Wastewater Treatment and Reuse in MENA Countries
What is Wastewater Reuse?
The term ‘wastewater’ refers to any water that is no longer wanted. In other words, it is the used/spent water discharged by households (from bathing, washing, flushing toilets, etc.), agriculture and industrial facilities. About 99% of wastewater is water and only 1% is solid waste. Therefore, wastewater has great potential to mitigate the freshwater shortage in arid and semi-arid regions.
Wastewater reuse or recycling can be defined as ‘using wastewater or reclaimed water from one application for another application. The deliberate use of reclaimed water or wastewater must be in compliance with applicable rules for a beneficial purpose (landscape irrigation, agricultural irrigation, aesthetic uses, groundwater recharge, industrial uses and fire protection).’
Types of wastewater reuse can be divided into the following categories:
- Urban reuse: irrigation of parks, playgrounds, yards, highway medians and residential landscapes, as well as for toilet flushing and fire protection in commercial and industrial buildings.
- Agricultural reuse: irrigation of non-food crops, such as fodder and fibre, commercial nurseries and pasture lands. For food crops, high-quality treated water is used.
- Recreational impoundments: ponds and lakes.
- Environmental reuse: creating artificial wetlands, enhancing natural wetlands and sustaining stream flows.
- Industrial reuse: mainly for process water and cooling water.
- Groundwater recharge: via direct injection to groundwater aquifers.
Overview of wastewater treatment process
Wastewater treatment is the process of removing contaminants from water through engineered physical, chemical and biological processes to produce an effluent that can be safely reused or discharged to the environment. There are four major stages of wastewater treatment:
- Preliminary treatment involves screening and grit-removal units to remove large and coarse objects found in the raw wastewater (sanitary items, plastics and rags, hair, rocks and gravel) that may block or damage mechanical equipment.
- Primary treatment separates the suspended solid matter from the wastewater by discharging the wastewater into sedimentation tanks to allow the solids to settle. The settled solids, called sludge, are scraped from the bottom of the tanks by large scrapers and pumped away for further treatment.
- Secondary treatment removes the biodegradable organics, suspended solids and nutrients by pumping the wastewater into aeration systems and biological treatment systems.
- Tertiary treatment removes specific constituents that cannot be removed by the previous steps, such as refractory organics, heavy metals and dissolved solids
 McKenzie, C. (2005). ‘Wastewater reuse conserves water and protects waterways’. The National Environmental Services Center (NESC). Available at: www.nesc.wvu.edu/ndwc/articles/OT/WI05/reuse.pdf.
 Evine, A.D., Asano, T. (2004). ‘Recovering sustainable water from wastewater’. Environmental Science and Technology, 38: 201A–208A.