Effluent treatment systems

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. 

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. 

Figure 26.1 A typical water and effluent treatment system.

Figure 26.53 presents a superstructure for the design of an effluent treatment system involving three effluent streams and three treatment processes17. The superstructure allows for all possibilities. Any stream can go to any effluent process and potential bypassing options have been included. Also, the connections toward the bottom of the superstructure allow for the sequence of the treatment processes to be changed. To optimize such a superstructure requires a mathematical model to be developed for the various material balances for the system and costing correlations included. Such a model then allows... 

Wang YP and Smith R (1994) Design of Distributed Effluent Treatment Systems, Chem Eng Sci, 49 3127. 

Design of Emergency Relief and Effluent Treatment Systems... 

Question 5 ("Is combustion with air the only chemistry intended at your facility ") can be answered YES in this case, assuming the "facility" being addressed is limited to the incinerator system. Due to the great number of combustion systems in operation, many other resources are available for ensuring safe design and operation of the combustion part of the incinerator facility. However, it should be noted that many combustors now have effluent treatment systems, such as selective catalytic reduction (SCR) systems, that involve intentional chemistry beyond the combustion reaction. 

This finding is based on EDS I CATOX tests by Parsons/Honeywell and also on the differences between the design tested and the offgas effluent treatment system proposed for the SILVER II process. Since the AEA CATOX unit is modeled after the Parsons/ Honeywell design, it can be expected to produce similar amounts of dioxin and furan. In addition, the gas treated by the AEA CATOX unit has a different source and therefore a different composition. No CATOX units have been tested on gases from this source. 

Figure Eleven (11) illustrates a total printed circuit effluent treatment system utilizing reverse osmosis to recover purified water from mixed rinses and the airscrubber. Bath dumps and reverse osmosis concentrate are chemically treated, producing a sludge for landfilling and effluent suitable for discharge.

Figure 11, Printed Circuit Effluent Treatment System...

One paper mill, Inland-Rome, in Rome, GA, ran four tests burning varying amounts of wood waste, TDF, biological sludge from the plants secondary effluent treatment system, and coal.2 One TDF test was run at 7 percent TDF and 93 percent wood waste particulate emissions were similar to baseline.2 Another test was run with 12.8 percent TDF, 12.1... 

Eliminate continuous catalyst promoter addition lower cost of construction materials and elimination of effluent treatment systems... 

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