Cool Water High-Rate Full-Scale Denitrification in Deep Bed Filters

Littleton-Englewood WWTP
Englewood, Colorado

Littleton-Englewood and Brown & Caldwell worked to meet the new TIN permit by enhancing nitrate removal with a new in-plant recycle and new denitrification filters. Advanced control strategies and instrumentation were included to improve reliability in meeting a daily permit. The final design included eight deep bed filters, each 3.6 meters by 29.3 meters, containing 2.4 meters of 2-3 mm rounded sand. A formal Process Performance Guarantee was required. Only partial denitrification was needed at certain times of the year. However, denitrification filters work best when fully denitrifying. Otherwise, partially converted nitrogen in the nitrite form discharges from the filter and causes a very high chlorine demand downstream. To solve this, the filter plant was designed with individual methanol feed to each filter. Each filter could be controlled individually to produce full efficient denitrification in some filters, while others simply provided solids filtration. This produces a blended effluent quality as chosen by the operators. Filtration of a majority of the plant flow was envisioned to aid phosphorus removal that might be required in the future. Each filter was equipped with two inlet gate valves that feed evenly dividing cut-throat flumes. Filters not being used for denitrification can be run with both flumes open to allow for doubled filtration rates. Source: WEFTEC 2009 Proceedings

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Posted: July 6th, 2010 | Filed under: Waste Water Treatment | Tags: Environmental Impact, Nitrogen Removal | No Comments »

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