Aerisa ‘clean air’ solutions leverage ionization technologies to produce oxygen-based ions which easily react and breakdown a broad set of chemical compounds, including volatile organic compounds (VOCs) and possibly bacterial, fungal and viral compounds. The application of Aerisa solutions in wastewater treatment facilities has been particularly effective at reducing hydrogen sulfide (H₂S) levels, the primary chemical created.

Aerisa systems provide a supply-side system as well as an exhaust-side system to treat air being supplied to a room, while treating any chemicals being produced inside, and exhausted from the room as well. This treatment occurs at each source of possible contamination which maximizes effectiveness. The reactions between oxygen ions and chemicals in the system will generally produce inert gases and/or precipitates with little or no negative impact. Aerisa Systems provide this total solution by distributing oxygen ions using air handling units (AHUs) at low energy costs due to low direct energy use by ionization units and little to no pressure drop in the AHUs.

Aerisa versus Scrubber Solutions

Aerisa Systems consist of low-energy consumption ionization units and, the main source of energy consumption, the fans and motors inside the AHUs that push air into and pull air out of the building. Bio-scrubbers’ energy consumption generally results from the fans and motors required to pull air out of the building, as well as any energy required to supply water and other ancillary equipment. The difference in energy use between the AHUs comes down to the fact that Aerisa systems have very little pressure drop through the system, while bio-scrubbers have a large pressure drop due to the need to push air through compact filtration media.

The importance of pressure drop to energy costs is related to the increased horsepower needed to provide the same amount of air flow. The horsepower required to overcome a specific pressure drop is calculated by multiplying the air flow volume by the pressure drop and dividing it by the efficiencies of the fan and the motor.

Where:

Q = air flow rate (CFM)

Δp = pressure drop (inches w.g.)

ε_m = efficiency of the motor (e.g. 90%)

ε_f = efficiency of the fan (e.g. 90%)

6356 = unit conversion factor

Typical bio-scrubber media can create between 0.2 and 5 inches pressure drop per foot of media, depending on a variety of factors including air velocity, and media composition and age. By assuming a few parameters, one can estimate energy costs due to increased pressure drops through the use of a larger horsepower motor. To determine the overall pressure drop, the thickness of the media needs to be determined.

For example, a 6000 cubic foot room, using 12 air changes per hour (ACH) results in a 12,000 cubic feet per minute (CFM) scrubber exhaust air flow requirement. Assuming 90% efficiency for both the fan and the motor, 25 feet per minute (FPM) velocity through the media, and a reasonable 15 second residence time, one can determine the diameter of a scrubber to be 24.7 feet, and a media thickness of 6.25 feet. With a conservative average pressure drop of 0.3 inches per foot, this creates a total pressure drop of 1.875 inches. By increasing the air velocity through the scrubber to 50 FPM, the diameter decreases to 17.5 feet, and the media thickness is increased to 12.5 feet. Neglecting the usual increase in pressure drop from higher velocity through the media, the total pressure drop increases to 3.75 inches. A different type of scrubber might allow a higher velocity and lower residence time, but usually a much higher pressure drop; an example would be 250 FPM, 0.2 second residence time, and a 3.6 inches per foot pressure drop (often given as 0.3 inches per inch of media). Calculations with these values result in a 3-inch overall pressure drop.

The horsepower required to compensate for the pressure drop through the media can be calculated. Through simple algebra, one can calculate kilowatt usage; then assuming a continuous operation, one can calculate the kilowatt-hours (kWh) per year. Knowing the utility rates per kWh, one can ultimately calculate the annual energy costs for an increase in horsepower necessary to accommodate the pressure drop.

Aerisa Systems have little to no pressure drop associated with its equipment. The majority of the pressure drop comes from the simple pre-filter providing from 0.2 up to 0.4 inches pressure drop on average. Because scrubbers also require a similar pre-filter, the calculations do not include this for either Aerisa or the scrubber; instead Aerisa systems will be estimated at a 0.15 inches of pressure drop to account for minimal drop through the AHUs and the ductwork for comparison purposes. The calculations for the Aerisa system use a doubled air flow (24,000 CFM) necessary for both a supply-side and an exhaust-side system; this assumes the scrubber uses a simple air vent to balance the air pressure.

Table 1 demonstrates the calculation steps of the costs associated with each pressure drop. Table 2 illustrates the energy and cost savings Aerisa provides over the two extreme pressure drops calculated above. The percentage of cost savings ranges from 84% to 92%. This should be a fair estimate, as conservative values were chosen for the assumed parameters. Even with Aerisa pressure drops over two and one half times higher, at 0.4 inches, perhaps due to longer and/or more treacherous ductwork, the lowest cost savings is still a minimum of 57% over the lowest scrubber estimates.

Table 1: Pressure Drop Energy Calculator

Table 2: Pressure Drop Energy Savings

Aerisa Systems save substantial money over scrubber systems due solely to pressure drop differences. The Palm Valley Water Reclamation Facility (PVWRF), in Goodyear, Arizona provides a real world example of the actual energy savings achievable using Aerisa Systems over scrubbers. An engineering study was performed by McBride Engineering Solutions (MES) comparing a chemical scrubber solution to an Aerisa System solution. The results indicated several advantages of the Aerisa solution over the chemical scrubber solution, one being a savings on energy costs. MES estimated a large reduction in energy usage costs from $90,263.04 for a chemical scrubber down to $12,249.98 annually for the Aerisa System, a savings of over 86%.

In addition to providing a better overall solution to indoor and outdoor air quality by attacking the odor sources both inside and out; and lowering maintenance costs for replacement of tubes versus chemical and media replacement costs, Aerisa solutions lower operational costs to the customer through a lower overall energy usage.