Probes for hydrogen peroxide - Achieve repeatable results in hydrogen peroxide measurement

Hydrogen Peroxide Probe Monitoring in Wastewater and Anti-Legionella Systems

Hydrogen peroxide (H₂O₂) monitoring plays a critical role in both wastewater treatment processes and anti-legionella disinfection systems. Accurate and continuous measurement ensures process efficiency, regulatory compliance, and operational safety.

1. Monitoring in Wastewater Treatment 

In wastewater applications, hydrogen peroxide is commonly used for: Advanced oxidation processes (AOP) - Odor control - Sulfide and organic load reduction - Post-treatment polishing before discharge A hydrogen peroxide probe, typically based on amperometric or potentiostatic measurement technology, continuously detects the residual H₂O₂ concentration in the effluent stream.

Key objectives of monitoring include: Maintaining optimal dosing control - Preventing chemical overconsumption - Protecting downstream biological processes - Ensuring compliance with discharge limits - The probe is usually installed in a flow-through cell or directly in-line within a bypass system. The measured signal is transmitted to a controller that regulates the dosing pump proportionally, maintaining a stable residual concentration. Continuous monitoring provides real-time feedback, enabling automatic adjustment of the dosing rate based on flow variations and pollutant load.

2. Monitoring in Anti-Legionella Systems

In anti-legionella applications, hydrogen peroxide is used as a disinfectant in domestic hot water systems, cooling towers, hospitals, hotels, and industrial water networks.

The primary objectives are: Preventing Legionella pneumophila proliferation - Maintaining a controlled residual disinfectant concentration - Avoiding underdosing (ineffective disinfection) or overdosing (material corrosion and safety risks) - The hydrogen peroxide probe continuously measures the disinfectant residual in the recirculation line or at critical control points within the system.

The monitoring system typically includes: Closed-cell amperometric sensor - Temperature compensation - Flow control for measurement stability - Integrated controller with alarm thresholds

Maintaining a stable H₂O₂ concentration ensures: Continuous microbiological protection - Reduced biofilm formation - Optimized chemical consumption - Regulatory compliance in healthcare and public facilities 

Conclusion

Reliable hydrogen peroxide monitoring is not simply a measurement task, but a fundamental control strategy for ensuring treatment effectiveness, operational safety, and regulatory compliance.

Proper probe selection, correct installation, and routine maintenance are critical to achieving stable and efficient system performance.

Careful monitoring and precise dosing control are key factors in guaranteeing long-term system reliability and optimized chemical management.

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Arkad Air-Operated Double Diaphragm Pumps

The Arkad series of air-operated double diaphragm (AODD) pumps delivers exceptional versatility and performance across a wide range of chemical dosing and liquid transfer applications. With flow rates from 7 to 880 litres per minute, easily adjustable via intuitive controls, these pumps offer precise handling for everything from highly corrosive acids to high-viscosity paints, adhesives and abrasive slurries. Engineered with no electrical components, Arkad pumps can be fully submerged without compromising performance. A broad selection of pump head sizes, materials and seal options ensures compatibility with even the most challenging fluids, making Arkad a reliable solution for demanding industrial environments.

Features

• Variable flow rates; easy to adjust without sophisticated controls 
• Portable and compact for multi-location use, optionally with trolley 
• Able to handle liquids with solid particles; ideal for abrasive and viscous media 
• Advanced air-management system; lube-free, non-stall, non-freeze 
• Wide options for sizes and materials to fit a variety of conditions and chemical fluids 
• Efficient performance; high flow rates thanks to optimal pump body design 
• Self-priming dry up to five metres; suitable for suction lift applications 
• Efficient air distribution design reduces air intake requirement 
• Hydraulic connections can be configured to perfectly fit the destination plant

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Spring MS1 - Spring-return mechanical diaphragm dosing pump

• The MS1 series offers multiple combinations of pump head motors, stroke lengths and materials that allows operators the chance to select the optimal combination appropriate to the specific application in hand. • Being membrane pumps, they represent an absolutely safe and leak-free solution to be used wherever chemical leaks, that are typical of plunger piston pumps, are not acceptable. • To change the flow rate of the pump, the stroke length can be adjusted manually with a knob or even automatically by using the Aktua kit controlled by a 4 - 20 mA signal or by a pulse emitter water meter. • Spring MS1 pumps can be supplied with a single or three-phase electric motor with IP55 protection, as well as with a DC motor working at 12 Vdc range that allows the pump to achieve flow rates between 23 and 620 l/h at pressure up to 16 bar.

