Wastewater Treatment - Nutrient Removal

Background

Significant portions of Virginia’s waterways are identified as impaired for not meeting certain water quality standards. Excessive nutrients (nitrogen and phosphorus) are one of the primary causes for this impairment.

Excessive nutrient discharges to state waters can have a significant impact on water quality and, in the right conditions, provide the necessary food for the growth of aquatic plants (algae). This is a major reason for the development of “dead zones” (oxygen levels at or near zero) in the Chesapeake Bay, Gulf of Mexico and many other bodies of water throughout the world.

Due to the environmental concerns caused by excessive nutrient discharges, state and federal regulatory agencies are implementing stringent limitations on both point source and non-point source nutrient discharges.

For wastewater treatment plants in Virginia, these nutrient limitations will require the upgrading of existing treatment systems or, in many cases, construction of new treatment plants to provide some form of biological nutrient removal (BNR). At the present time, the most widely used form of biological nutrient removal involves the use of suspended growth (activated sludge) treatment systems. These systems provide the biological steps necessary to remove nutrients (nitrogen and phosphorus) from the wastewater.  

BNR Process image

  1. Anaerobic step: Enhanced Biological Phosphorus Removal
  2. Anoxic step: Denitrification
  3. Aerobic step: Nitrification

Although nutrient removal processes in activated sludge treatment systems will normally follow these steps, other nutrient removal options are available. To find out more information on nutrient removal technology, click here.

 

Plant Optimization and Assistance

In many cases, treatment systems may be able to decrease the nutrient content of their discharge by adjusting the operations of the plant. The Operator Training and Assistance Program can assist in identifying and evaluating potential options for improved nutrient removal through process modification. A simple adjustment (i.e. Changing the way the aeration system operates) can have a significant impact on the level of nutrients discharged by the plant. To learn more about how one facility improved its nutrient removal performance, click here.

The Operator Training and Assistance Program can also assist treatment facilities who are experiencing operational problems or achieving less than expected levels of nutrient removal.

At the facility’s request, Operator Training staff can assist the plant staff in:

  • Evaluating current system operations.
  • Identifying process and/or system adjustments that would address the current problems.
  • Evaluating the potential impact of these adjustments on overall plant performance and compliance.
  • Implementing and evaluating the impact of the identified adjustments.

Contact program staff, if you are interested in obtaining assistance.

 

Related Links:

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000


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