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  • Q Does TN measured by PROBEST PCM200-TP include both NH₄–N and NO₃–N?

    A Yes. Total nitrogen (TN) includes organic nitrogen, NH₄–N, NO₂–N, and NO₃–N, so it is always greater than or equal to the sum of NH₄–N and NO₃–N.

  • Q What are the mainstream methods supported by PROBEST for nitrogen analysis?

    A
    1. PROBEST supports:

      ISE method (PINH3-900, PISE-NO3)
    •  
    • UV spectrophotometry (PUVNO3-900)
    •  
    • Total nitrogen digestion/oxidation methods (PCM200-TP) Continuous flow / segmented flow analysis (CFA/SFA)

  • Q Under what conditions can PCM200-TN TN approximately equal NH₄–N + NO₃–N?

    A When organic nitrogen and nitrite nitrogen (NO₂–N) are very low and negligible, TN ≈ NH₄–N + NO₃–N. This can be verified using PROBEST PINH3-900, PISE-NO3 or PUVNO3-900, and PCM200-TP.

  • Q What is the difference between PROBEST PISE-NO3 and PUVNO3-900?

    A
    • PROBEST PISE-NO3: Ion-Selective Electrode (ISE) method for fast field testing
    • PROBEST PUVNO3-900: UV spectrophotometric method for laboratory-grade NO₃–N analysis

  • Q Can I use PROBEST ISE electrodes for on-site rapid testing?

    A
    • Yes. The PROBEST PINH3-900 (NH₄–N ISE) and PISE-NO3 (NO₃–N ISE) are ideal for field, real-time, and on-site rapid measurement.
       

  • Q What principle does the PROBEST PUVNO3-900 use to measure NO₃–N?

    A The PROBEST PUVNO3-900 uses the ultraviolet (UV) spectrophotometric method to determine nitrate nitrogen (NO₃–N).


  • Q What are the available nitrate nitrogen (NO₃–N) measurement methods in PROBEST instruments?

    A
    1. PROBEST offers two NO₃–N measurement technologies:

      ISE method using PISE-NO3
    • UV spectrophotometric method using PUVNO3-900

    The PISE-900 sensor can flexibly select one or two ion-selective electrodes. At the same time, it is equipped with PH and temperature electrodes as standard, so that 4 parameters can be monitored simultaneously. The optional parameters of ion selective electrode include: Ammonia nitrogen (NH4+), Nitrate (NO3-), Potassium ion (K+), Chloride (CL-), Fluoride (F-). Different parameter combinations can also achieve mutual compensation, making the measurement data more accurate.

    PROBEST NO3 absorbs at 210 nm UV light. When the Spectrometer Nitrate probe is working, the water sample flows through the slit. When the light from the light source in the probe passes through the slit, part of the light is absorbed by the sample flowing in the slit, and the other light passes through the sample and reaches the other side of the probe. Calculate the concentration of nitrate.
     

  • Q Which PROBEST model is designed for total nitrogen (TN) analysis?

    A PCM200-TP is the PROBEST model used for total nitrogen (TN) continous measurement in water samples.
    The principle of ammonium molybdate spectrophotometry is to digest the sample with potassium
    persulfate and convert all the phosphorus contained into orthophosphate. In an acidic medium,
    orthophosphate reacts with ammonium molybdate to form phosphomolybdate heteropoly acid in the
    presence of antimony salt, which is immediately reduced by ascorbic acid to produce a blue complex
    whose absorbance is proportional to the concentration of total phosphorus.

  • Q What measurement principle does the PROBEST PINH3-900 use?

    A The PINH3-900 uses an Ion-Selective Electrode (ISE) for rapid, direct measurement of ammonium nitrogen (NH₄–N).

  • Q What nitrogen parameters can PROBEST instruments measure?

    A
    PROBEST provides solutions for Ammonium Nitrogen (NH₄–N), Nitrate Nitrogen (NO₃–N), and Total Nitrogen (TN) using models including PINH3-900, PISE-NO3, PUVNO3-900, and PCM200-TP.

  • Q How to reduce the concentration of non-compliant risk parameters in industrial wastewater?

