Thermal Mass Flow Meters are used in wastewater & aeration basins and are critical tools for municipal processes. Up to 60% of the energy used by wastewater treatment plants is from the aeration process. In this vital and costly secondary stage of wastewater treatment, blowers aerate the basins, removing about 85% of the organic matter by making use of the bacteria living within it.
Municipalities need precise mass flow measurement instrumentation to bubble the exact amount of air into these aeration basins so the bacteria can flourish. Increased public and private awareness of water quality, availability, and the cost is a driving force behind the demands for better efficiency and economy in these processes. Whether local needs call for new facilities or improvements to existing facilities, Thermal mass flow meters can meet these demands. At the same time, eliminate the undesirable system pressure drops and high maintenance costs associated with differential flow meters and rotary meters. Many municipalities used differential pressure (DP) devices to measure the mass flow rate of air delivered to their aeration basins. Still, these devices proved to be expensive to maintain, clogged easily, measured only volumetric flow, and required a separate pressure and temperature transducer and flow computer to deliver accurate mass flow.
Aeration Basin
Everyday use of Thermal Flow Meters at WWTP facilities means measuring the air (or oxygen) flow required for the secondary treatment of the activated sludge process when air and “seed” sludge are added to the wastewater to facilitate decomposition. To stimulate the growth of aerobic bacteria and other organisms that are present in the sewage, the air is pumped at a pre-determined rate into large aeration tanks where the wastewater and sludge are mixed. The rate of the airflow must be carefully monitored and adjusted, as necessary, throughout the tanks and the overall process for optimal efficiency. Adding too much or too little air can have a very noticeable negative impact on this vital step of the treatment process. So a reliable and adequately distributed air/oxygen supply in an aeration system is a critical element in any effective wastewater treatment plant. Providing accurate airflow measurement is often the primary application for thermal flow meters at treatment plants.
Potential points of measurement in a WWTP air system are:
A. Blower inlet air
B. Total air usage
C. Distribution pipes
D. Aeration basins
