Digging deep into a GAC filter – temporal and spatial profiling of adsorbed organic micropollutants

Measured concentrations in 24-h flow proportional samples from the effluent of the full-scale WWTP and composite grab samples from the influent to the UF pilot-scale unit. In between the sampling points was a pilot-scale drum filter, which is believed not influencing the micropollutant concentrations in the water.
Analyzed micropollutants with the limit of quantification (LOQ) and the relative standard deviations (RSD) for water samples. LOQ for GAC-media samples are given as the instrument quantification limit in relation to the extracted GAC amount.
Mean concentrations of micropollutants after each treatment stage in the full-scale WWTP and the pilot-scale UF treatment, and removals in the biological treatment, with standard deviations marked (±).
Micropollutant charge at 7.9 and removal in the GAC filter during different time periods. Mean and standard deviation (0‒6000 BVs, n=10; 6000‒12,000 BVs, n=7; 12,000‒18,000 BVs, n=8). Removals were not calculated for influent concentrations below the LOQ (*).
Influent and effluent concentrations of imidacloprid to the GAC filter together with the sampling events of GAC media for micropollutants (MP) extraction.
Effluent wastewater characteristics with standard deviations (n=48). The concentrations of the organic fractions (TOC, DOC and CODMn) effluent of the GAC filter increased over time as the removal efficiency of the filter decreased (*).
Effluent concentrations of the organic fractions total organic carbon (TOC), dissolved organic carbon (DOC), and chemical oxygen demand (CODMn).
Extracted amounts of micropollutants per amount of GAC media (µg/g) in each extraction cycle from GAC-media in the top layer of the filter at 7300 BVs.
Adsorption profiles of micropollutants through the GAC filter, expressed as the amounts of micropollutant extracted per amount of GAC media (µg/g). GAC media in the top layer (10-20 cm) of the filter at 7300 BVs were analyzed in triplicates, data resented as mean (n=3) and relative standard deviation (RSD, %).
Adsorption profiles of micropollutants through the GAC filter, expressed as the amount of micropollutant extracted per amount of GAC media (µg/g).
Estimations of accumulated removed amounts of micropollutants (µg micropollutant/g GAC) based on influent and effluent concentrations to the GAC filter, and extracted mean amounts of micropollutant of GAC media from 4 filter layers. Accumulated removals were not calculated when the influent concentrations were <LOQ, or effluent concentrations were <LOQ and LOQ>20% of the influent concentration (*).