How to measure COD
(chemical oxygen demand) content in wastewater with a quick method? Nowadays, the pollution of water quality is becoming more and more serious, and the damage to the ecological balance has completely affected the healthy existence of human beings. It is urgent to quickly detect the COD concentration in the water quality and deal with the discharge after reaching the standard! How to quickly detect COD? Prepared equipment: 1. A set of COD rapid tester: including two boxes of COD prefabricated reagents (one box for high and low), two pipettes (one for 1ml and one for 5ml), power cord, cleaning cloth, water sample, waste liquid One beaker, one bottle of distilled water. 2. A set of intelligent rapid digestion instrument: including a 16-hole digestion instrument, a protective cover, and a power cord. Detection steps: Step 1: 1. Turn on the power of the digestion instrument and select the COD digestion mode (165°C.15min). 2. Turn on the power of the host and preheat it. 3. Prepare a number of COD prefabricated reagent tubes in the colorimetric tube rack. (200mg /L is the low range, and above 200mg/L is the high range) Step 2: 1. Accurately measure 2ml of distilled water and add it to the blank reaction tube. (Low and high ranges need to be blank separately) 2. Accurately pipette each water sample 2-a. When the COD value of the water sample is 0-200mg/L, take 2ml of the water sample and add it to the low-range prefabricated reagent; 2-b. The COD value of the water sample is 200-1000mg /L, take 2ml of water sample and add it to the high-range prefabricated reagent; 2-c. When the COD value of the water sample is 1000-10000mg/L, dilute the water sample 10 times, take 2ml of the water sample and add it to the high-range prefabricated reagent Middle; 2-d. Cover and shake well; Step 3: 1. After the digestion instrument reaches the temperature, the buzzer beeps shortly to prompt, insert the digestion tube into the digestion hole, cover the protective cover, and press the 'OK' button to digest The instrument starts timing digestion. 2. After the digestion is completed, the buzzer of the digestion instrument will beep for a long time. Press any key to cancel the long beep. Place the digestion tube in the digestion tube stand to cool to room temperature (natural cooling or water cooling is acceptable). 3. After cooling, wipe the digestion tube clean, select the corresponding curve, measure the blank value, and then measure the sample. 4. Curve selection: Curve No. 01 (Low range) CODL: 0-200mg/L Select the curve and press the confirmation key to enter the blank measurement, put the digested blank into the detection pool and press the confirmation key to read the value, then press to take out the blank and put in the digested water sample, press Press the confirm button to read the concentration of the water sample. No. 02 curve (high range) CODM: 200-1000mg/L Select the curve and press the confirmation key to enter the blank measurement, put the digested blank into the detection pool, press the confirmation key to read the value, and then press to take out the blank and put it into the digested water sample, press the enter button to read the concentration of the water sample. No. 03 curve (high range) CODH: 1000-10000mg/L Select the curve and press the confirmation key to enter the blank measurement, put the digested blank into the detection pool, press the confirmation key to read the value, and then press to take out the blank and put it into the digested water sample, press the enter button to read the concentration of the water sample. Step 4: According to the needs, you can choose to save the concentration data and print it out directly. Note: 1. The main interference factor of COD measurement is chloride ion. This reagent comes with an anti-chlorine interference of 1000mg/L. 2. The samples cannot be left for a period of time or repeated tests and comparisons in different time periods. 3. The measurement data should be within the corresponding range. If it is not, you can only roughly judge the level of the water sample. If you need accurate data, you should choose low range or high range or measure after dilution, so that the measured data is within the corresponding range. 4. The solution after colorimetry cannot be placed in the digestion tube for a long time, and the digestion tube and its experimental equipment should be cleaned in time. 5. The water sample pretreatment process and colorimetric process should be completed compactly. 6. The solution after the colorimetry is completed cannot be dumped at will, and should be collected uniformly for centralized treatment. 7. If the digestion tube is scratched, please replace it in time to avoid affecting the accuracy of data.
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