Nitrogen removal performance and characteristics of gel beads immobilized anammox bacteria under different PVA:SA ratios

Abstract

Although polyvinyl alcohol and sodium alginate gel (PVA/SA) cell immobilization technology has been successfully applied in anaerobic ammonium oxidation (anammox) processes, there is no comprehensive evaluation of the PVA:SA ratio in PVA/ SA gel beads. Therefore, to determine the optimal PVA:SA ratio, the nitrogen removal performance and structure of PVA/SA anammox gel beads under different PVA:SA ratios were studied through batch experiments. The results suggested that cell immobilization technology could significantly improve the nitrogen removal rate (NRR). PVA concentration was positively correlated with the proportion of -macropore in the gel beads but negatively correlated with mechanical strength. Despite having poor mechanical strength, PVA/SA (12%/2%) gel beads had the highest NRR owing to the increased pore size and were experimentally determined to be the most suitable concentration of immobilized carrier. UASB reactor tests showed that compared with anammox granular sludge, the response time of anammox PVA/SA (12%/2%) beads to increased nitrogen load was shorter and the specific anammox activity was higher. Candidatus "Jettenia" was the dominant bacterium in anammox gel beads, accounting for 37.96% of the community. This study provides a reference for preparing PVA/ SA cell immobilization. © 2021 Water Environment Federation • Practitioner points• Increasing the concentration of PVA can reduce the apoptosis of microorganisms during the gel process. • The macropore of PVA/SA beads increased with the increase of the PVA:SA ratio.• This study provides a reference for preparing PVA/SA gel beads immobilized anammox bacteria.

Applications of Up-Flow Anaerobic Sludge Blanket (UASB) and Characteristics of Its Microbial Community: A Review of Bibliometric Trend and Recent Findings

“…For this reason, studies concerning the optimization of nitrogen removal by anammox bacteria in anaerobic conditions were developed. For instance, Wang et al [ 75 ] coupled UASB with gel beads in which anammox bacteria were immobilized aiming to optimize the ratio of polyvinyl alcohol and sodium alginate (PVA/SA) gel in beads. They found that highest performance in term of specific anammox activity (0.365 g N g VSS −1 d −1 ) were achieved with PVA/SA (12%/2%) gel beads [ 75 ].…”

“…For instance, Wang et al [75] coupled UASB with gel beads in which anammox bacteria were immobilized aiming to optimize the ratio of polyvinyl alcohol and sodium alginate (PVA/SA) gel in beads. They found that highest performance in term of specific anammox activity (0.365 g N g VSS −1 d −1 ) were achieved with PVA/SA (12%/2%) gel beads [75]. Karasuta et al [74] evaluated the influence of HRT and pH in anammox reactors and interestingly, they concluded that the varying pH in the effluent not necessarily means a lower nitrogen removal rate while anammox performance is strictly negatively correlated with the HRT of the system.…”

Preparation and Characterization of Temperature/pH Dual-Responsive Gel Spheres for Immobilizing Nitro Bacteria

“…The ultimate use of the gel spheres is to encapsulate microorganisms for the biological treatment of wastewater. As there is no unified evaluation standard, in order to evaluate the gel spheres quantitatively, a preliminary study was conducted by equally assigning weights to five aspects (sphericity, ,, swelling, − mechanical properties, − oscillatory breakage rate, ,, and mass transfer properties ,, ) on the basis of previous studies by other scholars (Table ). The orthogonal experimental design factors and scoring criteria are given in Tables and .…”

Polyethylene glycol as a robust, biocompatible encapsulant for two-stage treatment of food and beverage wastewater

“…Recovery time prior to microbial activity has been observed with other encapsulant chemistries, such as PVA/ alginate. 25 The lack of a lag period observed with the PEG beads was likely to have been a result of the high concentration of biomass that was encapsulated. In fact, methane production from the PEG-encapsulated biomass was only observed when a minimum threshold biomass concentration was encapsulated, with no methanogenic activity observed after the polymerization process when below this threshold concentration (Fig.…”

“…20,21 A variety of encapsulant chemistries have been presented in the literature. [22][23][24][25][26][27] Several of these are relatively easy to make and use (e.g., alginate, polyvinyl alcohol (PVA), polyethylene glycol (PEG)), 12,19,28,29 whereas others are more challenging (e.g., core-shell structures, microparticle addition). 26,[30][31][32] In addition, some of these encapsulants may be able to last for multiple years, 33 whereas the longevity of other materials is less clear.…”