Biomass concentration in PACT process

PACT (Powdered Activated Carbon Treatment) process was developed for the treatment of wastewater containing compounds which are difficult to oxidize. Enhancement properties of activated carbon added to activated sludge units are well known but not justified. In this work the process has been applied in lab plant for the treatment of a synthetic textile wastewater with an azodye used in the wool textile industry (Acid Orange 7, C.I. 15510). Microorganism growth on a carbon surface is only reached at low values of biomass concentration (low sludge age), and then a high percentage of dye removal is obtained (97.0 ± 1.6%). The influence of biomass concentration on COD and dye removal is discussed because this variable is essential especially in dye removal. The carbon surface is visualized by microscope techniques and it is shown that a strong dependence exists between pollutant removal and biomass concentration.