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FAQ

  • Q What to Consider When Selecting an Oxygen Demand Analysis Method?

    A

    What to Consider When Selecting an Oxygen Demand Analysis Method?

    • Specific test application scenario
    • Type of oxidant to be used
    • Time required for test completion
    • Measurement accuracy and precision

  • Q Why is COD an Important Water Quality Parameter?

    A
    COD is an important water quality parameter and is used in a wide range of applications, including:

    1. To confirm wastewater discharge and the waste treatment procedure meets criteria set by regulators

    2. To quantify the biodegradable fraction of wastewater effluent – ratio between BOD and COD

    3. COD or BOD measurements are also used as an indicator of the size of a wastewater treatment plant required for a specific location.

  • Q What Processes Require Chemical Oxygen Demand (COD) Monitoring?

    A
     
    -Municipal and industrial wastewater treatment
    -Primary Treatment.
    -Secondary Treatment.
    -Discharge limits.
    -Continuous monitoring of organic matter load in the sewage treatment process.
    -On-line real-time monitoring of influent and outflow water of the wastewater treatment.

  • Q How do these pollutants affect water quality and the environment? Probest's first hand water analyzer monitoring instruments factory

    A
    COD-related pollutants (organic + inorganic) harm water quality and the environment mainly through oxygen depletion, toxicity, and ecological disruption, ultimately affecting aquatic life and human health. Below is the condensed breakdown:

    1. Core Impacts of Organic Pollutants (Main COD Contributors)

    • Oxygen depletion kills aquatic lifeAerobic microorganisms decompose organic matter, consuming large amounts of dissolved oxygen (DO). When DO drops below 2 mg/L, most fish suffocate to death (e.g., wastewater from food processing plants or breweries can trigger large-scale "fish kills" in nearby rivers within days). At 2–5 mg/L DO, aquatic organisms grow slowly, biodiversity declines, and toxic anaerobic bacteria (producing methane or hydrogen sulfide) multiply—making water smelly and uninhabitable.
    • Specific toxicity damages food chains & human health
      • Hydrocarbons (e.g., benzene, oil): Stick to fish gills to block oxygen absorption and cause death; accumulate in aquatic organisms’ fat, and may cause cancer (e.g., benzene links to leukemia) when humans consume contaminated seafood.
      • Phenolic compounds: Kill algae and small invertebrates at concentrations as low as 0.1 mg/L (breaking the food chain base); make drinking water bitter and form toxic byproducts during chlorine disinfection, harming human liver and kidneys.
      • Surfactants (e.g., detergents): Cause bubbles in fish gills to inhibit oxygen exchange; promote harmful algal blooms (releasing toxins like microcystins) by trapping nutrients.
      • Dyes/polymers: Block sunlight, preventing aquatic plants from photosynthesizing (reducing oxygen production) and turning water into a "dead zone."

    2. Secondary Impacts of Inorganic Reducing Substances

    • Sulfides (e.g., hydrogen sulfide): Smell like rotten eggs; react with metals to form black precipitates that clog organisms’ gills; 0.5 mg/L can kill most freshwater fish.
    • Nitrites: Convert to carcinogenic nitrosamines; disrupt oxygen transport in fish blood (causing suffocation even with normal DO levels).
    • Ferrous ions (Fe²⁺): Oxidize into brown precipitates, staining water and destroying habitats for aquatic organisms.

    3. Indirect Impacts

    • Worsens water scarcity: Polluted water cannot be used for irrigation or drinking.
    • Contaminates soil: Toxins accumulate in soil via polluted irrigation water, reducing crop yields and entering the human food chain.
    • Causes economic losses: Billions of dollars are spent annually on COD pollution treatment.

  • Q Online COD BOD TSS Monitoring Sensor PUVCOD Chemical Oxygen Demand COD SensorCOD Sensor ManufacturerCOD BOD TSS Sensor used for Sewage Monitoring COD Sensor for River Water Monitoring Online COD Sensor Installed for Wastewater Quality Monitoring Online COD Sensor-PROBEST

    A

    What is COD, BOD, and TSS?

     

    COD, BOD, and TSS are core parameters in environmental science and wastewater treatment, widely used to assess water quality and pollution levels.

    COD: Chemical Oxygen Demand

     

    COD quantifies the amount of oxygen required to chemically oxidize both organic and inorganic substances in water. As a direct indicator of total pollution load (with a focus on organic pollutants), it is commonly used to evaluate water quality in industrial effluents and municipal wastewater. Its key advantage lies in rapid measurement, making it ideal for high-throughput monitoring of pollution levels.

    BOD: Biochemical Oxygen Demand

     

    BOD refers to the dissolved oxygen used by aerobic microorganisms to decompose organic matter in water. It specifically reflects the level of biodegradable organic pollution and the oxygen demand for aerobic biological processes to break down these pollutants. As a critical metric, it is used to assess the effectiveness of biological wastewater treatment systems and gauge the health of aquatic ecosystems (e.g., avoiding oxygen depletion in rivers or lakes).

