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Scientists grill for better air

2020-04-07T06:27:35.553Z


There is always stunk in the area of ​​kebab snacks and grill restaurants: residents feel bothered by the grill smoke. Scientists are now looking for technical solutions to the conflict.


There is always stunk in the area of ​​kebab snacks and grill restaurants: residents feel bothered by the grill smoke. Scientists are now looking for technical solutions to the conflict.

Stuttgart / Mannheim (dpa) - Mohammad Aleysa puts the kebab skewers on a grill rack, turns them around everywhere and personally serves the tasty result on a bun.

But the 41-year-old in a dark suit and white shirt is not a grill professional, but an environmental protection technician at the Fraunhofer Institute for Building Physics IBP in Stuttgart. On behalf of the Federal Environment Agency, this should analyze what odors and exhaust gases escapes from commercial charcoal grills and which methods can be used to minimize the nuisance.

In a nationwide survey by the Fraunhofer Institute IBP, 183 municipalities reported complaints about grill smoke - not only from kebab shops, grill snacks and grill restaurants, but also from pizza and bread ovens.

Emission control systems were only operated in 13 percent of the cases - and none of them made a significant contribution to solving the problem, Aleysa explains the findings from the survey.

According to the survey, there are mostly problems with the kebap shops. In Mannheim, for example, there are two dozen Turkish and Arabic restaurants competing around the market square.

This situation heats people's minds: Residents cannot open the windows in summer, market traders complain of being "smoked", vegetarians among the many guests in the outdoor dining area turn their noses up.

The city has therefore commissioned an expert opinion on "Determining the odor frequencies caused by grill restaurants". The city council can currently use the building law to temporarily prohibit the installation of new commercial grills. So far, an inquiry has been rejected on this basis. The expertise expected for early summer should serve to substantiate such cancellations, as a spokesman explains.

But which technology could solve the problem? Aleysa and his team of five have built a commercial grill with a huge exhaust gas cleaning system in a hall of the institute. The aim of the experiment is not only to identify the emissions from the grilling process, but also to evaluate the effectiveness of the multi-stage exhaust gas cleaning processes; the focus is particularly on the smell.

In stage one, the smell should be largely neutralized by a so-called ozone generator. One difficulty is the high dilution of the emissions: One square meter of grill produces 2000 cubic meters of polluted air - per hour. In this way, the entire amount of contaminated air cannot be recorded, explains Alesya. The exhaust gases are then washed out with soapy water, separated from the water with electrostatic filters and passed through activated carbon cartridges to filter out the remaining odors and fine dust.

According to Christian Liesegang from the Federal Environment Agency, the whole topic is currently taking place in a legal gray area: stationary commercial charcoal grills are largely exempt from the Federal Immission Control Ordinance, so there is no mandatory inspection by the chimney sweep. Emission limits do not exist.

The only thing that already applies to new grills and their exhaust gas cleaning systems is that the chimney only ends above the roof ridge. On the basis of the Stuttgart test results, the Federal Environment Ministry - advised by the Federal Environment Agency - should ultimately create legal clarity.

Because what the researchers found in the grill smoke, no resident will probably like to breathe. The pollutants measured so far are dust, nitrogen oxide, carbon monoxide, organic hydrocarbons, benzene and xylene; in the future, polycyclic aromatic hydrocarbons and odors will still be measured. Liesegang: "Some of these are carcinogenic substances, but not all of them are healthy together."

They experiment with lamb, but also with chicken, fish and vegetables. In total, the researchers burned several hundred kilograms of grilled food. Until the experiments are ended in September, Aleysa's colleagues can still look forward to the delicious results of applied science. Then the knowledge gained is used in the simulation. The project is expected to be completed in mid-2021.

Fraunhofer Institute for Building Physics IBP

Federal Environment Agency

Source: merkur

All news articles on 2020-04-07

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