Study type: Medical/biological study (experimental study)

Microwave radiation and reactor design influence microbial communities during methane fermentation med./bio.

By: Cydzik-Kwiatkowska A, Zielinski M, Jaranowska P
Published in: J Ind Microbiol Biotechnol 2012; 39 (9): 1397-1405
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Aim of study (acc. to author)

To determine the effect of reactor design and method of heating on the efficiency of methane fermentation and composition of microbial communities, especially methanogenic Archae.

Background/further details

Methane fermentation is a process used to manage diversified industrial wastewater (removal of organic compounds) as well as biogas production. In this study, two different reactor types (trickling-bed reactor and submerge-bed reactor) were put in chambers, heated by microwaves or by hot air (control group).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: 28 days (remark EMF-Portal: not sure if continuously exposed)
  • power: 5 W (per liter (trickling-bed reactor))
  • power: 12.8 W (per liter (submerge-bed reactor))

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration 28 days (remark EMF-Portal: not sure if continuously exposed)
Modulation
Modulation type CW
Exposure setup
Exposure source
  • magnetrons
Chamber trickling-bed reactor or submerge-bed reactor with a diameter of 3 cm and a working volume of 0.5 l
Setup two reactors of each type were placed in a chamber; in the trickling-bed reactors, wastewater from retention tanks located below the reactor was pumped to the surface of the bed (down-flow); in the submerge-bed reactors, wastewater from the reservoir was pumped from the bottom of the bed and returned to the reservoir (up flow)
Additional info fermentation was carried out at 35 +/- 1.5 °C.
Parameters
Measurand Value Type Method Mass Remarks
power 5 W - estimated - per liter (trickling-bed reactor)
power 12.8 W - estimated - per liter (submerge-bed reactor)

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:

Main outcome of study (acc. to author)

In both fermenter types heated by microwaves, statistically significant higher values for biogas production were found compared to heating with hot air. The highest biogas production was observed in the trickling-bed reactor with microwave heating, while the highest diversity of methanogenic Archae was found in the microwave heated submerge-bed reactor.
The authors conclude that heating with microwaves increased the efficiency of methan fermentation.

Study character:

Study funded by

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