volcanic rockPhysical characteristics:
1. Appearance: No pointed particles, low resistance to water flow, not easy to block, evenly distributed water and air; The surface is rough, the film-forming speed is fast, and the microbial film is not easily detached during backwashing.
2. Porosity: Volcanic rock is a natural honeycomb porous material, which is an ideal growth environment for bacterial colonies.
3. Mechanical strength: According to the national quality inspection department, it is 5.08Mpa. Practice has proven that it can withstand hydraulic shear of different strengths and has a much longer service life than other filter materials.
4. Density: Moderate density, easy to suspend and prevent material leakage during backwashing, which can save energy and reduce consumption.
The chemical composition is as follows:
Chemical composition SiO2 CaO MgO Fe2O3 FeO Al2O3 TiO2 K2O Na2O
Content% 53.82 8.36 2.46 9.08 1.12 16.89 0.06 2.30 2.55
1. Biochemical stability: Volcanic rock biofilter is corrosion-resistant, inert, and does not participate in the biochemical reactions of biofilms in the environment.
2. Surface Electricity and Hydrophilicity: Volcanic rock biofilter has a positive charge on its surface, which is conducive to the growth of microorganisms. It has strong hydrophilicity, a large amount of attached biofilm, and a fast speed.
3. In terms of its impact on biofilm activity, volcanic rock biofilter, as a biofilm carrier, is harmless and has no inhibitory effect on the fixed microorganisms. Practice has proven that it does not affect the activity of microorganisms.

Volcanic rock biological filter materialHydraulic characteristics:
1. Void ratio: The average porosity inside and outside is around 40%, which has low resistance to water. Compared with similar filter materials, it requires less filter material and can still achieve the expected filtration target.
2. Specific surface area: With a large specific surface area, high porosity, and inertness, it is conducive to the contact, film formation, and growth of microorganisms, maintaining a large microbial population, and facilitating the mass transfer of oxygen, nutrients, and waste generated during microbial metabolism.
3. The shape of filter material and the flow state of water: Due to the fact that volcanic rock biological filter material is non pointed granular and the pore size is mostly larger than ceramic particles, it has less resistance to water flow during use, saving energy consumption.

The average parameters for physical performance testing of volcanic rock biofilter are as follows:

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