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Water Treatment Operations
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Oxidation filtration technologies may be effective in arsenic removal technologies. Research of oxidation filtration technologies has primarily focused on greensand filtration. As a result, the following discussion focuses on the effectiveness of greensand filtration as an arsenic removal technology. Substantial arsenic removal has been seen using greensand filtration (Subramanian et al., 1997). The active material in “greensand” is glauconite, a green, iron-rich, clay-like mineral that has ion exchange properties. Glauconite often occurs in nature as small pellets mixed with other sand particles, giving a green color to the sand. The glauconite sand is treated with KMnO4 until the sand grains are coated with a layer of manganese oxides, particularly manganese dioxide. The principle behind this arsenic removal treatment is multi-faceted and includes oxidation, ion exchange, and adsorption. Arsenic compounds displace species from the manganese oxide (presumably OH− and H2O), becoming bound to the greensand surface—in effect an exchange of ions. The oxidative nature of the manganese surface converts arsenite to arsenate and arsenate is adsorbed to the surface. As a result of the transfer of electrons and adsorption of arsenate, reduced manganese (Mn) is released from the surface.
Miscellaneous Water Treatment Methods I
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
Manganese zeolites, also known as manganese greensand, is a granular material. Greensand is coated with manganese dioxide that removes soluble iron and manganese. The greensand also acts as a filter media. After the zeolite becomes saturated with iron and manganese oxides, it is regenerated using potassium permanganate to remove the insoluble oxides.
Characterization and mineral beneficiation of Egyptian glauconite for possible industrial use
Published in Particulate Science and Technology, 2019
S. S. Ibrahim, A. M. El Kammar, A. M. Guda, T. R. Boulos, A. Saleh
Glauconite-rich sediment is informally referred to as greensand, Tedrow (2002). This sediment has been historically used in Europe as a green pigment under the name green earth, Grissom (1986) and Eastaugh (2004). Glauconite was marketed as a natural fertilizer and soil conditioner for more than 100 years, Chopra and Kanwar (1966); Das and Datta (1973); Aulakh, Pasricha, and Dev (1977); Tiwari, Dwivedi, and Pathak (1984); Dooley (2006). Unfortunately, despite its large reserves and worldwide distribution, glauconite has not been used to any significant commercial extent because no major application has been found for a substance with its chemical composition and properties mostly due to a paucity of research on its potential commercial uses, Dooley (2006). However, it is expected that between 2012 and 2018, the demand for K will increase by 2.8% per year to 34 Mt. In 2018, the global fertilizer demand is expected to exceed 200 Mt for the first time, Heffer and Prud (2014); Fixen and Johnston (2011). Glauconite is slightly acidic and has the ability to absorb 10 times more moisture than ordinary sand; it contains marine potash, silica, iron, magnesium, and lime, plus up to 30 other trace minerals. Glauconite has the dual ability to bind sandy soils and loosen clay soils. Potassium (5–7%) is released very slowly from glauconite over 4–5 years.
Ozone Application for Arsenic and Manganese Treatment at the City of White Rock, BC, Canada
Published in Ozone: Science & Engineering, 2019
Greensand Plus filter media (AdeEdge Water Technologies) was selected for removing manganese from groundwater supplies of the City of White Rock (Sunnyside Aquifer). Greensand Plus manganese dioxide coated surface acts as a catalyst in the oxidation-reduction reaction of manganese. The silica sand core of Greensand Plus allows it to withstand waters low concentrations in silica, TDS, and hardness without breakdown. Greensand Plus is effective at higher operating temperatures and higher differential pressures than standard manganese greensand. Greensand Plus has the WQA Gold Seal Certification for compliance with NSF/ANSI 61 (AdEdge 2018). Two (2) pressure filter vessels supplied by AdEdge will be operating in parallel mode, Figures 7–8.
Comprehensive review on utilization of waste foundry sand in concrete
Published in European Journal of Environmental and Civil Engineering, 2023
Atish Bhardwaj, Pankaj Kumar, Salman Siddique, Abhilash Shukla
Clay bonded sand (greensand) is a mixture of silica sand (80-95%), bentonite clay (4-10%), carbonaceous additive (2-10%) and water (2-5%). Additional marginal components are cereals, flour, starches, and rice hulls. The silica present in the sand acts as a bulk medium to provide endurance under extremely high temperatures. The bentonite clay present in sand, combines the sand grains, and water acts on the clay to activate the binding process, adding plasticity to the sand. The carbonaceous addictive prevents the sand from fusing with the surface of the casting. Minor ingredients improve the fluidity and absorb moisture. Greensand also contains some chemicals, such as, titanium dioxide, potassium dioxide, and magnesium oxide. And green sand moulding is used for nearly 85% of casting irons on the planet. Contrary its name the colour of green sand is not green used as a sense in a wet stage (akin to green wood). Chemically bound sand, a combination of silica sand and chemical binder (1-3%) is utilized for the manufacturing of both molds and cores. Foundry industries use various chemical binders such as flake resins, phenolic urethane, alkyd (oil) urethane, phenolic no bake-acid, sodium silicate, phosphate, phenolic resole-ester, shell liquid/powered and furfuryl alcohol. A few of the chemical bounded sand that are most used are, hot box, resins coated sand, CO2 sand, and cold box. Most of the binders utilized in the foundry are the self-setting chemical binder. The subsequent sand binders or binders’ system are sulphur dioxide, phenolic esters, phenolic urethanes, phenolic hot box, phenolic no-bake, furan no bake, epoxy SO2, based core oil, alkyd urethane and alkyd oil- Sodium silicate and furan warm box used in their sand mould process. Chemical bounded sand is light in colour as compared to bounded sand (Singh & Siddique, 2012).