How can sewage treatment plants achieve standard discharge through PAC upgrade under the new environmental regulations

In the context of stricter environmental regulations, sewage treatment plants need to achieve standard discharge through technological upgrading and management optimization. As a core water treatment agent, the rational selection and application optimization of polyaluminum chloride (PAC) is key. The following are solutions based on the latest policies and industry practices:

1. Core requirements of environmental protection regulations for sewage treatment

1. Stricter emission standards

According to the "Implementation Opinions on Promoting Synergistic Efficiency in Wastewater Treatment and Carbon Reduction," by 2025, the industrial wastewater compliance discharge rate must reach 100%, with stricter limits on pollutants such as total phosphorus and heavy metals. Instantaneous exceedances are also included in regulatory oversight; for example, the new regulations from the Ministry of Ecology and Environment require that the instantaneous concentration of exhaust emissions must not exceed the limit.

2. Synergistic efforts to reduce pollution and carbon emissions

The policy clearly requires sewage treatment plants to reduce energy consumption and carbon emissions, and encourages the use of efficient low-consumption agents (such as high-purity PAC) and intelligent management technologies to reduce drug consumption and sludge production.

3. Reclaimed water utilization and resource recovery

Water-scarce cities need to increase the utilization rate of reclaimed water to more than 25%. While removing suspended matter and colloidal pollutants, PAC needs to take into account the compatibility with subsequent membrane treatment processes.

2. Five core strategies for PAC upgrade
1. Model selection optimization: matching water quality with regulatory requirements

High purity PAC meets drinking water standards

For drinking water treatment scenarios, food grade PAC with low aluminum residue (in line with GB158922020 standards) is selected to reduce the risk of excessive aluminum ion and improve water quality safety.

Customized salt base degree improves processing efficiency

Adjust the PAC salt base degree according to different types of wastewater (such as oily wastewater, dyeing wastewater) to enhance the flocculation effect (recommended 60%-90%). For example, high salt base PAC can reduce the settling speed of high turbidity wastewater faster, which can reduce the dosage by 30%.

2. Process coordination: combining pretreatment and deep treatment

Strengthen pretreatment to reduce subsequent load

The "PAC+ microfiltration" combination process is adopted to rapidly adsorb colloidal particles through PAC, reduce the pollution of the rear-end membrane and extend the life of the equipment. For example, a municipal sewage plant has increased the COD removal rate to 95% through this scheme.

It works synergistically with biological treatment

In the activated sludge process, PAC can enhance the biological flocculation, reduce the risk of sludge bulking, and improve the efficiency of nitrogen removal and phosphorus removal.

3. Intelligent dosing system: accurate control and cost reduction

Introduce the Internet of Things and AI algorithms

Through the real-time feedback of parameters such as turbidity and pH value by online water quality monitoring equipment, the PAC dosage can be dynamically adjusted to avoid waste of chemicals and increase of sludge caused by excessive dosage. For example, a smart sewage plant reduced the amount of PAC used by 20% through an intelligent system, saving more than 500,000 yuan annually.

case application

Shanghai Zhuyuan Sewage Treatment Plant realizes the PAC dosing error rate <5% through variable frequency dosing equipment and big data analysis, and simultaneously reduces carbon emissions.

4. Sludge reduction and resource utilization

Optimize PAC addition to reduce sludge production

By accurately controlling the ratio of PAC and coagulant (such as PAM), the sludge water content can be reduced by 30%, and the sludge disposal cost can be reduced. A chemical plant saves 2 million yuan in sludge treatment costs annually through this scheme.

Collaborative carbon capture technology

Exploring the use of PAC treated sludge for the preparation of biochar or building materials to realize resource utilization is in line with the policy orientation of "waste-free city".

5. Addressing emerging pollutants and complex pollution

Strengthen the removal of heavy metals and microplastics

Modified PAC (such as iron salt composite PAC) is used to adsorb heavy metals such as lead and cadmium efficiently through complexation, and microplastic particles in water are removed simultaneously.

Improved resistance to low temperature and impact load

For low temperature water in northern winter, high degree of polymer PAC (such as liquid high concentration product) is selected to ensure stable flocculation effect in low temperature environment.

3.  Implementation path and policy support
1. Application for funds for technological upgrading

According to the Notice on the Demonstration Work of Urban Renewal, eligible sewage plants can apply for 81.2 billion yuan/year special funds for pipe network renovation, which will be used for intelligent upgrading of PAC dosing system.

2. Construction of green benchmark factories

Participate in the national "100 Green and Low-carbon Benchmark Plants" program, optimize the energy consumption per ton of water treatment through PAC process optimization, and strive for tax incentives and carbon trading benefits.

3. Third-party testing and certification

Regularly publish the test reports of key indicators such as heavy metal content and salt base degree of PAC to enhance customer trust. For example, a brand has proved through third-party certification that the heavy metal content of its PAC is less than 50% of the national standard.

IV : Reference to typical cases

A sewage plant in an industrial park in Zhejiang province

Using high salinity base PAC (85%) + intelligent dosing system, the total phosphorus discharge concentration was reduced from 1.5mg/L to 0.3mg/L, saving 1.2 million yuan of chemical cost annually.

Tangjiatuo Sewage Treatment Plant

Through the optimization of PAC precise aeration and carbon source addition, the power consumption per ton of water is reduced by 15%, and it has been rated as a national green and low-carbon benchmark plant.

epilogue

Under the new environmental regulations, wastewater treatment plants must upgrade their PAC systems to meet discharge standards, integrating intelligent, resourceful, and collaborative treatment technologies to achieve dual goals of pollution reduction and carbon emission reduction as well as economic benefits. It is recommended that companies focus on three aspects: customized product development, process parameter optimization, and leveraging policy incentives, to quickly respond to regulatory requirements and seize market opportunities.