Wastewater Treatment with Biomass Attached to Porous Geotextile Baffles

A bench-scale study used nonwoven geotextiles as a compact biomass host media to treat wastewater from a combined sewer system. The geotextile coupons were used as baffles and suspended in an aerated reactor. Each baffle was offset in succession to form a sinuous channel with permeable boundaries. Filtering the total suspended solids (TSS) and micro-organisms formed a biomass floc in the interior of the baffles, which grew to emerge on the surface. Suspended and nonsettleable colloidal solids in the influent wastewater were captured by both filtration and adsorption from the channel flow. This bench-scale setup, named the geotextile baffle contact system, consistently provided secondary treatment to influent concentrations up to 318 mg/l of TSS and 114 mg/l of biological oxygen demand. Ammonia (NH3–N) concentrations were reduced over 90%, and mineralization of the nitrate (NO3–N) was also observed when the biofilm aged and thickened. Some of the influent TSS and sloughed biomass from the baffles settled to the bottom of the tank.