Water in a separator or concentrator recycling system can normally be reused several hundred times before it accumulates excess dissolved solids. Each time a gallon of water is reused, the need for discharge of that volume of water is eliminated, as is the need for additional replacement clean water from the tap. Two forms of solid contaminants may be present in wastewater, suspended and dissolved. Lower-cost recycling systems concentrate on removing the suspended contaminants and are not effective in removing dissolved contaminants. Systems that are able to remove dissolved contaminants employ much more sophisticated technologies, such as reverse osmosis or catalytic oxidation or thermo oxidation.
Testing is required of water samples to determine the extent to which contaminants are dissolved.
Should a condition exist where a high concentration of contaminants are found to be dissolved, steps may be taken to change the process which produce this condition. This will usually eliminate the need for the more sophisticated types of recycling equipment. Under some circumstances, however, such as the need for very pure rinse water, it may be necessary to apply the more complex technologies to minimize dissolved contaminants and a larger investment will be necessary. Typical suspended contaminants encountered in the pressure cleaning of heavy equipment are shown in Figure 1. The first is prepackaged for a specific application and set of operating parameters.