Are Sludge Management Costs Eating Your Biological Wastewater Treatment Program Alive?

Sludge Management

In the classic science fiction film, The Blob, a meteorite containing an amoeba-like alien lands near a small town. It soon escapes from its rocky prison and begins consuming everything in its path. As it does so, it grows larger and more menacing. It appears to be unstoppable.

For many wastewater treatment plant managers and operators, this plot may sound eerily familiar – except their nemesis is sludge, the by-product of biological wastewater treatment. Like the blob, its processing and removal consumes a seemingly uncontrollable amount of their time, manpower and operations budget.

A shocking amount of sludge is produced using suspended growth wastewater treatment: On average, it generates 0.75 lbs. of solids per 1 lb. of BOD removed. That means a 1 MGD plant with 250 mg/L of BOD influent produces about 1,564 lbs. of sludge per day  – or over a half million lbs. of sludge per year!

Sludge processing and removal is a multi-step process that requires a significant commitment of labor, energy and other costs:

  • Pump the sludge from a sludge treatment unit process (labor, equipment and energy costs)
  • Pre-treat it (labor and chemicals)
  • Dewater it (labor and energy costs)
  • Transport it from the wastewater treatment plant (pumping or hauling – labor, equipment and energy costs)
  • Land apply or landfill it in its new location (labor, equipment and energy costs)
  • According to the EPA, sludge management represents 40 to 60 percent of the total budget for a wastewater treatment facility.

In order to maintain a large mass of microorganisms in the system, suspended growth plants need to return activated sludge that settles in the secondary clarifiers back to the aeration tank.  This requires pumping and operational control which, in turn, requires energy, pump maintenance and close process monitoring.

A practical alternative

A different method of biological wastewater treatment reduces this large volume of sludge in some cases up to 80%. The Nebula MutliStage Biofilm System is an attached growth process from Aquarius Technologies using proprietary fixed textile media as the home for microorganism. Oxygen for respiration and mixing of the microbes is provided through a fine bubble diffused aeration system.

Sludge is minimized in the multistage plug flow treatment process by creating different treatment environments with specific microbial populations. Spatial separation of microorganisms creates a food chain, beginning with higher food-to-microorganism ratios in the early stages and progressing to low food-to-microorganism ratios in later stages.

A dramatic reduction in sludge production

This multistage approach to biological wastewater treatment results in significantly less sludge production: One installation consistently reports an 80% reduction in sludge generation.


In the movie The Blob, the enterprising townspeople eventually figure out that the evil pseudopod can be vanquished using cold air. They surround it with fire extinguishers and put it to sleep until an Army transport can whisk it away to Antarctica for safe keeping.

Don’t let sludge management costs run amok at your wastewater treatment plant. Cut them down to size by investing in a Nebula MultiStage Biofilm System.

To learn more about how you can do this, read these Aquarius blog posts:

Don’t Tolerate Inefficient Wastewater Treatment Methods In 2018

Nebula MultiStage – Less Sludge Means Lower Operating Costs

Attached Growth Biological Process – Wastewater Treatment

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