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- ItemFe0/H2O Filtration Systems for Decentralized Safe Drinking Water: Where to from Here?(Basel : MDPI, 2019) Nanseu-Njiki, Charles; Gwenzi, Willis; Pengou, Martin; Rahman, Mohammad; Noubactep, ChicgouaInadequate access to safe drinking water is one of the most pervasive problems currently afflicting the developing world. Scientists and engineers are called to present affordable but efficient solutions, particularly applicable to small communities. Filtration systems based on metallic iron (Fe0) are discussed in the literature as one such viable solution, whether as a stand-alone system or as a complement to slow sand filters (SSFs). Fe0 filters can also be improved by incorporating biochar to form Fe0-biochar filtration systems with potentially higher contaminant removal efficiencies than those based on Fe0 or biochar alone. These three low-cost and chemical-free systems (Fe0, biochar, SSFs) have the potential to provide universal access to safe drinking water. However, a well-structured systematic research is needed to design robust and efficient water treatment systems based on these affordable filter materials. This communication highlights the technology being developed to use Fe0-based systems for decentralized safe drinking water provision. Future research directions for the design of the next generation Fe0-based systems are highlighted. It is shown that Fe0 enhances the efficiency of SSFs, while biochar has the potential to alleviate the loss of porosity and uncertainties arising from the non-linear kinetics of iron corrosion. Fe0-based systems are an affordable and applicable technology for small communities in low-income countries, which could contribute to attaining self-reliance in clean water supply and universal public health.
- ItemWhite Teeth and Healthy Skeletons for All: The Path to Universal Fluoride-Free Drinking Water in Tanzania(Basel : MDPI, 2019) Ndé-Tchoupé, Arnaud; Tepong-Tsindé, Raoul; Lufingo, Mesia; Pembe-Ali, Zuleikha; Lugodisha, Innocent; Mureth, Risala; Nkinda, Mihayo; Marwa, Janeth; Gwenzi, Willis; Mwamila, Tulinave; Rahman, Mohammad; Noubactep, Chicgoua; Njau, KaroliFluorosis has been prevalent in the great East African Rift Valley (EARV) since before this region was given a name. In the Tanganyika days, Germans reported elevated fluoride concentrations in natural waters. In the 1930s, the clear relationship between high fluoride level and mottling of teeth was established. Since then, the global research community has engaged in the battle to provide fluoride-free drinking water, and the battle is not yet won for low-income communities. An applicable concept for fluoride-free drinking water in the EARV was recently presented, using the Kilimanjaro as a rainwater harvesting park. The Kilimanjaro concept implies that rainwater is harvested, stored on the Kilimanjaro mountains, gravity-transported to the point of use, eventually blended with natural water and treated for distribution. This article provides a roadmap for the implementation of the Kilimanjaro concept in Tanzania. Specifically, the current paper addresses the following: (i) presents updated nationwide information on fluoride contaminated areas, (ii) discusses the quality and quantity of rainwater, and current rainwater harvesting practices in Tanzania, (iii) highlights how low-cost water filters based on Fe0/biochar can be integrating into rainwater harvesting (RWH) systems to provide clean drinking water, and (iv) discusses the need for strict regulation of RWH practices to optimize water collection and storage, while simplifying the water treatment chain, and recommends strict analytical monitoring of water quality and public education to sustain public health in the EARV. In summary, it is demonstrated that, by combining rainwater harvesting and low-cots water treatment methods, the Kilimanjaro concept has the potential to provide clean drinking water, and overcome fluorosis on a long-term basis. However, a detailed design process is required to determine: (i) institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including prospects for government subsidy. By drawing attention to the Kilimanjaro concept, the article calls for African engineers and scientists to take the lead in translating this concept into reality for the benefit of public health, while simultaneously increasing their self-confidence to address other developmental challenges pervasive in Africa.
