Separation effluent treatment

Adsorption technology, 13 794-795 Adsorptive air separation, 17 753 Adsorptive bubble separation effluent treatment, 9 432... 

Additional separation and recycling. Once the possibilities for recycling streams directly, feed purification, and eliminating the use of extraneous materials for separation that cannot be recycled efiiciently have been exhausted, attention is turned to the fourth option, the degree of material recovery from the waste streams that are left. One very important point which should not be forgotten is that once the waste stream is rejected, any valuable material turns into a liability as an effluent material. The level of recovery in such situations needs careful consideration. It may be economical to carry out additional separation of the valuable material with a view to recycling that additional recovered material, particularly when the cost of downstream effluent treatment is taken into consideration. 

Figure 10.7 Effluent treatment costs should be included with raw materials costs when traded off against separation costs to obtain the optimal recovery. (From Smith and Petela, Chem. Eng., 513 24, 1991 reproduced by permission of the Institution of Chemical Engineers.)...

The capital cost of most aqueous waste treatment operations is proportional to the total flow of wastewater, and the operating cost increases with decreasing concentration for a given mass of contaminant to be removed. Thus, if two streams require different treatment operations, it makes no sense to mix them and treat both streams in both treatment operations. This will increase both capital and operating costs. Rather, the streams should be segregated and treated separately in a distributed effluent treatment system. Indeed, effective primary treatment might mean that some streams do not need biological treatment at all. 

The bubble size in these cells tends to be the smallest (10 to 50 Im) as compared to the dissolved-air and dispersed-air flotation systems. Also, very httle turbulence is created by the bubble formation. Accordingly, this method is attractive for the separation of small particles and fragile floes. To date, electroflotation has been applied to effluent treatment and sludge thickening. However, because of their bubble generation capacity, these units are found to be economically attractive for small installations in the flow-rate range of 10 to 20 mVh. Electroflotation is not expected to be suitable for potable water treatment because of the possible heavy metal contamination that can arise due to the dissolution of the electrodes. 

The wash water and the spent acid from all the pre-treatment tanks is also transferred to the effluent treatment plant for further treatment. Spent passivation liquor from the passivation tank is a strong waste and it may be provided with a separate pipeline to the effluent treatment plant, as shown in Figure A13.12. 

This term includes, power, steam, compressed air, cooling and process water, and effluent treatment unless costed separately. The quantities required can be obtained from the energy balances and the flow-sheets. The prices should be taken from Company records, if available. They will depend on the primary energy sources and the plant location. The figures given in Table 6.5 can be used to make preliminary estimates. The current cost of utilities supplied by the utility companies electricity, gas and water, can be obtained from their local area offices. 

Recently, Wang100 introduced a membrane sequencing batch reactor (membrane-SBR) process for groundwater decontamination, water purification, and industrial effluent treatment. A membrane-SBR is similar to conventional SBR except that membrane filtration is used (instead of sedimentation) for the separation of mixed liquor suspended solids (MLSS) from the mixed liquor. 

Figure 26.37a shows a system involving four effluent streams with different inlet concentrations that all need to be treated to remove mass load and bring down the concentration to an acceptable level for environmental discharge Ce. To obtain an overall picture, rather than deal with four separate effluent streams, the streams can be combined together to produce a composite effluent stream16. The construction is analogous to that for the limiting composite curve. The diagram is divided into concentration intervals and the mass load of the streams within each concentration interval combined together, Figure 37b. This provides a picture of the overall effluent treatment problem and what is required to happen to the effluent streams.

Artola-Garicano et al. [27] compared their measured removals of AHTN and HHCB [24] to the predicted removal of these compounds by the wastewater treatment plant model Simple Treat 3.0. Simple Treat is a fugacity-based, nine-box model that breaks the treatment plant process into influent, primary settler, primary sludge, aeration tank, solid/liquid separator, effluent, and waste sludge and is a steady-state, nonequilibrium model [27]. The model inputs include information on the emission scenario of the FM, FM physical-chemical properties, and FM biodegradation rate in activated sludge. 

The phosphate fertilizer industry is defined as eight separate processes phosphate rock grinding, wet process phosphoric acid, phosphoric acid concentration, phosphoric acid clarification, normal superphosphate, triple superphosphate, ammonium phosphate, and sulfuric acid. Practically all phosphate manufacturers combine the various effluents into a large recycle water system. It is only when the quantity of recycle water increases beyond the capacity to contain it that effluent treatment is necessary. 

The most important solid-phase separation materials for column-based separations in modern radioanalytical chemistry are extraction chromatographic materials, and these have been particularly important in automated radioanalytical chemistry. Solid-phase extraction materials based on the covalent attachment of ligands to solid supports also exist, and they have found application in large-scale separation processes for waste or effluent treatment.22 25 They have been commercialized as Analig or SuperLig materials by IBC Advanced Technologies (American Fork, UT). However, they are less well characterized or used for small-column analytical separations. 

In conclusion, a greater knowledge of the effect of the key controlling parameters of this powerful separation technique, as well as improvement in membrane life time of the currently available commercial electromembranes and reduction in their costs, would ensure further growth beyond desalination and salt production and foster ED applications in the food sector, as well as in the chemical, pharmaceutical, and municipal effluent treatment areas. This will of course need extensive R D studies and will highly likely result in hybrid processes combining ED to other separation techniques, such as NF, IE, and so on, so as to shorten present downstream and refining procedures. 

Gravity sedimentation techniques are used commonly in effluent treatment processes for separation of activated sludge from aqueous solutions, in fuel ethanol production for recovery of yeast cells from aqueous ethanol solutions for recycle to the fermenter, and in the pharmaceutical industry for separation of solvent and aqueous phases in product recovery and isolation of impurities. 

As the inert gas passes through the system, it becomes humidified, removing the water of reaction from the reaction mixture. Most of the energy required for the gas humidification comes from the heat of nitration. The wet gas is condensed and the inert gas is recycled to the nitrator. The condensed organic phase is recycled to the nitrator while the aqueous phase is sent to effluent treatment. The reaction mixture is phase separated and the sulfuric acid is returned to the nitrator. 

There has been very little publication/information on the treatment of palm oil refinery effluent. Osenga (41) introduced a treatment process consisting of a cross flow interceptor (CFl) for oil separation, physical and chemical treatment, and air flotation units to remove the floes followed by a batchwise activated sludge process for the liquid effluent treatment. This process also requires close supervision in order to achieve the desired treatment efficiency. 

Membrane-based separation methods are popular in chemical industry for effluent treatment, desalination, and gas purification. However, their application for separation of actinides relevant to nuclear industry is still at infancy stage. The past few decades saw the use of exotic reagents such as crown ethers, calrxarenes for the selective complexation and removal of actinides... 

Tailored copolymer resins are not the only exchangers to exhibit specific affinities towards selected ions. Many types of inorganic materials such as clays, zeolites, amphoteric oxides, heteropolyacid salts, and phosphates exhibit useful specificity towards selected monovalent and polyvalent ions. In the laboratory such media are often the basis of chromatographic separations, whilst industrially many such materials offer benefits in radioactive waste effluent treatment for removing nucleides such as caesium ( Cs) and strontium ( °Sr). 

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