Structure, features, parameters, installation and applications of elastic packing as a hanging biofilm carrier for biological contact oxidation.
← Back to Elastic PackingElastic packing — also written elastic three-dimensional media — is a hanging biofilm carrier. Polypropylene filaments are anchored along a central rope so that they radiate outward in three dimensions and keep that shape in water. The modules are threaded onto the rope at intervals and the ropes are hung vertically from an upper support frame, so the tank is filled with rows of modules rather than with loose media.
Aerated water and air rise through the rows and are redistributed as they pass each module. The biofilm grows on the filament surface, and the movement of the strands under aeration shears the film at a controlled thickness, so the inner layer of biomass stays in contact with the dissolved oxygen in the bulk liquid. That is the working principle of biological contact oxidation: the substrate in the water is transferred to the biofilm, oxidised by it, and the treated water leaves the tank carrying only the solids that are then separated downstream.
Because the strands are anchored rather than tied into free bundles, they do not collapse into a knot in the middle of the module. This is the main practical difference from soft packing, and it is why elastic packing is widely used both in new biological contact oxidation tanks and as a straight replacement in existing tanks that were originally filled with soft packing.
Each module consists of a central rope, elastic plastic filaments fixed along it, and the end fittings that hold the filaments in position. The filaments are evenly distributed around the rope, and the filament diameter and the spacing between filaments are set at manufacture — that is what fixes the surface area, the void space and the mass of the module. Standard module diameters on this line are Φ150 / Φ180 / Φ200 mm; the module length and the number of modules per rope follow the tank depth and the support arrangement.
| Parameter | Value |
|---|---|
| Type | Elastic three-dimensional packing (YDT type) · elastic wave-form packing (TA type) |
| Module (unit) diameter | Φ80 / Φ100 / Φ120 / Φ150 mm (the YDT reference table also lists 50 / 80 / 100 / 120 / 173 / 180 / 200 / 220 mm) |
| Filament diameter | 0.2 / 0.35 / 0.5 mm |
| Filament density | High density · medium density · medium-low density · low density |
| Specific surface area | 250 – 300 m²/m³ (YDT reference range 50 – 300 m²/m³) |
| Porosity | > 99% |
| Biofilm mass (after film growth) | 50 – 100 kg/m³ (YDT reference range 50 – 110 kg/m³) |
| Structure | Elastic filaments with corrugations and micro-burrs, fixed along a central rope in a spiral, radial three-dimensional arrangement |
| Material | Polyolefin / polyamide grades selected for corrosion, temperature and ageing resistance |
| Service | Aerobic · anoxic · anaerobic |
| Wastewater CODCr range | Aerobic 100 – 2,000 · anoxic 1,000 – 10,000 · anaerobic 5,000 – 30,000 (reference values) |
| MOQ / price | On request — confirm module diameter, quantity & destination |
The comparison is general practice for hanging carriers in biological contact oxidation and is given for orientation only; it is not a performance guarantee for a particular duty.