    TSS: Total Suspended Solids

     

    TSS represents the concentration of suspended solid particles in water—encompassing both organic (e.g., organic debris, microbes) and inorganic (e.g., silt, sediment) materials that do not dissolve. It is essential for evaluating water clarity, sedimentation potential, and overall water quality. Practically, it is used to verify the performance of sediment control measures (e.g., in construction sites) and the solid-removal efficiency of wastewater treatment processes.

  • Q Do PROBEST water quality sensors require regular calibration? What is the calibration cycle?

    A
    Yes, PROBEST water quality sensors require regular calibration. The calibration cycle varies by sensor type. It is generally recommended to calibrate every two weeks or based on usage frequency to ensure data accuracy.

  • Q What is the waterproof rating of PROBEST's online water quality monitoring sensors? Can they be used underwater for extended periods?

    A
    Answer: All genuine, high-quality PROBEST online digital water quality monitoring sensors meet the IP68 waterproof standard.
    They are designed for long-term underwater operation and can function reliably at depths up to 10 meters.

  • Q What signal output methods are available for PROBEST water quality analysis sensors? Can they be quickly integrated with existing monitoring platforms?

    A
    All PROBEST water monitoring analysis sensors are with the RS485 (MODBUS-RTU) signal output.
    This industry-standard, stable transmission protocol offers strong compatibility and enables seamless integration with various monitoring systems such as SCADA systems and smart water management platforms.
    No additional conversion modules are required; simply connect according to the standard wiring sequence to achieve real-time data upload.

  • Q What is the detection principle of online PROBEST cyanobacteria sensors?

    A
    Answer: By utilizing the fluorescence excitation properties of phycocyanin in cyanobacteria, a specific wavelength light beam excites the phycocyanin.
    The intensity of the emitted fluorescence is then measured to accurately calculate the cyanobacteria concentration.

  • Q Does water filtered through a water purifier still require regular testing?

    A
    Yes. Water purifier filter cartridges have a limited lifespan. Failure to replace them over time can lead to reduced filtration effectiveness and even bacterial growth. It is recommended to test the output water quality every 6-12 months to determine if the filter cartridge needs replacement.

  • Q Does tap water with an unusual odor (such as a chlorine smell or fishy odor) require water quality analysis?

    A
    Chlorine odor: This is typically residual chlorine from disinfection at the water treatment plant, which is normal. Boiling the water will eliminate the odor, and testing is generally unnecessary.

    Fishy or earthy odor: This may indicate aging pipes, contamination in secondary water supply tanks, or the proliferation of algae and microorganisms in the water. Testing for microbial and organic indicators is recommended.

  • Q Which indicators are key to determining drinking water safety?

    A
    Microbiological indicators: Such as total bacterial count and E. coli. Exceeding standards may cause diseases like diarrhea and gastroenteritis.

    Heavy metal indicators: such as lead, mercury, and arsenic. Long-term exposure can damage organs like the liver and kidneys, with greater impacts on children's development.

    Physical and chemical indicators: pH (normal range 6.5-8.5), residual chlorine (end-of-tap residual chlorine ≥0.05mg/L to ensure disinfection effectiveness), hardness (excessive levels may cause scale buildup, affecting taste and appliance lifespan).

  • Q What should be noted before water quality testing?

    A
    Sampling containers: Use clean, uncontaminated dedicated containers. Avoid using ordinary plastic or glass bottles (residual substances may affect results).

    Sampling timing: For tap water testing, open the faucet and let water run for 5-10 minutes after water supply resumes before sampling to avoid interference from stagnant water in pipes.

    Timeliness of submission: Submit samples promptly after collection (generally within 24 hours), especially for microbial testing, to prevent sample degradation.

  • Q What methods are available for individuals or households to test water quality?

    A
    Simple Tools: Use home water testing kits (to measure basic indicators like pH, residual chlorine, and hardness). These are easy to operate but have limited accuracy.

    Professional Testing: Engage a third-party testing agency that provides on-site sampling services.
    They can test comprehensive indicators such as heavy metals, microorganisms, and organic compounds, delivering more accurate results.

  • Q In which scenarios is water quality analysis primarily applied?

    A
    Domestic Scenarios: Testing tap water and drinking water safety to ensure freedom from harmful microorganisms or heavy metals.
    Industrial Scenarios: Testing industrial water (such as cooling water and production water) to prevent equipment corrosion or product quality issues.
    Environmental Scenarios: Monitoring water quality in rivers, lakes, seas, and groundwater to assess pollution levels and ecological health.
     

  • Q What is water quality analysis?

    A
    Water quality analysis is the process of using specialized methods to test physical, chemical, and biological indicators in water to assess whether the water meets usage standards (such as for drinking, industrial, agricultural, etc.).

