Desalination 237 (2009) 162–174
Perspectives on sustainable wastewater treatment technologies and reuse options in the urban areas of the Mediterranean region Ahmed N. Bdoura*, Moshrik R. Hamdib, Zeyad Tarawneha a
Department of Civil Engineering, bDepartment of Land Management and Environment, The Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan Tel. +962 (5) 390-3333; Fax: +962 (5) 382-6348; email:
[email protected] Received 14 March 2007; Accepted 18 December 2007
Abstract This paper discusses several options to achieve sustainability in wastewater treatment in urban areas of the Mediterranean region. The first was by decentralizing the treatment rather than installing expensive sewer systems that combine and increase the volume of the waste. The next involved choosing an appropriate treatment technology for the community where several types proposed included lagoons/wetlands, upflow anaerobic sludge blanket (UASB), and soil aquifer treatment (SAT). The common characteristic of all of the described types is that they encourage “zero-discharge” technology. This cyclical, rather than linear approach includes the reuse of the treated effluent for agricultural reuse. The reuse of the wastewater decreases the money spent on fertilizers and it is considered safe, since it has been treated for microorganisms. The traditional linear treatment systems must be transformed into the cyclical treatment to promote the conservation of water and nutrient resources. Using organic waste nutrient cycles, from point-of-generation to point-of-production, closes the resource loop and provides an approach for the management of valuable wastewater resources. The urban areas of many Mediterranean countries are growing rapidly, and ecological sanitation systems must be implemented that are sustainable and have the ability to adapt and grow with the community’s sanitation needs. In order to decide what the appropriate treatment system is, the developer must consider the area’s climate, topography, and socioeconomic factors. There is still a great need in this area for research to improve or optimize the current methods of wastewater treatment. The result of increased attention to this topic will improve the health, economic, and agricultural conditions of a developing community. Keywords: Wastewater treatment technologies; Sustainability; Decentralizing; Reuse; Socioeconomic factors
1. Introduction Water shortage is currently one of the biggest concerns of human beings world wide. According *Corresponding author.
to the Kyoto summit in 2003, two billion people will not have access to safe drinking water supplies in the year 2015 [1]. The Mediterranean countries belong to the regions most affected by water scarcity. Population growth, rising living
0011-9164/09/$– See front matter © 2008 Elsevier B.V. All rights reserved doi:10.1016/j.desal.2007.12.030
A.N. Bdour et al. / Desalination 237 (2009) 162–174
standards and urbanization increase the pressure on the resources, leading to increasing costs of water supply and emphasizing on the need for appropriate water management practices. Moreover, physical and commercial losses in water supply networks are high; water is often supplied for few hours per day or even per week; tariffs are low so that the operation and maintenance costs of the utilities are often not recovered, and wastewater, in most cases, is not adequately treated, leading to environmental and health hazards [2]. Very little investment has been made in the past on sewage treatment facilities; water supply and treatment often received more priority than wastewater collection and treatment. However, due to the trends in urban development along with rapid population increase, wastewater treatment deserves greater emphasis. Currently there is a growing awareness of the impact of sewage contamination on groundwater, rivers and lakes; wastewater treatment is now receiving greater attention from the World Bank and government regulatory bodies [3]. Several research studies showed that, treated wastewater, if appropriately managed, is viewed as a major component of the water resources supply to meet the needs of a growing economy [4–6]. Thus, the new strategy in the Mediterranean region is to fully utilize the reuse of treated wastewater effluents for irrigated agriculture which is the major sector of water consumption in the region [2,7]. The improvement of the security and safety of water supply in the Mediterranean region is the best recipe for social, economic and political stability. Implementing this strategy necessitates the needs for a safe, reliable and sustainable use of treated wastewater. The greatest challenge in implementing this strategy is the adoption of low cost wastewater treatment technologies that will maximize the efficiency of utilizing limited water resources, and ensuring compliance with all
163
