Pollution Control Equipment Used in Johnson County

Industries in Johnson County are required to control the emissions created by their processes. There are different types of control equipment to help them meet this requirement. Different equipment is used by different types of industry. In some cases, more than one form of control is used by a company. Pollution controls can range from simple and relatively cheap to complex and very expensive. Here are three examples:

• Ordinary water spray bars usually used in a rock crushing operation;
• Afterburners which effectively "burn" emissions often found at printing facilities;
• Baghouses which filter and collect particulates in asphalt plants.

Some types of control require a change in the manufacturing process. For instance, companies that use oil-based paints or inks would change to water-based paints or inks.

Click on any photo to enlarge

Water Spray Bars
		This is one of several rock quarry operations within the county. Water spray bars are located at various points through the system to control the dust emissions. This is one of the least expensive methods to control emissions, which in this case is the rock dust or "particulates." In the background you can also see the storage silo of an asphalt manufacturing operation located near the quarry in order to have easy access to the rock.
Afterburners
		These two afterburners are examples of air pollution control equipment. Afterburners effectively "burn" the emissions and are often found at printing operations. Some use natural gas as a fuel, which can be quite expensive. More companies are switching to catalytic afterburners which use natural gas to get started, but then use the volatile fumes as fuel, thereby reducing the cost of operation.. These units are located at a printing facility in Johnson County and were both operating at the time the photo was taken.
Baghouse
		This is one of several hot mix asphalt concrete plants located within Johnson County. The pollutant of concern is particulates, just like the rock crushing operations. This plant, however, uses a "baghouse" (yellow arrow) to control emissions, which are exhausted through the stack (red arrow). The baghouse has numerous chambers with "socks" inside that collect the particulate. This is more effective than water spray but is also considerably more expensive. This plant was in operation at the time the photo was taken.