Showing posts with label sludge. Show all posts
Showing posts with label sludge. Show all posts

Monday, August 29, 2016

Flow Measurement of Activated Sludge

Flexim flowmeter
Better, non-invasive,
alternative for
activated sludge.
Reprinted with permission from Flexim

A wastewater treatment plant that serves 1,800 households includes several mechanical and biological wastewater treatment facilities.

The mechanical treatment consists of a screening system and an aerated circular grit trap. The biological treatment is carried out in a combi-tank (biological treatment stage outside, secondary clarifier-settler basin inside).

The plant also includes facilities for the removal of nitrogen which is carried out by intermittent nitrification/denitrification. In addition, the plant also has a static sludge thickener. The activated sludge, which has been formed in the biological treatment stage through the growth of microorganisms, slowly separates via gravity in the secondary clarifier basin.

A portion of the activated sludge is fed back into the biological treatment stage as return sludge and mixed with the newly added nutrient-rich wastewater. The amount of return sludge should always be in a defined ratio to the current feed quantity. For this reason, the flow rate of the recirculation pipeline has to be measured.

The installation of a wetted magnetic-inductive flowmeter, which is very common in the water and wastewater industry, would have required modifications to the piping and subsequent expensive civil engineering work. The only available manhole location on the buried recirculation pipeline has not been suitable for retrofitting a magnetic-inductive flowmeter. Moreover, the pipeline in the manhole is always submerged in water.

Retrofitting the measurement point with a FLEXIM non-invasive ultrasonic flow meter, including IP68 fully submersible transducers, proved to be a convincingly simple, accurate, reliable and cost effective solution.

There is no need to open the pipeline when mounting the transducers onto the outside of the pipe and therefore no interruption to operation. The cramped installation point in the flooded shaft does not pose a particular challenge to FLEXIM’s measuring system: the IP68 transducers can be operated while permanently submerged and, since they were installed, they have been providing highly reliable measurements for automatic control of the pumps that convey the return flow quantity of the activated sludge.

  • Reliable and accurate flow measurement of activated sludge for automatic pump control
  • Secure automatic control of the recirculation proportional to the demand
  • Easy to retrofit measuring point during ongoing operation, without any pipe work and without the need to modify the existing pipeline system
  • No expense for civil engineering and excavation work
  • Submersible IP68 transducers guarantee long-term stable measurements

Monday, June 13, 2016

Choose Insertion Mass Flowmeters for Wastewater Activated Sludge Process

Insertion Mass Flowmeters for Wastewater
Insertion Mass Flowmeters in Wastewater Treatment
In wastewater treatment facilities, a variety of biological and chemical processes are employed to remove organic pollutants from water to ensure its reusability. One very common process is referred to as “the activated sludge method”. This process biologically treats the wastewater through the use of natural micro-organisms combined with the wastewater in large aeration basins.

The activated sludge method requires the pumping of compressed air into the aeration basins where a diffuser system ensures the air is distributed evenly for optimum treatment. Tiny micro-organisms in the aeration basins decompose biologically degradable organics in the wastewater. These micro-organisms rely on the aeration system to provide air for survival, but also by controlling the proper amount of air, the micro-organisms can thrive and optimally consume the organics in the wastewater. After a period of time, a flocculate forms with the non-biodegradable solids settling to the bottom of the basin.

Large amounts of compressed air is used to ensure the activated sludge method treats the water effectively before it can be moved along to the next stages, namely the clarifying basins, filtering, disinfection and other treatment processes. A very important step in this process is the accurate control of air released into the aeration basins. This is essential because, as stated above, the air flow controls the growth of micro-organisms that treat the wastewater.
Insertion Mass Flow Meter
Insertion Mass Flow Meter
(courtesy of FCI)

Flowmeters are typically installed in the aeration system piping to measure the amount of air flow and the flowmeters’ analog or digital outputs run to the wastewater treatment plant’s control system.

A highly accurate and reliable flowmeter is critical because the one of the largest energy costs in a wastewater facility is the air compressor operation. Energy management and efficiency continue to drive plant maintenance, and the compressed air system is a prime system component where considerable savings can be found. A well designed air flow metering, controlling, and reporting system for the aeration process is an excellent way to achieve measurable efficiency gains and provide a significant reduction in energy costs.

When choosing a flow meter, here are the important criteria to consider:
  • Flow Sensor Technology
  • Range and Accuracy
  • Operating Environment
  • Ease of Installation
  • Maintenance and Life
An excellent choice for these applications are insertion mass flowmeters. They provide an accurate, easy to install, no moving parts mass flow meter solution commonly used for compressed air and nitrogen flow. Their proven thermal dispersion technology provides direct mass flow measurement that results in higher performance at a lower cost than orifice plates, DP, Vortex shedding and other thermal devices. When combined with microprocessor electronics and precision calibration, they achieve excellent accuracy, fast response and virtually maintenance free operation.

For more information, contact:

Flow-Tech, Inc.

Maryland Headquarters
10940 Beaver Dam Rd
Hunt Valley, MD 21030
Ph: 410-666-3200

Central VA Office
10993 Richardson Rd#13
Ashland, VA 23005
Ph: 804-752-3450