Services in the field of MWIPs
Filter and fly ash washing (FLUWA process)
The acid filter and fly ash washing (FLUWA) process forms the core of the AIK systems. The FLUWA process currently handles more than 50% of the filter ash load generated throughout Switzerland. According to the motto “Recycling before landfilling”, the FLUWA process enables the recycling of heavy metals and minimises the amount of residue to be landfilled.
For optimum economic and ecological utilization, the FLUWA process uses the synergies of the residues of filter ash and scrubber wastewater which occur during wet flue gas cleaning. In acid fly ash extraction, the heavy metals contained in the filter ash are dissolved by the acid of the scrubber waste water. At the same time, the excess acid content of the scrubber wastewater is neutralized with the alkalinity of the filter ashes. The filter ash cake, which after the acid wash is low in heavy metals, can be recycled or disposed of together with the bottom ash.
Mercury separation is a process in which the dissolved mercury is adsorbed by a selective ion exchange resin. The mercury separation process can be used in various branches of industries. With this technology, the wastewater limits for mercury can be significantly undercut.
With the AIK Mercury Ion Process, approx. 98% of the total mercury input from a waste treatment plant can be recycled and thus kept away from landfills.
The process is based on two phases: pre-filtration of the scrubber wastewater, followed by mercury separation via selective ion exchange columns. Preliminary filtration of the wastewater significantly improves the mercury separation efficiency of the ion exchanger. Thus, high loading densities can be achieved using selective ion exchange resin.
Wastewater treatment (WWT)
AIK Technik AG wastewater treatment plants are designed to be flexible and hard-wearing. We will customize the process to match your individual requirements.
In the wastewater treatment process, the heavy metals contained in the wastewater are precipitated as metal hydroxides. The filtered, heavy-metal free water is in compliance with the Swiss Water Protection Ordinance and can be discharged into a suitable receiving watercourse. The resulting hydroxide sludge is dewatered using filtration systems. In the case of a previous FLUWA process, the dewatered sludge can be fed to a metal smelter as secondary raw material for zinc production.
Phosphorus production - Leachphos©
Phosphorus is a secondary resource contained in municipal sewage sludge. In cooperation with ZAR and AWEL, we have verified an urban mining process using wet chemical extraction from the sewage sludge ash resulting from thermal sewage sludge utilisation (mono-combustion) based on the FLUWA process in a demonstration plant (EWB Bern).
The AIK – LEACHPHOS© – process consists of
- Wet chemical extraction with diluted mineral acid
- Targeted heavy metal separation using reductive precipitation
- Targeted precipitation of the phosphorus product at ideal pH values
- Utilization of the resulting filter cake
About 5 tons of phosphorus were produced at the demo plant. Subsequent field tests confirmed the effectiveness of the LEACHPHOS© product as a fertilizer. Instead of using the phosphorus as a fertilizer, it would also be possible to produce phosphoric acid.