    A
     Technical solutions for reducing high-risk parameters, tailored to wastewater characteristics (high COD/BOD, oil content, acidic pH, etc.), include the following targeted control and reduction methods:
    1. COD / BOD (Core Organic Pollutants)
    Pre-treatment stage:
    Oil separation + Dissolved Air Flotation (DAF): First remove floating oil and emulsified oil to reduce subsequent biochemical load.
    Equalization tank homogenization: Stabilizes water quality and flow rate to prevent high-concentration shocks.
    Advanced oxidation (optional): For refractory COD, employ Fenton oxidation, ozone oxidation, etc., to cleave large organic molecules into biodegradable small molecules.
    Biological Treatment Stage:
    Anaerobic + Aerobic Combined Process (e.g., UASB+A/O, SBR): Anaerobic stage efficiently removes high COD concentrations; aerobic stage further degrades residual BOD/COD.
    Enhanced Sludge Activity: Control sludge concentration, DO, and nutrient ratio (C:N:P≈100:5:1) to boost microbial degradation efficiency.
    Advanced Treatment:
    Activated carbon adsorption / Sand filtration: Further removes residual refractory COD to ensure effluent compliance.
    2. Oils and Grease
    Source Control: Install oil separators in production sections to recover floating oil and prevent large amounts of grease entering the wastewater system.
    Physical Separation:
    Inclined Plate Oil Separator: Removes large particulate oil.
    Dissolved Air Flotation (DAF): Achieves efficient solid-liquid separation by trapping emulsified oil with microbubbles, reducing oils below 30 mg/L.
    Chemical Demulsification: Addition of demulsifiers/flocculants disrupts emulsion stability, enhancing flotation efficiency.
    3. pH (Acid-Base Balance)
    Online Neutralization: Install pH monitors in equalization tanks to automatically dose alkali (e.g., NaOH, lime milk) or acid, stabilizing pretreatment water pH between 6–9.
    Buffer Tank Design: Increase equalization tank capacity to buffer transient pH fluctuations, preventing sudden pH changes from impacting the biological treatment system.
    4. Total Suspended Solids (TSS)
    Pre-treatment: Primary sedimentation tanks / air flotation tanks remove most suspended solids.
    Biological End: Secondary sedimentation tanks achieve solids-liquid separation, ensuring clear effluent.
    Advanced Filtration: Sand filtration / precision filtration / membrane filtration further retain residual suspended solids, maintaining TSS consistently below 100 mg/L.
    5. Ammoniacal Nitrogen / Total Phosphorus
    Ammoniacal Nitrogen:
    Nitrification-Denitrification Process (A/O, A²/O): Nitrification in the aerobic stage converts ammoniacal nitrogen to nitrate, while denitrification in the anoxic stage reduces nitrate to nitrogen gas.
    If influent ammonia nitrogen is low, optimize recirculation ratios and control carbon source dosing to ensure complete nitrification.
    Total Phosphorus:
    Chemical precipitation: Add iron salts / aluminum salts / calcium salts to form precipitates with phosphate ions for removal.
    Biological Phosphorus Removal: Utilizes polyphosphate bacteria's ability to release phosphorus anaerobically and absorb it aerobically, removing phosphorus through sludge dewatering.
    Advanced treatment can incorporate filter beds to further reduce residual phosphorus.
    Operations and Management Recommendations
    Online Monitoring: Install online instruments for key parameters such as COD, BOD, pH, and ammonia nitrogen to enable real-time alerts.
    Process Stability: Avoid overload operation to maintain sludge activity and nutrient balance in the biological system.
    Contingency Planning: Develop emergency measures for high-concentration shocks or equipment failures, such as bypassing to equalization tanks or temporary chemical dosing.
    Standard Anticipation: Monitor local discharge standard upgrades and pre-reserve advanced treatment units (e.g., activated carbon, membrane filtration).
    Instrumentation Locations
    Adjustment Tank: Install PROBEST pH/Conductivity Analyzer to monitor pH and conductivity in real time, ensuring stable water quality post-neutralization and preventing impacts on subsequent biochemical units.
    Post-Dissolved Air Flotation: Install PROBEST Oil/Turbidity Analyzer to verify oil and TSS removal efficiency, preventing high loads from entering the anaerobic section.
    Post-anaerobic reactor: Install PROBEST COD/TOC online analyzer to evaluate anaerobic treatment efficiency and adjust process parameters promptly.
    Post-advanced treatment (pre-discharge): Install PROBEST Total Phosphorus/Ammonia Nitrogen online analyzer to verify final effluent compliance with discharge limits and enable regulatory compliance alerts.

  • Q How to stable the ORP value in industrial process monitoring?

    A In industrial process monitoring, stability is even harder to achieve due to high-frequency noise, flow variations, and chemical interference.

    Here is how to stabilize your ORP data specifically for industrial environments:

    1. Address Electrical Noise (Ground Loops)

    Industrial sites are rife with stray currents from pumps and motors.

