As water pollution problems intensify and environmental protection standards improve, the limitations of traditional water treatment equipment have gradually become apparent - such as low efficiency due to regular shutdown and backwashing, and difficulty in removing refractory pollutants with single filtration. As a new type of integrated water treatment equipment, activated sand oxygen-based filter integrates physical filtration, biodegradation and chemical oxidation functions. With the advantages of continuous operation and efficient purification, it has become one of the core technologies in the field of municipal sewage, drinking water and industrial wastewater treatment.
1. Core principle: synergistic effect of filtration and oxidation
The working mechanism of the activated sand oxygen-based filter can be divided into two key links, which work together to achieve deep water purification:
1. Continuous activated sand filtration
Sewage flows through the filter bed from bottom to top. The biofilm (composed of nitrifying bacteria, heterotrophic bacteria, etc.) on the surface of the sand particles and physical interception effectively remove suspended solids (SS), colloidal particles and some organic matter. Different from traditional sand filters, this equipment continuously transports the "dirty sand" at the bottom to the top sand washer through the air lifting system. After being washed with clean water, the clean sand falls back onto the filter bed, enabling 24-hour continuous operation without the need for shutdown and backwashing, greatly improving processing efficiency.
2. Oxygen oxidation reaction
Set up an aeration device or add oxidants (such as ozone, hydrogen peroxide) in the filter bed, and use the strong oxidizing properties of active oxygen free radicals to decompose refractory organic matter, ammonia nitrogen and color substances in the water:
- Ammonia nitrogen removal: The oxygen provided by aeration provides conditions for nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen;
- Oxidation of organic matter: Oxidants such as ozone destroy the molecular structure of organic matter, decompose macromolecules that are difficult to degrade into small molecules, and even mineralize them into CO₂ and H₂O;
- Decolorization and deodorization: Oxidation removes pigments and odor substances in water to improve the sensory quality of the effluent.
2. Equipment structure: modular design and intelligent control
The active sand oxygen-based filter has a compact structure and mainly consists of the following modules:
- Filter body: filled with quartz sand or modified sand (such as iron-loaded sand, activated carbon sand) of specific grades to enhance adsorption and oxidation capabilities;
- Water distribution system: ensure uniform distribution of water flow and avoid local blockage of sand layer;
- Air lifting device: Lifts dirty sand to the sand washer through compressed air to achieve circular cleaning of sand;
- Aeration/oxidant dosing system: Provides oxygen or chemical oxidant required for oxidation;
- Automated control system: Real-time monitoring of flow, pH, dissolved oxygen and other parameters, automatically adjusting operating status and reducing manual intervention.
3. Core advantages: efficient, stable and economical
Compared with traditional water treatment equipment, activated sand oxygen-based filters have significant advantages:
1. Continuous operation, improved efficiency: no need to shut down for backwashing, the processing efficiency is more than 30% higher than that of traditional sand filters, and it is suitable for large-flow water treatment scenarios;
2. Integrated processing: Complete filtration, oxidation, and biodegradation in one step, reducing the equipment footprint (50% less space than traditional processes) and investment costs;
3. Stable effluent water quality: The sand layer has strong self-cleaning ability, the effluent SS can be stabilized below 5mg/L, the ammonia nitrogen removal rate reaches more than 90%, and the COD removal rate increases by 20%-30%;
4. Easy to operate: high degree of automation, only need to replenish sand regularly, low maintenance cost;
5. Strong adaptability: The thickness of the sand layer, aeration intensity or oxidant dosage can be adjusted according to the water quality. It is suitable for various scenarios such as advanced treatment of municipal sewage, purification of drinking water, and pretreatment of industrial wastewater.
4. Application scenarios: covering water treatment needs in multiple fields
1. Municipal sewage treatment
As an advanced treatment unit, it removes SS, COD, ammonia nitrogen, etc. from the secondary effluent so that the effluent reaches Class A or reclaimed water reuse standards. For example, after a certain urban sewage treatment plant adopted this equipment, the effluent SS was reduced from 20mg/L to 3mg/L, and the ammonia nitrogen was reduced from 5mg/L to 0.5mg/L, with a daily treatment capacity of 50,000 tons.
2. Drinking water purification
Remove algae, organic matter, odors and disinfection by-product precursors from raw water to improve drinking water safety. In a drinking water plant application, this equipment effectively removed algal toxins and humic acid in the water, and the effluent TOC (total organic carbon) dropped by 40%.
3. Industrial wastewater treatment
For wastewater from printing and dyeing, papermaking, food processing and other industries, it can remove suspended solids, color and refractory organic matter. For example, after a printing and dyeing factory adopted this equipment, the color of wastewater dropped from 200 times to less than 10 times, and the COD removal rate increased to 75%.
4. Landscape water management
Improve the transparency and water quality of landscape water such as lakes and rivers, and inhibit the growth of algae. In an urban river management project, this equipment increased the transparency of the water body from 0.5m to 1.5m, and reduced the algae biomass by 60%.
5. Future Outlook
With the continuous improvement of environmental protection requirements, the technological upgrade direction of activated sand oxygen-based filters will focus on:
- Material innovation: develop new modified sand (such as photocatalytic sand) to enhance oxidation ability;
- Oxidant optimization: Use more environmentally friendly and efficient oxidants (such as electrolytic ozone);
- Intelligent upgrade: Combined with IoT technology to achieve remote monitoring and predictive maintenance.
As an efficient and sustainable water treatment technology, activated sand oxygen-based filters will play an increasingly important role in water resource recycling, water environment management and other fields, providing strong support for building a green and low-carbon water treatment system.
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