Wet Scrubbing ‘Most Versatile, Cost Effective Air Pollution Control’

Of all available air pollution control technologies, wet scrubbing remains the most cost effective and versatile, reports Pollution Engineering.

Techniques for wet scrubbing typically remove more than 99 percent of air particulate matter and remove aerosols less than 3 µm, the industry publication reports.

Venturi scrubbers — one of the industry’s most popular types of wet scrubber — remove particles from 1 µm to 100 µm at very high efficiencies. These types of scrubbers achieve the efficiencies by forcing contact between particulate matter and fine water droplets through a tight space known as a venturi throat. Advances in throat design have lead to increases in efficiency, responsiveness to variables in flow level and the ability to remove very small particles, the publication reports.

The system has also proven to be effective at treating gases and odors. Examples of gas treatment include scrubbing water soluble volatile organic compounds from coco roasting and oxidizing NO_X with H₂O_2.

At one coco plant in an Ozone Non-Attainment Zone, the system was used to remove VOCs emitted from the natural oils in the coco. The scrubber removed more than 99 percent of the chemical families related to acids, alcohols and ketones found in the emissions, the publication reports.

A venturi scrubber offers numerous advantages to industrial sites wishing to mitigate air pollution: they are small and compact, operate at a high efficiency, are reliable and can be easily expanded due to their modular design, Pollution Engineering says.

In June 2013 Alcoa announced that it was piloting a scrubber technology that should halve water use and require 30 percent less energy, compared to traditional wet scrubbers, and reduces scrubber installation costs and operating costs by about one-third for aluminum smelters and refineries.

The company said its In-Duct Scrubber, under construction as part of a commercial-scale demonstration project at the company’s baked anode and calcined coke facility in Lake Charles, La., will remove up to 90 percent of sulfur dioxide, particulate matter and hydrogen fluoride emissions at the plant. Alcoa expects commissioning and on-site testing of the project to be complete in August.

Photo Credit: Steel smoking stack via Shutterstock.