    Solution: Use a Differential Pre-amplifier or an instrument with a Solution Ground (a third electrode or a stainless steel pin in contact with the liquid). This drains away stray voltages that cause "ghost" readings. Analytical Technology provides detailed guides on solving ground loop issues.

    2. Control Flow & Pressure (The "Flow Effect")

    ORP is flow-sensitive; changes in pipe pressure or velocity will cause the reading to jump.
    Solution: Install the sensor in a Flow Cell (bypass line) rather than directly in the main high-pressure pipe. Maintain a constant flow rate (typically 500 mL/min to 1 L/min) to ensure a stable boundary layer on the platinum tip.

    3. Combat Electrode Poisoning (Chemical Fouling)

    In industrial processes, the reference junction often gets "clogged" or "poisoned" by the process chemicals.
    Solution: Use a Double Junction or Teflon Junction sensor. These are designed to slow down the migration of contaminants (like sulfides or heavy metals) into the reference electrode, significantly reducing drift.

    4. Implement Signal Smoothing (Software Fix)

    Raw ORP signals are inherently "noisy."
    Solution: Increase the Damping or Filter Factor in your transmitter settings. Setting a 30-60 second moving average filter can smooth out minor fluctuations without losing the overall trend.

    5. Automated Cleaning Systems

    If your process involves oils, calcium, or biological growth, manual cleaning is insufficient.
    Solution: Use a sensor with an Integrated Spray Cleaning system (water or acid jet) or an ultrasonic cleaner to keep the platinum surface active without manual intervention.

     

    Quick Stability Test
    To determine if the issue is the sensor or the environment:
    Take a sample of the process liquid in a plastic beaker.
    Test the ORP away from the pipes/motors.
    If stable in the beaker but unstable in the pipe: You have a grounding or flow issue.
    If unstable in the beaker: Your sensor is fouled or the junction is dry.

    Are you monitoring a specific process like cyanide destruction, chrome reduction, or cooling tower treatment? This would help pinpoint the exact chemical interference. If need contact Probest. 

  • Q ORP (Oxidation-Reduction Potential) sensors exhibiting data jumps, drift, or instability during calibration or measurement represent one of the most common issues in water quality monitoring?

    A
    ORP (Oxidation-Reduction Potential) sensors exhibiting data jumps, drift, or instability during calibration or measurement represent one of the most common issues in water quality monitoring. This is typically not due to sensor failure but rather inherent to its operating principle (measuring minute potential differences).
    Below are the primary causes of instability and corresponding solutions:
    I. Common Cause Analysis
    Polarization Effect:
    New sensors or those stored dry for extended periods have not yet established electrochemical equilibrium on the electrode surface.
    Reference Electrode Contamination/Poisoning:
    Presence of sulfides, cyanides, or proteins in water samples can clog the reference electrode's salt bridge, causing potential drift.
    Electromagnetic Interference (EMI):
    ORP signals are extremely weak (high-impedance signals). Nearby frequency converters, motors, or sensor cables running parallel to power lines can generate severe fluctuations.
    Flow Rate and Pressure Sensitivity:
    ORP is highly sensitive to flow velocity. Measured values typically differ significantly between static and flowing water samples.
    Electrode Surface Fouling:
    Oil residues, biofilms, or calcium deposits on the platinum (or gold) sensing surface inhibit redox reactions.
    II. How to Stabilize Data?
    1. Thorough Pre-treatment (Resolving “Initial Instability”)
    Soak Activation: New electrodes must be soaked in 3.3 mol/L KCl solution for 2-4 hours before use.
    Ensure Environmental Consistency: During calibration, ensure the test cup and probe have been rinsed 2-3 times with the sample water to eliminate residual effects from previous liquids.
    2. Check Electrolyte Interface (Resolves “Slow Response/Drift”)
    Inspect the electrolyte (typically KCl) inside the reference electrode for sufficiency or discoloration.
    If the interface is clogged, immerse it in hot KCl solution at 60°C and allow it to cool naturally to unclog micro-pores.
    3. Physical Environment Optimization (Resolves “Value Fluctuations”)
    Shielding Protection: Ensure sensor cables use shielded wiring and avoid routing them in the same conduit as AC power cables.
    Single-Point Grounding: Ensure instruments and transmitters are properly grounded to eliminate interference from ground potential differences.
    4. Standardized Comparison Methods (Resolving “Large Deviations”)
    Do not take readings in air: ORP measurements are meaningless in air; the electrode must be fully submerged.
    Control Agitation Speed: When using a stirrer during comparison, maintain constant rotation speed. Wait 5-10 minutes for complete potential equilibrium before reading values.
    Calibrate with Quinone Hydroquinone Solution: Verify sensor accuracy using standard ORP calibration solutions (e.g., 256mV or 465mV).
    5. Electrode Cleaning (Resolving “Inaccurate Measurements”)
    Oil residue: Wipe with dish soap or diluted isopropyl alcohol.
    Inorganic deposits: Immerse in 10% dilute hydrochloric acid for several minutes.
    Note: After cleaning, rinse with deionized water and re-activate by soaking in KCl.
    Recommended Procedure
    First, soak in 3.3 mol/L KCl solution for 24 hours. If readings still fluctuate slowly in standard calibration solution afterward, the reference electrode may be degraded (poisoned) and requires replacement with a new sensor.

