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MARRAKECH MUNICIPAL WASTEWATER TREATMENT
MARRAKECH MUNICIPAL WASTEWATER TREATMENT
BIOLOGICAL TREATMENT
With well over a million habitants, Marrakech is Morocco’s fourth largest city. During recent years, booming tourism has contributed to the city’s rapid urban and demographic growth. Until 2008, the sewage of the Marrakech-Tensift El Haouz region was disposed in the Wadi Tensift after minimal treatment.
Today, the wastewater treatment process makes uses of conventional biological water treatment, often referred to as activated sludge treatment. The process includes pretreatment a primary treatment, a secondary or a biological treatment and a tertiary treatment, making the water ready for reuse.
PRETREATMENT OF INCOMING SEWAGEThe pupose is to prevent the incoming sewage from damaging the equipment.
� Screening: coarse and fine screens keep debris out � Grit removal: removing sedimentary wastes like sand, silt and grit � Grease removal: removal of oil and grease disturbing the treatment process
PRIMARY TREATMENTAfter pretreatment, the water flows to the primary sedimentation tanks or primary settlers. The suspended solids settle by gravitation and are collected by a rotating scraper into a hopper in the base of the tank. The clear water is decanted and ready for the secondary or biological treatment. The suspended solids or sludge are collected and thickened.
SECONDARY TREATMENTDuring secondary or biological treatment, the biological pollution is degraded by micro-organisms in aerated reactor tanks.The waterborne micro-organisms eliminating biodegradable soluble organic contaminants are referred to as activated sludge. After treatment, the purified water is separated from the activated sludge in 4 clarifiers, and sent back into the Wadi Tensift. As with the primary sludge, the secondary sludge is collected at the bottom of the clarifiers and then thickened.
TERTIARY TREATMENT.The purpose is to provide a final treatment stage to raise effluent quality before it can be used for agriculture and irrigation.
� Coagulation: adding ferric chloride for destabilizing colloidal suspensions � Flocculation: adding polymers for the suspended solids to form larger flocs � Sand filtration: eliminating the flocs of suspended solids � Treating bacterial contamination: ultraviolet disinfection (UV) and chlorination
DIGESTIONDuring the sludge treatment, the biological sludge coming from the secondary treatment is mixed with the sludge from the primary treatment in a closed digester. This reactor creates an anaerobic environment, favoring the degradation of the organic matter from the sludge and thus creating biogas.
GREEN ENERGY PRODUCTIONThe biogas is stored into methane tanks and fuels a cogeneration unit consisting of 4 engines, producing green electricity and heat, providing up to 50 percent of the plant’s energy needs.
AIR TREATMENTIn order to reduce impact for workers onsite and for neighboring inhabitants, 80.000 Nm³ of air/h is treated. Volatile Organic Compounds (VOC) and odors are treated using biofilters and bioscrubbers, an environmental neutral process, requiring neither chemical treatment nor additional energy.
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Operation and MaintenanceThe Marrakech wastewater treatment plant is being operated by Waterleau for a 10-year period.
UNFCCC CertificationThe Marrakech wastewater treatment plant, designed and built by Waterleau, has been validated by the UNFCCC for the Clean Mechanism Development criteria of the Kyoto Protocol for its reduction of CO2 emissions due to the methane production and biogas recovery. The methane production and biogas recovery prevents 60.000 tons of CO2 emissions into the atmosphere.
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Capacity
Population equivalent
Biogas production
Energy production
CO2 reduction
Air treatment
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120.000 m³/d
1.300.000
18.000 Nm³/d
1,6 MWe
60.000 tons CO2 /year
80.000 Nm³/h
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THE FIRST SEWAGE TREATMENT PLANT IN THE REGION, INTEGRATING BIOGAS PRODUCTION AND WATER REUSE
DESIGNENGINEERINGCONSTRUCTIONOPERATIONMAINTENANCE
PROTECTING THE 4 ELEMENTS
We all have the responsibility to handle our natural resources in a careful and sustainable way. Waterleau develops environmental technologies and offers sustainable solutions for water, air and waste treatment, as well as for energy recovery. As an EPC contractor and operator, Waterleau counts more than 1500 references for municipal and industrial clients around the world.
Boulevard La Corniche, Immeuble Marina Centre 01, Appt. N°20, Casablanca, Moroccot. +212 5 22 27 15 38 - f. +212 5 22 20 02 [email protected] – www.waterleau.com
