A new approach for treating ammonia-rich wastewater deficient in organic matter: A tandem process for nitrification/nitritation in MBBR followed by sulfur-based denitrifying column reactor

Abstract

As an advanced wastewater treatment technology, Moving Bed Biofilm Reactor (MBBR) offers high treatment efficiency for ammonia-rich wastewaters due to immobilized slow-growing nitrifying microorganisms onto biofilm carriers. In this study, the integration of MBBR with a sulfur-based autotrophic denitrification (S-based DN) process is proposed as a promising approach for total nitrogen removal, as it eliminates the need for an external carbon source. A lab-scale MBBR system was operated under varied HRT across seven periods. Ammonium oxidation reached 86% efficiency in the acclimation phase. Then, complete nitrification at a 12-hour HRT was observed, although nitrite accumulation occurred at 6 h. The tandem operation of an MBBR system followed by an S-based DN system facilitated efficient N-removal in wastewater with low organic matter content, thereby eliminating the requirement for an external carbon source. After the startup of the tandem operation of MBBR and S-based DN reactors, total inorganic nitrogen (TIN) removal exceeded 95% when the HRT was 10 h for the denitrification process. However, TIN removal efficiency declined to 72% when the HRTs of the MBBR and the denitrifying column were 5 and 2.5 h, respectively. Denitrification efficiency was impacted by both the HRT of the S-based DN reactor and the MBBR, which generates nitrite or nitrate depending on its HRT. Throughout the process, the observed sulfate production and nitrogen gas generation were consistent with theoretical predictions. In conclusion, this study highlights MBBR with S-based DN tandem operation as highly effective and sustainable solution for ammonia-rich wastewater treatment, with potential for real-scale applications.