ENHANCING THE PERFORMANCE OF PARTIAL NITRIFICATION-ANAMMOX BY USING HYDROTALCITE COMPOSITE BIOFILM CARRIERS
One-stage partial nitrification-anammox(PN/A),as an autotrophic nitrogen removal technology,has made the low-carbon treatment of wastewater possible.However,maintaining stable and efficient partial nitrification and increasing the biomass retention of anammox bacteria remain the main challenges for the successful application of the PN/A process.In this study,a novel composite carrier composed of layered silicate minerals and nonwoven fabric was developed to enhance the nitrogen removal performance of the PN/A process.The adsorption characteristics between the carrier and microorganisms,as well as the influence of the composite carrier on the microbial community in the PN/A process,were investigated.The results showed that the reactor with the addition of layered silicate minerals achieved the highest nitrogen removal rate of 131.4 mg/(L·d),which was significantly higher than control group without layered silicate minerals addition(97.2 mg/(L·d)).Surface thermodynamic analysis and the extended DLVO theory indicated that layered silicate minerals formed strong electrostatic attractive forces with the microbial community,promoting microbial adsorption and extracellular polymeric substance secretion.In addition,the surface of the silicate minerals contains abundant metal ion which can promote sludge aggregation and facilitate the retention and growth of anammox bacteria.The hydrotalcite composite carrier provides an effective method for rapid start-up and stable operation of the PN/A process.
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