Rainwater tank capacity and potential for potable water savings by using rainwater in the residential sector of southeastern Brazil

Rainwater has been used in many countries as a way of minimising water availability problems. In Brazil, it has been reported that the potential for potable water savings by using rainwater may range from 48% to 100% depending on the geographic region. In southeastern Brazil, water availability is about 4500 m³ per capita per year, but it is predicted to be lower than 1000 m³ per capita per year from about 2100 onwards. The main objective of this article is to evaluate the potential for potable water savings by using rainwater in 195 cities located in southeastern Brazil. Rainwater tank sizes are also assessed for some cities in order to evaluate the ideal tank capacity as a function of potable water demand and rainwater demand. Results indicate that average potential for potable water savings range from 12% to 79% per year for the cities analysed. Ideal rainwater tank capacities for dwellings with low potable water demand range from about 2000 to 20,000 litres depending on rainwater demand. For dwellings with high potable water demand, ideal rainwater tank capacities range from about 3000 to 7000 litres. The main conclusion drawn from the research is that the average potential for potable water savings in southeastern Brazil is 41%. It was also concluded that rainwater tank capacity has to be determined for each location and dwelling as it depends strongly on potable water demand and rainwater demand.     

Urban water and nutrient flows in Kumasi,Ghana

Material flow analysis was applied to model different scenarios which help better identify and quantify water supply and wastewater pollution problems in the city of Kumasi, Ghana. Results show that despite a relative abundance of water resources in the surrounding area of the city, drinking water consumption will remain at a low level (from 49 ± 4 l/cap/day in 2006 to 59 ± 5 l/cap/day in 2015). Changing sanitation practices to using more flush toilets will require significantly more water if these toilets are to be used adequately. The water–nutrient balance shows that total nitrogen (N) and phosphorus (P) outputs of the modelled area are 10 times higher than system inputs, most of this being attributed to human wastes from sanitation. A number of possible measures to reduce nutrient flows into water bodies were identified and quantified, showing the usefulness of the applied model in providing estimates for municipal decision-makers.     

Online water-use feedback: household user interest,savings and implications

This paper reports on the short- and long-term impacts of online water-use feedback provided via a smart metering trial involving 120 households in New South Wales, Australia. Near-real time water consumption feedback was provided via an online portal to half of the sample. Water consumption was uniquely analysed one year pre- and post-intervention, and in conjunction with login data. During one year of available access, the intervention group saved an overall average of 24.1 litres per household per day (L/hh/d) (4.2%). Regression analysis showed the significant savings of active users related specifically to portal login activity. Significant short-term effects persisted for 42 days, averaging at 63.1 L/hh/d. The article discusses the implications for research and practice, including a consideration of how, in addition to providing ongoing access, online portals could be leveraged further by water authorities to help meet urgent short-term supply constraints such as in drought.     

Economic implications of water efficiency measures I: assessment methodology and cost-effectiveness of micro-components

Economic efficiency has recently become one of the primary objectives of water management decisions. In particular, as vulnerability of freshwater systems has become evident and there is a trend for water supply managers to look towards water demand management, identifying the cost of such measures is becoming increasingly important. In England and Wales, Part G of the Building Regulations requires that water consumption of a new dwelling should not be more than 125 litres/capita.day. However, while compliance with this is determined by the water use characteristics of the installed micro-components (WCs, showers, basin taps, kitchen taps, baths, dishwashers and washing machines), the cost to consumers resulting from installing water efficient micro-components is not clear. This paper evaluates the potential economic implications of water saving micro-components, assessed from the consumers’ perspective. A methodology has been developed and implemented to assess the cost-effectiveness of several types of water efficient micro-components. A range of cost assessment methods was applied, and critically reviewed comparing their outcomes. It was found that conventional cost assessment methods are unsuitable for identifying the least cost options to consumers. Of the applied methods, the modified annualised assessment method appears to be a relatively better option.     

