Solvay saves millions in waste and energy improvements

Chemical company Solvay has cut energy consumption and waste at its Lostock works in Cheshire by half while increasing productivity by 80% since taking over the site in 1999. The improvements have saved the company over £1 million per year and helped it comply with the new integrated pollution prevention and control (IPPC) regime.

Solvay Speciality Chemicals produces precipitated calcium carbonate at its Lostock works near Northwich. The Belgian firm bought the site from Zeneca in 1999.

Precipitated calcium carbonate is essentially chalk dust with a soapy coating. The product is widely used as a filler in plastics, paints, rubber and varnishes. Solvay takes liquid calcium hydroxide from the neighbouring Brunner Mond chemical works and treats it with carbon dioxide and stearic acid to form precipitated calcium carbonate. The product is filtered, dried and milled to form a powder.

Since taking over the business, Solvay has transformed the performance of the site. Lostock's manufacturing director Andrew Willson suggests that the previous owners Zeneca had invested little in the works, treating it as a "cash cow" for its pharmaceutical business.

As a result, Mr Willson said, the site was operating very inefficiently and close to levels permitted by the Environment Agency in the site's integrated pollution control authorisation.

In contrast, precipitated calcium carbonate is a core business for Solvay, which owns four other such plants in Europe. The company launched a programme to improve the site's performance.

Solvay has driven down energy consumption by 45% over the last five years, and the site's energy costs have dropped by 70% since 2000. It was helped by a combined heat and power plant built by Brunner Mond in 2000, which supplies Solvay with steam, along with a wide range of energy saving projects.

One innovation was the replacement of conventional press filters with centrifuges to separate the product from the liquor. Solvay believes that Lostock is the first site in the sector to use this process. The centrifuges are more efficient and produce a drier cake, so that less steam is needed in the drying process.

Solvay has also made significant improvements in effluent treatment. In part, the need for these improvements was driven by the increase in production capacity created by the centrifuges.

Effluent from the process is treated by Brunner Mond in large lagoons which settle out the solids. Sludge is dredged out of the lagoons and sent to landfill. Previously, Solvay pre-treated the effluent in its own settling tank in order to meet limits set by Brunner Mond. This process was inefficient and the effluent discharged was very close to the limit on suspended solids.

Solvay invested more than £150,000 on a new filter to separate the sludge and water prior to the settling tank. The sludge is recycled back into the process.

The effluent treatment system, among other improvements, has helped reduce the total amount of waste from 78 to 37 tonnes per month, with a further reduction to 25 tonnes planned for 2005.

Solvay achieved further energy savings through installing a computerised process control system and replacing a number of electric pumps and motors with energy efficient models.

The computerised system measures energy usage per tonne of product, with continuous displays so that operators can see the cost. The performance of each shift of operators is fed back to the teams. Greater automation of the plant has also enabled process water use to be cut from 8.6 to 5.2m3 per tonne of product.

Solvay's environmental management system has recently been certified to international standard ISO14001. In July, the Chemical Industries Association gave the company a sustainable development award in recognition of its improvements.

The improvements will also help Solvay to demonstrate that it is using the "best available techniques" to control pollution and manage resource consumption, as required by the IPPC regime. The company is due to apply to the Agency for a permit by the end of August.

Andrew Willson said that Solvay had introduced the improvement programme "because of a deep-seated sense of corporate responsibility and because it made good business sense.

"As the projects have developed, so the employees at the site have become increasingly aware of their own contribution in reducing energy and raw material usage and waste production," he said. "The key to any team activity is to raise awareness, set realistic goals and to give every person the tools necessary to measure their own performance. The improvements that have been made account for more than £1 million per year of savings and ultimately far less time is spent on incident management."