The Enhanced Denitrification Project - Biological Nutrient Removal

The Rockaway River is the source of potable water for a large population of Northern New Jersey residents. During a prolonged period of drought during the late 1990’s the State regulators and planners decided to take steps to ensure the quality and quantity of water available for public consumption. The State engaged the services of a consulting engineering firm to come up with a study followed by a plan of action for the Rockaway River. 

The study showed that during a low river period the treated effluent from the Rockaway Valley Regional Sewerage Authority (RVRSA) treatment plant was in essence 80 % of flow of the river of the potable water supply. The study also revealed that the RVRSA treatment process produced elevated levels of nitrate. 

Nitrate in water has caused infant cyanosis (“Blue Baby disease”) in infants who have been given water or fed formulas prepared with water having high nitrates. With this knowledge the state regulators suggested RVRSA operational personnel to make certain changes to the treatment process. 

Normally the treatment process at RVRSA (which is an activated sludge process) required the addition of a high quantity of oxygen. To lower the nitrates it was suggested to lower the aeration in the oxidation ditches thus creating a change in the treatment process to “Enhanced Denitrification Mode”, which called for a reduced amount of oxygen to be added.  

The NJDEP concurred and agreed to hold harmless the RVRSA of any violation of the permit during this trial period. The Enhanced Denitrification process was started in 2000 and has been the mode of operation continuously since that time, except for very brief periods. 

The effluent levels of nitrate have been at acceptable levels, other pollutants have also been reduced below permit levels, and chemical and energy costs have also been significantly reduced. 

In conclusion, the Enhanced Denitrification Process has greatly improved the quality of the RVRSA Effluent and the Rockaway River, and the RVRSA has implemented effective biological nutrient removal.