Wastewater treatment alumina

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

Like enzymes, whole cells are sometimes immobilized by attachment to a surface or by entrapment within a support. One motivation for this is similar to the motivation for using biomass recycle in a continuous process. The cells are grown under optimal conditions for cell growth but are used at conditions optimized for production of a secondary metabolite. A hollow-liber reactor, similar to those used for cross-flow filtration, can be used to entrap the cells while allowing input of the substrate and removal of products. Attachment of the cells to a nonreactive material such as alumina allows a great variety of reactor types including packed beds, fluidized and spouted beds, and air-lift reactors. Packed beds with a biofilm on the packing are commonly used for wastewater treatment. A semicommercial process for beer used an air-lift reactor to achieve reaction times of one day compared to five to seven days for the normal batch process. Unfortunately, the beer suffered from a mismatched flavor profile that was attributed to mass transfer limitations. 

Biological treatment would seldom be selected as the primary means of treating a CMP wastewater, but it is useful to consider the fate and potential impacts of alumina, ceria, and silica particles in a biological wastewater treatment process. At many fabs, waste-water is pretreated and discharged to a municipal wastewater treatment system where dilute industrial waste effluents are combined with municipal sewage flows and treated in a biological wastewater treatment process. Some fabs have an onsite biological wastewater treatment process, but they are believed to be in the minority. 

Three principal considerations arise with regard to the potential influence of alumina, ceria, and silica nanoparlicles in a biological wastewater treatment system ... 

Alumina, ceria, and silica particles are removed in biological wastewater treatment processes by a combination of aggregation, heteroaggregation, and sorption onto biosolids and/or extracellular polymeric substances. Some studies indicate that silica particles are less easily removed than ceria and aluminum particles. Most information on alumina, ceria, and silica removal in biological wastewater systems is from pilot- or laboratory-scale experiments, and relatively few smdies involving real CMP... 

A review of the wastewater treatment literature suggests a number of research needs. Efforts to characterize alumina, ceria, and silica particles in both waste materials and natural water systems face difficult metrology challenges. There is a need for vahdated methodologies that can discriminate quantitatively between individual types of nanomaterials and evaluate concentration by size, number count, and mass concentration within real environmental matrices. The few published evaluations of alumina, ceria, and silica nanoparticle removal in wastewater treatment processes have primarily addressed removal in municipal-type biological wastewater treatment processes whereas relatively little information is available regarding alumina, ceria, and silica nanoparticle removal in the types of physicochemical treatment processes that are often used by fabs to pretreat wastewaters prior to discharge. 

For most of applications, it is required to purity BPA from the mentioned byproducts before its further processing. Therefore, the BPA production line consists of a condensation reactor and the units responsible for the BPA purification. Among them, there is usually a unit for crystallization of the BPA-phenol adduct and stripping tower, where the adduct is cracked and phenol is recovered (as it was described earlier). There are also a recrystallization unit, a cracker for the o,p-isomers of BPA and a wastewater treatment facility. Additionally, there may be an isomerization unit, where the mother liquor is contacted with an acidic or amine-based ion-exchange resin as the isomerization catalyst under the conditions effective to convert the BPA byproducts to BPA. Next, the effluent from the isomerization zone can be contacted with a solid particle guard bed, composed of alumina, titanium oxide, silica, zirconium oxide, tin oxide, charcoal or silicon carbide [55]. This guard... 

Solubilization in polymer-surfactant aggregates adsorbed at the solid—liquid interface has been recently presented by Esumi et al. as a promising tool in wastewater treatment research [46]. Their study concerns the adsolubilization of 2-naphtol into PVP-anionic surfactants adsorbed at the alumina-water interface. Two surfactants were used SDS and Aerosol OT. 

Asymmetric Alumina Hollow-Fiber Membranes FOR Wastewater Treatment... 

Lee, M. et al.. Micro-structured alumina hollow fibre membranes—Potential applications in wastewater treatment. Journal of Membrane Science, 2014. 461 39-48. 

Formuia Al2(OH)nCI, n = 1-5 Uses Coagulant and flocculant for industrial water, wastewater, potable water treatment, sewage/plant effluent treatment, paper processing applies. alum replacement in alkaline papermaking processes fire-resist, ceramic paste binder alumina fiber raw material catalyst raw material textile finishing agent food-contact applies. 

Sakoda, A., Nomura, T., and Suzuki, M. (1996). Activated carbon membrane for water treatments application to decolorization of coke furnace wastewater. Adsorption 3 93-98. Miller, J. R., and Koros, W. J. (1990). The formation of chemically modified y-Alumina microporous membranes. Sep. Sci. Technol. 23 1237-1280. 

This chapter summarized the occurrence, behavior, and treatment of alumina, ceria, and silica particles in CMP wastewater. Many fabs treat CMP wastewater in order to achieve effluent discharge requirements for copper and other metals, but at present... 

CMP slurries are formulated with a variety of surface active chemical additives that are added to the slurry mixture with the intent of influencing particle behavior. The role of these additives in influencing particle behavior and removal in real wastewater streams needs to be addressed. All waste treatment processes generate a concentrated waste solids product in some form. The fate and ultimate stability of the alumina, ceria, and silica nanoparticles that are removed into waste solids is an important consideration that needs to be addressed by the research community. 

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