The floor of a biofilter has to meet some stringent requirements. It should provide an excellent drainage with a stream of air with a very high humidity. In addition, the floor has to be loaded with a heavy biofilter medium and it should not be allowed to warp, bend or collapse. The UK company Hahn Plastic Ltd. has developed Hanit®, a new set of plastic grills and legs made of recycled material that is able to stand a biofilter media in extremely harsh conditions.
The traditional option when designing a biofilter floor is using a pre-cast concrete grill. This is often a very convenient way of flooring a a biofilter. The pre-cast concrete structures are resistant, durable under normal conditions and can be easily dismantled, when required.
However transport and handling charges are often a handicap for pre-cast concrete grills. In addition, this flooring has some problems when the air flow has a very high H2S concentration. Concrete gets corroded in these cases and a replacement of the floor has to be made, sometimes after a few years.