Application of Sodium Acetate Series Carbon Source Products in Sewage Treatment of Municipal Sewage Treatment Plant

In municipal wastewater treatment plants, the denitrification process requires sufficient biodegradable carbon sources to ensure effective total nitrogen removal. To address the common issue of low carbon but high nitrogen in municipal wastewater, the following four core products can precisely meet the carbon source requirements for different operating conditions. Specific application details are as follows:

1. Liquid sodium acetate (industrial grade 20%/25%)

Core function: Serving as the primary carbon source for municipal wastewater denitrification, it provides readily available organic nutrients to denitrifying bacteria, facilitating the reduction of nitrate nitrogen to nitrogen gas. This ensures stable compliance with total nitrogen discharge standards while also assisting in pH regulation of the biochemical system.

Product Advantages: Liquid finished product requires no on-site dissolution, offering high dosing accuracy and compatibility with automated systems; the denitrification rate far exceeds that of traditional carbon sources such as methanol and starch, with high bioavailability and no residual refractory by-products; non-flammable and non-explosive, ensuring safe and compliant transportation and use.

Usage: Calculate the dosage based on the ratio of influent BOD5 to total nitrogen (BOD5/TN) ≥4:1. The standard dosage concentration is 30-50mg/L, which is directly added to the denitrification tank via a dosing pump. Adjustments can be made in real-time according to the effluent water quality.

Common issues: Crystallization is prone to occur in low-temperature environments, necessitating proper insulation of storage tanks and pipelines; excessive dosing may lead to elevated COD in the effluent, thereby increasing treatment costs.

2. Sodium acetate (industrial grade, 58%-60%)

Core function: Serves as a conventional carbon source supplement for small and medium-sized municipal wastewater treatment plants, balancing denitrification and nitrogen removal with pH buffering in biochemical systems to stabilize microbial growth conditions.

Product Advantages: Solid crystalline form for convenient transportation and storage; stable purity, good flowability, and low tendency to caking; rapid denitrification start-up, suitable for intermittent dosing scenarios.

Usage: First prepare a 20%-30% aqueous solution in the dissolution tank, then meter the solution into the denitrification section using a metering pump. The dosage should be precisely calculated based on a carbon-to-nitrogen ratio of 4:1.

Common issues: Inadequate dissolution may lead to clogging of the dosing tubing; high hygroscopicity requires sealed storage after opening to prevent clumping and loss of efficacy.

3. Anhydrous Sodium Acetate (Industrial Grade 98%-99%)

Core function: A high-concentration, fast-acting carbon source, suitable for municipal wastewater treatment plants with significant fluctuations in influent total nitrogen and severe low-carbon source shortages. It rapidly enhances denitrification efficiency to address water quality and quantity shocks.

Product Advantages: Higher effective carbon content, requiring lower dosage for equivalent denitrification efficiency; fewer impurities with no adverse effects on the biochemical system, extended storage duration, and significantly lower hygroscopicity compared to sodium acetate trihydrate.

Usage: Dissolve and prepare a 10%-20% aqueous solution for application, primarily used in emergency carbon supplementation scenarios. Under normal operating conditions, it can be combined with liquid sodium acetate to reduce overall costs.

Common issues: The dissolution process releases heat, requiring proper cooling protection for the tank; high-concentration solutions are prone to crystallization at low temperatures, necessitating control of dissolution and storage temperatures.

4. Composite Carbon Sources

Core function: A composite long-term carbon source designed for stable operation of municipal wastewater treatment plants, balancing denitrification efficiency with sludge reduction, particularly suitable for low-temperature and low-load biochemical systems.

Product Advantages: Scientifically formulated with multiple components, offering superior bioavailability compared to single carbon sources; low freezing point ensures no crystallization in cold environments; prolonged denitrification duration reduces residual sludge production and lowers sludge disposal costs.

Usage: The concentrate is directly added to the denitrification tank without dilution. The dosage is dynamically adjusted based on total nitrogen in the influent, ensuring seamless integration with automated dosing systems.

Common issues: Significant compatibility differences exist between products with different formulations, requiring preliminary pilot testing for confirmation; long-term storage requires sealing to prevent product deterioration caused by contamination from foreign microorganisms.

Industry Use Cases

A municipal wastewater treatment plant in a city, designed to handle 160,000 m³/d of wastewater, complies with the Class A Standard of the Urban Wastewater Treatment Plant Pollutant Discharge Standard. The raw water entering the plant had a BOD5 concentration of 262.5 mg/L and total nitrogen concentration of 70 mg/L, with a carbon-to-nitrogen ratio of merely 3.75:1. This ratio fails to meet the carbon source requirements for denitrification, resulting in the effluent total nitrogen consistently fluctuating between 18-22 mg/L and failing to achieve stable compliance with standards.

To address this issue, the plant adopted 25% industrial-grade liquid sodium acetate as an external carbon source, with continuous dosing at a theoretical concentration of 33.7 mg/L. The automated dosing system dynamically adjusted the dosage based on real-time influent water quality. After implementation, denitrification efficiency improved significantly, achieving over 80% denitrification within two hours. Total nitrogen in the effluent stabilized below 10 mg/L, while other parameters including COD and ammonia nitrogen consistently met standards. Compared to traditional methanol-based carbon sources, the plant reduced annual operating costs by 12%, completely eliminating the safety risks associated with methanol's flammability and explosiveness. Sludge production in the biochemical system showed no significant increase, enabling safe, stable, and cost-effective nitrogen removal operations.