Fate and behaviour of copper and zinc in secondary biological wastewater treatment processes: II. Removal at varying sludge age.
Environ Technol
; 31(7): 725-43, 2010 Jun.
Article
en En
| MEDLINE
| ID: mdl-20586235
ABSTRACT
The mechanisms for the removal of heavy metals during secondary biological treatment of wastewater, with particular emphasis on the activated sludge process, are considered. It is concluded that the predominant mechanism is the entrapment and co-settlement of insoluble metal species in the mixed liquor (biomass). Secondary extracellular polymeric materials, particularly extracellular polysaccharides and other capsule-forming materials, may also play a role. In general, removal of both copper and zinc was superior at the higher sludge ages employed in this study, 4.3 and 8 days, and can in part be attributed to the superior removals of both biochemical oxygen demand and effluent suspended solids achieved at these sludge ages compared with the lowest sludge age studied, 3.6 days. For both copper and zinc there is an increase in soluble metal across the activated sludge process. However, significant removal of both metals occurs as a consequence of the removal of substantial amounts of insoluble metal. The presence of returned sludge liquors, high in settleable solids, to the mixed liquor appears to moderately enhance the percentage removal of copper and zinc. Membranes used in place of secondary sedimentation also enhance removal of both metals by reducing effluent suspended solids. It is concluded that there is potential for maximizing metal removal by optimization of secondary biological treatment in a sustainable manner, without recourse to energy-intensive or chemically-dependent tertiary treatment technologies.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Aguas del Alcantarillado
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Bacterias Aerobias
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Microbiología del Agua
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Contaminantes Químicos del Agua
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Zinc
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Purificación del Agua
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Cobre
/
Modelos Biológicos
Idioma:
En
Revista:
Environ Technol
Asunto de la revista:
SAUDE AMBIENTAL
/
TOXICOLOGIA
Año:
2010
Tipo del documento:
Article
País de afiliación:
Reino Unido