End‐use analysis of household water by metering: the case study in Korea

The purpose of this study is to estimate the real water use for a person per day by analysing water use trend of respective metered data. To investigate the unit amount used and component ratio of residential water usage in households, 146 households nationwide were selected as ‘representative samples’, and each end‐use usage was monitored by actual metering from 2002 to 2006. From the results of analysing the acquired data, it was found that the unit amount used in a household was 165.8 litres per capita day (lpcd). Additionally, the unit amount used consisted of six end‐uses; toilet water was the greatest, at 25% (38.5 lpcd), laundry water represented 20% (30.8 lpcd), kitchen water was 19% (28.4 lpcd), bathtub water was 16% (24.7 lpcd), washbowl water was 10% (15.4 lpcd) and miscellaneous use of water represented 9% (13.5%). Comparing the unit amount used according to housing type, 141 lpcd was shown in the case of single houses, and 155 and 159 lpcd were derived in the cases of multi‐unit houses and apartments, respectively. Moreover, the proportions of the aged (50 and over) among the total number of members in single, multihouse and apartment houses were 68.2, 38.1 and 32.4%, respectively. In addition, comparing the amount used and the component ratio among United Kingdom, United States and Korea, the end‐use amount and component ratio in Korea are similar to those in the United States. The total amount of water use in the United Kingdom was less than that in both Korea and the United States.     

高校节水措施探析

就我国目前人均淡水资源短缺的现状,分析了城市用水大户的学校用水存在的问题,提出了校园节水的一些措施以及开发新水源、提高节水意识等建议.     

Pressure transient suppression in drainage systems of tall buildings

ABSTRACT

The suppression of pressure transients in building drainage systems is essential for reducing cross-contamination by the spread of pathogens. The topic is now much better understood due to work following the invention of the first drainage-specific positive-pressure transient-attenuation device in the year 2000. The present research addresses the attenuation of much larger problematic air-pressure transients found in tall buildings. The development of a new technique is described for the attenuation of positive air pressure transients of approximately 2000?mm water gauge (wg) (20?kPa) for which there is currently no means to alleviate. The performance of the new technique was validated by numerical simulation and full-scale test-rig experiments. The full-scale test rig represented a 44-storey building with a 150?mm main drainage stack. The pressure wave generator applied a 2000?mm wg pressure transient from a large accumulator compressor delivering 270 litres of air at 10 bar pressure. This resulted in a capacity of 2700 litres of air at atmospheric pressure delivered into the system within 0.2?s. Results show that a prototype device using the new technique is capable of reducing the applied pressure transient by 88%, rendering it harmless and returning the system to normal operation in a matter of seconds.     

Reducing the concentration of assimilable organic carbon (AOC) in treated drinking water

This study focuses on reducing the concentration of assimilable organic carbon (AOC) in treated drinking water. Experiments were conducted to evaluate the efficiency of AOC removal by biological activated carbon filters (BACF) in a pilot-scale system. The measured values of AOC in treated drinking water were approximately 59.0 ± 8.6 μg acetate-C/L. The results show that BACFs reduce the total concentration of AOC. The concentration of AOC primarily indicates microbial growth in a water supply network, and the amount of AOC in the water is significantly reduced after BACF treatment. After BACF treatment, the removal of AOC was approximately 58% after 40 min of empty-bed contact time. An AOC empirical equation was established by determining the relationship between water quality parameters, such as total organic carbon, dissolved organic carbon, UV₂₅₄, ammonia nitrogen, and total phosphorous.     

Combined space cooling and water heating system for Hong Kong residences

The combined space cooling and hot water preheating system that utilizes the rejected condenser heat is considered one of the most cost effective energy conservation measures. However, simultaneous consumption characteristics are absent in public domain. Questionnaire surveys have been conducted to obtain the relevant information from 126 households residing in high-rise public rental residential buildings in Hong Kong, achieving a confidence level of 95%. The candidate households were selected by a convenience sampling approach, and the questionnaire was constructed using either forced-choice format or in numeric response format. The data obtained were verified by correlation analysis. Data collected includes the occupancy pattern, the installed air-conditioner and water heater characteristics, and the utilization pattern of air-conditioning and hot water. Based upon the collected data and site measurements, hourly, daily and monthly heat recovery and hot water heating demand profiles were established, as well as the correlation between tap water and outdoor air temperatures. The combined profiles enable the evaluation of the feasible use of the combined system, and for future sizing of hot water storage tanks. The potential energy and fuel cost saving associated with the use of the proposed combined system for typical public rental housing in Hong Kong was estimated to be 50%.     

