Effluent treatment oxidation treatments

The process is designed from a knowledge of physical concentrations, whereas aqueous effluent treatment systems are designed from a knowledge of BOD and COD. Thus we need to somehow establish the relationship between BOD, COD, and the concentration of waste streams leaving the process. Without measurements, relationships can only be established approximately. The relationship between BOD and COD is not easy to establish, since different materials will oxidize at different rates. To compound the problem, many wastes contain complex mixtures of oxidizable materials, perhaps together with chemicals that inhibit the oxidation reactions. 

Fig. 4. Schematic of a leather tanning faciUty fitted with a wastewater treatment plant. Treatment of the combined wastes using sulfide oxidation and waste effluent pH adjustment greatiy decreases the suspended soHds and BOD loading (3). Courtesy of Krieger Publishing Co.

Chemical oxidation is a more recent method of effluent treatment, especially chemical effluent. This procedure uses strong oxidi2ing agents like... 

Ozone (O3) is a powerful oxidant, and application to effluent treatment has developed slowly because of relatively high capital and energy costs compared to chlorine. Energy requirements for ozone are in the range of 10 to 13 kWh/lb... 

DAF is used to remove suspended solids by decreasing their apparent density they then rise and float on the water surface. DAF is also used to remove soluble iron, VOCs, oils, and surface active agents by oxidation, air stripping, and surface adsorption. The flotation technology is becoming one of the most important technologies for groundwater decontamination, industrial effluent treatment, and water purification.58-6170... 

Efficiencies for removal in the wastewater treatment plant were estimated for total and soluble BOD, total COD, soluble COD, color, total suspended and dissolved solids, and total solids. The removal efficiencies summarized in Table 21.14 are high for total BOD, soluble BOD, and suspended solids, at 96%, 96%, and 95%, respectively. The removal efficiencies for total and soluble COD were significantly lower at 76% and 66%, respectively. The removal efficiency for color was only about 38%. This value is typical for biological treatment of pulp and paper wastewater, and may be due, at least partially, to the formation of new colored groups when the bleach effluents are oxidized in the treatment system. 

When viewing effluent treatment methods, it is clear that the basic problem of disposing safely of waste material is, in many cases, not so much solved but moved from one place to another. If a method of treatment can be used that allows material to be recycled, then the waste problem is truly solved. However, if the treatment simply concentrates the waste as concentrated liquid, slurry or solid in a form, which cannot be recycled, then it will still need to be disposed of. Landfill disposal of such waste is increasingly unacceptable and thermal oxidation causes pollution through products of combustion and liquors from scrubbing systems. The best method for dealing with effluent problems is to solve the problem at source by waste minimization, as will be discussed in Chapter 28. 

Accent [Aqueous carbon compound effluent treatment] A process for oxidizing organic contaminants in aqueous streams by catalyzed oxidation with sodium hypochlorite. The catalyst is promoted nickel oxide, which retains active oxygen at its surface, as well as adsorbing the organics. Developed by ICI Katalco and first offered in 1998. 

BIOX [biological oxidation] A general term for effluent treatment processes employing biological oxidation, such as the Activated Sludge process. 

Mechanical and biological methods are very effective on a large scale, and physical and chemical methods are used to overcome particular difficulties such as final sterilization, odor removal, removal of inorganic and organic chemicals and breaking oil or fat emulsions. Normally, no electrochemical processes are used [10]. On the other hand, there are particular water and effluent treatment problems where electrochemical solutions are advantageous. Indeed, electrochemistry can be a very attractive idea. It is uniquely clean because (1) electrolysis (reduction/oxidation) takes place via an inert electrode and (2) it uses a mass-free reagent so no additional chemicals are added, which would create secondary streams, which would as it is often the case with conventional procedures, need further treatment, cf. Scheme 10. 

Powerful oxidant treatments are also necessary to remove multi-dmg-resistant bacteria [122] and residues of medicaments with ecotoxicological effects from hospital effluent, in order to reduce their impact on the final receiving water bodies. Advanced oxidation processes, including the Fenton reaction, are likely candidates [123]. 

The oxidation system consists of towers where air is forced into the effluent to oxidize the sodium sulfite to sodium sulfate. Effluent from the oxidation towers, which is now cleaned of catalyst (suspended solids) and has a low COD level, can be processed in the refinery wasfewafer system or possibly directly discharged from the refinery. A typical purge treatment system that employs a filter press is illustrated in Figure 16.8. 

Flocculation - [ACRYLAMIDE POLYMERS] (Vol 1) - [FLOCCULATING AGENTS] (Vol 11) - [SEDIMENTATION] (Vol 21) -dye water effluent treatment [DYES, ENVIRONMENTAL CHEMISTRY] (Vol 8) -of emulsions [EMULSIONS] (Vol 9) -minerals processing [MINERALS RECOVERY AND PROCESSING] (Vol 16) -PEO in [POLYETHERS - ETHYLENE OXIDE POLYMERS] (Vol 19) -useofethyleneimines [IMINES,CYCLIC] (Voll4) -useofSCFs [SUPERCRITICALFLUIDS] (Vol 23) -water treatment for steam prdn [STEAM] (Vol 22)... 

Akmehmet, I. and Arslan, I., Application of photocatalytic oxidation treatment to pretreated and raw effluents from the Kraft bleaching process and textile industrial, Environ. Pollut., 103(2-3), 261-268, 1998. 

Chemical-oxidation treatments of wood preserving wastewaters containing phenols have been successfully conducted on both a laboratory and commercial scale using either chlorine or a chlorine compound, principally calcium hypochlorite. Its effectiveness varies with the type of phenolic compound in the effluent, either cresols from creosote treatments or pent achlorophenol from treatments enploying that chemical. Also influential in this regard are effluent pH, the effectiveness of pretreatment, particularly flocculation and filtration, and the amount and type of organic materials other than phenols present in the wastewater. 

The usual gaseous effluent of SCWO treatment of waste containing carbon, hydrogen, oxygen, and nitrogen consists of the oxidation products... 

Oxidation of phenols, dyes, and polycyclic aromatic hydrocarbons [48,49], decolorization of Kraft bleaching effluents, binding of phenols and aromatic amines with humus [47] Transformation of phenols, aromatic amines, polyaromatic hydrocarbons, and other aromatic compounds, decolorization of Kraft bleaching effluents, treatment of dioxins, pyrene [86-89,114] Improved sludge dewatering [59]... 

The patent literature claims that olefins can be partially oxidized to epoxides (73) or hydroxy epoxides (74) and alcohols may be oxidized to ketones or aldehydes (75) using various metal ion-exchanged zeolites. In the examples given, the selectivities or conversion levels to the desired products are not particularly attractive. Metal ion-exchanged zeolites do, however, appear to be quite useful catalysts for effluent treatment. For example, Cu2+X and Cu2+Y are claimed to be good catalysts for the total oxidation (incineration) of chlorinated organic compounds (76). 

Lissens, G., Verhaege, M., Pinoy, L. and Verstraete, W. (2003), Electrochemical decomplexing and oxidation of organic (chelating) additives in effluents from surface treatment and metal finishing. 1. Chem. Technol. Biotechnol., 78(10) 1054—1060. 

The technology behind Fenton s treatment dates back over a hundred years to 1894 when M.J.H. Fenton reported that ferrous ion promoted the oxidation of tartaric acid with aqueous hydrogen peroxide." Ferrous-catalysed hydrogen peroxide at acidic pH has since come to be known as Fenton s reagent and is widely used in both oxidative treatment of industrial effluents and in the manufacture of several types of polymers and polyelectrolytes. Subsequently,... 

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