  • Q 2026 USD/CNY Exchange Rate Forecast

    A
    Xiong Yi, Chief Economist for China at Deutsche Bank Group, stated in a research report that the renminbi exchange rate may reach a trend inflection point as trade tensions ease. Deutsche Bank Research forecasts that by the end of 2026, the RMB is expected to appreciate to 6.7 against the US dollar.

    The firm believes factors such as seasonal export patterns, low short positions in offshore RMB against the dollar, and improving inflation expectations could drive the RMB back toward its long-term appreciation trend.

  • Q National Standard Methods for Determining Total Nitrogen in Water

    A
    National Standard Methods for Determining Total Nitrogen in Water
    The primary national standard methods for determining total nitrogen in water are as follows:
     
    “Water Quality - Determination of Total Nitrogen - Potassium Persulfate Alkaline Digestion and Ultraviolet Spectrophotometric Method” (HJ 636-2012)
     
    Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.
    Principle: At 120-124°C, alkaline potassium persulfate solution converts nitrogen in nitrogen-containing compounds to nitrate. Absorbance is measured at wavelengths of 220 nm and 275 nm using ultraviolet spectrophotometry. The relationship between corrected absorbance and total nitrogen content is calculated.
    Detection Range: 0.2–7 mg/L, detection limit 0.05 mg/L.
    Interferences and Elimination: Iodide ions, bromide ions, hexavalent chromium ions, and trivalent iron ions may cause interference. These can be eliminated by dilution or addition of hydroxylamine hydrochloride solution.
    Water Quality - Determination of Total Nitrogen - Gas Phase Molecular Absorption Spectroscopy (HJ 199-2023)
     
    Scope of Application: Surface water, groundwater, domestic sewage, industrial wastewater, and seawater.
    Principle: Using alkaline potassium persulfate as an oxidant, nitrogen in the sample is oxidized to nitrate nitrogen via high-temperature high-pressure digestion or online UV digestion. It is then reduced to nitric oxide by titanium trichloride and measured using a gas phase molecular absorption spectrometer.
    Detection Range: Detection limit is 0.05 mg/L for both high-temperature high-pressure digestion and online UV digestion; lower limit of quantification is 0.20 mg/L.
    Interferences and Mitigation: Hexavalent chromium, trivalent iron, and high concentrations of organic matter may cause interference. Mitigate by dilution or optimizing digestion conditions.
    Water Quality - Determination of Total Nitrogen - Flow Injection-Hydrochloric Acid-Naphthylenediamine Spectrophotometric Method (HJ 668-2013)
     
    Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.
    Detection Range: 0.12–10 mg/L.
    Water Quality—Determination of Total Nitrogen—Continuous Flow-Hydrochloric Acid Naphthylenediamine Spectrophotometric Method (HJ 667-2013)
     
    Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.
    Detection Range: 0.16–10 mg/L.
    Among the above methods, HJ 636-2012 and HJ 199-2023 are currently the most commonly used laboratory determination methods. The specific selection may be determined based on sample type, detection range, and laboratory conditions.

  • Q Total Chromium > Hexavalent Chromium

    A
    Interrelationships Among Water Testing Parameters in Environmental Monitoring
    Relationship Between Hexavalent Chromium and Total Chromium
     
    Chromium in water typically exists as trivalent and hexavalent forms, which can convert under certain conditions. Total chromium is the sum of trivalent and hexavalent chromium. Therefore, for the same water sample, the following logical relationship holds:
     
    Total Chromium > Hexavalent Chromium
     
    Relationship Between Sulfides and Heavy Metals
     
    In the same water sample, high sulfide concentrations correlate with lower concentrations of heavy metals (Cu, Pb, Zn, Cd, etc.). However, this relationship may not hold if heavy metals exist in complexed forms.
     
    Relationship Between Total Bacteria Count, Coliform Bacteria, and Fecal Coliform Bacteria
     
    Coliform bacteria represent only one population among bacterial species and have limited contamination pathways. Long-term testing indicates that samples detecting coliform bacteria also detect total bacteria count. Conversely, samples with high total bacteria counts do not necessarily detect total coliform bacteria. Fecal coliform bacteria belong to the total coliform group and are detected at 44.5°C, which is higher than the 37°C detection temperature for total coliform bacteria. Therefore, fecal coliform values are typically lower than total coliform values, i.e., fecal coliform value < total coliform value.

  • Q Interrelationships Among Water Quality Parameters in Environmental Monitoring Relationship Between Nitrite Nitrogen and Total Nitrogen

    A
    Interrelationships Among Water Quality Parameters in Environmental Monitoring
    Relationship Between Nitrite Nitrogen and Total Nitrogen
     
    Nitrogen primarily exists in aquatic environments as nitrate, nitrite, ammonia, and organic nitrogen. Therefore, total nitrogen should equal the sum of nitrite nitrogen and organic nitrogen. For the same water sample, the following logical relationships hold:
     
    Total Nitrogen > Ammonia Nitrogen Total Nitrogen > Sum of Ammonia Nitrogen, Nitrate Nitrogen, and Nitrite Nitrogen
     

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