Water-Availability Assessment and Corresponding Public-Health Implications for a Rural Area in Nigeria

This paper presents a case study which describes water-availability problems and corresponding public-health implications for a rural area in Nigeria. A water-availability assessment was carried out in eight villages which are controlled by the Jalingo Local Government of Taraba State. Questionnaires were used to obtain data from sixty households (approximately 650 participants) concerning issues of water-supply sources, water quantity, water quality and community participation in water-resources projects. It was found that (i) community well water is the major source of water, (ii) 35% of the inhabitants depend on well water during the wet season, and (iii) 69% depend on it during the dry season. About 80% of the households have access to less than 30 litres of water per person per day and, because of low water availability, there is a prevalence of water-related diseases.     

人均综合用水量法在西南城市中的应用探讨

科学的需水量预测是城市水源规划和供水工程建设的重要依据。结合实例对我国西南某城市总体规划中市域范围需水量预测方法进行了探讨,并提出人均综合用水量法是预测需水量的有效方法之一。     

Underground water resources in Kazakhstan

The assessment of natural resources and the ecological demand for underground water in Kazakhstan is based on a water-balance equation which considers underground lateral flow, hydrogeoecological regions and river basins. We propose a methodology to estimate the underground water resource for this region. The flow of water in all the rivers of Kazakhstan is estimated at 102.3 km³/year, of which 57.6 km³/year originates in the territory of the country, and 44.7 km³/year in the adjacent countries. With potential increase of the underground water usage up to 15.5 km³/year, the surface water volume could be decreased to 5 km³/year. Optimization of water resource use should be based on the introduction of the water-efficient process of reinjecting and recycling the water supply in all branches of industry, and a reduction in losses during distribution.     

居住建筑使用阶段CO2排放量构成分析

对马鞍山市某典型住户总耗电量、各用电设备分项耗电量、燃气用量、用水量、室内外温湿度变化等进行了为期一年的实测。通过数据分析,得到了测试期间该住户的CO2排放总量、单位面积及人均CO2排放量。分析了不同终端设备的CO2排放量构成及电视机负荷的逐时变化规律。     

Rural domestic water consumption behavior: A case study in Ramjerd area, Fars province, I.R. Iran

Identifying the factors that affect domestic water demand and consumption is very important in management of available regional water resources. In this study, relationships between water consumption and rural household activities are determined by comparing a snapshot of water consumption with rural household behavior of low, medium and high water consumers. In addition, the factors affecting water consumption in rural households are also determined. The data for this study were collected from a survey of 653 rural households in 33 villages of Ramjerd area, Fars Province, in southern Iran, using a simple random sampling technique. The daily water consumption data for a 5-year period (1999-2004) were used. Results of the study revealed that the daily average water consumption for the area was found to be 121.7 l per person per capita per day (Lpcd) (SD=59.2). Water consumption was also found to be significantly correlated with explanatory variables such as “household size” and “age of household's head”. Finally, the results of discriminant function analysis showed that in rural households, garden size, greenhouse size, and garden watering times per month with tap treated water are associated with water consumption.     

Estimating irrigation water demand for green spaces in humid areas: seeking a sustainable water management strategy

Quantifying the irrigation water demand of green spaces (IWDG) is an important part of smart urban water management. However, the IWDG in humid cites is not well characterized. Moreover, the alteration of natural hydrological processes caused by urbanization leading to the dependence of green spaces on irrigation is becoming more common. To better understand the IWDG in humid areas, we developed an estimation model and used the Yangtze River Delta in China as a case study. Results showed that the amount of water required by the green spaces in the Yangtze River Delta was approximately 354 × 10⁶ m³, which was equivalent to 12% of the urban residential water consumption in 2011. This study also investigated the spatial-temporal changes of urban green spaces and estimated their effects on irrigation water demand. These findings provide policymakers an integrated view of the water demand of green spaces associated with sustainable management.     