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Kontrol 100 - Single-parameter instrument for high-precision applications

Maximum precision The Kontrol 100 family is ideal for professional water-treatment applications that require accurate measurement of critical parameters. The devices feature a reinforced galvanic isolation and guarantee high-precision measurement. PID algorithm The Kontrol 100 series allows the user to programme outputs relating to the parameter detected according to a PID algorithm, widely used in industrial applications for process control. RS485 Modbus RTU / ASCII serial port - The RS485 serial port, on which a standard Modbus RTU / ASCII communication protocol is installed, allows the device to be connected to the local network of an existing system. The same port can also be used to connect the device to a local SEKO hub to then be managed over the internet via the SekoWeb portal. Digital & analogue outputs Kontrol 100 units have two normally-open status relays, which can be associated with measurement, probe washing, temperature or alarm repetition; they also have two 4 - 20 mA outputs and two frequency outputs, easily programmable by the end user. Probe washing It is possible to programme one of the two relays to activate a probe washing cycle. The washing method is based on three phases: activation; waiting time for measurement stabilisation after washing; waiting before a new subsequent wash. TDS function The conductivity measurement can be also visualised in ppm (parts per million) for cooling tower treatment applications and ohms (resistivity) for reverse osmosis applications; this is due to the total dissolved solids function. Temperature measure function One of the two relays, one of the frequency outputs or one of the 4 - 20 mA analogue outputs can be associated with the temperature measure. QR codes These tools have a QR code that returns the current configuration of the device on a smartphone, including advanced settings and calibration values. This function is used for helping plant technicians identify incorrect settings or understand how to improve device performance.

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Chlorine probes - FCL HP - Free high-pressure chlorine sensor

Application: Wastewater Treatment Plant Effluent

A closed-cell potentiostatic probe for free chlorine is an electrochemical sensor specifically designed for continuous monitoring of residual free chlorine (Cl₂/HOCl) in treated wastewater discharged from a treatment plant. This type of sensor is typically connected to a dual-channel controller (pH / chlorine), which allows real-time correlation between chlorine concentration and pH, ensuring safe and compliant disinfection control.

Operating Principle

The probe works according to the potentiostatic amperometric method:

Inside the probe, a working electrode and a counter electrode are separated from the sample by a selective membrane.

A constant polarization voltage is applied between the electrodes. 

Free chlorine diffuses through the membrane and is reduced at the electrode surface.  

This electrochemical reaction generates a current directly proportional to the free chlorine concentration. 

The controller converts this current into a chlorine value (ppm or mg/L). 

The closed-cell design includes an internal electrolyte chamber and membrane, isolating the electrodes from the wastewater and providing stable, repeatable measurements even in dirty or variable process conditions.

Installation in a Wastewater Discharge Line

The probe is installed in a flow cell on a bypass line downstream of the disinfection stage (chlorination). A constant and bubble-free sample flow is required to ensure accurate readings.

The dual pH / chlorine controller continuously: 

Compensates the chlorine reading based on pH 

Displays both values 

Controls chemical dosing pumps 

Generates alarms when discharge limits are exceeded

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Spring MSV - Spring-return diaphragm dosing pump

• MSV pumps are the latest addition to the Spring range. These diaphragm dosing pumps are designed to ensure reliable and effective long-term dosing of chemicals at an affordable cost. They feature motorised mechanisms with high-performance, high-efficiency motors, mounted vertically over their PP casing to save space, especially where pumps are installed adjacent to one another. 
• Thanks to its double-camshaft mechanical structure, the pump offers high levels of stability while maintaining quiet operation and exceptionally accurate flow rates. 
• Adaptable to a wide range of uses, Spring MSV stands as an excellent compromise between cost and a high dosing accuracy across a wide variety of liquids, sludge and chemicals.

