Denitrification Deep Bed Filter Tank

Denitrification deep bed filter process

The denitrification deep bed filter process combines biological nitrogen removal and filtration into a single treatment unit, offering a dual-process treatment method. Most filter beds tend to become clogged or hardened at the surface, quickly losing head pressure. In contrast, the uniform quartz sand in the denitrification deep bed filter allows solid impurities to pass through the surface of the filter bed and penetrate into the filter medium within the filter pool, meeting the requirement of retaining solid matter throughout the entire depth of the filter pool.
Denitrifying deep bed filter tank, utilizing narrow and elongated channels for uniform water inflow; filter brick structure ensures excellent backwashing effect; nitrogen gas produced during denitrification can cause air blockage in filtration, which is mitigated by expelling nitrogen to ensure optimal filter tank operation.
In operation with an added carbon source, it is a deep bed denitrification filter with denitrification capabilities, capable of removing TN, SS, and TP. Without the added carbon source, it becomes a deep bed filter, capable of removing SS and TP simultaneously.
The denitrification deep bed filter is essentially a fixed film reactor in a packed form. It is a biological membrane process for wastewater treatment combined with water filtration, categorizing under biological filtration technology. Bacteria and other microorganisms grow as a film on a solid medium, and when the fluid flows over the solid filter material, it removes pollutants by utilizing the dual action of the filter material's interception and the biological degradation of the biofilm on the filter material.

Filter Bed Structure

System Composition

Filter Media: Natural sea sand, silicon content ≥95%, particle size: 1.7-3.35mm, filter media thickness ≥1.83m, K60<1.4, specific gravity ≥2.6 tons/m³>6.

The gravel support layer is composed of natural cobblestone, with particle sizes ranging from 3-38mm and a thickness of 380-420mm. It is layered in 5-6 layers to support the filter material.

Filter Bricks: Constructed with a concrete cast outer HDPE (high-density polyethylene) shell, "T" type air-water distribution filter bricks, offering backwashing air-water distribution performance.

Anti-siphon pipe: Material SS304, the anti-siphon intake pipe provides uniform distribution of backflush gas.

Inlet weir plate: Made of SS304 material, thickness of ≥4mm, providing conditions for uniform distribution of incoming and backwashing water.

Control System: PLC programmable controller, capable of system controlling all operational equipment within the filter pond.

Valves: Manual and automatic valves control the inflow and outflow of water and air.

Carbon Source Storage and Supply System: Typically using sodium acetate, the addition amount of carbon source is controlled based on the nitrate nitrogen entering the filter pond.

Backwashing Pump: Provides backwashing water for filter bed backwashing and nitrogen release system.

Rinsing Blower: The Roto-Blower supplies air at the set volume, feeding the backwashing air through the entire bottom of the filter basin.

Other Equipment: Field instruments, valves, pipelines, and denitrogenation systems, etc.

Process Features

1. Integrated system technology for air-water combined backflushing units, gas distribution systems, and operational processes, which resolves issues such as direct filtration and biofilter biofilm detachment causing filter clogging.

2. The denitrification deep bed filter continues to operate, removing NO3-N while producing nitrogen gas to form a "gas blockage." As it continues to run, the loss in filtration resistance increases continuously, potentially leading to short-circuiting in the filtration process and worsening the effluent water quality.

3. Complete, integrated automation systems and technologies, online monitoring equipment, and computer program control enable the overall process to run continuously, long-term, stably, and reliably, including operations such as air-water backflushing and nitrogen purge. This addresses process control issues that cannot be achieved through manual operation.

4. The effluent quality meets the water body standards.

Current Standard Process: T-Shape Filter Brick Air-Water Distribution System