at District Metered Areas entry points.     

Assessment of apparent losses in urban water systems

Apparent losses relate to water that is consumed but not paid for. Most research carried out in the last decade particularly in the United Kingdom focused mainly on leakage. Until now, there are no set procedures and guidelines for assessment of apparent losses. Much work remains to bring it to par with the available tools and methodologies for leakage management. In the absence of adequate data and proper methodology, most developed countries use default values, which tend to be lowest values for well‐managed water systems, for computation of apparent losses. These may not be appropriate for developing countries. This paper presents a methodology for the assessment of different components of apparent losses based on field audit and operational data for Kampala city's water distribution system in Uganda. Metering inaccuracies and illegal use have been found to be significant components of apparent losses. Appropriate intervention strategies have been developed based on the assessment.     

城市供水规划中人均综合用水量指标的确定方法

在城市供水规划中，用水量指标值的合理制定是预测用水量的关键步骤。根据同一城市人均综合用水量与生活用水量之间相对稳定的比例关系，得出了城市用水量指标的预测公式；该公式中的系数由城市多年的用水规律得出，而且还可根据城市发展进程和规划目标的变化作出及时调整。采用该方法对南方某城市新一轮规划的城市人均综合用水量指标进行了预测，其结果与目前居住小区规划中使用的数据相吻合，说明这一方法是比较合理的。     

An approach to optimising compressed air systems in production operations

A low-cost, non-intrusive method of quantifying the energy consumed by compressed air systems (CASs) and lost through system leaks is described, with various means of minimising energy consumption presented. Case studies across different industrial facility types are examined where the approach used in quantifying energy losses due to system leaks has been implemented. Monitoring across 5 sites identified circa 500,000?kWh of waste energy due to leaks of which 30–60% can be saved. The approach has reduced waste electrical consumption by 60% on one site. Non-energy-related benefits arising from awareness of CAS losses are described. The proposed approach effectively illustrates the benefits of CAS energy analysis in a manner which can be quickly and easily implemented using off-the-shelf energy monitoring and data-logging equipment. The methodology can be regularly applied to provide continual monitoring and management of the optimal state of an industrial facilities CAS.     

Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor

In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.     

城市供水规划中人均综合用水量指标取值讨论

根据同一城市人均综合用水量与生活用水量之间相对稳定的比例关系建立人均综合用水量指标模型，采用该方法对广东某城区新一轮规划的城市人均综合用水量指标进行了预测，其结果与目前居住小区规划中使用的数据相吻合，说明这一方法是比较合理的。     

Experimental investigations of a decentralized system for heating and hot water generation in a residential building

Nowadays, modern heat supply technologies are preferred by the decentralized municipal sector because they considerably reduce heat transfer losses. One such solution is a heating system using residential thermal stations (RTS). The advantages of a heating system with RTS, as compared with hot water storage vessels, include stabilizing heat costs, saving energy and a decrease in heat transfer losses.This paper presents the results of an experiment investigating heat consumption in a residential building using RTS. The building, located in Lublin, Poland, was supplied by the local district heating network. The energy consumption was monitored from April 2007 to April 2009. The efficiency of this system was 71.4% during the period when heat was required (winter) and 61.5% during the summer; an annual average efficiency of 67.1%. The energy consumption of the space heating system varied from 0.03 to 0.53 GJ m⁻² of the flat's surface area, with the average value being 0.22 GJ m⁻². The influences of the location of the flat within the building and the surface area of the flat on the quantity of heat required for space heating were analysed. Specific attention was paid to the occurrence of local heat flows between flats.     

The apparent losses due to metering errors: a proactive approach to predict losses and schedule maintenance

The effects of water meter age and private tanks on the apparent losses due to metering errors were evaluated by experimental and theoretical analyses. A monitoring campaign on a small district metered area (DMA) was carried out to determine the causes of apparent losses and implement a numerical model. Metering errors are affected by the flow rate passing through the meter, which is dependent on the network pressure and water level of the private tank. A node model that reproduces the effect of private tanks was coupled with EPANET and was applied to the DMA. The proposed modelling approach was used to identify where apparent losses are higher and to schedule maintenance. The model predicted the results of the installation of a device that minimises the effect of private tanks on apparent losses, the unmeasured flow reducer (UFR), the economic impact of losses and substitution programmes.     

A novel water heater using injected hydrogen combustion exhaust

With the aim of mitigating the necessity of water storage when using electric heaters and the losses and pollutant emissions produced by natural gas heaters, this article proposes a water heater based on a gas turbine system, fed with hydrogen and oxygen obtained by electrolysis within the same unit.By applying a thermodynamic analysis to the whole process, a global energy efficiency of 100% can be obtained. This high efficiency makes sense because the electrolysis losses occur in the form of heat losses, which can be used by the cold water. Because the potential of the electrolysis increases, the heat generation due to the electrolysis heat losses increases and, although the electrolysis efficiency is reduced, the global energy efficiency of the water heater remains at 100%. However, the increase in the electrolysis potential also reduces the response speed of the heater, because of the switch in both convection and conduction heat transfer. Convection heat transfer takes place when the combustion exhaust is injected directly in the cold water flow, downstream of the turbine, avoiding the losses associated with a heat exchanger and a high-temperature exhaust. The electrolysis heat losses are transferred to the water by conduction through the electrolyser walls.     

Environmental implications of water efficient microcomponents in residential buildings

The Code for Sustainable Homes (CSH) in England sets out various water efficiency targets/levels, which form part of environmental performance criteria against which the sustainability of a building is measured. The code is performance based and requires reduction in per capita water consumption in households. The water efficiency related targets can be met using a range of water efficient microcomponents (WC, showers, kitchen taps, basin taps, dishwashers, washing machines, and baths). However, while the CSH aims at reducing the adverse environmental implications associated with the dwellings by promoting reduction in water consumption, little is known about the energy consumption and the environmental impacts (e. g. carbon emissions) resulting from water efficient end uses. This paper describes a methodology to evaluate the energy consumption and carbon emissions associated with the CSH's water efficiency levels. Key findings are that some 96% and 87% of energy use and carbon emissions, respectively associated with urban water provision are attributable to in-house consumption (principally related to hot water), and that achieving a defined water efficiency target does not automatically save energy or reduce carbon emissions.     

Experimental verification of a method for estimating energy for domestic hot water production in a 2-stage district heating substation

In this paper we compare our estimate of energy consumption for domestic hot water production in a building with the measured value. The energy consumption for hot water production is estimated from the measured total power consumption. The estimation method was developed using computer simulations, and it is based on the assumption that hot water production causes rapid and detectable changes in power consumption. A comparison of our estimates with measurements indicates that the uncertainty in estimation of hot water energy consumption is ±10%. Thus, the estimate is comparable to class 3 energy meter measurements, which have an uncertainty of ±2-10%.