## 3 Results and Discussions
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Total Removed** & **Analysed in GAC** & **Adsorbed** \\  & **mg/kg GAC** & **mg/kg GAC** & **\%** \\ \hline Citalopram & 29.2 & 1.09 & 3.7 \\ Diclofenac & 67.9 & 0.13 & 0.2 \\ Furosemide & 49.2 & 0.57 & 1.2 \\ Hydrochlorothiazzide & 143.4 & 3.97 & 2.8 \\ Ibuprofen & 8.1 & 0.01 & 0.1 \\ Carbamazepine & 41.2 & 13.1 & 31.8 \\ Metoprolol & 82.5 & 3.15 & 3.8 \\ Oxazepam & 54.3 & 7.03 & 12.9 \\ Propranolol & 6.7 & 0.87 & 12.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Total amount of removed pharmaceutical residues in the GAC-biofilter. GAC-biofilter. Interestingly, faecal coliform removal was absent during the first weeks of operation while a reduction of more than 90% was achieved after 3 months of operation. This might be explained by the established biology in the filter that outcompetes faecal coliforms. The studied phenolic compounds tricolosan and bisphenol A were reduced to below detection limit. Most of nonylphenol and octylphenol was removed as well. It was difficult to extract several of the phenolic compounds from the carbon. Thus, a mass balances for these compounds over the GAC-biofilter was not possible to perform. High levels of nonylphenol, triclosan and bisphenol A in the backwash water suggested that they were largely bound to the flushed biomass and thus returned to the biological process in the main treatment. Not a single microplastic particle was detected in the MBR-effluent (removal efficiency 100%), whereas effluent water from the full-scale CAS-process including a final sand filtration contained both plastic fibres and plastic fragments (removal efficiency 90.7 %). Non-synthetic fibres were found in both MBR and CAS effluents. Compared to complimentary treatment of the final effluent from the main WWTP Henriksdal, that is the same influent water, [16; 52], a significant reduction of clogging and backwash frequency was achieved in the GAC-biofilter when treating MBR-effluent. Both aspects have a direct impact on the operational cost of the GAC-biofilter system. The better quality of MBR-effluent compared to traditional CAS-effluent (even with sand filtration [15]) provided better conditions for the GAC-biofilter operation. The initial adsorption of pharmaceuticals substances and thus concentration build-up on the filter material provides good conditions for the establishment of a biology. Compared to treatments system that use the same technology combination but in a different order [51], are more specialized biology may be able to establish as easier degradable organic contaminants have already been removed by the preceding MBR-process. High oxygen concentrations in the effluent from the MBR due to continuous air scouring of the membranes may enhance the biological breakdown of organic micropollutants in the following biofilter. The evaluation of the pilot operation and related removal of micropollutants indicates that some aspects need further confirming experiments in order to utilize the findings in the most optimal way. Here the recovery of the removal capacity in the biofilter is the most interesting aspect for further investigation as also pointed out by [50].