Wetherby Tertiary Nitrifying Trickling Filter

Constructing Excellence

In AMP5, OFWAT funded the Chemical Investigation Programme (CIP) 1 scheme which tested wastewater treatment technologies to assess their effectiveness at removing certain substances from the works effluent. In AMP6 the CIP2 scheme was implemented to carry out full stage installations of certain technologies highlighted in CIP1, of which one was a Tertiary Nitrifying Trickling Filter (TNTF). The requirements of the project were that it treated a population of at least 12,000 people and contained the priority substances tested for as part of the CIP programme. Wetherby was selected as the preferred site for the full scale TNTF trial.

A Nitrifying Trickling Filter is a wastewater treatment system that removes organic matter, nitrogen and ammonia by filtering through a circular bed of coarse stones or plastic. A nitrification / denitrification process is used to remove the nitrogen. Although these are used elsewhere, the intention of the Wetherby TNTF is that it will demonstrate the filters ability to remove the unwanted materials. This will enable the works to exceed Environment Agency (EA) compliance levels and will future-proof the works against expected improved EA requirements.

The expectation is that this project will demonstrate the effectiveness of a TNTF system and would enable these to be implemented on a wider scale across the region, greatly enhancing the quality of waste water discharged into rivers across the Yorkshire Region. The shared learning nature of the CIP scheme means that this learning will be shared across the country, with all water authorities feeling the benefits.