| Parameter | Value |
|---|---|
| Type | Elastic three-dimensional packing (YDT type) · elastic wave-form packing (TA type) |
| Module (unit) diameter | Φ80 / Φ100 / Φ120 / Φ150 mm (the YDT reference table also lists 50 / 80 / 100 / 120 / 173 / 180 / 200 / 220 mm) |
| Filament diameter | 0.2 / 0.35 / 0.5 mm |
| Filament density | High density · medium density · medium-low density · low density |
| Specific surface area | 250 – 300 m²/m³ (YDT reference range 50 – 300 m²/m³) |
| Porosity | > 99% |
| Biofilm mass (after film growth) | 50 – 100 kg/m³ (YDT reference range 50 – 110 kg/m³) |
| Structure | Elastic filaments with corrugations and micro-burrs, fixed along a central rope in a spiral, radial three-dimensional arrangement |
| Material | Polyolefin / polyamide grades selected for corrosion, temperature and ageing resistance |
| Service | Aerobic · anoxic · anaerobic |
| Wastewater CODCr range | Aerobic 100 – 2,000 · anoxic 1,000 – 10,000 · anaerobic 5,000 – 30,000 (reference values) |
| MOQ / price | On request — confirm module diameter, quantity & destination |
| Parameter | Value |
|---|---|
| Type | Elastic three-dimensional packing (YDT type) · elastic wave-form packing (TA type) |
| Module (unit) diameter | Φ80 / Φ100 / Φ120 / Φ150 mm (the YDT reference table also lists 50 / 80 / 100 / 120 / 173 / 180 / 200 / 220 mm) |
| Filament diameter | 0.2 / 0.35 / 0.5 mm |
| Filament density | High density · medium density · medium-low density · low density |
| Specific surface area | 250 – 300 m²/m³ (YDT reference range 50 – 300 m²/m³) |
| Porosity | > 99% |
| Biofilm mass (after film growth) | 50 – 100 kg/m³ (YDT reference range 50 – 110 kg/m³) |
| Structure | Elastic filaments with corrugations and micro-burrs, fixed along a central rope in a spiral, radial three-dimensional arrangement |
| Material | Polyolefin / polyamide grades selected for corrosion, temperature and ageing resistance |
| Service | Aerobic · anoxic · anaerobic |
| Wastewater CODCr range | Aerobic 100 – 2,000 · anoxic 1,000 – 10,000 · anaerobic 5,000 – 30,000 (reference values) |
| MOQ / price | On request — confirm module diameter, quantity & destination |
Price is quoted on request for every configuration; no price is published on this page.
The ropes are hung vertically from an upper frame at the spacing the aeration layout requires, and the modules are fixed along each rope so the filaments spread freely without touching the neighbouring row. The frame carries only the weight of the packing and the biofilm, so in most retrofits it sits on the tank wall or on the existing walkway structure. Fill ratio, rope spacing and the number of modules per rope are confirmed with the quotation, because they follow the tank volume and the loading rather than a single fixed figure.
This reference is compiled from the product record held for this line and from general practice for hanging biofilm carriers in biological contact oxidation. Module diameters Φ150 / Φ180 / Φ200 mm are the standard sizes offered on this line. Filament diameter, filament spacing, specific surface area, porosity, module length, unit mass, service temperature and service life all follow the medium, the tank and the loading, so they are confirmed in writing with the quotation rather than fixed on this page.
Where a figure is not confirmed for your duty it is marked On request rather than estimated. Please send your tank volume, flow rate and target effluent quality and we will return the module selection, quantity and packing data with the offer.
Elastic three-dimensional packing is made by twisting pine-needle-like filament into a central rope, forming a radial, three-dimensional structure. The filaments are elastic and carry corrugations and micro-burrs; different filament lengths give different transverse diameters. YDT-type packing is normally made from selected polyolefin / polyamide grades with good corrosion, temperature and ageing resistance. Compared with rigid honeycomb packing its voidage is more variable and it does not plug; compared with soft packing it lasts longer and does not stick or ball; compared with semi-soft packing it offers a larger surface, faster biofilm formation and lower cost — regarded as a fourth-generation, high-efficiency energy-saving packing.
Features: the filaments are embedded evenly along the central rope, giving resistance to high temperature, acids and alkalis, and fast biofilm renewal; the packing keeps a large specific surface, distributes air and water well, removes organics efficiently and transfers mass well. Oxygen utilisation and power efficiency are much improved; it does not ball in long service and needs no backwashing.
TA-type elastic wave-form packing: each unit is assembled from several packing sheets fastened to a central rope with sleeves; each sheet is formed by pressing elastic, wave-shaped filaments into a radial pattern around a central ring, and the number of sheets per unit is adjusted to suit the process.
Parameter values follow the reference tables for YDT packing (unit diameter, filament diameter, filament density, specific surface area, porosity and biofilm mass) and the general elastic-packing data (module diameter Φ80 / Φ100 / Φ120 / Φ150 mm; specific surface area 250 – 300 m²/m³; biofilm mass 50 – 100 kg/m³). The wastewater CODCr bands are published reference values; confirm the final selection against the tank design and the effluent target.