生物除臭原理

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Bio-soil odor removal

Theory ：

The odorous compounds, mainly referred to hydrogen sulfide and organic gas, flow upwards through the bio-filter packing medium, then are temporarily adsorbed in the surface of the pipe, or the surface of the microbial cell, or adsorbed in the thin water layer, which formed between the surface of the granule and bacteria. Before adsorbed by the microbe, the odorous gas molecule had already been distributed for many times.

After the adsorption, the organic gas participates in the metabolism of the microbe, oxidized into CO2 and H2O. These microbe were locally, commonly existing surrounding us. The bio-filter medium provides oxygen, water and mineral nutrition for the microbe.

In BOHN Bio-filter the organic gas were degraded into CO2 、 H2O and microbial biomass. As the amount of the biomass is very tiny, it would not result in the backup of the medium. At the same time, H2S and ferric oxide react on the surface of the medium pipe, forming into FeS and FeS2. When the bio-filter was under the aerobic conditions, with the chemical and biological oxidation, these compounds are oxidized into sulfur. Then, in the BOHN Biofilter medium bearing strong buffering capacity, sulfur was oxidized into CaSO4.

Soil medium：

In the hermetic establishment, the contaminated odor generated from the odor source is collected by the collection system then via the blower is passed through the well engineered air distribution system, then enter into activated soil layer for odor removal treatment. Contaminated air is channeled through a cultivated soil porous medium that contains large populations of microbes. These microbes completely oxidize the contaminants, converting them to CO2, water and microbial biomass.

To design and select a good bio-soil filter system, the most important factors shall be considered are the composition and reliability of the filter system, BOHN Bio-soil blending formula has a global patent registration in U.S.A.. A properly constructed and maintained soil bed biofilter houses an active, thriving ecosystem. Ultimately, its effectiveness- and that of the waste air treatment-depends upon the integrity of the media supporting the ecosystem.

The critical factors for the system's destruction efficiency are the biochemistry of the contaminants, the airflow rate, and the composition of the soil media. The microbial population adapts to the composition of the contaminated air, further optimizing oxidation.

The bio-soil filter includes a reinforced soil medium. The air distribution consisted of perforation pipe surrounded by grit layer locates on the bottom of the biofilter. The collected odors from various hermetic constructions are pumped into the perforation pipe, and then slowly treated in the soil medium.

Soil media in comparing with Compost or Organic media:

Characteristic	Soil medium	Compost or organic media
Lifespan	Permanent ( ≥ 20 years )	Replace every 2-5 years
pH adjustment	Mineral content buffers PH, no adjustment is required	Possible periodic adjustment is necessary
Airflow	Uniform and consistent	Air-channeling, back pressure increases, lose to insure the treatment efficiency
Hydration prosperities	Hydrophilic, readily adsorbs water( wet or dry )	water-repellent Difficult to hydrate when dry
Cost	One time low investment cost	Recurring cost to remove and replace media every 2-5 years secondary pollution

Main odor treatment process flow：

Odor source hermetic system → Odor collection system → Fan → Air distribution system → Activated soil medium

Applications: Bio-soil filter systems can

★ Municipal WWTP waste water odor removal and control
★ Off-gases odor removal from landfill and refuse plant
★ Wastewater odor removal for the food processing industry
★ Off-gases odor removal from petroleum and refinery plants

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Nanjing BOHN Environmental Engineering & Complete Equipment Co., Ltd.