Potable Reuse Of Wastewater Research Articles

Technologies for wastewater treatment appropriate for reuse: Potential for applications in Greece

During the past 15 years, a wide variety of technologies have been developed that can be used for the treatment of wastewater for reuse applications. To assess the need for alternative technologies, potential reuse applications are reviewed. Changes in wastewater management, including the growing importance of decentralized wastewater management, is examined. The role of decentralized wastewater management is considered with respect to wastewater treatment, reclamation, and reuse. Technologies are presented and discussed for a wide range of reuse applications, ranging from individual homes to large centralized systems. The performance of representative technologies is assessed. A brief review of the water resources of Greece is presented to provide some perspective on the potential for wastewater reclamation and reuse in Greece.

Wastewater Reuse Potential in Turkey: Legal and Technical Aspects

Treated wastewater is one of the potential water resources in especially arid and semi arid regions. Overall, Turkey is not poor in terms of water sources. However, due to distribution of water in time and in space water shortage is felt. Wastewater reuse potential is especially high during summer months for agricultural and recreational purposes. In coastal areas of Turkey treated wastewaters from the coastal settlements are reused to irrigate the green areas and parks. Surplus effluents are discharged into the sea by use of marine outfall pipes. Extended aeration type of activated sludge processes followed by chlorination is the most common form of the treatment. Agricultural reuse is encouraged in inland rural regions. Simple wastewater treatment methods such as stabilization ponds are popular in rural areas. Water quality standards regulating irrigational wastewater reuse are recently set in Turkey. Guidelines given by World Health Organization (WHO) are generally adopted except the limits for the intestinal nematodes and the residual chlorine. Irrigational reuse standards as well as the degree of the treatment have to be revised based on the local experiences. Assurance of a given effluent quality is one of the major problems in management of the wastewater reuse in rural areas. Local examples are presented to illustrate this point.

Agricultural and Municipal Use of Wastewater

Areas in relatively dry climates often have water shortages and there is competition between municipal and agricultural (irrigation) water use. The problem can be alleviated by using the water twice, first for the cities and then for agriculture after the municipal wastewater has been properly treated. There are now two sets of water quality standards for irrigation with wastewater: a stringent set for developed countries, and a less stringent set for developing countries. Also, more and more cities will have to use their wastewater internally for irrigation of parks, etc., and even for drinking. The latter requires advanced wastewater treatment. Part of this treatment can be supplied inexpensively by a groundwater recharge and recovery system, which also provides storage and enhances the aesthetics of direct potable reuse of wastewater by breaking the pipe-to-pipe connection. The renovated water from a recharge or “soil-aquifer treatment” system generally can be used as such for unrestricted irrigation, but potable use requires additional treatment.

Role of Groundwater Recharge in Treatment and Storage of Wastewater for Reuse

Reuse of municipal wastewater requires treatment so that the water meets the quality requirements for the intended use. Irrigation of vegetables consumed raw requires absence of pathogenic organisms. To achieve this, fecal coliform concentrations should be essentially zero and the water should be filtered. This requires intensive treatment. For developing countries, however, where adequate sewage treatment often is lacking, the World Health Organization allows up to 1000 fecal coliform bacteria per 100 ml, which can be obtained by lagooning. Potable reuse requires much more intensive treatment, including lime clarification, denitrification, carbon adsorption, reverse osmosis, and disinfection. Where hydrogeologic conditions permit groundwater recharge with surface infiltration facilities, considerable water quality improvement is obtained by the movement of the wastewater through the soil, vadose zone, and aquifer. The resulting soil-aquifer treatment costs are less than 40% of the costs of equivalent in-plant treatment. Soil-aquifer treatment systems also are simple and robust, offer storage of the water to absorb differences between supply and demand, and enhance the aesthetics of potable reuse of wastewater. Hence, they can play an important role in wastewater reuse.

Research Required to Establish Confidence in the Potable Reuse of Wastewater

EPA, AWWA, and WPCF sponsored a workshop to define and establish priorities and provide direction for a potable reuse research program. This article highlights the conclusions and recommendations of the various workshop groups in dealing with the topics of wastewater treatment, treatment reliability and quality control, health effects associated with inorganic pollutants, organic pollutants, and biological pollutants, and socio‐economic considerations.