Peristaltic pumps safely dose ferric chloride in primary treatment plants

摘要

Peristaltic dosing pumps solve potential difficulties in primary wastewater treatment plants that use the highly corrosive, yet cost-effective ferric chloride. Ferric chloride is gaining in popularity as a coagulant and to remove odour-inducing sulphides, competing with alternatives such as alum (aluminium sulphate) or polymers. Many water companies, such as Thames Water in the UK, have been using ferric chloride for some time, but only recently have they begun to use the chemical as a flocculent to help them conform to the AMP 3 biochemical oxygen demand (BOD) parameter. Thames Water's South East Provinces Wastewater site in Cranleigh, UK, uses the Watson-Marlow Bredel 520UN/R2 peristaltic dosing pump for ferric chloride to be added as a flocculating agent. Very few pumps can handle the corrosive nature of ferric chloride, and even fewer can provide flexible control over flow and dosing.