Sludge monitoring for water and wastewater industry - Water and Wastewater - Sludge Management

Improved monitoring and automation can deliver more efficient waste treatment and reduced energy consumption and improved effluent quality. The cost of treatment and the quality of effluent discharge can thus be significantly reduced.

There is a need to monitoring the sludge blanket level in primary and secondary settlement tanks to identify a rising blanket which can affect the physical quality of effluent discharge and also to ensure correct surplusing of sludge. A simple optical sensor can be position to alarm when the sludge blanket rises to at a critical level but this technology is limited in the information it can report. The ability to track the blanket and raise a number of alarms before the critical limit is reached is preferential. Ultrasonic techniques are therefore advantageous by tracking the blanket allowing operators a greater certainty that correct process control is in place.

Biological treatment is extensively used to treat sewage and industrial effluent, principally to remove ammonia and reduce organic loading. Controlling aerobic and anaerobic digestion using Dissolved Oxygen and more recently ammonium probes is extensively installed to optimise treatment and regulate aeration - saving money. Many sites could also benefit from the installation of reliable suspended solids monitoring to ensure the correct solids concentrations are maintained. The ability to set multiple points of correlation against gravimetric dry solids (establishing a calibration curve) is key to delivering a reliable installation.

The Visolid 700 IQ sensor can also be used to monitor in-pipe when used with special weld on sockets allowing correct insertion and removal. The technology continuously reports concentrations against a site correlation taking into account site specific sludge characteristics. The continuous ultrasonic cleaning is an important feature to maintain the sensor and minimise bio-fouling of the optical sapphire window.