Nutrient TMDL in Aeration Stabilization Basins

Benthic Layer in Aerated Stabilization BasinRecent Total Maximum Daily Load restrictions for industrial Waste Water Treatment Plants have Paper Mills concerned about the release of nutrients from the benthic layer in an Aeration Stabilization Basin (ASB). These nutrient releases increase the residuals of nitrogen and phosphorous at the back end of the Aerated Stabilization Basin.   Many industries find nutrient addition of nitrogen and phosphorous to Aeration Stabilization Basin systems necessary to maintain bacterial health and optimize COD/BOD conversion. Paper Mill Aeration Stabilization Basins are especially nutrient deficient.   The fate of these nutrients depends both on biological and physical processes within the Aeration Stabilization Basin. Addition of nitrogen is generally in the form of ammonia; and phosphorous is generally in the form of polyphosphates or phosphoric acid. In the aerated portion of the Aeration Stabilization Basin, bacteria consume and store soluble nutrients incorporating them into organic materials or storing them in vacuoles. Organic cells contain a ratio of 100:5:1 of incorporated carbon, nitrogen, and phosphorous respectively.

Environmental Business Specialists specializes in optimizing ASBs biological health to maximize biological uptake of nutrients in the aerated zone. Biological health can be analyzed by various tests done at EBS in addition to a Microscope Examination. Well-aerated sections inhibit settling, which in turn keep bacterial cells in suspension moving towards the effluent. Settling and quiescent zones allow bacterial cells to settle out and over time these cells are buried by additional cell sedimentation. Physical forces drive the release of nutrients back into the Aeration Stabilization Basin; diffusion, temperature, and sediment disturbances are the main physical controls for benthic nutrient feedback. Biological activity in the benthic layer balances these physical forces. Anaerobic bacteria in the sediments continue to cycle nutrients in various forms, both releasing inorganic nutrients into the pore spaces as old cells die and in turn incorporating the released nutrients back into organic matter by new cell growth. Nutrient optimization in addition to engineering controls and careful monitoring can be used to control nutrient residuals at the effluent.

EBS can provide all these services as part of our commitment to helping clients better utilize our products to improve water quality.   Contact us at 985-674-0660 or

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