Enhanced Simultaneous Nitrogen and Phosphorus Removal Performance by Anammox–HAP Symbiotic Granules in the Attached Film Expanded Bed Reactor

Abstract

Dissolved nitrogen and phosphorus compounds are responsible for eutrophication and usually are treated by separate processes in wastewater treatment plants. In this study, the simultaneous, long-term, stable removal of phosphorus and nitrogen was achieved in a high-loading anammox attached film expanded bed (AAFEB) reactor. As an energy-saving and high-efficiency biological process, the anammox reaction performed stable and high nitrogen removal. In addition, the chemical environment and hydrodynamic conditions of the AAFEB system, as well as the microenvironment of the anammox granules, induced the crystallization of hydroxyapatite (HAP). As an inorganic carrier of anammox biofilms, HAP enhanced the settling velocity and shear strength of the anammox granules and thus promoted the operational stability of the AAFEB reactor. In the coupled anammox–HAP system, the nitrogen removal rate reached 44.8 g fo N/(L/day), with a stable phosphorus removal rate of 71.61 ± 6.82%. The results indicated that the coupled anammox–HAP system enhanced the nitrogen removal performance and provided a possible phosphorus recovery pathway through biomineralization processes.

The short‐term and long‐term effects of Fe(II) on the performance of anammox granules

“…The abiotic reduction of NO − 2 by Fe(II) is an important N 2 O source in wastewater treatment and should not be ignored. Additionally, N 2 O emissions increased linearly during each phase (Figure 6), which was mainly due to the high sludge retention ability of the AAFEB reactor (Zhang, Ma, Lin, et al, 2018), resulting in the continuous accumulation of Fe(II). Therefore, N 2 O was formed chemically from Fe(II) and NO − 2 via abiotic reactions in this study.…”

“…As shown in Figure 1, an AAFEB reactor with a working volume of 2.5 L, the same as that used in a previous study (Zhang, Ma, Lin, et al, 2018), was used in this experiment. The temperature of the reactor was controlled at 34 ± 2°C by a water jacket, while the outside of the reactor was covered with opaque foam to prevent the reactor from the effects of light.…”

Recovery of Phosphorus from Waste Water Profiting from Biological Nitrogen Treatment: Upstream, Concomitant or Downstream Precipitation Alternatives

“…Previous experiences concerning simultaneous biological N oxidation or removal and biologically induced P precipitation within the same bioreactor in the framework of waste water treatment, aimed at promoting P recovery, are summarised in Table 3 [70][71][72][168][169][170][171][172] (an extended version of this table is provided as Supplementary Material). This approach allows simplifying the configuration of the treatment system.…”

“…Recent works conducted at Tohoku University (Japan) with anammox biomass in expanded bed reactors showed that, using synthetic substrate and under optimised bioreactor operation, simultaneous N removal and P uptake were feasible at rates as high as 16.7 g N L r −1 d −1 and 1. d −1 at 35 • C (using inner mineral cores of granules as biofilm carriers) [170]. A highly mineralised sludge grew within these reactors, with a relative volatile content that could fall down to values below 25% of the dry weight.…”

Hydroxyapatite Formation in a Single-Stage Anammox-Based Batch Treatment System: Reactor Performance, Phosphorus Recovery, and Microbial Community

“…Recent works integrating anammox and CaPprecipitation reactions evidenced the feasibility of the formation of a dense HAP core wrapped by an external biofilm. 21,22 As a consequence, a highly mineralized sludge is produced within the bioreactor. Once this sludge is harvested, the high P content makes it an interesting resource for subsequent valorization.…”