Effects of linear anionic surfactant (SDBS, SLS and SDS) on nitrogen removal performance of anammox biomass(Time New Roman, 12pt, Justified, Bold) Tian Tian (oral presenter with underline), Sen Qiao*(corresponding author with * mark), Jiti Zhou, Xin Yin Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, P. R. China(Authors and Department, Time New Roman, 10.5pt, Justified) Introduction(Chapter title 1, Time New Roman, 12pt, Bold, Justified) Linear anionic surfactants (LAS), such as sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SLS) were the most widely used and spread in detergents and cleaning products in the world (Garcia et al., 2006). The presence of LAS in the industrial wastewater and domestic sewage can inhibit self-purification process of water courses and increase sewage bubbles, which would decrease the effluent quality and cause subsequent problems (Delforno et al., 2012). Since many nitrogen-rich wastewaters, such as kitchen wastewater and washing wastewater, contain high concentration of LAS, it is imperative to study the potential mal-effect of LAS on the anammox process. However, to our best knowledge, there are few literatures focusing on the effects of LAS on anammox bacteria. The objective of this work presented here was to investigate the effects of three kinds of widely used LAS, which were SDBS,SLS and SDS (sodium dodecyl sulfonate), on the nitrogen removal performance of anammox biomass through batch experiments. Furthermore, the relationship between the collected LAS and the key enzymes of anammox bacteria was also studied.(Text, Time New Roman, 12pt， Justified, single space) Materials and Methods(Chapter title 1) Batch Assays(Chapter title 2，Time New Roman, 12pt, Overstriking, Justified) Three batch assays were conducted to test the effects of anionic surfactant on the nitrogen removal performance of anammox biomass. Batch activity tests were performed in triplicate and incubated in a water shaker (150 rpm) controlled at 35 ± 1 ℃ for 16 h. The serum flasks (120 mL) were supplied with basal mineral medium (100 mL) and inoculated with 1670 mg-VSS/L of anammox granules. Enzyme Activity Assays(Chapter title 2) The activities of hydrazine dehydrogenase (HDH) and nitrite reductase (NIR) were measured using a spectrophotometer (V-560 UV/VIS, Jasco Corporation, Japan). Briefly, the HDH activity was detected as reduced cytochrome c generated rate with substrates of hydrazine and cytochrome c，and the NIR activity was described as nitrite decreasing rate. Results and Discussion(Chapter title 1) Fig. 1 (a) showed that the SAA was obviously inhibited by SLS and SDS addition. Carefully examination showed that the SAA changes were closely related with the nitrite removal efficiency changes (Fig. 1b and 1c) and it could be indicated that the inhibition effects caused by SLS and SDS were irreversible and the intensity of LAS toxic effects on anammox biomass was SLS > SDS > SDBS. 50 mg/L 150 mg/L 6.0 4.5 3.0 1.5 0.0 Nitrite removal efficiency (mg-N gVSS-1h-1) control 100 mg/L Ammonium removal efficiency (mg-N gVSS-1h-1) TN removal efficiency (mg-N gVSS-1h-1) 7.5 (c) (b) 9.0 SDBS SLS 6.0 control 100 mg/L 50 mg/L 150 mg/L 3.0 1.5 control 50 mg/L 100 mg/L 150 mg/L 3.6 2.4 1.2 (d) 12 4.5 0.0 4.8 0.0 SDS Anionic surfactant NIR activity (mM-N mg-pro-1min-1) (a) 10 SDBS SLS SDS Anionic surfactant control 100 mg/L 50 mg/L 150 mg/L 8 6 4 2 0 SDBS SLS Anionic surfactant SDS SDBS SLS SDS Anionic surfactant Fig. 1 Total nitrogen (a), ammonium (b), nitrite (c) removal rate and NIR activity (d) of anammox biomass with different AS additions.(Figure legends, Time New Roman, 10.5pt, Justified) All the three kinds of LAS showed heavy inhibiting effects on the NIR activity, and the inhibition effect and the LAS injection dose were positively correlated. The increase in the LAS concentration resulted in a decrease in the enzymatic activity. It was suggested that the decrease in NIR activity caused by SLS and SDS addition might be the main reason for the decrease in the nitrogen removal performance of anammox bacteria, based on the fact that simultaneous decline of NIR activity and SAA with intact cell structure were observed. Conclusion(Chapter title 1) The nitrogen removal efficiency of anammox biomass was irreversibly suppressed by adding SLS and SDS. Further enzyme activity test indicated that the inhibition effect of SLS and SDS on the NIR activity of anammox bacteria might be the main reason for the decrease in the SAA. However, SDBS did not show certain inhibitory effects on the anammox bacteria, which suggesting that the feasibility of anammox process for treating ammonia-nitrogen wastewater with SDBS contained. Reference (Chapter title 1) Garcia M.T., Campos E., Sánchez-Leal J., Ribosa I., 2006.Effect of linear alkylbenzenesulphonates (LAS) on the anaerobic digestion of sewage sludge. Water Res. 40, 2958-2964.(Reference, Time New Roman, 10.5pt, Justified) Delforno T.P., Okada D.Y., Polizel J., Sakamoto I.K., Varesche M.B.A., 2012. Microbial characterization and removal of aniobic surfactant in an expanded granular sludge bed reactor. Bioresour. Technol. 107, 103-109.