THE WATER EFFICIENCY OF RETROFIT DUAL-FLUSH TOILETS: EXPERIENCE FROM SOUTHERN ENGLAND

In Water Resources Plan submissions to the Environment Agency in 1999, water companies predicted increases in demand over the next twenty-five years. With significant environmental and economic constraints on new resource developments, attention has focused upon the potential savings that water-efficiency measures can achieve.
The use of water for toilet flushing accounts for about 30% of household consumption, thereby offering considerable potential for water saving. The conversion of existing single-flush siphonic cisterns to dual-flush operation could be one method of achieving a desired reduction in water use, in accordance with the 'twin-track' approach to balancing supply and demand.
This small study, which was jointly funded by Southern Water and the Environment Agency, sought to measure the effectiveness of dual-flush toilets in reducing water consumption through an eight-month study of five retrofit devices which were installed in thirty-three unmetered domestic properties in West Sussex.     

浅谈我国水资源状况及保护对策

阐述了我国水资源的状况及保护对策 ,从人均占有量少、水资源分布不均、水环境污染等方面介绍了我国水资源的现状 ,并提出了通过道德、科技、经济、法律等手段来解决的办法     

An index directly indicates land-based pollutant load contributions of domestic wastewater to the water pollution and its application

As indices directly indicate land-based pollutant load contributions to public water pollution, pollutant load per capita flowing into the water body (PLCwb) for the drainage areas of inner city rivers in Chiba City, Chiba Prefecture, Japan, was analyzed. It was reaffirmed that PLCwb was different by the drainage area. For example, the biochemical oxygen demand (BOD) load per capita flowing into the water body (PLCwb-BOD) was calculated as 0.83 g BOD person(-1) day(-1) for population served with wastewater treatment plant (WWTP). In regards to the three types of on-site domestic wastewater treatment methods in Japan: 0.4-2.1 g BOD person(-1) day(-1) for combined jokaso (CJ), 4.5-21 g BOD person(-1) day(-1) for simple jokaso (SJ) and 4.3-19 g BOD person(-1) day(-1) for night soil treatment (NST). In regards to nutrient parameters of the three on-site treatment methods, population weighted average of PLCwb were almost the same, however, relatively small PLCwb were observed for CJ and SJ through the analysis. Environmental accounting housekeeping (EAH) books for domestic wastewater were prepared based on the analysis results as the application of the indices. EAH books are effective tools for water pollution mitigation in public water bodies. The results of the preliminary correlation analysis of the indices showed that high-efficiency treatment methods including WWTP, agriculture village wastewater treatment facility (AVETF) and CJ are effective in reducing pollutant load flowing into the water body, and that PLCwb have second-order equation relationships with population density of the drainage area. Judging from these characteristics and the analytical results of this study, PLCwb may be useful as an index for demonstrating the benefit of wastewater treatment in reduction of water pollution in the water body.     

多星协同卫星遥感技术在湖南平江抽水蓄能电站水土保持监管中的应用

抽水蓄能电站施工占地范围大,地形复杂,水保监管难度大。而传统水保监测手段主要依靠人工现场调查,耗时耗力,急需引入一种新的技术手段进行抽水蓄能电站水土保持监管。在国家放管服政策实施下,利用以高分系列卫星为主,结合World View遥感卫星的多星协同技术,对平江抽水蓄能电站施工阶段进行扰动面积、施工道路及水保措施的监测。结果表明,利用多星协同技术进行平江抽水蓄能电站多频次水土保持监管,获取的扰动面积提取精度在95%以上,施工道路长度提取精度在95%以上,宽度提取精度在90%以上,均满足工程需要。此外,多星协同技术能及时发现施工现场水保问题并解决,有效减少安全隐患,保护水土,保障电站施工顺利进行,对抽水蓄能电站安全建设具有一定的指导意义。