On the other hand, in the industrial manufacturing sector, the wastewater from one plant is usually very different from every other plant. This "dissimilarity" of industrial wastewater streams requires a disciplined approach to designing the optimum treatment system.    

For a specific application, the following approach is recommended:

• What’s in the wastewater? A complete chemical analysis of the wastewater must be obtained. Because concentrations of contaminants vary as a function of time, a "worst case" sample should be analyzed.
• Where can this treated water be used? Back in the manufacturing process? Cooling tower feed? Boiler feed? Product rinsing? Toilet flushing? Landscape irrigation? There is usually no shortage of potential applications.
• The choice of the water use(s) will determine the quality requirements of the treated water.
• Quality requirements will dictate the selection of treatment technologies. This requires an understanding of the chemistry of the specific contaminants as well as the plethora of available treatment technologies. There are usually several excellent technologies appropriate for the removal of each class of contaminants. The key is to identify the optimum technology for this particular application.
• For those skilled in wastewater treatment, it is possible to quickly narrow down the treatment technology choices most appropriate for this application. Because more than one class of contaminant will usually have to be removed, several different technologies will usually be required for the total treatment system. The selection of a specific kind or model of a technology may require initial testing, and a pilot test to establish performance parameters for the final design.
• As part of the design process, it is possible to estimate the capital and operating costs to allow the company to determine if this recovery and reuse program has sufficient merit to proceed.