The Avenue Coking Works is the site of a former coking plant that was opened in 1956 and ceased operations in 1992. It was a fully integrated plant producing odourless fuels and it processed by-products formed by the carbonisation of coal. These by-products included acid tar, ammonium sulphate, pure benzene and toluene, naphthalene, nickel, zinc, thiocyanate, phenols and other acids and organic compounds.
After decades of industrial productivity, the heavy contamination of the site, and the subsequent contamination of the adjacent River Rother, the Avenue site has been dubbed one of the worst single point sources of pollution in the UK. Consequently, the runoff water of the 100 ha site, process water and groundwater had to be purified.
To remove a wide variety of contaminants from the water such as heavy metals (zinc and nickel), thiocyanates and cyanides, COD, ammonium, phenols and naphthalene, a tailored physico-chemical and biological wastewater treatment plant was developed. This had a capacity of 25 m³/h.
The installation consisted of an oil/water separator, a coagulation and a sedimentation stage. The settled sludge is removed for bioremediation. The overflow of the sedimentation stage goes to an activated sludge reactor (SBR), an oxidation step by means of hypochlorite dosing, a sand filtration and activated carbon filters. As a final step ion exchange is used to facilitate the removal of cyanides/thiocyanate and heavy metals.