Effects of short-term exposure to linear anionic surfactants (SDBS, SLS and SDS) on anammox biomass activity

Abstract

This work demonstrates, for the first time, the feasibility of nitrogen removal from wastewater containing linear anionic surfactants (LAS), including sodium dodecyl benzene sulfonate (SDBS), sodium lauryl sulfate (SLS) and sodium dodecyl sulfonate (SDS), by using the anammox process. Experimental results showed that the nitrogen removal rate (NRR) of anammox biomass was irreversibly inhibited by exposure to SLS and SDS. As the dosages of SLS and SDS increased from 0 to 150 mg L⁻¹, the NRR decreased from 6.7 ± 0.6 to 1.4 ± 0.1 mg-N per gVSS per h (with SLS addition) and 1.0 ± 0.2 mg-N per gVSS per h (with SDS addition). However, NRR was not significantly affected in the presence of SDBS. Further investigation indicated that exposure to SDBS, SLS and SDS did not induce membrane damage to anammox cells. Enzyme activity assays proved that the nitrite reductase (NIR) activity of anammox biomass was suppressed by both SLS and SDS, and the depression effects showed a dosage-response relationship. The increase in the SLS and SDS concentrations (from 0 to 150 mg L⁻¹) resulted in sharp decreases in the NIR activities, which reached the minimum values of 16.2 ± 4.9% and 14.5 ± 3.6% of the control with 150 mg L⁻¹ SLS and SDS, respectively. The NIR suppression was positively correlated with NRR inhibition, suggesting that the negative influence on anammox biomass was induced by NIR denatured exposed to SLS and SDS. These findings could provide useful information to the application of the anammox process on treating nitrogen-rich wastewater containing LAS.