Industrial wastewater refers to the wastewater that arises from industrial production processes (e.g. in the food, paper, chemical, textile, and metal industries). The composition of the industrial wastewater can vary greatly depending on which branch of industry is involved. Wastewater in the paper industry contains organic substances that are not easily degradable. Oils, greases, and heavy metals are found in metalworking. Industrial wastewater must be cleaned before disposal. The treated water can either be returned to the production process or discharged into the sewers.

Example: treating wastewater from electroplating

In a plating bath, objects made of base metals such as zinc or iron are given a protective finish. This coating can consist of chemical elements such as copper or nickel. The first wastewater treatment stage for plating wastewater is cyanide and chromate detoxification. Detoxification is performed in continuous-flow systems. Once detoxification is complete the next stages take place: neutralization precipitation, removal of the precipitation products, and disposal of the sludge. At this point the cleaned wastewater is delivered to the sewer system.

pH measurement in plating plants

A pH value of at least 10 is necessary for cyanide detoxification. Chromate is removed from the wastewater in the acidic range. Here, pH measurement is used to monitor the plating baths and the detoxification processes.