Neutralization treatment of wastewater

The manufacturer of high-voltage electrostatic circulating water will explain the neutralization treatment of wastewater.

A. Neutralization of acid and alkali wastewater (or waste residue): 1) neutralization of acid-base wastewater can be quantitatively calculated according to the law of equivalence: Nava = nbvb, where Na and Nb are the equivalent concentration of acid and alkali respectively; VA and VB are the volume of acid-base solution respectively. In the process of neutralization, the equivalence point of neutralization reaction is called when the equivalent number of acid and base is exactly equal. When the neutralization of strong acid and strong base reaches the equivalent point, the generated strong acid and alkali salt will not hydrolyze, so the equivalent point is the neutral point, and the pH value of the solution is equal to 7.0. However, if the neutralizer is a weak acid or a weak base, the salt generated in the neutralization process is hydrolyzed in water. Therefore, although the equivalent point is reached, the solution is not neutral. According to the hydrolysis of the generated brine, it may be acidic or alkaline, and the pH value is determined by the degree of hydrolysis of the generated salt.

B. Neutralization by dosing: neutralization by dosing is a widely used neutralization method. The most commonly used alkaline agent is lime, sometimes caustic soda, sodium carbonate, limestone or dolomite. When selecting alkaline reagents, not only the solubility, reaction speed, cost, secondary pollution and convenience of use should be considered, but also the properties, quantity and treatment cost of neutralization products should be considered.

C. Filtration neutralization method: it is generally applicable to the treatment of a small amount of acid wastewater with low acid concentration (sulfuric acid < 20g / L, hydrochloric acid and nitric acid < 20g / L), but not applicable to acidic wastewater containing a large amount of suspended solids, oil, heavy metal salts and other toxic substances. Limestone or dolomite can be used as filter material. The reaction speed of limestone filter material is faster than that of dolomite, but the allowable concentration of sulfuric acid in influent water is lower than that of dolomite filter material. Both hydrochloric acid and nitric acid wastewater can be neutralized. Dolomite is suitable for neutralizing sulfuric acid wastewater.