Lava filter

[1] This community of microorganisms, known as the periphyton, break down the odor components in the air, such as hydrogen sulfide.

In order for this to work, sufficient oxygen as well as water and nutrients (for cell growth) is to be supplied.

Water is supplied through the surface of the biofilter and trickles down over the lava rock to the bottom, where it is collected.

Percolating water collected at the filter bottom contains odour components as well as sulfuric acid from the biological oxidation of hydrogen sulfide.

Finally, in addition to plants, locally grown bacteria and non-predatory fish are also added to eliminate pests.