Wastewater from the chemical and petrolchemical industries varies greatly with the processes used. It can be pratically clean cooling water or highly toxic wastewater. The following is a partial list of processes producing great quantities of wastewater:

- Manufacture of soda                                      - highly dispersed oxides

- pharmaceuticals                                             - production of carbohydrates

- perborate manufacture                                   - chemical fiber manufacture

- production of barium                                       - fertilizer production

- compounds                                                      - oil refineries

Treatment depends greatly on the origin of the wastewater and its contents. The following treatment processes are in use:

- screening                                                          - reverse osmosis

- sedimentation with or without additives           - absorption

- distillation                                                          - neutralization

- flotation after flocculation and sedimentation   - detoxification

- filtration                                                             - biological processes: anaerobic and aerobic     

- ion exchange                                                                                  

Measuring probes may be used for flow and level measurements, for analysis and other purposes. They must stand up to whatever acids, bases or other corrosive materials may be present in the wastewater.

Gaskets made of suitable materials should protect probes and moving parts from carbohydrates and oils.

Each country or community regulates wastewater  discharge into public drains. Specifications include chemical oxygen demand (COD), toxicity for fish, temperature, pH, active chlorine, AOX, phenol index, carbohydrates from a not-sedimented, homogenized sample, nitrogen in the form of nitrates and a series of other parameters.