David S Smith Packaging - Newmarket

Effluent Plant Treatment

David S Smith Corrugated, part of David S Smith Packaging, has found an environmental way of resolving the scale build-up in its effluent plant by installing the patented ENiGMA scale control system from Environmental Treatment Concepts (ETC). Not only has the company substantially improved the performance of its plant but has also received a payback on the system in just 7 months, based on chemical savings alone.

Situated in the very hard water area of Newmarket in Cambridgeshire, David S Smith Corrugated manufactures around 2 million square metres of corrugated fibreboard a week. The board is sold to a wide range of end users including bakeries, pet food manufacturers and pharmaceutical companies.

As part of the process, the company produces around 25 cubic metres a day of effluent mix, comprising of wheat starch, with a high pH value of 13, and print wash-down with a pH value of 4. Lime and ferric sulphate is added to the effluent mix at the treatment plant to flocculate the solids from the liquids. The combined effluent cocktail with its high pH values, together with the high levels of calcium in the mains water, caused severe scaling in the effluent plant's vacuum pumps. This necessitated the company having to strip down and acid clean the pumps every week, resulting in six hours downtime.

Following a site survey conducted by an ETC engineer, it was agreed that an ENiGMA system would be installed throughout the effluent plant to cover the complete effluent and treatment process. The system included the installation of a single ENiGMA unit to deal with the main effluent to the treatment plant, two further units to handle the lime make-up water, both in and out of the treatment plant, and a fourth unit to treat the effluent back to the neutralising tank.

The ENiGMA system was rented for a three-month evaluation period in order that David S Smith Corrugated could appraise its benefits. During this period, the system was closely monitored for scale deposition and it was noted the system was remaining scale free.

"We were delighted with the results", said Ian McLaren, Engineering Manager. "Not only have we reduced our chemical usage by between 25 to 30 per cent, which is far better for the environment, but we have also substantially lowered our costs on chemical disposal, downtime and maintenance." As an added bonus, the ENiGMA system has also removed the scale from the probes, which are used by the plant to automatically measure the pH balance. These probes now give a more accurate measurement, which has allowed the plant to have tighter tolerance levels.