New system tackles coloured waterways
A pollution problem preventing the effective clean-up of rivers and streams, particularly in traditional textile dyeing industry areas, may finally have been solved.
Chemisolv, a Manchester applied technology company established 12 years ago and specialising in effluent solutions, has now completed full-scale plant trials to remove colour from trade effluents, particularly textile dyes.
For generations, companies have tried to find a cost-effective method of removing the colour from waste dye before it is discharged to rivers or underground sewers, without building special in-house treatment works costing upwards of 1million pounds (UK).
Liquid dye is diluted when it is mixed with sewage effluent or water but still adds unsightly colour - the main culprit being purple or blue - to rivers and streams, even after it has passed through a conventional sewage plant. While this colouring of watercourses is not regarded as harmful, it is coming under the increased scrutiny of statutory agencies responsible for pollution control.
"Now there is a solution," said Paul McKenzie, UK Sales Manager of Chemisolv. "Companies which have had no alternative but to discharge coloured dye effluent untreated directly into the sewer - because of the unrealistic cost of installing expensive plant - can now simply add Spectrosolv, our novel chemical formulation which removes the colour.
"We have blended special coagulants to develop the Spectrosolv range of liquids, which is currently being patented. These customised products need no capital expenditure and only a minimal amount of space because they are dosed directly into the trade effluent discharge.
"The formulation removes any colour from the effluent, lowers the pH and reduces chemical oxygen demand. The suspended solids settle rapidly at the primary settlement stage at the sewage works, producing clear uncoloured water at the outfall, which of course can be recycled.
"The typical cost of using our clean-up chemical solution is in the thousands of pounds, compared to millions for traditional plant. This might add less than one tenth of a penny to the cost of dyeing a tee shirt - a small price to pay for solving a major pollution problem.
He added: "Certain commercially-available water treatment polymers are known to have a serious effect on the performance of sewage treatment works, as they inhibit the function of nitrifying bacteria, and therefore impair the plant's ammonia removal capability. But our products have been shown to have no detrimental effect on sewage works."
A pilot project, using the new technique, was first evaluated at a dyeworks in Scotland three years ago. The authorities had threatened to refuse to accept the water from the processing plant, which was discharging coloured effluent into waters flowing through a local beauty spot.
"Thanks to our technology, the threat has been lifted," said Paul McKenzie. "This was a crucial testbed site, where we demonstrated that our system works on all shades of dyes under production conditions.
"Our products have been extensively tested by an independent water company
to ensure no adverse effect at treatment works. We have worked closely
with Severn Trent Water in the formulation of our new products which they
have comprehensively tested and approved. Severn Trent have now accepted Spectrosolv
technology as one of the few methods available to safely achieve satisfactory colour removal."
