Acid-base neutralization in wastewater tanks
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100 tons of wastewater with a pH of 3 in the tank area’s wastewater pool need to be neutralized using 30% alkaline solution in order to bring the pH to 6 for wastewater treatment； I would like to know what simple formula can be used for calculation, and how much alkali solution is needed.
You can use this simple formula for the calculation: Amount of alkali solution (liters) = Amount of acid to be neutralized (mol/L) × Volume of wastewater (liters) ÷ Concentration of alkali solution. First, you need to determine the concentration of acid corresponding to the current pH value; calculate the acid concentration in mol/L based on the pH, then multiply it by the volume of wastewater (100 tons equals 100,000 liters), and finally divide by the concentration of the alkali solution (30%) to obtain the required volume of alkali solution. Then convert the volume into the mass or volume of the alkali solution actually added. Since pH is a logarithmic value, a change of 1 in pH corresponds to a ten-fold change in the acid or base concentration; the chemical equation for the specific acid-base reaction also needs to be taken into account. Note that in practice, it is best to add the alkali solution gradually in batches, while continuously monitoring the pH value, to avoid excessive neutralization. .
The neutralization of wastewater should not be calculated based on pH value; instead, it should be calculated using specific acid value data. Because the acids in wastewater are not necessarily all strong acids; only when there is a certain proportion of weak acids does a buffer system form. When the pH value of the buffer system is the same, the amount of acid or base required for neutralization can vary significantly.
The simplest approach is to take a sample for titration and then scale it up proportionally. Industrial operations also require consideration of practical issues such as mixing and sampling