The European waste water industry will need to develop denitrification processes to remove nitrogen as pressures increase to reduce nutrient levels discharged in effluents.
In the USA deep bed filter technology has been used extensively to provide denitrification to levels less than 5 mg/l TN. This paper describes this technology and the full scale performance at some waste water plants in Florida, USA. This paper also describes a pilot study in the United Kingdom at Severn Trent Water. The results of the pilot plant study indicate that denitrification in deep bed sand filters is a sound robust technology using methanol addition. Nitrogen removals greater than the 70% required in the EC Directive 1991 are possible at winter sewage temperatures.
The process is most suitable for achieving nitrogen removal at trickling filter plants. The cost of methanol addition is calculated to be ₤10/1000m3.