Hygrade bio-filters, bio-scrubbers and bio-trickling filters are mainly used for the removal of hydrogen sulphide, general odour control in sewage treatment and other waste handling applications. They are available with a range of media, including inert pumice (lava rock) woodchip and structured plastic packing, specially selected to suit individual use.

Media is housed within vertical, GRP towers, or for larger systems in a rectangular housing manufactured from flat GRP panels. Hygrade systems are all custom designed and built to individual applications, including the type of media, housing and irrigation system design.