Biological Treatment

Biofiltration
Biofiltration uses living material to capture and biologically degrade process pollutants and biodegradable matter. Common uses include the processing of wastewater and capturing of harmful chemicals or silt from surface runoff. Trickling filters use dual purpose rapid granular media filter for the removal of biodegradable organic matter by biological oxidation and particle removal.

Denitrification
Denitrification is the biological conversion of nitrate (NO3-) to nitrogen gas (N2). The denitrification process is an anoxic process that is typically used for the conversion of nitrates (produced by the nitrification process on landfill leachate) to nitrogen gas. Two types of bioreactors are used: suspended growth (activated sludge – denitrification) and attached growth (biofilter – dinitrification).

Nitrification
Nitrification is the biological conversion of ammonia (NH3) to nitrate (NO3-) and is typically used for the conversion of ammonia, found in landfill leachate or other surface wastewater, to nitrate for subsequent removal by denitrification. This anaerobic process uses the following reactors: suspended growth (activated sludge, aerated lagoon, tertiary lagoon or aerobic digester), attached growth (trickling filters, biofilters, rotating biological contactors), hybrid or combined growth.

Activated Sludge
Activated sludge is a process whereby air or pure oxygen is introduced to a mixture of primary treated or screened sewage. Together with the biomass organisms, this oxygen promotes the growth of biological floc that substantially removes organic material. Once the sewage or effluent is sufficiently treated, excess biological mass (mixed liquor) is discharged into settling tanks before the settled sludge is drawn off for further treatment. Part of the settled sludge is then returned to the aeration system to reseed incoming effluent.