Tertiary Nitrification Using Moving-Bed Biofilm Reactor: A Case Study in Tunisia

Performance and mechanism of simultaneous nitrification-denitrification and denitrifying phosphorus removal in long-term moving bed biofilm reactor (MBBR)

The long-term moving bed biofilm reactor (MBBR) with carrier-attached biofilm was successfully operated for simultaneous removal of nitrogen, phosphorus, and COD at various C/N ratios. Results indicated that 99.60%, 63.58%, 78.94%, and 59.64% of NH₄⁺-N, NO₃^--N, TN, and TP were removed at C/N ratio, hydraulic retention time (HRT), and carrier film amount of 5, 40 h, and 1.2 mg·g^-1. Nitrogen balance analysis showed that more than 89% of nitrogen (C/N = 20, 15, 10, 5) was converted to gas products. Extracellular polymeric substances (EPS), electron transport system activity (ETSA), and enzyme activity of biofilm were evaluated. Protein (PN)/polysaccharose (PS) values and ETSA decreased with the decrease of C/N ratios. Metagenomics sequencing further revealed that the prominent phyla for nitrogen and phosphorus removal were identified including Proteobacteria, Acidobacteria, Nitrospirae, and Chloroflexi. Proteobacteriaand Gammaproteobacteria were identified as the dominant denitrifying phosphate accumulating organisms (PAO) at the phylum and class level, respectively.

Bio-carrier and operating temperature effect on ammonia removal from secondary wastewater effluents using moving bed biofilm reactor (MBBR)

This study investigates the impact of bio-carriers' surface area and shape, wastewater chemistry and operating temperature on ammonia removal from real wastewater effluents using Moving bed biofilm reactors (MBBRs) operated with three different AnoxKaldness bio-carriers (K_3, K_5, and M). The study concludes the surface area loading rate, specific surface area, and shape of bio-carrier affect ammonia removal under real conditions. MBBR kinetics and sensitivity for temperature changes were affected by bio-carrier type. High surface area bio-carriers resulted in low ammonia removal and bio-carrier clogging. Significant ammonia removals of 1.420 ± 0.06 and 1.103 ± 0.06 g - N/m². d were achieved by K₃(A_s = 500 m²/m³) at 35 and 20 °C, respectively. Lower removals were obtained by high surface area bio-carrier K₅ (1.123 ± 0.06 and 0.920 ± 0.06 g - N/m². d) and M (0.456 ± 0.05 and 0.295 ± 0.05 g - N/m². d) at 35 and 20 °C, respectively. Theta model successfully represents ammonia removal kinetics with θ values of 1.12, 1.06 and 1.13 for bio-carrier K₃, K₅ and M respectively. MBBR technology is a feasible choice for treatment of real wastewater effluents containing high ammonia concentrations.