Compact passive filtration

TASOTFILT Type 4 is designed for outdoor installation beneath manhole covers. Sewer gases generated within the wastewater system can move through the manhole as pressure and flow conditions fluctuate. When a filter is installed, the gas stream passes through the cartridge before reaching the surrounding environment.

The system requires no electrical power. The cartridge can be accessed and replaced without special tools, supporting practical field maintenance.

• Outdoor installation
• No electrical power consumption
• Quick cartridge access and replacement
• Designed for harsh environmental conditions
• Reference service life based on H₂S concentration and gas flow

Twelve-layer filtration architecture

Field testing identified preferential flow paths within filter media that could reduce effective media utilisation and shorten cartridge service life. The Type 12 design was developed to address this behaviour through a staged, multi-layer filtration structure.

TASOTFILT Type 12 consists of 12 filtration layers, each 4 cm thick. The carbon-containing initial stage is designed to condition and homogenise the incoming gas before it enters subsequent filtration stages. This promotes broader use of the cartridge rather than allowing the gas stream to remain concentrated along a preferential path.

The cartridge incorporates six dry-chemical layers, five of which contain carbon. The combination of dry chemical media and carbon forms the filtration structure developed for higher gas-load applications.

Biological H₂S control at the source

TASOTFILT BIO is designed for wastewater pumping stations, deep collector manholes and inspection chambers. Instead of transporting contaminated gases through additional pipework, the system is designed to address H₂S close to its source.

The system uses a dedicated monofilament medium that is continuously wetted with wastewater. This creates the moist surface required for biological activity and supports the presence of Sulfobacter oxydans within the system.

A portion of the wastewater is pumped through the system, distributed across the medium and returned to the wastewater stream. This closed-loop circulation supports continuous wetting and biological activity.

Oxygen and nitrate-assisted oxidation

In low dissolved oxygen conditions, wastewater bacteria may use sulfate as an alternative electron acceptor, contributing to sulfide formation. Maintaining suitable oxygen conditions in the wet well is therefore an important part of controlling septic conditions.

The resulting sulfur is separated from the gas phase and, according to the system process description, becomes part of the wastewater/sludge stream for removal.

Preventing septic conditions

In pumping stations and other locations where wastewater remains for extended periods, the BIO system documentation recommends aeration of the wet well using a blower system. The stated objective is to maintain dissolved oxygen above 3 ppm and reduce the conditions that favour H₂S formation.

Aeration is a separate process component from the biological filtration medium. The blower maintains the wastewater conditions, while the biological filter provides a treatment stage for the gas stream.

Built for practical maintenance

TASOTFILT systems are designed to keep routine field intervention straightforward. Type 4 documentation specifies quick cartridge access, replacement without special tools and cleaning of the filter outlet with water below 4 bar when required.

Type 4 installation uses steel hooks positioned beneath the manhole cover. The filter can be installed or removed by opening the cover and lifting the unit from its mounting points.

For Type 4, the documented reference service life is approximately 180 days at 40 ppm H₂S and 30 m³/h gas flow, with longer life expected at lower H₂S concentrations.