Abstract

Reclaimed wastewater use is crucial for increasing water availability, improving water resources management, minimising environmental pollution and permitting sustainable nutrient recycling. However, wastewater also contains microbiological and chemical pollutants posing risks to human health and the environment, and these risks have to be handled. Successful use of reclaimed wastewater requires stringent standards for its treatment, disposal and distribution. This report summarises global and country-specific wastewater quality standards for different reclaimed wastewater use schemes, discusses specific standards and describes reclaimed wastewater use applications in two selected countries, Spain and Abu Dhabi Emirate. The World Health Organization (WHO) Guidelines for the Safe Use of Wastewater for Agriculture focus on the protection of public health. The European Commission does not directly regulate wastewater use, but discharge of treated wastewater into water bodies is regulated by Council Directive 91/271/EEC, which requires treated wastewater to have a maximum of 25 mg BOD5/L, 125 mg COD/L and 35-60 mg total solids (TS)/L. In sensitive areas, sewage treatment plant effluent must comply with a maximum of 2 mg total phosphorus/L and 15 mg total nitrogen/L. EU Council Directive 2008/105/EC also sets environmental quality standards for priority substances, i.e. pesticides, polycyclic aromatic hydrocarbons, phenolic compounds and volatile organic compounds. In Spain, the EU directives and Royal Decree 1620/2007 regulate use of reclaimed wastewater. The Royal Decree sets quality criteria for microbial parameters, solids and turbidity for different applications. The Regulation and Standards Bureau (RSB) of Abu Dhabi Emirate sets the quality criteria for water discharging to marine and land environments and used for irrigation. These include limits for organic matter, solids, nutrient, pathogen indicators and helminths. In Spain, agriculture is the largest sector for reclaimed wastewater use, consuming approx. 350 Mm3/year. Landscape irrigation and maintenance of natural hydrological regimes are the second largest users, consuming approx. 50-60 Mm3/year of wastewater each. In contrast, only <0.5% of the water used in industry is reclaimed wastewater. In Abu Dhabi Emirate, reclaimed wastewater is not used in crop cultivation, but most of the wastewater produced is used for irrigation of public parks and roadsides (287 Mm3/year) and in forestry (130 Mm3/year). District cooling in residential areas is another application for wastewater use in Abu Dhabi Emirate. The technologies used to facilitate wastewater treatment vary. The Barcelona metropolitan wastewater treatment plant (Spain), which supplies reclaimed wastewater for use, conducts biological treatment with activated sludge, tertiary treatment with coagulation-flocculation, filtration, UV disinfection, post-disinfection and oxygen saturation. The effluent wastewater complies with the Royal Decree and EU directives. In contrast, five treatment plants in the Navarra region of Spain use secondary treatment with trickling filters or activated sludge, two having lagoons for tertiary treatment. The hygiene quality of effluent from these plants does not comply with the Royal Decree and several fail to remove persistent organic compounds and pharmaceutical residues effectively. In Abu Dhabi Emirate, the largest sewage treatment plant, Mafraq, carries out conventional activated sludge treatment, followed by sand filtration and chlorination. Its effluent complies with RSB standards, but occurrence of pharmaceutical residues in effluent wastewater has been documented in Abu Dhabi. Besides standards and regulations and appropriate treatment, other aspects which need consideration in planning reclaimed wastewater use for various applications include: cultural and socio-economic aspects, willingness of users to accept and pay for treated wastewater, online and real-time water quality monitoring, and reduced energy use and waste generation.

Keywords

Reclaimed wastewater use; Spain; Abu Dhabi

Published in

Rapport (Institutionen för energi och teknik, SLU)
2014, number: 70
Publisher: Department of Energy and Technology, Swedish University of Agricultural Sciences & IVL Swedish Environmental Research Institute

SLU Authors

• Dalahmeh, Sahar

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Other Environmental Engineering


Permanent link to this page (URI)

https://res.slu.se/id/publ/55200