The Effects of High Temperatures on Wastewater Treatment Systems
The effects of High Temperatures are a major factor in water treatment. Because they are so important, they must be monitored for any water treatment system. Like humans and many other organisms, bacteria in wastewater treatment systems work best within a certain temperature range – typically between 68 and 95 degrees Fahrenheit (20 – 35 degrees Celsius). The good thing about temperatures at the lower end of this range is that the bacteria are still able to function, but they work much more slowly. However, at the upper end of this spectrum and beyond, the bacteria slow down and eventually stop working at all. In the world of wastewater treatment, we call this a disturbance (not a simple disturbance).
Laboratory Tests Required for the Operation of Wastewater Treatment Plants
Proper operation and control of activated sludge wastewater treatment plants depends on the operators’ knowledge of what activated sludge is, its components, and the factors that affect its activity and efficiency.
The operation and control of the proper operation of activated sludge wastewater treatment plants depends on the physical, chemical, and biological analyses of wastewater and activated sludge and correct operating data and instructions based on the use of chemical analyses in conducting calculations related to operation and control of operation and determining the causes of any problem that may occur in the treatment plant and how to treat it and determining the efficiency of each stage of treatment separately and determining the efficiency of the plant as a whole and knowing the specifications of the water resulting from the plant to determine the extent of its compliance with the standards.
We will explain the most important laboratory experiments conducted for the operation and control of activated sludge treatment plants the places where samples are collected to conduct them and the importance of these experiments in controlling operation:
- Temperature.
- Measuring dissolved oxygen (DO).
- pH.
- Measuring biological oxygen demand (BOD).
- Chemical oxygen consumption (COD).
- Measuring the concentration of suspended solids (TSS).
- The concentration of volatile suspended solids (VSS).
- Measuring ammonia – nitrogen.
- Nitrate – Nitrogen.
- Measuring organic nitrogen concentration (TKN).
- Sulfides.
- Measurement of oils and grease.
- Solids in sludge.
- Measurement of free residual chlorine.
Reasons for measuring temperature
Bacterial growth and activity are affected by water temperature. Biological treatment is considered a biochemical reaction and is affected by water temperature. The higher the water temperature, the higher the rate of reproduction, growth, activity and oxidation of organic matter by aerobic bacteria. Conversely, the lower the water temperature, the lower the rate of reproduction, growth and activity of bacteria and the rate of oxidation of organic matter. Water temperature is measured in raw water and final water.
What are some of the main signs of bacterial stress associated with high temperatures?
De-agglomeration and increased percentage of suspended solids in waste
The effects of High Temperatures on the quality of bacterial agglomeration begin to deteriorate. Under the microscope, you can observe the agglomeration that has already formed and the dispersed bacteria that have not yet entered the structure of the agglomeration break down and remain dispersed. On a large scale, de-agglomeration can be observed in the form of the increased percentage of suspended solids in waste.
High BOD in Waste
At high temperatures, bacterial metabolism can be inhibited. Inhibited metabolism can lead to high BOD in waste through two different mechanisms: Low or failed bacterial metabolism
High-suspended solids in waste – bacteria are organic in nature and contribute to the oxygen demand for the BOD test
Low dissolved oxygen
At high temperatures, oxygen is less soluble in water. This is coupled with high BOD and at high temperatures, the quality of the bacterial masses will begin to deteriorate.
High dissolved oxygen
That’s right. Low or high dissolved oxygen can indicate a temperature-related problem in your wastewater treatment system. High dissolved oxygen seen at high temperatures can indicate a lack of oxygen uptake, which could be due to low BOD or inhibited bacteria.
Temperature is one of the most difficult elements to control and fix within wastewater treatment systems. However, care must be taken to select valves, anti-scaling devices, and all equipment that are compatible with high temperatures. With a good monitoring program, problems related to high temperatures can be identified and controlled.
Effects of High Temperatures on wastewater
The temperature of wastewater is higher than the water supply temperature, due to the addition of hot water from domestic and industrial activities. The change in temperature affects wastewater as follows:
- High temperature increases the viscosity within wastewater, as it increases the readiness to settle suspended objects. If the temperature drops sharply, it negatively affects the efficiency of settling.
- Bacterial activity increases with temperature if the temperature reaches (60°C) and then the activity of bacteria decreases.
- This temperature characteristic affects the design of wastewater treatment units and their efficiency.
- The dissolution of gases in wastewater decreases with increasing temperature, followed by the expulsion of dissolved oxygen and other gases from wastewater. This leads to a reduction in the self-purification of waterways, an increase in bacterial growth, and an increase in the rate of biochemical reaction treatment for high temperatures, which leads to a reduction in the amount of dissolved oxygen from surface waters and can cause a sharp decrease in dissolved oxygen concentration, especially when large amounts of relatively warm wastewater are discharged into water bodies.
- Increasing the wastewater temperature affects aquatic organisms in water bodies such as some plants, fish, and fungi.