health and safety standards regarding reuse of treated wastewater effluents. It is crucial that sanitation systems have high levels of hygienic standards to prevent the spread of diseases. Other treatment goals include the recovery of nutrient and water resources for reuse in agricultural production and to reduce the overall user-demand for water resources [3]. Innovative and appropriate technologies can contribute to urban wastewater treatment and reuse. Based on extensive successful experience in Canada and elsewhere on cost effective and environmentally sound practices of sludge application on agricultural land, there is tremendous potential for the safe disposal of sewage sludge on agricultural land [8]. Currently, in the Mediterranean countries the uncontrolled growth in urban areas has made planning and expansion of water and sewage systems very difficult and expensive to carry out [9]. In addition, many of those moving to the city have low incomes, making it difficult to pay for any water system upgrades [8]. Approximately 60% of the populations in the region are connected to sewerage system [1]. It is a common practice to discharge untreated sewage directly into bodies of water or put onto agricultural land, causing significant health and economic risks. The problem associated with the current treatment technologies is they lack sustainability [10]. The conventional centralized system flushes pathogenic bacteria out of the residential area, using large amounts of water and often combines the domestic wastewater with rainwater, causing the flow of large volumes of pathogenic wastewater. In fact, the conventional sanitary system transfers a concentrated domestic health problem into a diffuse health problem for the entire settlement and/or region. In turn, the wastewater must be treated where the cost of treatment increases as the flow increases. The abuse of water use for diluting human excreta and transporting them out of the settlement is increasingly
164
A.N. Bdour et al. / Desalination 237 (2009) 162–174
questioned and being considered unsustainable [11]. In addition, many treatment systems in region are not successful and therefore unsustainable, since they were simply copied from Western treatment systems without considering the appropriateness of the technology for the culture, land, and climate. Often local engineers educated in the Western development programs supported the choice for the inappropriate systems. Many of the implemented installations were abandoned due to the high cost of running the system and repairs [11]. On the other hand, conventional systems may even be technologically inadequate to handle the locally produced sewage. For example, in comparison to the United States and Europe, domestic wastewater in arid areas like the Middle East are up to five times more concentrated in the amount of oxygen demand per volume of sewage. This is extremely high and may cause a large amount of sludge production [11]. This paper discusses several options to achieve sustainability in wastewater treatment in the urban areas of the Mediterranean region. The
Fig. 1. Vicinity map of the selected countries in this study.
first was by decentralizing the treatment rather than installing expensive sewer systems that combine and increase the volume of the waste. The next involved choosing an appropriate treatment technology for the community where several types proposed included lagoons/wetlands, upflow anaerobic sludge blanket (UASB), hybrid reactor, and soil aquifer treatment (SAT). For the purpose of this paper, examples on the wastewater treatment technologies and reuse options from four countries in the Mediterranean region have been selected, namely, Jordan, Turkey, Lebanon, and Palestine. Furthermore, this study explores various reuse practices in the urban areas of the Mediterranean countries. Fig. 1 shows the vicinity map of the selected countries.
2. Existing wastewater treatment technologies Various methods for wastewater treatment have been used in the Mediterranean countries over the past decades. Many are conventional, such as activated sludge and biofilters, and others
A.N. Bdour et al. / Desalination 237 (2009) 162–174 Table 1 Overview of the wastewater treatment technology types in the selected countries Country
Treatment type
Jordan
Activated sludge Biofiltrataion Stabilization ponds Extended aeration Activated sludge/extended aerated Trickling filter Stabilization ponds Grit and scum removal Extended aeration Stabilization ponds Oxidation ditches Anaerobic Rock filter Imhoff tank and trickling filter Anaerobic sludge stabilization
Turkey
Lebanon Palestine
slightly less conventional, such as oxidation ditches, aerated lagoons and natural treatment systems such waste stabilization ponds. Table 1 summarizes the various types of treatment technologies in the selected countries. In Jordan, the first generation of WWTP of trickling filter and activated sludge types functioned properly without any major problems except for becoming overloaded with time as a result of population growth and forced migration into the country as well as due to the increase in the members of houses connected to the sewerage network. Therefore, the highest priorities in the Government of Jordan nowadays are given for upgrading the existing wastewater treatment plants and the monitoring facilities to fully comply with the World Health Organization (WHO) effluent water quality standards. Furthermore, the export market for food crops grown in Jordan has suffered from restrictions imposed by some of the importing countries of the Arabian Peninsula and Persian Gulf because wastewater, or inadequately treated wastewater, is used to irrigate crops in
165
some parts of Jordan. More recently, standards for exporting crops to Europe have become more rigorous, stressing the importance of addressing the role of wastewater in the water used for irrigation [12]. To address this, the Government of Jordan is implementing an aggressive campaign to rehabilitate and improve the wastewater treatment plants in the country. Of primary importance is the need to establish reasonable standards to protect the health of farmers and the consuming public from infectious agents that can possibly be carried by inadequately treated wastewater. In Turkey, generally three main types of treatment plant were used: (1) stabilization ponds for small communities (
