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The true face of conventional water quality testing items

by:BOQU     2022-01-04

Nowadays, there are many kinds of sewage testing projects, let's take you to see the real body of conventional water quality testing projects today! I would like to recommend the self-checking instrument for related items.

COD: is the English abbreviation of Chemical Oxygen Demand, which refers to the amount of oxidant consumed when the reducing substances in water are oxidized and decomposed under the action of an external strong oxidant under certain strict conditions, usually in mg/ L said. The chemical oxygen demand reflects the degree of pollution by reducing substances in the water. After sewage containing reducing pollutants enters natural water bodies, it will consume dissolved oxygen in the water, cause fish and shrimp to die, and form stagnant water. These substances include: organic matter (such as Alcohol, glucose, etc.). Nitrite, ferrous salt, sulfide, etc. However, the amount of inorganic reducing substances in general water and wastewater is relatively small, and it is common for the water used in our lives to be polluted by organic matter, so COD It can be used as a comprehensive indicator of the relative content of organic substances.

BOD: Biochemical Oxygen Demand is an important indicator that uses the amount of dissolved oxygen consumed by microbial metabolism to indirectly indicate the degree of pollution of water bodies by organic matter. It is defined as the amount of free oxygen consumed by aerobic microorganisms to oxidize and decompose organic matter per unit volume of water under aerobic conditions, expressed in mg/L. It is a part of COD, which refers to the oxygen consumed by the organic matter that can be decomposed by microorganisms in COD. The big role is to reduce COD in sewage treatment. If the BOD/COD value is high, it can be treated well by adding microorganisms and aeration. This method produces little pollution, good effect, and low cost. If the BOD/COD value is low, only It can be treated by adding chemicals.

Ammonia nitrogen: refers to the nitrogen in the form of free ammonia (NH3) and ammonium ions (NH4) in water. Ammonia nitrogen is a nutrient in the water body, which can lead to water eutrophication and the algae and plankton in the water multiply. It leads to a decrease in dissolved oxygen in the water and is the main oxygen-consuming pollutant in the water body. For fish and aquatic organisms, ammonia nitrogen is a toxic substance, and when the content is high, it will directly cause the death of fish.

Total Nitrogen: The total amount of various forms of inorganic and organic nitrogen in the water. Including NO3-(nitrate), NO2-(nitrite). NH4+ (ammonium ion) and other inorganic nitrogen and organic nitrogen such as protein, amino acid and an organic amine, calculated in milligrams of nitrogen per liter of water. Organic nitrogen will generate nitrate under the action of nitrification, and nitrate can be converted into nitrite and ammonia nitrogen. Nitrite is a strong carcinogen; ammonia nitrogen consumes dissolved oxygen in the water and is harmful to fish.

Turbidity: reflects the brightness of water and natural water. Refers to the degree of obstruction of light transmission by suspended matter in the water. Suspended substances in water are generally soil, sand, fine organic and inorganic substances, plankton, microorganisms, and colloidal substances, etc. The water quality analysis stipulates that the turbidity formed by 1 mg of SiO2 in 1L of water is a standard turbidity unit, referred to as 1 degree. Generally, the higher the turbidity, the more turbid the solution, and the unit of turbidity are JTU. The turbidity displayed by modern instruments is the turbidity unit NTU, also called TU. 1NTUu003d1JTU. Recently, it is internationally believed that the turbidity standard prepared with urotropine-hydrazine sulfate has better reproducibility and is selected as the national unified standard FTU. 1FTUu003d1JTU. Turbidity control is an important part of industrial water treatment and an important water quality indicator. According to different uses of water, there are different requirements for turbidity. The turbidity of drinking water shall not exceed 1NTU; the turbidity of supplementary water for circulating cooling water treatment is required to be 2 to 5 degrees; the influent (raw water) of desalinated water treatment is turbid The degree should be less than 3 degrees; the turbidity of the water is required to be less than 0.3 degrees for man-made fibers.

Residual chlorine: Residual chlorine means that after chlorine is put into the water, in addition to the bacteria, microorganisms, organics, and inorganics in the water, it consumes a part of the chlorine, and there is a part of the remaining chlorine. This part of the chlorine is called residual chlorine. . In order to ensure that tap water meets safety and sanitation requirements and avoid the occurrence of water-borne infectious diseases, disinfectants should be added to tap water in the water purification process to eliminate pathogenic microorganisms in live water. Because of its high cost performance, it is widely used in the domestic water treatment industry. As an effective means of sterilization and disinfection, it is still used by more than 80% of water plants in the world. Therefore, a certain amount of residual chlorine must be maintained in municipal tap water to ensure the safety of drinking water microbiological indicators. National standard requirements: After 30 minutes of contact with water, the residual chlorine should not be less than 0.3mg/L. In addition to the factory water that should meet the above requirements for centralized water supply, the end water of the pipe network should not be less than 0.05mg/L.

Total Phosphorus: Refers to the result of determination after the water sample has been digested to convert various forms of phosphorus into orthophosphate, measured in milligrams of phosphorus per liter of water sample. The total content of phosphorus in the water body is one of the indicators that the water body is rich in organic matter. Excessive phosphorus content can cause excessive growth of algae plants, eutrophication of water bodies, blooms or red tides, and disturb the balance of water bodies.

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