- Raw wastewater is run through a bar screen. The deflected large solids may be hauled away or reground and reintroduced to the treatment process.
- After passing through the bar screen, the influent enters the grit chamber. This is a large basin that allows the water to slow down and the grit to settle out. Grit includes sand, coffee grounds, and eggshells. This material cannot be broken down and must be hauled away.
- The remaining water reaches a grinding pump, called a comminutor. Large pieces in the water are shredded, making it easier for the microorganisms to consume it.
- Water enters the aeration chamber where oxygen enriches the water, and microorganisms are added. The organic matter begins to break down.
The microorganisms multiply rapidly and consume the biochemical oxygen demand (B.O.D.) very quickly. B.O.D. is simply the food matter in the water. This organic matter will be consumed in a couple of hours. The air that bubbles up not only feeds oxygen into the process but keeps the microorganisms suspended so they do not settle out.
- Following the aeration chamber, water enters the clarifier or sedimentation tank. Once the organic matter is consumed, the microorganisms have food, grit, and particulates stuck to their outer enzyme coating.
The added weight makes them sink, or “floc out” to the bottom of the clarifier. Some of this sludge is removed and some of it returns to the aeration chamber to help seed the next batch.
- Following the aeration process, the water enters another tank with a sand filter bottom. HOFFMAN & LAMSON blowers are used to backwash the sand to keep it filtering properly.
- The sludge that will return to the aeration tank is held for ten days in a holding basin. Each day, a new layer of sludge is added. The oldest layer moves daily to seed the activation chamber.
During the ten-day period, the sludge is activated (stressed) so that it becomes extremely hungry and ready to multiply. About one-fifth of the sludge that is removed from the process can be used as a soil conditioner after dewatering or in liquid form. Another method of sludge removal is landfilling.
- When landfill space is not available, wastewater treatment plants turn to incineration. HOFFMAN & LAMSON blowers are used in fluidized bed incinerators and in other incinerators to aid in combustion.
- After the clarifier, the water is called “supernate”. Chlorine is added and the water sits in the disinfection chamber while the disease-causing microorganisms are killed.
- The water is now safe to be released into a natural body of water.
Anchored In Tradition
Hoffman & Lamson is recognized around the world as a leading global provider of blower & exhauster solutions for water & wastewater treatment applications.
For over a century, our customers have trusted the quality performance our blowers provide. That is why our blower portfolio remains the most comprehensive offering.
Our priority continues to be unparalleled responsiveness to meeting our customer’s needs. Our unwavering commitment to engineering innovative product designs, and quality manufacturing is evident with over 100,000 installations.