Used to determine optimal coagulant dose on a water treatment plant Pi’s range of Laboratory Charge Analysers accurately measure colloidal and ionic charge using the streaming current principle (electrokinetic charge), which is comparable to zeta potential. Charge demand is determined with titration to the isoelectric point using the plant coagulant, either manually or by use of an automatic titrator.
In addition, the LabSense can help (in conjunction with jar testing) to determine the optimum alkali addition in soft water applications.
Pi’s LabSense Laboratory Charge Analysers are intuitive, flexible and give great repeatable charge demand determinations time after time.
Principle of Operation of LabSense
LabSense is an essential coagulation optimisation tool for water treatment. LabSense allows the user to determine the ideal coagulant dosage needed to achieve optimum NTU and TOC reduction in typically less than 5 minutes, earning it the description “5 minute jar tester”.
The measurement cell consists of a reciprocating piston in a probe assembly. Particles and dissolved materials are attracted to the surfaces of the probe by Van Der Waals forces. Counter ions surround these particles. The motion of the piston generates shear forces, which causes the counter ions to migrate. Electrodes in the probe measure the flow of counter ions, inherently defined as an electrical current. The current is electronically processed and displayed on the screen as the Streaming Current Value (SCV). For most samples in a paper mill, the SCV will be negative, indicating a net anionically charged sample.
The process of finding the optimum dosage simply involves feeding in a measured volume of coagulant into the raw water sample until the reading indicates complete charge neutralisation has been obtained.