Abstract: Lebanon is currently embarking on a massive program for wastewater treatment. More than eighty percent of the population will be served, generating approximately 640,000 m3 of treated sewage daily, a highly considerable amount of effluent planned solely to be dumped into the sea. The amounts are so substantial that reusing even a percentage of it generates opportunities of tapping into a huge water resource that is basically being wasted, a water resource that may alleviate existing water imbalances and enable fresh water resources to be devoted to higher quality needs. The use of the treated water for the single largest water consumer in the country (namely irrigation) and in combating major problems resulting from seawater intrusion into fresh water aquifers along the Lebanese coast, are two applications that seem promising enough to justify an extensive study of the subject. The work basically encompasses a detailed planning and management study on water reuse in the country, and concludes with a layout of the usage options for the currently generated and projected wastewater treatment effluents. Optimal solutions as related to the reclamation and reuse or sea disposal of the water will be recommended based on economic, environmental, and social feasibility studies.

Key Words: Lebanon, water resources, wastewater treatment, recycling, irrigation, ground water recharge.

Introduction: Through the natural water cycle, the earth has recycled and reused water for millions of years, and man has adopted nature’s philosophy to realize technologies that are able to simulate and speed up this natural process. Reuse projects have been able to produce reclaimed water that can satisfy most water demands. Treated effluent have been brought up to standards suitable for a variety of nonpotable purposes, the most significant of which is agricultural irrigation and industrial usages (namely cooling, process, and washdown water and boiler feedwater) and the less considerable of which involves its utilization for recreational and environmental purposes. Furthermore, a number of projects have successfully used recycled water indirectly for potable purposes. These projects consist of recharging ground water aquifers where recycled water is spread or injected into aquifers to augment ground water supplies, and to prevent salt-water intrusion in coastal areas.

Lebanon is currently embarking on a massive program for wastewater treatment. A number of major treatment plants are planned for construction along the sea coast to handle the flow from the major urban centers, in addition to a few inland plants that are being implemented to handle flows from different cities. More than eighty percent of the population will be served, generating approximately 640,000 m3 of treated sewage daily, a highly considerable amount of effluent planned solely to be dumped into the sea. The amounts are so substantial that reusing even a percentage of it generates opportunities of tapping into a huge water resource that is basically being wasted, a water resource that may alleviate existing water imbalances and enable fresh water resources to be devoted to higher quality needs. The use of the treated water for the single largest water consumer in the country (namely irrigation) and in combating major problems resulting from seawater intrusion into fresh water aquifers along the Lebanese coast, are two applications that seem promising enough to justify an extensive study of the subject.

The intended thesis will examine all local wastewater treatment plants that are currently practicing or are being planned to practice effluent discharge into the sea and try to determine whether sewage reuse in agriculture, groundwater recharge or other beneficial applications is justifiable. The work basically encompasses a detailed planning and management study on water reuse in the country, and concludes with a layout of the usage options for the currently generated and projected wastewater treatment effluents. Optimal solutions as related to the reclamation and reuse or sea disposal of the water will be recommended based on economic, environmental, and social feasibility studies.

En plus, la mauvaise gestion de l'eau dans l'agriculture due à l'absence des réseaux collectifs d'irrigation mène l'agriculteur à l'utilisation de sa propre source d'eau principalement basée sur l'exploitation des nappes souterraines par l'intermédiaire des puits artésiens sans aucune restriction. En effet, entre 1992 et 1995, plus de 2000 puits ont été ajoutés à un total de 10.000 puits surtout dans la région côtière sud du Mont Liban, au nord et dans la Békaa centrale (FAO, 1996). Ce puisement anarchique des puits a induit une pollution des nappes phréatiques par l'eau salée et une élévation des valeurs de la salinité du sol (El Moujabber et Bou Samara, 2001 ; Atallah et al., 1997).

Scope of Work: Conceptual planning of a reuse project typically consists of the following tasks:

1. Definition of project objective, ranging from pollution control to the need for alternative water supplies.

2. Gathering of background data, regarding existing wastewater and water facilities, existing pollution problems, future needs for water supply, quality and quantity of wastewater treatment plant effluents, current and projected price of water, and social willingness to use reclaimed water.

3. Delineation of the project study area that should encompass all locations within a practical distance of the project that can potentially benefit from reclaimed water.

4. Determination of requirements for reuse by identifying use categories according to health and water pollution control regulations.

5. Identification of a potential market for reclaimed water, needed to determine project profit to counterbalance project expenses.

6. Screening and analysis of alternatives; primarily the two main alternatives considered are either the continuation with the current practice of sea disposal, or the usage of the water for reclamation purposes.

7. Resolution of optimal final decision by determining the most well-rounded, multidimensional satisfying alternative.

Methodology:

1. Detailed research pertaining to the subjects of wastewater reuse in irrigation, groundwater recharge, and industrial usage, will be conducted.

