Impact of Fe0 amendment on methylene blue discoloration by sand columns

Since the realization in the 1930s that elevated fluoride concentrations in drinking water can have detrimental effects on human health, new methods have been progressively developed in order to reduce fluoride to acceptable levels. In the developing world the necessity for filtration media that are both low-cost and sourced from locally available materials has resulted in the widespread use of bone char. Since the early 1990s metallic iron (Fe 0 ) has received widespread use as both an adsorbent and a reducing agent for the removal of a wide range of contaminant species from water. The ion-selectivity of Fe 0 is dictated by the positively charged surface of iron (hydr)oxides at circumneutral pH. This suggests that Fe 0 could potentially be applied as suitable filter media for the negatively charged fluoride ion. This communication seeks to demonstrate from a theoretical basis and using empirical data from the literature the suitability of Fe 0 filters for fluoride removal. The work concludes that Fe 0 -bearing materials, such as steel wool, hold good promise as low-cost, readily available and highly effective decentralized fluoride treatment materials.

Section: Beyond Steel Wool Filtersmentioning

confidence: 99%

Section: Optimizing the Efficiency Fe 0 Filtersmentioning

confidence: 99%

Technologies for Decentralized Fluoride Removal: Testing Metallic Iron-based Filters

Ndé-Tchoupé

Crane

Mwakabona

et al. 2015

“…Achieved results are summarized in the following section. [135,156,158,159]. The suitability of MB for this purpose arises from the fact that MB (cationic) has a very low affinity for iron hydroxides/oxides (pHpzc > 6.0) covering the surface of Fe 0 in Fe 0 /H2O systems.…”

Section: Discussionmentioning

confidence: 99%

Testing Metallic Iron Filtration Systems for Decentralized Water Treatment at Pilot Scale

Tepong-Tsindé

Crane

Noubactep

et al. 2015

There are many factors to consider for the design of appropriate water treatment systems including: cost, the concentration and type of biological and/or chemical contamination, concentration limits at which contaminant(s) are required to be removed, required flow rate, level of local expertise for on-going maintenance, and social acceptance. An ideal technology should be effective at producing clean, potable water; however it must also be low-cost, low-energy (ideally energy-free) and require low-maintenance. The use of packed beds containing metallic iron (Fe 0 filters) has the potential to become a cheap widespread technology for both safe drinking water provision and wastewater treatment. for decentralized water treatment particularly in the developing world. A design for safe drinking water to a community of 100 people is also discussed as starting module. It is suggested that Fe 0 filters have the potential for significant worldwide applicability, but particularly in the developing world. The appropriate design of Fe 0 filters, however, is site-specific and dependent upon the availability of local expertise/materials.

“…In fact, the in situ generation of FeCPs which coats the admixing aggregates lowers the absorptive affinity of the whole system for MB. This shortens the experimental duration and makes MB a reactive indicator [18].…”

Section: Introductionmentioning

confidence: 99%

“…Ulsamer [13] recently summarized the state-of-the-art designing approaches, culminating at the point that it is uncertain whether sand admixture is a blessing or a curse for Fe 0 filters. A science-based progress has been recently presented [14][15][16] demonstrating that sand admixture is even a prerequisite for sustainable (long-term efficient) Fe 0 filters [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

The Suitability of Pozzolan as Admixing Aggregate for Fe0-Based Filters

Ndé-Tchoupé

Makota

Nassi

et al. 2018

Continuous gravity-fed column experiments using the methylene blue (MB) discoloration method were performed to characterize the suitability of a pozzolan (PZ) specimen as alternative admixing aggregate for metallic iron filters (Fe 0 -filters). Investigated systems were: (i) pure sand, (ii) pure PZ, (iii) pure Fe 0 , (iv) Fe 0 /sand, (v) Fe 0 /PZ, and (vi) Fe 0 /sand/PZ. The volumetric proportion of Fe 0 was 25%. The volumetric proportions of the Fe 0 /sand/PZ system was 25/45/30. The initial MB concentration was 2.0 mg·L −1 , 6.0 g of Fe 0 was used, and the experiments lasted for 46 days. The individual systems were fed with 3.9 to 8.4 L (7.80 to 16.69 mg of MB) and were characterized by the time-dependent changes of: (i) the pH value, (ii) the iron breakthrough, (iii) the MB breakthrough, and (iv) the hydraulic conductivity. Results showed that the Fe 0 /sand/PZ system was the most efficient. This ternary system was also the most permeable and therefore the most sustainable. The suitability of MB as a powerful operative indicator for the characterization of processes in the Fe 0 /H 2 O system was confirmed. The tested PZ is recommended as an alternative material for efficient but sustainable Fe 0 filters.