Understand the filtration accuracy of the “3-Free” direct filtration technology in one article.

Release time:

2026-04-13

When traditional filtration technologies discuss “filtration accuracy,” they typically refer to the pore size of the filter medium—for example, 5 microns, 1 micron, or 0.1 micron. This represents a static, physical sieving precision: particles larger than the pore size are retained, while those smaller than the pore size pass through.

　　How should the filtration accuracy of the “three-no” direct filtration technology be understood?

　　In contrast, the filtration accuracy of the “three-no” direct-filtering technology is dynamic and adaptive, with a fundamentally different underlying logic:

　　1. Precision does not stem from the pore size of the filter element, but from the “mud film itself.”

　　In a three-nothing direct filtration system, the filter element serves solely as a supporting framework; the true filtration layer is the “dynamic sludge film” that forms on the surface of the element due to suspended solids. This sludge film is built up layer by layer from particles that have been intercepted, and its pore structure is far denser and more complex than that of any artificially manufactured filter medium.

　　To draw an analogy: traditional filtration is like sifting flour through a sieve, with the precision determined by the size of the sieve holes; in contrast, “three-no” direct filtration is like snow covering the ground—its density dictates how much fine particulate matter it can trap.

　　2. Accuracy is “adaptive”: the poorer the water quality, the higher the accuracy.

　　This is a counterintuitive yet remarkably sophisticated design: as the concentration of suspended solids in the influent increases, the rate of biofilm formation accelerates, leading to a denser sludge layer and, consequently, improved filtration accuracy. The system automatically adjusts the compactness of the filtration layer in response to changes in influent water quality, thereby maintaining highly efficient particle interception at all times.

　　·Low-concentration influent: the biofilm is relatively thin, and the removal efficiency remains at the baseline level;

　　·High-concentration influent: the sludge biofilm thickens and becomes denser, automatically improving treatment accuracy;

　　·Sudden shock load: the sludge blanket responds rapidly, resulting in effluent quality that not only does not decline but actually improves.

　　3. Precision is a “dynamic equilibrium”: stable, not rigid.

　　Conventional filtration operates at a fixed precision: a 0.1-μm membrane can capture particles 0.1 μm and larger, but it is powerless against particles as small as 0.09 μm. In contrast, the sludge membrane in three-no direct filtration maintains an optimal thickness and compactness through a dynamic cycle of “formation–shedding.” Under this state, its interception performance is continuous and stable—flux does not decline due to excessive membrane thickness, nor does interception fail due to an overly thin membrane.

　　4. The Actual Level of Accuracy That Can Be Achieved

　　According to engineering application data, the “three-no” direct filtration technology achieves a suspended solids (SS) removal rate of 95% to 99.5%, with effluent SS consistently below 10 mg/L and often falling within 5 mg/L in most applications. In terms of particle size interception, it can effectively remove suspended particles ranging from several micrometers to tens of micrometers; moreover, even some fine particles can be efficiently retained through adsorption and interception by the sludge membrane.

　　This level of accuracy is fully sufficient to meet:

　　· Municipal wastewater advanced treatment discharge standards;

　　·Primary filtration prior to industrial wastewater reuse;

　　·Post-biochemical system sludge–water separation and filtration;

　　·Pre-treatment protection for membrane systems (such as RO).

　　5. Comparison of Accuracy with Traditional Techniques

　　Conclusion:

　　The filtration precision of the “three-no” direct-filtering technology should not be defined in terms of “so many microns,” but rather in terms of “how stable the effluent is.” Rather than relying on a fixed pore size as the benchmark, it uses a dynamic sludge membrane as a barrier to achieve adaptive, shock-resistant, and continuously stable solid–liquid separation.

　　For users, this means: no need to worry about how fine the filter cartridge can trap particles—just rest assured that, regardless of changes in the incoming water quality, the output will always be clear and consistent.

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How should we understand the “no-discrimination-inlet-water” principle of the 3-Free direct filtration technology?

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