Image
Biological exhaust air purification in textile finishing processes
Published on 04 September 2018
Germany
Chemnitz
This is the good practice's implementation level. It can be national, regional or local.
About this good practice
Flame lamination is a highly economical and widespread process in the textile industry for the production of textile composites consisting of e.g. textile webs, artificial leather or foils with a foam layer in between.
During the flaming of the foams, exhaust gases are formed, which need to be removed by suctioning. The composition of the exhaust gases is extremely diverse. This makes a treatment of the exhaust air necessary. Released cyanides are highly toxic, soluble in water and classified as highly water-endangering substances. Toxicity is based on the blockade of tissue respiration in living beings by inhibition of enzymes.
The main content of the Good Practice was the development of a novel process concept for the biological elimination of highly toxic cyanides from industrial exhaust air of flame lamination. The process was developed starting from lab scale, over pilot scale up to large scale. After the use of bacterial strains in the biological trickling filter at laboratory scale and testing of their effectiveness in the cyanide decomposition, the process was extended to a pilot plant. There, both relevant process parameters and first optimal operating conditions have been identified: air flow, temperature within the reactor, retention time of exhaust air within the reactor, load of HCN, nutrition supply, pH, humidity. Then, the process was extended into a large plant and controllable conditions were created.
During the flaming of the foams, exhaust gases are formed, which need to be removed by suctioning. The composition of the exhaust gases is extremely diverse. This makes a treatment of the exhaust air necessary. Released cyanides are highly toxic, soluble in water and classified as highly water-endangering substances. Toxicity is based on the blockade of tissue respiration in living beings by inhibition of enzymes.
The main content of the Good Practice was the development of a novel process concept for the biological elimination of highly toxic cyanides from industrial exhaust air of flame lamination. The process was developed starting from lab scale, over pilot scale up to large scale. After the use of bacterial strains in the biological trickling filter at laboratory scale and testing of their effectiveness in the cyanide decomposition, the process was extended to a pilot plant. There, both relevant process parameters and first optimal operating conditions have been identified: air flow, temperature within the reactor, retention time of exhaust air within the reactor, load of HCN, nutrition supply, pH, humidity. Then, the process was extended into a large plant and controllable conditions were created.
Resources needed
The biological air purification plants are custom-made, adapted to the specific flame lamination plants. Therefore, the financial resources required to set up and run the practice differ from case to case. The maintenance costs are about 3-4 T € / year for maintenance by external contractors.
Evidence of success
The practice is considered as good since it provides a reliable cleaning of exhaust air from flame lamination processes by biological elimination of hydrogen cyanide/cyanide. The process operates very reliably and effectively when the optimum operating conditions are ensured. With estimated 5,000 operating hours per year, emissions of 200 kg of hydrogen cyanide and 125 kg of dust per year can be avoided by the biological exhaust air cleaning at the locations.
Potential for learning or transfer
The design and construction of the biological trickling filters need to be adapted to the local conditions (ambient temperature, air humidity, etc.) and the specific flame lamination plant parameters.
It is expected that due to the environmental relevance of the topic, the regional pilot character will spread beyond both Saxony and the textile sector. In Germany, currently about 32, in Europe approximately 50 flame lamination plants are operated, which can potentially be supplemented by biological exhaust air purification. In addition, the strategies for problem solving implemented in the project and parts of the developed technical solutions are also transferable to other industrial sectors (e.g. electroplating: detoxification of cyanide-containing sewage). One of the most important results here is the elaboration and derivation of plant specifications (operating conditions) and operating instructions to ensure high stability and functionality.
It is expected that due to the environmental relevance of the topic, the regional pilot character will spread beyond both Saxony and the textile sector. In Germany, currently about 32, in Europe approximately 50 flame lamination plants are operated, which can potentially be supplemented by biological exhaust air purification. In addition, the strategies for problem solving implemented in the project and parts of the developed technical solutions are also transferable to other industrial sectors (e.g. electroplating: detoxification of cyanide-containing sewage). One of the most important results here is the elaboration and derivation of plant specifications (operating conditions) and operating instructions to ensure high stability and functionality.
Further information
Website
Good practice owner
You can contact the good practice owner below for more detailed information.
Organisation
Saxon Textile Research Institute
Germany
Chemnitz
Contact
Scientific staff