The desired conditions in biological wastewater treatment must be maintained for the enzymes of the desired bacteria to work adequately. A simplified way to think of enzymes and their environments is as the “keys to unlocking reactions.” If the desired bacterial enzymes cannot carry out their processes, other bacteria (often undesirable for specific treatment goals) step in and gain a competitive advantage.
Conditions including pH, alkalinity, sludge retention time, temperature, dissolved oxygen, nutrients and more must be within targeted values. For example, most bacteria in traditional aerated biological processes are not suitable for thermophilic conditions (around 104 degrees F or higher), meaning that at these higher temperature thresholds their enzymes are no longer functioning and other bacteria (thermophilic bacteria) begin to grow. The impacted bacteria that no longer function in the new environment may become inhibited (enzymes no longer work) or in other instances may cease to be alive/viable depending upon the severity of the incident.
Enzymes
For microbes to carry out the desired treatment in biological wastewater treatment the enzymes must operate properly. Enzymes assist bacteria by facilitating the necessary biochemical reactions. Bacteria degrade organic matter by releasing specific enzymes targeted to break protein into amino acids, break oils and grease into glycerol and fatty acids, break starches and carbohydrates into simple sugars, detoxify pollutants, and more.
When bacteria detect the presence of specific organic compounds, the genes responsible for releasing their necessary enzymes become activated. Through enzyme synthesis bacteria produce proteins capable of breaking down the specific compound the bacteria are trying to digest. Substrate may enter through the cell membrane of the bacteria immediately (absorption), or in other instances is adsorbed to the outside of the cell wall where bacteria secrete enzymes to produce smaller molecules to then be absorbed.
Dr. Michael Richard liked to use the analogy of picturing bacteria’s “mouth” as a filter; if the food is small enough, it enters immediately, and if the pieces are too big, it is caught on the filter to be broken down into smaller pieces by enzymes before it is available.
Enzymes are also necessary for cellular processes including energy production, nutrient breakdown, DNA replication and repair, and regulating metabolic pathways.
Summary
The efficiency of biological treatment depends largely on the ability of the desired bacteria to produce properly functioning enzymes. The synergistic relationship of bacteria and enzymes is highly complex, but the most important thing to understand from a wastewater operational perspective is that the proper environment is needed to select the desired bacteria and their assisting enzymes.
An announcement
As of Oct. 1, 2024 Ryan Hennessy Wastewater Microbiology is operating an independent LLC. Extra thank you to all of those who have assisted in this great journey, especially the late Dr. Michael Richard.
About the author: Ryan Hennessy is the principal scientist at Ryan Hennessy Wastewater Microbiology. He was trained and mentored by Dr. Michael Richard for over 10 years in wastewater microbiology, and serves as a microbiology services consultant. Hennessy is a licensed wastewater treatment and municipal waterworks operator in the state of Wisconsin and fills in as needed for operations at several facilities. He can be reached at ryan@rhwastewatermicrobiology.com. Hennessy's new book Wastewater Microbiology: Filamentous Bacteria Morphotype Identification Techniques, and Process Control Troubleshooting Strategies is now available on Amazon.
