Study On The Enhanced Total Nitrogen Removal From The Piggery Biogas Effluent By The Step-fed Sequencin" Membrane Batch Reactor Combined With Denitrification Biofilter

To solve the problem of low ratio of carbon to nitrogen (C/N) and nitrogen removal efficiency, the combination of sequencing batch membrane bioreactor(SMBR) and polyhydroxybutyrate valerate copolyesters(PHBV) denitrification biofilter were set up. The C/N of biogas effluent was adjusted and the effects of step-fed SMBR treating the adjusted biogas effluent were revealed. The relationships between membrane fouling of step-fed SMBR, extracellular polymers(EPS) and soluble microbial products (SMP) were discussed. The release kinetics denitrification performance, microstructure of surface structure and chemical functional groups of four different carbon solid carbon source material (PLA, PHBV, PVA (10%starch), PBAT (25%starch)) were compared. Moreover, the solid carbon source of denitrification biofilter was selected by comparation of denitrification efficiency and carbon releasing. The result demonstrated that step-fed SMBR and PHBV denitrification biofilter combined process applied as a method for removing the nitrogen from biogas effluent was feasible. The main results of the study were drawn as follows:(1) Step-fed SMBR enhanced nitrogen characterized by a anoxic feeding for supplying the organic carbon source to denitrifier.When the ammonium load at0.026-0.052gNH4+-N/(gVSS·d), the total removal rates of NH4+-N and TN of SMBR for treatment with biogas effluent were generally more than89%.The total removal rates of COD was above90%and the total removal rate of TP was between75%-97%. With the increase of influent load, SMP and EPS concentrations increased and protein was a major constituent of SMP and EPS. The dimensional fluorescence spectra (EEM) analysis of EPS and SMP showed the response relation between tryptophan-like protein and influent load.(2) The TOC releasing curve of PHBV preferably fitted the second order behavior. The denitrification rate was53.5mg/(L·d). The SEM and FTIR indicated that PHBV was more conducive to maintaining internal structure in denitrification process. While the treatment effect was7.7g PHBV/g NO3--N and the treatment cost was0.39Yuan/g NO3--N.(3) When the influent loading was0.052gNH4+-N/(VSS·d) without C/N adjustment, total nitrogen removal rate was higher than94%and the effluent concentration of NO3--N, NH4+-N and COD was less than10mg/L,35mg/L and200mg/L, respectively by the combination of step-fed SMBR and PHBV denitrification biofilter. Moreover, the concentration of COD in effluent from the denitrification biofilter meet the discharge standard of "The livestock and poultry breeding industry pollutant emission standards"(GB18596-2001), the concentrations of NH4+-N and TN meet the coming discharge standard.The total nitrogen removal rate of step-fed SMBR and denitrification biofilter were77.9%and16.4%respectively. Denitrification biofilter had a strong ability of nitrogen removal because the advantage of bacillusit was enriched on the surface of denitrification biofilter.