For continuous in-line cleaning applications, it is recommended to check solution concentration twice per 8 hour shift. Today, aqueous cleaners are primarily liquids. There are some powdered products, but they tend to have certain drawbacks. Most powders take a long time to dissolve. If the powder is not completely dissolved, it can form a sludge that may redeposit on the parts.
Powders also tend to dust and can create an inhalation hazard.
Many manufacturers of competitive products tell customers that it is acceptable to sewer the aqueous portion of a spent bath. A complete review with local discharge regulations should be done before putting anything down the drain. While it is true many cleaning agents do not contain harmful materials, the soils washed off during cleaning can often present a problem.