pH measurement in water & wastewater

The marathon runners among measuring points

In treatment plants and water processing, pH measurement runs around the clock - it monitors the biological treatment stages (whose microorganisms only work within a narrow pH window), controls neutralisation and precipitation, and documents discharge limits. An electrode that needed weekly attention here would be out of place: standing times of weeks to months between services are expected.

What makes process electrodes different

• Rugged build: Impact-resistant shafts, fouling-resistant junctions (open-hole or PTFE junctions) and gel-filled or polymer reference systems that never need topping up.
• Fittings: The electrode sits in immersion, flow-through or retractable fittings that protect it mechanically and allow removal during operation.
• Signal paths: Over long cable runs to the control room, transmitters or digital sensors make the high-impedance electrode signal interference-proof.

Fouling: the daily bread

Activated sludge, fats and biofilms coat membrane and junction faster than in any other application. Proven measures: defined cleaning intervals (from weekly rinsing to automatic spray cleaning at the fitting) and monitoring the calibration values as an early indicator. If the zero point wanders steadily, the junction is usually clogged - cleaning instead of buying new.

Special case: drinking water and ultrapure water

It sounds paradoxical: the cleaner the water, the harder the measurement. Low-ion water conducts poorly and produces unstable, drifting readings on standard electrodes. For this there are special electrodes with increased electrolyte outflow or flow-through cells that guide the sample past the membrane in a defined way. If you measure drinking water, boiler feed water or reverse-osmosis permeate, reach specifically for such low-conductivity electrodes.

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