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Solenoid pump head covers

 

Tekna - Wall-mounted solenoid-driven dosing pumps

• Numerous Tekna models are available, with analogic or digital interface, to satisfy almost any request from the market. • Tekna delivers reduced energy consumption thanks to an embedded stabilised multi-range power supply (100 – 240 Vac, 50/60 Hz). Thanks to the SEKO patented algorithm, the solenoid only draws the power strictly required to activate the pump, based on the actual working conditions, which improves pump efficiency and saves energy. The algorithm also compensates for any fluctuation of the power supply voltage, for giving a precise and accurate dosage in any condition. • Tekna is also available in ATEX standard-compliant versions, with constant or proportional dosage functions and a digital interface. This model comes with a SS316L pump body as standard.

Features

• Pump body in PVDF • Kit available in PVDF or PVDF-T • Patented algorithm for driving the solenoid • AKS: Constant, with analogic interface (potentiometer) • AKL: Constant with level, analogic interface • APG: Proportional dosing (4 - 20 mA/pulse), analogic interface • TPG: Multifunction proportional dosing (4 - 20 mA/pulse), digital interface • TPR: Instrument-pump with pH/ORP input, digital interface • TCK: Weekly timed pump, digital interface • Available in ATEX-certificated models (Zone 2) • Models available with 24 Vac and 12 Vdc power supply • Available with special seals in PTFE or FFKM • Available with auto-degassing pump head in PVDF • Available with Modbus RTU RS485 port for: - Integrating the pump in a more complex plant, locally managed by a PLC or an industrial PC, where other Modbus devices are already present - Connect the pump to a KommBox or a KommSpot and, through them, to the internet for management via the SekoWeb app or online portal

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Kosmo - MM2 Mechanical-return diaphragm dosing pump

• Among the Kosmo pump range, the MM2 series pumps provide superior dosing performance, making them suitable for the most demanding applications. Constructed in hard-wearing metal with a cast-aluminium housing, Kosmo MM2 can handle the largest output with flow rates as high as 2,300 l/h, at pressures up to 10 bar.

• As with all SEKO pumps Kosmo is designed using materials chosen for their robustness and chemical compatibility and is conceived to work for long periods of continuous operation thanks to the benefits derived from its variable eccentric system. SEKO’s Kosmo PTFE diaphragm is directly linked to the mechanism’s moving parts, meaning Kosmo makes use of the motor’s power both in the suction and delivery phases which allows it to deal with high suction head conditions.

• All components feature permanent lubrication, using ball bearings for the principal moving parts to help prevent overheating and extend pump life with the added benefit of quiet-running operation.

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Invikta - The market’s most user-friendly solenoid-driven dosing pumps

• The premium components chosen for the Invikta series ensure full chemical compatibility across multiple applications and guarantee long product lifespan. Invikta’s PVDF-T pump body, ceramic balls and PTFE diaphragm (guaranteed for five years) reflect SEKO’s commitment to product quality, whether affordable or high-end.

• Invikta’s compact dimensions and a truly minimal electronic control board allow SEKO to offer a cost-effective product that represents the right solution where simple functionality is a priority.

• As with all other SEKO solenoid-driven pumps, Invikta is housed within a polypropylene casing and delivers IP65 protection. This provides excellent dust and water resistance, meaning Invikta can be used safely in a multitude of environments.

• Pump body and fittings in PVDF-T • PTFE diaphragm, guaranteed for 5 years • Simple analogic interface: potentiometer and LED • KCS: Constant, without level, with adjustable flow rate • Standard seals in FKM-B or EPDM • Bracket for wall mounting • Bleed tap facilitates priming • KCS Low-Noise model available for spa applications Features

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