Browsing by Author "Wydra, Kerstin"

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Making Fe0-Based Filters a Universal Solution for Safe Drinking Water Provision
(MDPI, 2017-07-12) Naseri, Elham; Ndé-Tchoupé, Arnaud; Mwakabona, Hezron; Nanseu-Njiki, Charles; Noubactep, Péguy; Njau, Karoli; Wydra, Kerstin
Metallic iron (Fe0)-based filtration systems have the potential to significantly contribute to the achievement of the United Nations (UN) Sustainable Development Goals (SDGs) of substantially improving the human condition by 2030 through the provision of clean water. Recent knowledge on Fe0-based safe drinking water filters is addressed herein. They are categorized into two types: Household and community filters. Design criteria are recalled and operational details are given. Scientists are invited to co-develop knowledge enabling the exploitation of the great potential of Fe0 filters for sustainable safe drinking water provision (and sanitation).
Metallic iron for safe drinking water provision: Considering a lost knowledge
(Pergamon, 2017-06-15) Mwakabona, Hezron; Ndé-Tchoupé, Arnaud; Njau, Karoli; Noubactep, Chicgoua; Wydra, Kerstin
Around year 1890, the technology of using metallic iron (Fe0) for safe drinking water provision was already established in Europe. The science and technology to manufacture suitable Fe0 materials were known and further developed in this period. Scientists had then developed skills to (i) explore the suitability of individual Fe0 materials (e.g. iron filling, sponge iron) for selected applications, and (ii) establish treatment processes for households and water treatment plants. The recent (1990) discovery of Fe0 as reactive agent for environmental remediation and water treatment has not yet considered this ancient knowledge. In the present work, some key aspects of the ancient knowledge are presented together with some contemporised interpretations, in an attempt to demonstrate the scientific truth contained therein. It appears that the ancient knowledge is an independent validation of the scientific concept that in water treatment (Fe0/H2O system) Fe0 materials are generators of contaminant collectors.
Removal of fluoride and pathogens from water using the combined electrocoagulation-inline-electrolytic disinfection process
(IWA Publishing, 2023-07-01) Njau, Oscar; Otter, Philipp; Machunda, Revocatus; Rugaika, Anita; Wydra, Kerstin; Njau, Karoli
The consecutive removal of fluoride (defluoridation) and pathogens (disinfection) in drinking water through combined electrocoagulation-inline-electrolytic disinfection (EC–ECl2) process with aluminum and dimension-stable mixed oxide electrodes was reported in this study. Laboratory trials were conducted on the effects of flow rate, initial pH, current density, and supporting electrolytes for defluoridation and disinfection processes. The results have shown that with a flow rate of 10 L/h, initial pH of 6, the current density of 9.4 mA/cm2 (EC cell) and 3.1 mA/cm2 (ECl2 cell), supporting electrolyte concentration of 165 mg/L, and electrolysis time of 50 min, a defluoridation rate of 88% (initial concentration of 12.3 mg/L) and complete disinfection (initial fecal coliforms of 19,700 colony-forming units per 100 mL (CFU/100 mL)) can be reached. The final concentration of fluoride and pathogens in treated water was 1.44 mg/L and 0 CFU/100 mL, which are within the acceptable limit of the World Health Organization and the Tanzania Bureau of Standards of 1.5 mg/L and 0 CFU/100 mL, respectively. The EC–ECl2 system is a promising approach for consecutive defluoridation and disinfection of water to save millions from fluorosis and waterborne diseases. However, optimization potential with regard to energetic efficiency and system complexity was identified.