Sodium bicarbonate (NaHCO₃), commonly known as baking soda, is a mildly alkaline inorganic salt with neutralizing, buffering, environmentally friendly, and low-corrosive properties. It has demonstrated significant effectiveness in various industrial wastewater treatment scenarios. Beyond pH regulation, its applications include heavy metal precipitation, desulfurization byproduct neutralization, alkalinity maintenance in biological systems, odor suppression, and coagulation assistance, offering high practical engineering value.
1. Metal Processing and Electroplating Industry
Heavy Metal Ion Precipitant
NaHCO₃ is used to treat wastewater containing Cu²⁺, Pb²⁺, Zn²⁺, Ni²⁺, and other heavy metals. It slowly releases carbonate and hydroxide ions, helping control precipitation rates and forming stable, insoluble metal carbonates or hydroxides, reducing the risk of re-dissolution.
Electrolytic Cell Effluent Adjustment
Acidic wastewater from electroplating or anodizing can be pre-neutralized using NaHCO₃, minimizing shock to subsequent biological systems and prolonging equipment lifespan.
2. Chemical and Fine Chemicals Industry
Such wastewater often contains strong acids (e.g., H₂SO₄, HNO₃) and toxic organics. NaHCO₃ provides buffering neutralization, reducing the risk of splashing due to violent pH changes, making it safer and easier to manage.
Neutralization of Oxidizing Wastewater
In oxidizing wastewater involving H₂O₂ or NaClO, NaHCO₃ helps suppress side reactions (e.g., chlorine gas release) caused by local high pH and adjusts the system's reactive range.
3. Pharmaceutical Industry
PH Stabilization of Antibiotic/Hormone Wastewater
Pharmaceutical wastewater often contains weak organic acids. NaHCO₃ enables gradual pH increase, enhancing the performance of advanced oxidation processes like Fenton and ozone treatment.
Alkalinity Support for Bioreactors
NaHCO₃ helps maintain pH between 6.5 and 8.5 in nutrient-rich biological treatment, promoting microbial balance and improving ammonia nitrogen and COD removal.
4. Waste Incineration and Flue Gas Scrubbing
Neutralization of Dry Desulfurization Wastewater
NaHCO₃ neutralizes scrubber effluents containing sulfite residues (e.g., from spray drying desulfurization), controlling SO₂-related pollution and producing easily treatable byproducts.
Treatment of Fly Ash Leachate
In stabilizing fly ash, NaHCO₃ aids multi-stage pH adjustment, supporting heavy metal immobilization and enhancing fly ash resource utilization.
5. Steel and Metal Smelting Industry
Adjustment of Acidic Flue Gas Scrubbing Effluent
NaHCO₃ neutralizes nitrous/sulfurous acids and their salts in acidic, saline wastewater from SOx/NOx scrubbing, ensuring system stability.
Pretreatment of Acidic Leachate
In hydrometallurgy, such as copper leaching or rare earth extraction, NaHCO₃ raises pH for easier transition to coagulation-precipitation treatment.
6. Textile Dyeing and Papermaking Industry
PH Stabilizer for Fluctuations
NaHCO₃ neutralizes strong acids/alkalis in textile wastewater, maintaining optimal pH for coagulation and enhancing dye removal.
Decolorization Aid for Colored Wastewater
NaHCO₃ boosts performance of coagulants like PAC/PAF, enhancing sedimentation of dye-additive complexes and reducing color levels.
7. Leather and Adhesives Industry
Chromium Precipitation in Tanning Effluent
NaHCO₃ neutralizes Cr³⁺-containing tanning waste to form Cr(OH)₃, facilitating chromium recovery.
Odor Control and Buffer Regulation
NaHCO₃ reacts with odor gases like H₂S and ammonia to form non-volatile salts while buffering pH, curbing further release.
