Wastewater physical methods

Generally, wastewater treatment methods can be broadly classified into biological, physical (i.e. mechanical) and chemical [3, 12-14]. Biological... 

Chemical and physical methods of treating wastewater. Forest Prod. J. 22(12) 25-30. 

Chemical pretreatment methods have an advantage of being easily applied as soon as it is required (Mohan, 2008). However, one of the inherent disadvantages of chemical treatment methods, as compared to physical methods, is that they are additive processes (Metcalf Eddy, 1991). As a result, there is usually a positive increase in the dissolved constituents in the wastewater. This additive aspect is in contrast to physical and biological treatment methods that may be described as being subtractive because material is removed from the wastewater. Another drawback of chemical methods is that they are all intensive in operating costs (Metcalf Eddy, 1991). The costs of some of the chemicals are tied to the cost of energy and thus can be expected to increase similarly. 

Calculate the mass or weight of chemical in the wastestream being treated by multiplying the concentration (by weight) of the chemical in the wastestream by the flow rate. In most cases, the percent removal compares the treated effluent to the influent for the particular type of wastestream. However, for some treatment methods, such as Incineration or solidification of wastewater, the percent removal of the chemical from the influent wastestream would be reported as 100 percent because the wastestream does not exist in a comparable form after treatment. Some of the treatments (e.g., fuel blending and evaporation) do not destroy, chemically convert, or physically remove the chemical from its wastestream. For these treatment methods, an efficiency of zero must be reported. 

In applying these general criteria, one should focus on the intended application. In wastewater treatment applications, filtration can be applied at various stages. It can be applied as a pretreatment method, in which case the objective is often to remove coarse, gritty materials from the waste-stream. This is a preconditioning step for waste waters which will undergo further chemical and physical treatment downstream. 

Various physical, chemical, and biological methods have been used for the treatment of dye-containing wastewater. However, these conventional technologies have disadvantages like poor removal efficiency and high running cost. Therefore, low-cost sorbents which can bind dye molecules and be easily regenerated have been extensively searched and tested [3-7]. 

The specific purpose of this chapter is to describe the chemical and physical pretreatment methods required for nickel-chromium plating wastewater, to describe the upgrades needed by a municipal wastewater treatment system to manage this waste, and to relate the methods and upgrades to the operation of the total treatment system. Special emphasis is placed on presentation of the following ... 

Treatment of dye wastewater involves physical, physico-chemical, chemical, and biological methods. Physical processes are dilution, filtration, and gamma radiation. Physico-chemical includes adsorption, coagulation, flocculation, precipitation, reverse osmosis, ion exchange, etc. 

The method consists of the retention by sorption of the porphyrins on poly (vinyl alcohol) (PVA) hydrogels. Poly (vinyl alcohol) (PVA) is selected as the polymer of choice for the purification of industrial and medical wastewaters due to its capacity to form physically crosslinked hydrogels with the advantages of non-toxic, non-carcinogenic and biodegradable properties. 

One difference between these systems and the biological treatment of nonhazardous wastewater is that the exhaust air may contain volatile hazardous substances or intermediate biodegradation products. Therefore, the air must be treated as secondary hazardous wastes by physical, chemical, physico-chemical, or biological methods. Other secondary hazardous wastes may include the biomass of microorganisms that may accumulate volatile hazardous substances or intermediate products of their biodegradation. This hazardous liquid or semisolid waste must be properly treated, incinerated, or disposed. 

Wastewater effluents discharged to pubhcly owned treatment facilities are sometimes treated by physical or chemical systems to remove pollutants potentially hazardous to the POTW or which may be treated inadequately in the POTW. Such treatment methods are numerous, but they generally fall into one of three broad categories in accordance with their process objectives. These include pH control, removal of dissolved materials, and separation of phases. 

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