Determination of Mixing Zones for Wastewater With Receiver Waters

Abstract

INSTRODUCTIONWhen determining the impact of a sewage treatment plant on particular elements of an aqueous environment, it is often improperly assumed that the receiver waters are mixed with purified sewage at the point of discharge or not far from that site. The route of total mixing of pollutants with receiver waters may be several hundred times longer than the width of the riverbed. In fact, the total mixing of wastewater with receiver waters does not always occur at a short distance from the discharge. Determining the distance, at which full mixing should be considered in a given river cross-section in vertical and transverse dimensions [Rutherford, 1994, Miakoto, 2005. Determining the distribution of pollutants within the mixing zone is essential to understand the impact of purified wastewater on aquatic organisms, fish migration, and the health of people using the surface water. Due to this, it is also possible to simulate changes in the quality of river water and to obtain information on the possibility of discharging the purified sewage to surface waters. When forecasting changes in surface water quality, it is very important to learn the concentration distribution within the mixing zone because a large area of excessive concentration of harmful and hazardous components can be found within it. This would result in a reduction in water intake for utility purposes and disturbance of habitats responsible for biodiversity conservation [Adamski, 2000, Ostroumov, 2004, Miakoto, 2005.Mixing of wastewater with receiver waters is possible due to the advection and turbulent and molecular diffusion. The result of these processes is balancing the concentrations of wastewater constituents in the whole volume of water [Ru- Research Article ABSTRACT Discharges from wastewater treatment are among the key sources of pollution, if norms included in the applied legal acts are exceeded. In determining the impact of these objects on water environment it is often assumed that complete mixing wastewater with surface water is in the point or close to the discharge. In fact, the complete mixing of waste water in a short distance from the discharge occurs incidentally depending on the type of sewage receiver. The size and type of specific sewage receiver determines the conditions of self-purification. Complete mixing zone has a huge impact on the intensity of self-purification processes. Therefore, the possibility to determine the size zone of complete mixing of the waste water from the water receiver is important. The issue involves a series of methods, the most computational, which more or less allows to evaluate the distance of mixing waste water. advection, turbulent and molecular diffusion affect mixing wastewater with surface waters. The article discusses the factors influencing the mixing process and the impact of mixing on the self-purification surface waters. The aim of the article is a review of several methods for determining the distance of the segment mix completely discharged wastewater, with regard to the location o...

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