Blowers are a critical component of wastewater treatment, whether in a municipal plant processing sewage or an industrial plant removing pollutants from their process water. There are many different ways to treat wastewater and most of them involve injecting air into the wastewater.
Industrial and municipal plants use a combination of methods in their wastewater treatment. Here are some of the most common ways blowers are used:
Aerated Grit Chambers
Especially important in systems that have stormwater runoff in addition to sewage, grit chambers are designed to remove coarse solids. Ranging from sand and rocks to eggshells and coffee grounds, these gritty particles cause a lot of wear and tear to pumps and other equipment down the line, so removing them is one of the first steps. There are a number of different types and designs, but the basic principle of a grit chamber is to slow down the flow of the sewage so solid pieces can settle down to the bottom while the lighter particles and fluid can continue on to the next stage of treatment. In this type of application air is injected to create the desired flow of the wastewater.
Lagoon Aeration
Commonly used in both municipal and industrial wastewater treatment, lagoon aeration refers to a large holding tank of water (often a pond or lagoon) that is aerated either by a mechanical process (picture a big mixer that sits at the surface of the water and stirs it constantly) or by releasing air from submerged pipes at the bottom. The purpose of aerating the water is to increase the oxygen content which promotes the growth of the aerobic microorganisms that break down the organic pollutants. Positive displacement blowers are typically the best choice for this type of aeration due to the large volume of airflow they can provide.
One of our customers has an innovative approach to lagoon aeration with a floating aerator (powered by a blower) that can provide both aeration and mixing.
Digester Gas
As sewage sludge is broken down and decomposed, a methane-rich gas is produced by the microorganisms as a byproduct. This wastewater digester gas or biogas is primarily composed of methane and carbon dioxide, with trace amounts of nitrogen, oxygen and hydrogen sulfide also present. The high concentration of methane makes this biogas an attractive energy source that can be burned to create electricity, heat the tanks to speed decomposition, or even heat the facility. Blowers, specially designed to handle the corrosive biogas, are used to convey the gas as well as boost the pressure to meet the burner demand.
Airlift Pumps
To move raw sewage, grit, sludge, and chemicals throughout the different stages and tanks of the treatment system, blowers are often used to power airlift pumps. Airlift pumps inject air into the bottom of a pipe that is conveying liquid wastewater. The air is less dense than the wastewater, so it quickly rises carrying the liquid along with it. Airlift pumps use low pressure air so they are an energy efficient and cost-effective solution for any wastewater treatment application with a required lift of 5 feet or less.