Article | August 12, 2016

Stir It Up: Five Tips for More Effective Industrial Aeration

Source: RWL Water
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Stir It Up: Five Tips for More Effective Industrial Aeration

By Linda Dailey Paulson

We all know that aeration is a simple but versatile secondary treatment, with uses ranging from removing gases and dangerous compounds from wastewater, to encouraging the action of microbes as they break down solids.

If you’re using aeration in an industrial setting, you may be producing streams with concentrations of biological oxygen demand (BOD), chemical oxygen demand (COD), and ammonia that are orders of magnitude higher than in municipal waste streams. So, it’s particularly important to keep your equipment operating at peak efficiency to meet regulatory goals in the most economical way possible.

We spoke with RWL Water Industrial Sales Manager Jason VerHoef, Product Manager Andy Wrzos, and Product Sales Managing Engineer Dina Palumbo about some of the common problems they see with aerators, and advice for customers to improve their operations.

If you’re working with aeration equipment for industrial applications, here are five tips to help you maximize the effectiveness of your system — and the sustainability of your operations.

1) Check for Even Distribution of Air

Visually inspect your aeration system to make sure air is being distributed evenly, then make adjustments if it’s not. Regular assessments can increase treatment efficiency by eliminating dead zones. Proper mixing helps ensure uniform oxygen distribution, and can prevent stratification and sedimentation.

2) Monitor Equipment Depth

Setting a mechanical aerator to the correct depth will maximize mixing and aeration at the lowest possible amperage. This should be monitored regularly to keep energy expenditure as low as possible.

3) Every Aerator in Its Place

Routinely check the location of your aeration equipment so it precisely matches design specifications, since vibrations can cause shifting. In the case of floating equipment, ensure moorings are secure and well maintained.

4) Perform Regular Maintenance

Improper equipment maintenance can lower performance and raise costs. Units subjected to constant, excessive vibration may fail, which means equipment will have to be fixed or replaced.

Regular inspections can prevent small problems from becoming larger ones. Typical maintenance items include:

  • Checking seals
  • Lubricating bearings
  • Measuring amperage draw to detect fouling
  • Inspecting air inlets and air delivery equipment
  • Making sure filters aren’t clogged

With your sub-surface aeration equipment:

  • Make sure diffusers are not broken, clogged, or damaged
  • Check the motor periodically for leaks
  • Remove debris that may have collected on the equipment

5) Regularly Test Dissolved Oxygen Profiles

It’s important to go beyond visual inspection and regularly test the level of oxygen in various parts of your basin. Try using dissolved-oxygen control sensors, and stage unit operation to match the DO demand.

See if you can lower DO set points a little at a time. Since each system is unique based on its biomass and treatment stream, some plants may require a DO level of 2 to 3 mg/L, while a similar facility with similar reactor conditions and treatment goals can run properly with a DO level of less than 2 mg/L.

Don’t forget that water temperature can be a factor in the dissolved oxygen levels.

It’s important to:

  • Clean, calibrate, and repair any field-installed probes to ensure accurate readings.
  • Confirm that aeration readings are consistent
  • See that SCADA readings match those of a handheld probe

In addition to regularly testing DO parameters, you should be measuring oxygen uptake rates (OUR). This measurement of respiration rates determines the oxygen demand of the biomass.

Collect samples throughout the reactor and compare results to determine if the target parameters are being reduced and how quickly they are being reduced. Monitoring helps users calibrate aerator speeds to prevent over- or under-aeration.

You also may want to consider using control systems to better regulate the aeration system output.

Custom-Tailored Aeration Solutions

If you need information about the best available aeration equipment for your wastewater treatment challenges, contact RWL Water and let our technical experts help you determine the proper sizing, layout, and operation of your next aeration or mixing system.