Measurement technology can raise capacity of wastewater plants
6 Feb 2012
Helsinki – Metso has developed an on-line measurement technology, which it claims, can enable municipal and industrial wastewater plants to improve their performance and reduce the amount of chemicals used in sludge drying process by up to a third.
The Metso LS ’low solids’ measurement system is claimed to be the first online measurement technology for municipal and industrial wastewater treatment plants that enables measurement of a media with very low solids contents in difficult applications like centrifuge centrate.
Timo Rantala, product manager for Metso’s automation business line reports that “a large North American wastewater treatment plant has calculated that it saves up to 30% in its annual $2.5 million chemical costs.
“In addition, a municipal plant in Finland using Metso LS estimates that they will achieve annually Euro15,000 savings in polymer and centrifuge usage only by keeping reject water total suspended solids lower that 1000mg/l”.
The system, which is based on LED and laser technology, continuously measures the suspended solids content within the range of zero to 5000 mg/l and also the entrained air index, which indicates overdosing of polymer. It dearates, filters, and measures the process solids.
A higher solids content of concentrated sludge results in higher thermal energy in the subsequent incineration process, or alternatively reduces transportation costs when shipping to a landfill. Users can also control polymer usage and thus improve throughput and function of the centrifuge.
The new device can be connected online to the process and is able to measure continuous sample flow through the system by utilising an integrated centrifugal pump. The device has two light sources, LED and laser, that measure absorption, scattering and depolarisation of these sources as they pass through the flowing media.
