New hybrid reactor concept incorporating a filter mesh for nitritation–anammox treatment of sludge return liquid

Abstract

A new approach to perform partial nitritation-anammox in a single tank was investigated. The tank incorporated a mesh (opening size 1.0 × 1.2 mm) as permeable barrier to create two distinct reaction zones (aerated and anoxic). The study reports on the operation and optimization of a 13 L laboratory scale reactor to treat sludge reject water with an NH-N concentration of ∼750 mg·L. Performance throughout 250 days at increasing nitrogen loading rates is presented. The maximum loading rate applied was 1.5 kg NH-N·m·d at a hydraulic retention time of 12 h. Typical composition of the effluent was ∼50 mg·L NH-N; <5-10 mg·L NO-N and ∼60 mg·L NO-N. The corresponding average N removal rates were 85% for total nitrogen and 90% for NH-N, respectively. Process control was very simple. It comprised only regulation of the aeration rate to maintain a pre-set pH (7.1) in the nitritation zone. Performance data clearly indicate that the investigated reactor configuration offers distinct advantages over currently installed processes. It demonstrated high robustness without the need for sophisticated process control. Apparently, the use of a permeable mesh to establish different reaction conditions in a single reactor provides new features of high potential.

Critical design factors for polyvinyl alcohol hydrogel entrapping ammonia-oxidizing bacteria: biomass loading, distribution of dissolved oxygen, and bacterial liability

“…The single-stage PN-AMX process is based on the biofilm system of heterogeneously distributed AOB and AMX bacteria. In general, AMX bacteria are reversibly and irreversibly inhibited with the DO concentrations of 2.5 mg/L and 5.0 mg/L [22][23][24]. In a previous study on the effects of the concentration of DO on the PN-AMX process, TN removal efficiency of 88.9% was achieved at a DO concentration of 1.21 mg/L but TN removal was reduced at a higher DO level [25].…”