WaterSubject

The effect of employing demand and pressure management techniques on the cost of water reticulation systems is analysed in this paper. The analysis is based on the cost of supplying a cluster of 4000 households serving a range of hourly demands using pipes of various pressure classes. Demand management reduces costs by 25–45% and pressure management increases savings by a further 20–55%. For demands below 50 l per household per hour there is a cost shift from reticulation infrastructure, to properties, to ... Read More

Owing to development pressure for land bordering the Vaal river, in South Africa. Rand Water are revising their development policy. Restrictions were in place to avoid flooding and obstructing the flood flow of the river. Relaxation of the regulations will permit controlled development along the river. A flood hazard-risk index was developed to indicate where development could be permitted. An economic comparison of costs and benefits supports the relaxation.The Vaal Barrage is the original water source for Johannesburg and surrounding areas. The ... Read More

Extensive arsenic contamination of surface and groundwater has been reported in many parts of the world. The possible long term effects and the risks associated with the ingestion of arsenic contaminated water have compelled the regulatory agencies to promulgate a lower standard for arsenic in drinking water. The World Health Organization (WHO) standard for arsenic is 10 ?g/l. The maximum acceptable concentration for arsenic is 25 ?g/l in Canada; recently the United States Environmental Protection Agency (USEPA) adopted a new arsenic standard ... Read More

As the world emerges into the 21st century, many of the major cities may face water crises. The World Meteorological Organisation predicts that explosive growth of urban cities will rapidly deplete our water resources. By the turn of the next decade, world water demand is likely to claim almost half of the total global water runoff that is available every year. Between 1900 and 1995, water use has increased by a factor of six, which is more than double the population increase ... Read More

The objective of the paper is to investigate the attitudes and preferences of the residential water users of the city of Thessaloniki, in order to evaluate the demand management aspects of the urban water policy. A field survey has been conducted in the city of Thessaloniki and investigated among others the reliability of the utility’s services and infrastructure, the acceptability of various water demand options, the willingness to pay of the consumers and the level of public awareness. Straightforward comparisons with the ... Read More

An understanding of pollutant characteristics on impervious surfaces is essential to estimate pollutant washoff characteristics and to design methods to minimise the impacts of pollutants on the environment. This paper presents data on surface pollutant characteristics on an urban road surface in Melbourne, Australia, from samples collected over a 36 day period. The data indicate that buildup over the dry days occurs relatively quickly after a rain event, but slows down after several days as redistribution occurs. The surface pollutant also becomes ... Read More

The aim of this paper is to study the performance of a combined waste stabilisation pond after three years of functioning and the reuse of treated wastewater for irrigating potatoes and lettuce culture. The combined ponds showed good functioning conditions and excellent performances either for organic load (90%), faecal coliform (6 log units) or helminth eggs (100%) and produced a high and perennial effluent quality. The effluent could be used for non-restrictive irrigation, with a clear improvement of culture production and hygienic ... Read More

Based on previous observations of the 45° junction manhole for supercritical flow in the main and lateral branches, the hydraulics of the more common 90° junction manhole were explored. Using a selected manhole geometry involving: (1) a short straight piece in the lateral branch to inhibit full development of the bend wave, and (2) the addition of the junction extension as used in previous designs for the bend manhole, the present study gives results that are in basic agreement with those collected ... Read More

Modern methodologies for planning and design of urban drainage systems are based on the idea of minimising the receiving water pollution. However, in order to implement this concept of ambient water quality standards in practice, there is a need for simple tools that can establish a clear cause––effect relation between the drainage measures and the impact on the receiving water ecosystem. REBEKA is a software tool that has been developed to provide such a tool for a particular type of receiving waters––small, ... Read More

Combined sewer overflows (CSO) are part of common combined drainage systems. Due to the improvement achieved in the efficiency of wastewater treatment plants, the discharge of such CSO became the focus of discussion regarding the quality of the natural water bodies. Thus operation of combined sewer systems and especially of existing detention facilities aims at an extensive avoidance of combined sewer discharge. To fulfil this task, real-time control may be one of the possible solutions. In Germany many communities already made the ... Read More