Sweeter smell for wastewater

Using the natural elements in the UK

A UK water-company project is using natural elements such as bark, wood chips, seaweed and seashells lining water-filled tanks to provide a solution to a smelly problem - the unpleasant odour that can come from wastewater treatment works.

At Peel Common Wastewater Treatment Works in Hampshire, southern England - which serves nearly a quarter of a million people - Southern Water say they are on course for the lowest recorded number of odour complaints against the site.

Feasting bugs live on the natural material in the tanks and treat the gas hydrogen sulfide that causes the smells. The gas is sucked away by extractors before going through carbon filters back into the atmosphere.

Says Southern Water's principal process scientist Nigel Palmer: "By the time the gas passes through the layers of bark and seaweed, the bacteria and carbon have removed most smells."

In the seashell tanks the system comprises an odour filter filled with cockle shells which are constantly washed by a pumped system and develop a biological film on them.

This film neutralises the gases further, helped by the calcium present in the seashells, and an activated carbon filter later 'polishes up' the air.

The shell filter holds 95,000 L of seashells gathered from around the coast of the UK and Ireland but, after a period of three to six years, the shells will dissolve and have to be replaced. Some 30 m3 of seaweed comes from local beaches, Cornwall and the Irish Sea.

Local residents and councillors in the area had previously been so upset by the smells from the site that they had formed an Odour Forum to work together with Southern Water to identify problem areas and solutions. But in a recent visit to Peel Common, the forum found the results of the new green solution to be "fantastic".

Southern Water process scientists are always looking to adopt and adapt appropriate technologies such as these to benefit the environment.

The seashell odour treatment system was originally developed by the Irish Group Bord Na Mona, which now supplies shells to 10 Southern Water wastewater treatment works.