Journal of
Environmental Chemistry and Ecotoxicology

  • Abbreviation: J. Environ. Chem. Ecotoxicol.
  • Language: English
  • ISSN: 2141-226X
  • DOI: 10.5897/JECE
  • Start Year: 2009
  • Published Articles: 185

Full Length Research Paper

Influence of pre-oxidation with potassium permanganate on the efficiency of iron and manganese removal from surface water by coagulation-flocculation using aluminium sulphate: Case of the Okpara dam in the Republic of Benin

Zogo D.1, Bawa L. M.2*, Soclo H. H.3 and Atchekpe D.1
  1Société Nationale des Eaux du Bénin (SONEB), Republic of Bénin. 2Laboratoire de Chimie de l'Eau, Faculté Des Sciences, Université de Lomé, BP 1515, Lomé, Togo. 3Unité de Recherche en Ecotoxicologie et Etude de Qualité (UREEQ), Université d’Abomey-Calavi, Republic of Bénin.
Email: [email protected]

  •  Accepted: 24 November 2010
  •  Published: 31 January 2011




Okpara dam water contained significant amounts of iron and manganese that could   create problems for consumers. This study perfected a deferrization and demanganization technique preceded or followed by oxidation with potassium permanganate. The maximum iron and manganese contents varied from 30 to 50 and 1.5 to 4.5 mg/L respectively. Under the best conditions, simple coagulation-flocculation was allowed to obtain iron removal yields of 18 to 75%. Manganese was eliminated between 8 and 24%. Pre-oxidation with 2.5 mg/L potassium permanganate allowed attaining of about 99% elimination of iron and about 72% of manganese at a pH of 6.5. The treatment plant composed of a clarification stage followed by oxidation with potassium permanganate at pH 8.5 allowed a complete elimination of iron and manganese.


Key words: Surface water, water clarification, chemical coagulant, potassium permanganate, deferrization, demanganization.