Challenge

In early 1990, ministers of the European countries on the North Sea declared that ocean disposal of industrial wastes should cease by the end of 1992.

To comply with the mandate, the Sterling Organics' facility at Dudley, Northumberland, England, had to investigate treatment of a high-strength, highly colored para-aminophenol (PAP) wastewater generated in the production of the pain reliever Paracetamol. 

Solution

After investigating several treatment options, Sterling Organics chose a wet air oxidation system from Siemens Water Technologies.

In the wet air oxidation process, liquors are pumped to system pressure, mixed with compressed air, and brought to oxidation temperature. In the reactor, the oxidation is autothermal and destroys complex organics or reduces them to biodegradable forms or to carbon dioxide and water.

Prior to the full-scale installation, batch tests of the wet air oxidation process were conducted by Siemens Water Technologies in an autoclave shipped to the Sterling site. Encouraging test results prompted pilot plant testing at the Zimpro facility in Rothschild, Wisconsin. Positive test results from the pilot testing prompted procurement of the full-scale system.

The system was designed to treat 30 gallons per minute of wastewater.

Results

Key parameters of COD, phenol, PAP and color in the treated effluent are substantially below guarantee maximum values. The effluent - biodegradable and nearly colorless - is trucked to a public wastewater treatment plant for discharge to the public sewer system.