It is important to remember, and often overlooked, that the real work at the sewage treatment plant is done by the wastewater treatment bacteria and other microorganisms.
Bacteria are single celled organisms that multiply by binary fission; that is one bacteria cell divides into two and two into four, etc.
With an adequate food supply, bacteria are capable of reproducing every 20 minutes.
To illustrate to yourself how fast this cell reproduction can be consider that once every 20 minutes means three cell divisions per hour. So get a calculator and hit 2 times 2, times 2, times 2, etc.
After a mere seven hours, that initial wastewater bacteria has the potential to multiple into over one million bacterial cells. This amazing growth at a wastewater treatment plant is generally fueled by two things; adequate food supply and adequate oxygen supply.
As a quick footnote, I’m not suggesting that all wastewater bacteria require oxygen but generally the aerobes grow at a much faster rate. Additionally, other factors such as temperature and pH will effect the growth rate of wastewater bacteria. For the purposes of this post, we’ll assume that the sewage plant is operating under normal conditions.
All sewage treatment plants take advantage of, and count on, this rapid growth of wastewater treatment bacteria, usually called the logarithmic growth phase. For as the wastewater bacteria are growing, they are using the organic components of the wastewater as a food and energy source. In other words, the wastewater treatment bacteria are creating more bacteria, carbon dioxide, and water while they utilize the organic components of the wastewater.
Bacteria accomplish this growth rate and the use of the organic compounds within the sewage treatment plant by use of enzymes, both cellular and extracellular. In fact, bacteria can be thought of as enzyme producing factories. Enzymes produced by wastewater treatment bacteria are substrate specific. That is, the enzymes work on a specific compound or compounds. Typical enzymes that are important in wastewater treatment are lipases (fat and lipid enzymes), amylases (starch enzymes) and proteases (protein enzymes).
It is very important to note that while wastewater treatment bacteria reproduce, enzymes do not.
END PART ONE