- ItemPost-IR IRSL dating of K-feldspar from last interglacial marine terrace deposits on the Kamikita coastal plain, northeastern Japan(Warsaw : De Gruyter, 2017) Ito, Kazumi; Tamura, Toru; Tsukamoto, SumikoTo establish a suitable luminescence dating protocol for marine terrace deposits in Japan, we tested the applicability of K-feldspar post-infrared (IR) infrared stimulated luminescence (IRSL) (pIRIR) dating using a marine isotope stage (MIS) 5e terrace deposit from the Kamikita coastal plain (NE Japan), where independent age control from a tephra is available. One of the most commonly used pIRIR signals, measured at 290°C with the first IR stimulation temperature at 50°C (pIRIR50/290), faded with a mean g2days value of 1.94 ± 0.19%/decade. In contrast, the pIRIR signal with a higher first IR stimulation temperature of 200°C (pIRIR200/290) had a much lower fading rate (g2days = 0.16 ± 0.49%/decade). The average fading-uncorrected and -corrected pIRIR200/290 ages of MIS 5e subtidal sediments obtained from two sampling sites were 126 ± 3 ka and 132 ± 2 ka, which is in good agreement with the independent age control. We conclude that is it is now possible to use pIRIR protocol to estimate the ages of not only marine terraces formed during MIS 5 substages (5a, 5c) but also of older marine terraces, for which age evidence is limited.
- ItemQuartz OSL and K-feldspar post-IR IRSL dating of sand accumulation in the Lower Liao Plain (Liaoning, NE China)(Warsaw : De Gruyter, 2017) Li, Yan; Tsukamoto, Sumiko; Hu, Ke; Frechen, ManfredThe timing of the formation of extensively distributed sand dunes in the Bohai coastal area and its forcing factors are poorly understood. In this study, the chronology of a well-preserved sand dune located in Panjin Forest Park (PJ) in the Lower Liao Plain (LLP) is investigated using quartz optically stimulated luminescence (OSL) and K-feldspar postinfrared (IR) infrared stimulated luminescence (IRSL) (pIRIR) dating. For the pIRIR measurements, the combination of preheating at 180°C and pIRIR stimulation at 150°C (pIRIR150) is exploited. The quartz results show that the sand dune accumulated from c. 120 a (1890 AD) to c. 70 a (1940 AD) before present, and the underlying sandy soil sediments deposited from c. 5.0 ka to c. 0.13 ka as marsh sediment after the sea level highstand since the mid-Holocene. From the evidence in historical coastline records, the PJ sand dune is an inland sand dune and not a coastal sand dune. Based on further information of climate and temperature change after the Little Ice Age (LIA) and human activity in northeastern China, we conclude that the PJ sand dune accumulation was very likely impacted by the immigrants and land reclamation at the end of Qing dynasty. The fading corrected IR50 ages, the apparent and fading corrected pIRIR150 ages are consistent with quartz ages for two sandy soil samples but overestimate those for six sand samples. The overestimation of the feldspar ages is derived from the residual signal which has not been bleached before burial. The offset obtained from the difference between the quartz OSL and the feldspar pIRIR150 ages are ~20-160 a (predicted residual dose: ~0.08-0.60 Gy), whereas the measured residual dose after bleaching 4 h in a solar simulator yielded age overestimation of ~10-40 a (~0.05-0.16 Gy). The age discrepancy calculated from the predicted residual was larger than those obtained from the laboratory measured residuals. We conclude that the pIRIR150 of aeolian sediment is applicable for samples older than ~1000 years where the effect of the residual dose become negligible. © 2016 Y. Li et al.
- ItemGeothermal potential of the Buntsandstein and Keuper aquifers in NE Bavaria with a focus on deep thermal aquifer storage(Berlin ; Heidelberg : Springer, 2019-9-26) Kunkel, Cindy; Agemar, Thorsten; Stober, IngridIntermediate and deep geothermal resources of Germany are limited to medium and low enthalpy resources. These resources are predominantly used for balneological applications, space and district heating and for power production at nine separate sites. This study focuses on confined aquifers in northeast Bavaria, which can be used for balneology as well as energy storage. Data from pumping tests and production data were interpreted to map the hydraulic conductivity of the main Keuper and Buntsandstein aquifers with a large spatial distribution for geothermal applications deeper than 100 m. Furthermore, temperature estimates as well as the depth of the two aquifers (Keuper 100 to 650 m, Buntsandstein 100 to 1400 m) are incorporated. The results will be visualized in the form of spatial distribution maps of the hydraulic conductivity and temperature, and will be integrated into the geothermal information system GeotIS (https://www.geotis.de). Altogether, about 80% of all 243 sampling sites show hydraulic conductivity values sufficient for geothermal energy utilization. For the Keuper aquifer, even 90% of all 155 sampling sites show transmissivities sufficient for geothermal energy utilization. However, these maps do not replace a feasibility study for specific geothermal projects because detailed geological site assessment is essential when planning a subsurface geothermal system.