Multiple contaminant wastewater minimisation

The industrial case study was centred on the four mixers found in the toiletries area, as described above. Due to the multiple products found in the area, the residues within the system were not all the same (Table 6.7). This coupled with compatibility considerations between the various contaminants in the wastewater meant that the multiple contaminant wastewater minimisation methodology was suited to the problem. 

Multiple contaminant wastewater minimisation was dealt with in Chapter 6 wherein it was assumed that there were no compatibility issues with wastewater produced containing different contaminants and that all the contaminants present in the system could be mixed. However, in certain instances this is not the case. Such instances arise when there are different contaminants in each stream that cannot necessarily be mixed, or there is a unit that can only receive wastewater contaminated with a certain contaminant. In such instances it would be advantageous to have... 

As with the multiple contaminant wastewater minimisation model, the mathematical model for multiple storage vessels comprises of two modules, namely, a mass balance module and a scheduling module. The constraints that comprise the mass balance module are described first. 

The constraints used for the scheduling of the recycle/reuse in the model are similar to those used in the previous multiple contaminant wastewater minimisation methodology, (see constraints (6.31), (6.32), (6.33), (6.34) and (6.35)). Again, the reader is alerted to the fact that the following constraints apply to water using operations, i.e. they are not as generalised as in Chapter 6. This is due to the fact that... 

Wastewater contaminated with multiple contaminants is a common occurrence in any industrial facility. Past wastewater minimisation methodologies have been focussed on single contaminant systems. This restricts the application of the methodologies to a small range of problems. Therefore the development of a multiple contaminant wastewater methodology is mandatory since it finds broader industrial application. 

Wastewater Minimisation in Multipurpose Batch Plants Multiple Contaminants... 

The methodology presented in this chapter deals with wastewater minimisation where the wastewater contains multiple contaminants. The methodology determines... 

The second illustrative example deals with wastewater minimisation in an operation involving four processes. Wastewater produced from processes 1 and 2 contain the same single contaminant Cl, while wastewater produced from processes 3 and 4 contain multiple contaminants, namely, contaminants Cl, C2 and C3. Processes 1 and 2 cannot receive water contaminated with multiple contaminants, while processes 3 and 4 can receive any type of wastewater. Table 7.3 provides the required maximum inlet and outlet concentrations for each process as well as the mass load of each contaminant in each process. 

Chapter 6 presents a technique for wastewater minimisation in multipurpose batch plants characterised by multiple contaminants. 

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