What is neutralization treatment? How to use caustic soda and sulfuric acid [Basic Knowledge]

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■Is it better for chemicals to be concentrated? If the chemicals used for neutralization are too concentrated, it can lead to excessive pH swings, resulting in a phenomenon known as "hunting." The same applies if too much chemical is added. Variability in concentration can also cause treatment to fail. Use chemicals at a concentration that stabilizes the pH. ■Caution with wastewater containing metals regarding re-dissolution When neutralizing with caustic soda, depending on the type of metal, if the pH is raised too high, hydroxides that have formed may re-dissolve. ■Unique precautions for carbon dioxide! Alkaline wastewater can also be neutralized using carbon dioxide. In this method, it is important to regularly check the remaining amount in the gas cylinder to ensure a continuous supply. It is also essential to confirm that sufficient neutralization has occurred. ■Where to place the pH meter? The pH measuring electrode should be placed near the outlet of the neutralization tank, while the point where chemicals are added should be away from the electrode. The neutralization tank should be well mixed to ensure uniform pH throughout. ■Be cautious of over-addition If too little chemical is added, neutralization will be insufficient. Conversely, adding too much can hinder the treatment process. It is important to check not only the quantity but also whether the concentration of the chemicals is appropriate.

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■Can I trust the readings? When the electrode gets dirty, the pH meter will no longer show accurate values. In fact, there have been cases where debris on the electrode prevented accurate pH measurement, leading to violations of standards. Even if the readings on the instrument are within standards, the actual wastewater can be outside the standards. ■How do I maintain the pH meter? 1. Cleaning: Wash the electrode according to the level of dirt. Use neutral detergents for oil stains. 2. Calibration: Calibrate using two types of pH standard solutions. 3. Record keeping: Document the results of inspections in a logbook or similar. Also, check daily that the pH recorder in the monitoring tank has enough paper and ink, and write the date on the chart paper. ■Running out of chemicals can lead to standard violations! If chemicals run out, there is a risk that wastewater will flow without being neutralized. Check the levels of chemicals in tanks and gas cylinders to prevent running out of liquids or gases. ■Control to stabilize pH There is a method called "time-proportional control," which shortens the operating time of the chemical pump as it approaches the target pH. This method makes it easier to suppress overshooting and hunting of pH levels. Keeping a record of the situation in daily operation reports can help you notice abnormalities quickly. Please feel free to consult us first.