The Role of Bacteria in the Industrial Wastewater Treatment Process
Here’s the next part of our series on bacteria in the industrial wastewater treatment process.
The typical growth rate curve of a bacterial culture, known as the bacterial growth rate curve, is a result of the four following phases of bacterial growth:
The Bacterial Growth Cycle
- Lag Phase (Sometimes called initial phase). When bacteria are first introduced into an environment, little growth will take place until they adapt to their new environment. In fact, it generally takes several generation times before the bacterial numbers begin to significantly increase. In practice, the lag phase typically lasts three hours or longer.
- Log Phase (Logarithmic Phase). Once full growth and cell reproduction is underway, the bacterial growth curve develops the log phase. This is the phase where the bacteria are rapidly dividing. This phase is limited by the food source and waste buildup.
- Stationary Phase. This phase occurs when some bacteria are growing and reproducing while others are dying. The actual number of living, viable organisms will remain fairly constant.
- Death Phase (Sometimes called log death phase). After a period of time, the environment becomes loaded with bacterial waste products, food supply is depleted, and the entire system begins to die off. This die off occurs because the external conditions are no longer right for maintaining the bacterial population in such high numbers. The death phase is also logarithmic.
Since the log phase and the death phase increase and decrease at the same respective rates, the bacteria growth curve is a bell shaped curve. This growth curve has several important parts that have a great effect on the use of bacteria in the industrial wastewater treatment process. We’ll discuss those aspects as we move along in this article.
Bacteria Produce Enzymes
Microorganisms and their enzyme systems are responsible for many different chemical reactions produced in the degradation of the organic material in industrial wastewater. As bacteria metabolize, grow and divide they produce a wide variety of enzymes. Enzymes are high molecular weight proteins. There are many types of enzymes are they are classified by the chemical reactions that they enter. First, enzymes are group into two broad classes; endoenzymes and exoenzymes. Exoenzymes are produced within the bacterial cell but migrate out of the cell. Once outside the bacterial cell, exoenzymes break down the larger organic compounds to a size that can pass through the cell membrane. The endoenzymes are also produced within the cell but they remain inside the cell to convert organic materials to products needed by the cell to grow and reproduce.
It is important to recognize the fact that bacteria produce enzymes. In fact, one way to think of bacteria is to think of them as enzyme factories. The enzymes that are manufactured by bacteria are substrate specific. That is they will metabolize only the organic compound that they are designed to metabolize. So providing that you have the right bacteria, that is bacteria that have the correct genetic code to metabolize an organic compound, you have your own enzyme factory for metabolizing your organic wastes. Importantly, enzyme cannot reproduce themselves; however, bacteria, of course, can reproduce.
End part 2 – The role of bacteria in the industrial wastewater process.
Link for part 3