Equipment Name: Ceramic Granule-Based Integrated Denitrification Direct Filtration Unit

· Full English name: Integrated Ceramsite-Based Denitrifying Filter

· English abbreviation: ICBDF

This device creates a unique microenvironment that efficiently integrates physical filtration, nitrification, and denitrification into a single system, thereby achieving the core objectives of “high-efficiency nitrogen removal, energy conservation and resource efficiency, and simple maintenance.” It represents a highly promising and attractive solution for addressing nitrate pollution in aquatic environments, particularly well-suited for intensive aquaculture, ornamental aquariums, landscape water bodies, and decentralized wastewater treatment applications.

Ceramic-granule-based direct-filter cartridge

The principle is as follows:

1. Formation of an oxygen gradient:

· The water flow is first forced to pass through the external layer of ceramic pellets. In the outer layer and channels of the pellet bed, dissolved oxygen in the water is consumed by aerobic nitrifying bacteria and heterotrophic bacteria.

· As the water flows deeper into the ceramsite bed and across the surface of the filter media, a gradient develops from oxic to anoxic to anaerobic conditions.

2. Creation of a denitrification zone:

· In the ceramsite zone near the filter cartridge surface and within the cartridge’s internal micropores (provided the cartridge is sufficiently dense), the environment tends to be anaerobic, which precisely meets the growth requirements of denitrifying bacteria.

3. Division of Labor and Collaboration:

· Ceramic granule layer:

· Outer layer: Primarily carries out nitrification (converting ammonium nitrogen NH₃/NH₄⁺ into nitrite NO₂⁻, which is then further oxidized to nitrate NO₃⁻).

· Inner/deep layer: primarily carries out denitrification (converting nitrate NO₃⁻ into nitrogen gas N₂).

· Meanwhile, the ceramsite bed itself can also trap some larger particulate matter, thereby performing preliminary physical filtration.

· “3-Free Direct-Filter” filter element:

· Acts as the final barrier, providing precise physical filtration to ensure crystal-clear effluent.

· Its dense structure helps maintain an anaerobic environment within and around it.

· The filter cartridge features a porous, densely packed structure, with internal pores that can also harbor denitrifying bacteria, thereby serving as part of the reaction site for denitrification.

4. Carbon Source Issue:

· This is the key to denitrification. The system requires an additional carbon source. In practice, several approaches are available:

· Utilizing organic matter in the raw water: If the influent (e.g., pond water, domestic sewage) contains sufficient organic matter (such as fish feces and food residues), it can serve as a carbon source.

· Additional carbon source supplementation: In systems with stringent requirements—such as marine aquariums and koi ponds—it may be necessary to slowly add methanol, ethanol, or a dedicated denitrification carbon source upstream of the filter.

· Slow-release carbon source: Solid slow-release carbon source particles (such as PHA and PHB) are mixed into the ceramic pellets.

Key Advantages

The advantages of this ICBDF design combination are highly significant:

1. Efficient collaboration, multi-functionality in one device:

· Physical filtration, nitrification, and denitrification are all accomplished within a single compact unit. Traditional systems, by contrast, require multiple separate filter chambers or pieces of equipment to achieve these functions.

2. Thoroughly resolve the issue of nitrate accumulation:

· Traditional filtration systems can only convert ammonium nitrogen into nitrate, without effectively removing it, leading to continuous nitrate accumulation that stimulates algal growth and imposes stress on aquatic organisms. In contrast, this system fundamentally converts nitrate into nitrogen gas for discharge, thereby achieving a perfect closed-loop nitrogen cycle.

3. Extremely low operation and maintenance costs:

· No power required: saves on electricity costs and eliminates the need for additional equipment.

· No consumables: the filter cartridge can be repeatedly cleaned and reused, and the ceramic media is theoretically durable indefinitely, significantly reducing long-term maintenance costs and waste generation.

· Easy maintenance: Maintenance primarily involves periodically backwashing or cleaning the “3-Free direct-filter” filter element, making the operation straightforward.

4. High system stability and reliability:

· Ceramic proppants provide a vast biofilm attachment surface, fostering a large and stable microbial community that can effectively withstand fluctuations in water quality.

· Biofilms adhere to fixed carriers, making them less prone to washout compared with the activated sludge process.

5. Small footprint and wide applicability:

· Compact design, making it particularly suitable for space-constrained applications such as home aquariums, small koi ponds, courtyard landscape water features, and decentralized wastewater treatment.

Application Scenarios

· High-density aquaculture: In settings such as koi ponds, goldfish tanks, and marine aquariums, nitrate accumulation is the primary water-quality issue.

· Courtyard landscape water features: Maintain water clarity and prevent eutrophication and green algae blooms.

· Small-scale decentralized domestic wastewater treatment: particularly in sensitive areas with stringent nitrogen and phosphorus discharge requirements.

· Upgrading and retrofitting conventional filtration systems: this unit can be installed at the downstream end of the existing filtration process specifically for denitrification.

· Robust, corrosion-resistant design: A carbon steel main structure, combined with specialized anti-corrosion treatment for parts in contact with water, ensures long-lasting durability of the equipment. 
· Efficient and energy-saving operation: Distinguishes between backwash mode (high power) and routine operation (low power), resulting in low actual energy consumption and cost-effective operation. 
· Flexible Custom Solutions: To meet the diverse needs of different projects, we offer a range of customized services for non-standard flow rates and materials.