In order to monitor the process of reverse osmosis and ensure that deposits do not clog up membranes and reduce system efficiency, Martens, a member of the GHM Group, has combined its Condix 4623 digital 4-electrode conductivity converter with the GHM-ONE multi-function HMI controller.

The conductivity device detects whether the untreated water is suitable for operation in the system or not, while the multi-function HMI controller provides the measurements to the superordinate PLC via a ProfiNet fieldbus, where it is easily integrated by means of a GSDNL device description file.

GHM Messtechnik process water analysis

Accurate analysis and monitoring of process water serves to prevent membrane clogging and resultant system inefficiencies.

Reverse osmosis produces the permeate, which is the filtered raw water, as well as retentate, the concentrate that is unable to pass through the membrane. It is a process that can reduce the efficiency of a water treatment system and result in damage if deposits accumulate as a result of the scaling effect – where the dissolved contents exceed the solubility limit. An over-saturation of calcium carbonate must also be prevented.

In order to counteract both these effects, an anti-scalent is added to reduce the precipitation level and the water to be treated is adjusted to an acidic pH to prevent oversaturation with calcium carbonate.

Jan Grobler, Managing Director of GHM Messtechnik South Africa, says, “The pH value at this point is the measured variable for the correct dosing. The objective is to minimise the use of additives to achieve maximum filter effect. The development of ammonia, which is toxic for fish, must be avoided. The concentration increases and decreases analogously to the prevailing pH value – therefore, the pH value is monitored in the process input and upstream from the discharge and conditioned as necessary.

“The combination of the Condix 4263 and the GHM-ONE multi-function controller offers a superior analysis technology specifically for process water monitoring to prevent membrane clogging that results in inefficient system performance. Accurate analysis protects the material of the system from undesired deposits which would require cleaning. The obvious benefits are reduced downtime and increased productivity,” Grobler adds.

The precise, process-relevant, quality-relevant measuring results are visualised by the GHM-ONE, which is connected with the measuring probes via RS485 (Modbus RTU). The measured values can be read at any time on the display, so that conclusions can be made about the status of the system throughout the process chain.

Martens is part of the GHM Group, which brings together specialist instrumentation entities offering solutions across all industries.

For more information contact Jan Grobler at Messtechnik South Africa. Tel: +27 (0)11 902 0158, email: info@ghm-sa.co.za