How is the wastewater flow monitored?

Date: 05/07/19 | In: Water Meters

The most effective, and accurate way to monitor wastewater flow is by devising and implementing a specific wastewater flow survey. Or for a more permanent solution, implement an ongoing monitoring project to gather data and generate regular analysis reports that can be used inform and improve.

Wastewater flow meters are predominantly used to calculate the volumetric or mass flow of wastewater, sewage or trade effluent. They work by measuring the amount of wastewater that flows through, under or around flow meter sensors.

There are three specific ways to measure open channel water using a wastewater flow meter, each of which works in a different way:

1) Insertion wastewater flow meter:

Usually referred to as an ‘area velocity flow meter’. The MSFM is a perfect example of an insertion wastewater flow meter. Installed at the bottom of the pipe in the water, an insertion wastewater flow meter will measure depth and velocity and calculate flow. It is one of the most effective methods of wastewater flow monitoring.

Detectronic sensors measure the depth of water above the sensor and use programmed pipe/channel parameters to calculate the wetted cross-sectional area. This is then multiplied by the velocity (measured using ultrasonic Doppler) of the effluent stream to provide flow.

The benefit of this type of monitoring is that it is highly accurate due to its position directly within the effluent stream.

2) Non-contact water flow meter:

Works similarly to an insertion flow meter but measures level and surface velocity and is installed above the flow of wastewater rather than in the actual pipe.

Similar to the insertion wastewater flow meter, this meter also calculates flow using velocity multiplied by wetted cross-sectional area.

A non-contact flow meter is ideal for circumstances where equipment cannot come into contact with the flow but isn’t as accurate as an insertion wastewater flow meter since surface friction will always affect data.

3) Primary device:

Hydraulic structures, such as weirs and flumes, are both examples of primary devices that can be used to monitor flow measurement. Our equipment is used extensively in these applications. Using an ultrasonic level-only system, such as the MFSM Lite or Orakel Primary Device, and the known mathematical relationship detailed in ISO 1438:2008 (Hydrometry – open channel flow measurement using thin-plate weirs), flow can be calculated without the need for insertion flow meters.

The downside of this method is that it often demands a degree of civil engineering work before it can be realised due to the forward planning required for the physical installation of the primary device. Channels are narrowed too which can cause potential blockages meaning that primary devices are rarely suitable for network monitoring, but they are often used for measuring trade effluent in industrial applications.

Making the decision to invest in and implement wastewater flow monitoring is a crucial step for any industrial company and one the Detectronic team can support with. By visiting your site and understanding your specific requirements, objectives and existing infrastructure limitations, we can design and install a bespoke wastewater flow monitoring scheme. We will ensure you understand exactly how your wastewater flows will be monitored, provide expert analysis and insight from the data gathered and, ultimately, evidence the benefits that wastewater monitoring can deliver.