Alternative treatment wins chemists prize

An environmentally friendly alternative to polyacrylates, for the treatment of detergents in sewage sludge, has won four chemists from the Lanxess group the 2005 Friedrich Wöhler Prize. The German Chemical Society's award, for production processes that conserve resources, went to Torsten Groth, Winfried Joentgen, Alfred Mitschker and Nikolaus Müller who have developed polyasparagine acid, a biodegradable alternative to polyacrylates.

Polyacrylates replace phosphates in detergents and are absorbed on the surface of sewage sludge at sewage treatment plants. For detergents alone, the demand for polyacrylates in Europe is 90,000 tonnes per year.

In the early 1990s, most of the sewage sludge produced was used as fertilizer. However, there was a risk of polyacrylates sedimenting and remobilising heavy metals hazardous to groundwater.

In the production of polyasparagine acids, which go by the product name Baypure DS 100, the chemists used a patent that describes the production of the acids from maleic anhydride (MSA), ammonia and caustic soda solution. Since these raw materials are widely available and cost-effective, Baypure DS 100 is not only ecologically superior to polyacrylates, it also has an economic edge.

The process circuits for Baypure DS 100 are closed. This means that the product is manufactured without waste; the only waste substance is the water used for cleansing. The raw materials used to produce Baypure DS 100 are fully recycled and/or designed in such a way that they can be used for other purposes.

Another advantage of the process is that production as a whole is almost energy-neutral. This is because the production of MSA is largely exothermic. Four tonnes of steam are generated per tonne of MSA, and these can be reused.

In the context of the research and development work carried out for the polyasparagine acid production process, an environmentally friendly chelating agent was developed. The iminodisuccinate also biodegrades easily and, like polyasparagine acid, has a good overall ecotoxicological profile.

The product is marketed under the brand name Baypure CX 100 and is used in personal hygiene products such as hair shampoos, shower gels, detergents and a range of surface cleaning agents. The product flows used in the production of Baypure® CX 100 are closed and waste-free.

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie