Abstract:Exceeding the permitted manganese (Mn2+) and ammonium (NH4+-N) levels is a frequent seasonal occurrence in a water treatment plant in south China. An iron Fe–Mn complex oxide film was found capable of removing more than 95% of Mn2+ and NH4+-N at a water temperature of 20 °C and an alkalinity level of 30 mg/L. It could remove up to 5.5 mg/L of Mn2+ and up to 3.5 mg/L of NH4+-N in a stable manner. Alkalinity is a crucial factor in the removal process. The morphology, elemental composition, and micro-structure of… Show more
“…The Mn element has 11 valence states, ranging from −3 to +7; however, only +2, +3, and +4 are naturally present in the biosphere [5]. Dissolved Mn 2+ can be found in a variety of water bodies, including surface water (rivers and lakes) [6][7][8], groundwater [9,10], and oceans [11]. Because free or dissolved Mn 3+ is extremely unstable, it is easily transformed into Mn 2+ or Mn 4+ through disproportionation [12], or an oxyhydroxide (MnOOH) is formed.…”
Groundwater serving as a drinking water resource usually contains manganese ions (Mn2+) that exceed drinking standards. Based on the Mn biogeochemical cycle at the hydrosphere scale, bioprocesses consisting of aeration, biofiltration, and disinfection are well known as a cost-effective and environmentally friendly ecotechnology for removing Mn2+. The design of aeration and biofiltration units, which are critical components, is significantly influenced by coexisting iron and ammonia in groundwater; however, there is no unified standard for optimizing bioprocess operation. In addition to the groundwater purification, it was also found that manganese-oxidizing bacteria (MnOB)-derived biogenic Mn oxides (bioMnOx), a by-product, have a low crystallinity and a relatively high specific surface area; the MnOB supplied with Mn2+ can be developed for contaminated water remediation. As a result, according to previous studies, this paper summarized and provided operational suggestions for the removal of Mn2+ from groundwater. This review also anticipated challenges and future concerns, as well as opportunities for bioMnOx applications. These could improve our understanding of the MnOB group and its practical applications.
“…The Mn element has 11 valence states, ranging from −3 to +7; however, only +2, +3, and +4 are naturally present in the biosphere [5]. Dissolved Mn 2+ can be found in a variety of water bodies, including surface water (rivers and lakes) [6][7][8], groundwater [9,10], and oceans [11]. Because free or dissolved Mn 3+ is extremely unstable, it is easily transformed into Mn 2+ or Mn 4+ through disproportionation [12], or an oxyhydroxide (MnOOH) is formed.…”
Groundwater serving as a drinking water resource usually contains manganese ions (Mn2+) that exceed drinking standards. Based on the Mn biogeochemical cycle at the hydrosphere scale, bioprocesses consisting of aeration, biofiltration, and disinfection are well known as a cost-effective and environmentally friendly ecotechnology for removing Mn2+. The design of aeration and biofiltration units, which are critical components, is significantly influenced by coexisting iron and ammonia in groundwater; however, there is no unified standard for optimizing bioprocess operation. In addition to the groundwater purification, it was also found that manganese-oxidizing bacteria (MnOB)-derived biogenic Mn oxides (bioMnOx), a by-product, have a low crystallinity and a relatively high specific surface area; the MnOB supplied with Mn2+ can be developed for contaminated water remediation. As a result, according to previous studies, this paper summarized and provided operational suggestions for the removal of Mn2+ from groundwater. This review also anticipated challenges and future concerns, as well as opportunities for bioMnOx applications. These could improve our understanding of the MnOB group and its practical applications.
Human society and environment are based on water resources. Hard water with iron and manganese excess is spread across the world and softening of drinking water is widely applied for reasons of public health, client comfort, economic and environmental benefits. Also, from industrial or commercial point of view, using it produce scale deposits in water systems and equipment often result in ample technical and economic problems. Solutions of reducing its hardness and iron/manganese excess exists on the market, even with the substances presented in the work. The novelty this study brings comes from using high intensity permanent magnets arrangements and CO2 nanobubbles treatment that increased the speed, the volume of treatment, while decreasing the energy and complexity of the installation, also decreasing the pollution mark of the system. The detrimental contributions of softening, in particular the use of chemicals and energy, are taken into account in the carbon footprint of the drinking water companies. The beneficial contributions have not been included in the carbon footprint. For carbon capture in the crystallized calcite and dissolution of CO2 into the softened water, the carbon footprint is compensated by the net carbon benefit of softening.
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