2. Background data will be collected from local municipalities, the ministry of environment, and CDR. Social attitudes and reactions towards the proposed plan will be established from surveys.

3. The use of a digitized GIS map will be utilized for the generation of study area plans, and to build a clear and easily accessible spatially associated database of all relevant information.

4. Market assessment will be performed by building an inventory of potential users and their water quality and quantity need requirements, determination of amount of their demand that can be replaced with reclaimed water, and the establishment of health and environmental related requirements.

5. The analysis of alternatives will be based on technical, monetary, environmental, and social factors. Monetary analyses will include economic and financial analysis. The economic analyses focuses on the value of the resources invested in the project to construct and operate it, the financial analysis is based on the market value of goods and services at the time of the sale.

6. The final resolution is decided upon with the help of computer models that allow the above mentioned parameters to be inputted as the factors on which to base the decision making process.

Project Significance: Lebanon has always enjoyed an abundance of water up to the present day, but overconfidence in the fact that the situation will remain so for many generations to come has placed water conservation practices a long way down on the priority list of local officials.

The average rainfall in this country is estimated to be around 8,600 million cubic meters (MCM) per year. Of which only 2000 MCM is available for use (i.e. 24% of total rainfall) and this may drop drastically (by about 55%) during dry years, that usually occur with a frequency of one out of 10 years but sometimes goes down to 3 consecutive years, as it happened in 1989, 1990, 1991. Comparing projected water demand to supply, conclusive studies conducted by Jaber (1995) show clearly that within the coming 25 years water deficiency is expected to be about 24.5% of the total water demand (see Table 1).

The rising demand for water associated with the ever growing population of the country which in and by itself foresees a shortage of water in the near future, is coupled with even further unfortunate circumstances. Old water resources are increasingly loosing ground as safe sources of potable water because of the increasing haphazardly manner of sewage disposal in the country, and the acute sea intrusion problem associated with over pumping in coastal city centers has rendered a large number of drinking water wells totally obsolete. A properly implemented reclamation program will not only be able to procure an added amount of usable water, but will also be able to save our ever declining fresh water resources for more highly valued purposes.

In addition to providing a dependable, locally controlled water source, water recycling provides tremendous environmental benefits. By providing an additional source of water, water recycling can help us find ways to decrease the diversion of water from sensitive ecosystems. Plants, wildlife, and fish depend on sufficient water flows to their habitats to live and reproduce. The lack of adequate flow, as a result of diversion for agricultural, urban, and industrial purposes, can cause deterioration of water quality and ecosystem health. Water users can supplement their demands by using recycled water, which can free considerable amounts of water for the environment and increase flows to vital ecosystems. In addition, the impetus for water recycling comes both from a water supply need, and from a need to eliminate or decrease wastewater discharge, in our case to the ocean. When pollutant discharges to oceans, rivers, and other water bodies are curtailed, the pollutant loadings to these bodies are decreased. Moreover, in some cases, substances that can be pollutants when discharged to a body of water can be beneficially reused for irrigation. For example, recycled water may contain higher levels of nutrients, such as nitrogen and phosphorus, than potable water. Application of recycled water for agricultural and landscape irrigation can provide an additional source of nutrients and lessen the need to apply synthetic fertilizers. Furthermore, recharging groundwater aquifers with recycled water may also impede the increasing inflow of seawater due to unregulated over pumping, and reduce, stop, or even reverse declines of groundwater levels.

References:

1- Asano, T., Wastewater Reclamation and Reuse, Water Quality Management Library-Volume 10, Technomic Publishing Co., Pennsylvania, 1998.

2- Cowdin, S., Peters, H., “The Economics of Groundwater recharge Projects”, ASCE, Proceedings of the International Symposium on Artificial Recharge of Ground Water, New York, 1988.

3- EPA, www.epa.gov/region9/water/recycling, Water Recycling and Reuse: The Environmental Benefits, Water Division Region 9, EPA/909-F-98-001, May/29/2000.

4- EPA/USAID, Guidelines for Water Reuse, Technology Transfer Manual, EPA/625-R-92-004, Cincinnati Ohio, September1992a.

5- EPA, Wastewater Treatment/Disposal for Small Communities, EPA/625/R-92/005, Cincinnati Ohio, September 1992b.

6- EPA, Process Design Manual for Land Treatment of Municipal Wastewater, EPA625/1-81-013, Cincinnati Ohio, October 1981.

7- Fawaz, Mohammad, واقع المياه في لبنان, الحلقة الدراسية الأولى, Beirut, 27-28 November, 1992.

8- Huisman, L., Olsthoorn, T.N., Artificial Groundwater Recharge, Pitman Advanced Publishing Program, Melbourne, 1983.

9- Jaber, B., Water Resources, Unpublished document (Arabic edition), 1995.