Removal of tryptophan in drinking water using biological activated carbon filter

Tryptophan (Trp), an important nitrogenous organic compound commonly present in water sources and posing a serious threat to human health, was selected as the main object in the removal trial by utilizing a laboratory-scale biological activated carbon (BAC) column. The laboratory-scale BAC column was divided in a three-part composition: upper layer (UL) (0–20 cm), middle layer (ML) (20–40 cm) and bottom layer (BL) (40–60 cm). The removal efficiencies of Trp in the three layers were 45.4%, 86.4% and 43.2%, respectively, while the adsorption of granular activated carbon (GAC) for Trp did not show a similar tendency (the average adsorption yields were 10.98 ± 1.17 mg/g, 7.45 ± 0.80 mg/g and 3.32 ± 0.39 mg/g, respectively), which indicated that the biodegradation of microorganisms attached to the GAC played an important role. Furthermore, a high-throughput quantitative polymerase chain reaction (HT-qPCR) was utilized to determine the relative abundance of the first eight bacterial genera in the three BAC layers and results revealed the relative abundance of Aquincola, Pseudomonas and Ensifer were highest in the ML.