Effect of HRT on the Enhanced Nitrogen Removal in Synch With the Removal of PAEs by 3DBER-S Technology

In order to study the operation characteristics of 3DBER-S (three-dimensional biofilm-electrode reactor coupled with sulfur autotrophic denitrification technology) in the aspect of denitrification and simultaneous removal of PAEs (phthalate esters), the removal of TN (total nitrogen), PAEs, variation of sulfate and pH value as well as the denitrification route and the removal ability of PAEs in the coupling system was traced and analyzed according to three different HRT (hydraulic retention time) which was 12h, 6h and 3h respectively. The result show that under different HRT, the removal efficiency of TN is about 95%, the average effluent concentration of TN is under 2mg/L and the average removal rate of PAEs is above 80%. Also, the average removal rate of DBP (dibutyl phthalate) exceedes 97%, while the number of DEHP (di-2-ethylhexyl phthalate) is more than 83%. The systems optimal hydraulic retention time is 6h,the TN mass concentration of effluent maintaines around 0.80mg/L at this time interval, which meet the IV TN standard of Surface Water Environment Quality Standard (1.5mg/L). The average removal loading of DBP and DEHP is 594.79mg/(m ³·d) and 188.13mg/(m ³·d) respectively. The elemental sulfur and the hydrogen produced by the cathode can remedy the relative shortage of denitrification electronic donor resulted from HRT decreasing and N $\begin{array}{c}{O}_3^{-}\end{array}$ -N load increasing in the influent, meanwhile can maintain the high efficiency and stability of the system, the strong elimination capacity of PAEs is due to the synergistic effect of filler absorption, biodegradation and electrochemical oxidation.