  • Q How often does the PCT-600 need to be calibrated, and what is the calibration method?

    A

    How often does the PCT-600 need to be calibrated, and what is the calibration method?


    It is recommended to calibrate the PCT-600 once every 6-12 months (the specific cycle can be adjusted according to the actual water quality and monitoring requirements). The product supports two calibration methods: sample calibration and slope calibration. We will provide standard calibration procedures and related accessories in the product package. If you need professional calibration services, our after-sales team can also provide on-site support.

  • Q What application scenarios is the PCT-600 suitable for?

    A

    The PCT-600 has a wide range of applications, including but not limited to
    Drinking water plants Finished water color quality evaluation and factory inspection
    Aquaculture and landscape water bodies Real-time color monitoring to ensure ecological stability.
    But not suitable for the following:
    Sewage treatment plants Color control in treatment processes and effluent compliance monitoring;
    Industrial enterprises Process water color monitoring in chemical, electronics, food, and other industries;
    Environmental monitoring Color monitoring and pollution source tracing

    This color sensor is mainly tap water, and it is yellow colored. The dyeing industry, on the other hand, will be very complicated and is not recommended. This is generally to be a professional color sensor, rather than our simple single wavelength color sensor.

  • Q Can the cable length of the PCT-600 be customized according to on-site needs?

    A

    Can the cable length of the PCT-600 be customized according to on-site needs?


    Yes. The standard cable length of the PCT-600 is 10 meters. If you need a longer cable for on-site installation (such as deep water monitoring or long-distance wiring), we support customization and can extend the cable length to a maximum of 100 meters without affecting data transmission stability. Please note that you need to specify the required cable length when placing an order.

  • Q Is the PCT-600 certified, and what quality guarantees does it have?

    A

    Is the PCT-600 certified, and what quality guarantees does it have?


    All PCT-600 products have passed CE, RoHS, and ISO9001 certifications, and undergo 100% full inspection before shipment to ensure stable and reliable quality. PROBEST has a professional R&D team of over 50 people and a production base of more than 7,000 square meters. We provide a one-year warranty for the product (excluding consumables and man-made damage) and offer lifelong technical support to solve your usage problems in a timely manner.

  • Q What is the operating temperature and pressure range of the PCT-600?

    A

    What is the operating temperature and pressure range of the PCT-600?


    The operating temperature range of the PCT-600 is 0-45℃ (no freezing), and the storage temperature is -15-50℃. It can adapt to most indoor and outdoor monitoring scenarios. The pressure range it can withstand is ≤0.4Mpa, which is fully compatible with common water treatment pipelines, ponds, and natural water body monitoring conditions.

  • Q What is the maintenance cycle of the PCT-600, and how to maintain it?

    A

    What is the maintenance cycle of the PCT-600, and how to maintain it?


    The PCT-600 color probe is designed for low maintenance. It is equipped with an automatic scraper cleaning function, which can regularly remove attachments on the sensor surface and reduce manual cleaning frequency. Under normal operating conditions, routine maintenance (such as checking cable connections and confirming calibration status) only needs to be performed every 3-6 months. For special harsh environments, we recommend adjusting the maintenance cycle appropriately. Calibration supports sample calibration and slope calibration, and the operation is simple and easy to master.

  • Q How to integrate the PCT-600 with the existing automatic control system of our enterprise?

    A

    How to integrate the PCT-600 with the existing automatic control system of our enterprise?


    The PCT-600 supports the standard MODBUS RS485 communication protocol and is equipped with 3-way 4-20mA analog outputs and three-way relay outputs. It can be seamlessly connected to most industrial automatic control systems (such as PLC, DCS) on the market. Our technical team will provide detailed integration guidelines and after-sales support to ensure smooth docking and realize functions like real-time data transmission, automatic early warning, and process interlock control.

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