Blowers for Wastewater Treatment
Proper aeration and blower selection are two of the most important considerations at a wastewater plant. Aeration energy consumption at wastewater treatment plants typically consumes 60% of all electrical usage. Blowers can offset some of the energy requirements. To ensure the most effective results, we can help you select the proper size, type and layout of blower equipment.
Blower Basics
Blowers create air flow (flow rate). The total blower system creates pressure (back pressure) through resistance to air flow. By combining the flow rate and back pressure, you can identify the actual operating air flow. Optimal energy use is achieved when the pressure in headers is just sufficient to overcome the static pressure. Because many wastewater treatment plant operators tend to set pressure points too high, excess blower discharge pressure occurs – which wastes power.
Main Components in Blower System
- Blower
- Motors and engines
- Drive components
- Air filters
- Silencers
- Piping
- Tanks
- Valves and fittings
- Gauges and switches
- Controls and instruments
- Heat exchangers
While the purpose of the blower is to create additional air flow, the purpose of blower controls is to provide the correct air flow at any time, which in turn provides enhanced aeration efficiency. Besides matching the air flow to existing demands in the most efficient manner, the blower control system also monitors and makes further adjustments, such as running the smallest number of machines and running them within their best range of efficiency.
Providing for the correct oxygen level at any moment requires automatic flow adjustments. Blower systems must therefore be most efficient, stable and adaptabe to changing conditions. Various solutions can address these fluctuations, including throttling suction, adjusting speed drives or cycling different blowers.
- Some aeration systems cycle individual blowers for various lengths of time and use the oxygen retention capability of the wastewater to adjust the oxygen feed.
The overall goal is to offer adaptive oxygen supply at an affordable energy cost.
Air Flow Efficiency
Proper air supply is critical to various functions in wastewater treatment facility:
- Keeps bacteria suspended
- Aids flocculation
- Supplies sufficient oxygen transfer for BOD removal and nitrification
The essential function of an aeration control system is to fulfill oxygen demands and maintain the treatment process at the lowest possible costs. A common measurement of proper air flow for the treatment process is to check the DO (Dissolved Oxygen) Concentration. Finding the correct level is a key step in optimizing the efficiency of your Aeration System.
- TOO LOW – Too low of DO concentration does not provide sufficient process performance and can encourage undesirable organisms to develop
- TOO HIGH – Too high of DO concentration may prevent proper settling, encourage undesirable organism growth, cause “oxygen poisoning” and wastes power
Blower Energy Efficiency Considerations
- Match blower air flow to process requirements
- Optimize blowers so they are running in their most efficient range
- Run the least number of blowers (a blower that is turned off is not consuming energy)
- Minimize system discharge pressure and inlet losses
- Provide flexibility and adequate turndown for loading variations
- Avoid idle operation and bleeding off of air
- Schedule blower operations to maximize longevity and maintenance intervals
- For wastewater treatment plants that use different submersion depths, it may be more beneficial to use separate blowers for the various depths of aeration.
Mooers provides custom aeration blowers and blower controls for optimizing water treatment and waste water treatment systems in the USA. What type of blower is best for you?
