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Sludge treatment and disposal
Published in Nick F. Gray, Water Science and Technology: An Introduction, 2017
Lime (Ca(OH)2) is nearly always used in conjunction with copperas (ferrous sulphate FeSO4 ⋅ 7H2O) unless iron salts are present in the sludge, when lime can be used on its own. The combination is used almost exclusively in association with filter presses, not being suitable for belt presses or centrifuges, which require a more rapid flocculation that can only be obtained from using polyelectrolytes. Copperas is kept in a crystalline form and is dissolved as required. It is an acidic and highly corrosive liquid, and special precautions have to be taken with its use. The lime is delivered by bulk tanker and is normally kept in a silo ready for use. Lime is usually added after the copperas, with doses of 10% copperas and 20% lime (DS) used for raw sludges and 40% copperas and 30% lime for digested sludges. The large weights of chemicals used result in a significant increase in the weight of solid cake that has to be disposed; in the case of lime and copperas, this can be as much as 50% of the solids in the final cake. Aluminium chlorohydrate (Al2(OH)4Cl2) is just one of the aluminium salts used for conditioning sludge prior to dewatering and is delivered to the site as a concentrated solution, which needs to be diluted before use. It is only suitable for filter presses and drying beds and has the advantage over lime and copperas of not significantly adding to the mass of sludge cake produced. Lime addition (5%–10%) is sometimes used to control the emission of odours, especially if the sludge has been stored for longer than 4–5 days.
Investigating aluminum salt containing hydrogels in water versus sweat mimics
Published in Journal of Coordination Chemistry, 2022
Chandra Ade-Browne, Alexander Greenwood, Taylor Neal, Stevan Jones, David Swaile, Harshita Kumari
The materials for this project can be divided into three categories: antiperspirant actives, sweat mimic, and NMR experimental design. The Procter & Gamble company (Ohio, USA) provided the antiperspirant actives including Aluminum Zirconium Trichlorohydrex Glycine Complex (TRI; CAS #: 13475-99-8), Aluminum Zirconium Tetrachlorohydrex Glycine Complex (TETRA; UNII: 8O386558JE), Aluminum Zirconium Octachlorohydrex Glycine Complex (OCTA, 30 w/w%; CAS #: 90604-80-1) and Aluminum chlorohydrate (ACH, 50 w/w%)/(Trade name: Aluminum chloride hydroxide (Al2Cl(OH)5; CAS # 134375-99-8). The first two are in powder form while the remaining two are in solution form.