The core of treating acidic wastewater is to neutralize acidity and achieve standard discharge. It is necessary to select suitable equipment based on the acidity, water volume, and pollutant types of the wastewater. The core equipment and applicable scenarios are as follows: 1、 Core neutral equipment (basic essential) Acid base neutralization tank (reaction tank) The most basic and widely used equipment is divided into intermittent and continuous types. By adding alkaline agents (lime, sodium hydroxide, sodium carbonate, etc.) to the pool and thoroughly mixing and reacting with acidic wastewater, the pH value is adjusted to 6-9 (within the standard range). Suitable for various acidic wastewater (such as electroplating, chemical, and mining wastewater), it can be used alone (small wastewater) or as a pre-treatment equipment for subsequent deep treatment. Neutralization tower (spray type/packing type) Suitable for acidic waste gas washing wastewater or low concentration acidic wastewater (pH ≥ 2), using spray method to make the wastewater come into reverse contact with alkaline spray solution (such as alkali mist), efficiently neutralizing while removing a small amount of dust and volatile acidic substances (such as HCl, SO ₂) in the wastewater. The advantages are small footprint, high neutralization efficiency, and suitability for continuous wastewater treatment. 2、 Enhanced processing equipment (including complex pollutants) If acidic wastewater contains heavy metals (such as copper and zinc), suspended solids, organic matter, etc. in addition to acidic substances, the following equipment should be used to ensure compliance: Inclined tube (plate) sedimentation tank After neutralization reaction, a large amount of sediment (such as calcium sulfate and heavy metal hydroxides) will be generated in the wastewater. The sedimentation tank accelerates the sedimentation of sediment through the guiding effect of inclined pipes/plates, separates the supernatant (discharged in compliance with standards) and sludge, and avoids sediment blocking subsequent pipelines or causing secondary pollution. Filter press (plate frame/box type) Used to treat the sludge generated in the sedimentation tank (including neutralized sediment and heavy metal sludge), the sludge is dehydrated by high-pressure pressing to form a sludge cake (easy to transport and dispose of), and the separated filtrate can be returned to the neutralization tank for reprocessing, achieving the resource recovery of wastewater and sludge. Heavy metal trap For acidic wastewater containing heavy metals (such as electroplating wastewater), heavy metal capture agents (such as sodium sulfide and chelating agents) are added after neutralization. Through the stirring reaction in the equipment, insoluble chelates are formed from heavy metal ions. Then, solid-liquid separation is completed by combining sedimentation tanks and filter presses to ensure that heavy metal emissions meet the standards (in accordance with the Comprehensive Wastewater Discharge Standard GB 8978-1996). Filtering equipment (quartz sand filter/activated carbon filter) Suitable for acidic wastewater with low concentration and low suspended solids, after neutralization, the residual fine suspended solids, pigments, and small amounts of organic matter in the wastewater are removed through filtration media (quartz sand, activated carbon), further improving the effluent quality and meeting the requirements for reuse or strict discharge. 3、 Specialized equipment for special scenarios Electrolytic neutralization equipment Suitable for high concentration acidic wastewater (pH<1) or acidic wastewater containing reducing pollutants (such as Cr ⁶⁺, Fe ² ⁺), through electrolysis reaction, it can neutralize acidity and oxidize and reduce heavy metal ions (such as reducing Cr ⁶⁺ to Cr ³ ⁺, and then removing it through neutralization precipitation). The advantage is that it does not require a large amount of alkaline agents, but the disadvantage is that it has high energy consumption and is suitable for small and difficult acidic wastewater treatment. Membrane separation equipment (reverse osmosis RO/nanofiltration NF) Suitable for acidic wastewater reuse scenarios (such as chemical and electronic industries), the wastewater that meets neutralization standards is intercepted by membranes to remove trace ions and organic matter from the water, producing pure water that can be recycled. The concentrated solution needs further treatment (such as evaporation crystallization). The advantages are high reuse rate and good effluent quality, but the disadvantages are high investment and operating costs, and strict requirements for influent quality (suspended solids, hardness). Core principles of selection Low concentration acidic wastewater (pH 2-5): Neutralization tank+simple filtration (quartz sand) can meet the standard; High concentration acidic wastewater (pH<2): electrolytic neutralization equipment+neutralization tank+sedimentation tank; Acidic wastewater containing heavy metals: neutralization tank+heavy metal trap+sedimentation tank+filter press; Acid waste gas washing wastewater: neutralization tower+sedimentation tank; Wastewater reuse requirements: Neutralization pretreatment+membrane separation equipment.
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