[Bacterial Community Shifts and Nitrogen Removal Characteristics for a SNAD Process Treating Anaerobic Digester Liquor of Swine Wastewater (ADLSW) in a Continuous-Flow Biofilm Reactor (CFBR)].

To realize a simultaneous partial nitrification, ANAMMOX (anaerobic ammonium oxidation), and denitrification (SNAD) process treating anaerobic digester liquor of swine wastewater (ADLSW) in a continuous-flow biofilm reactor (CFBR), we first gradually increased the influent ammonium (NH4+-N) concentration, and then enhanced the ADLSW ratio in the influent during operation; dissolved oxygen (DO) was controlled at (0.4±0.1) mg·L-1 by adjusting the air flow rate, and the temperature was kept at (30±1)℃. Meanwhile, high-throughput sequencing and quantitative PCR (polymerase chain reaction) techniques were used to analyze the bacterial community shifts and the amount of dominant nitrogen removal bacteria. The results demonstrated that a successful start-up of the SNAD process was accomplished in 150 d, and replacement of the actual biogas slurry was completed in 298 d. The effluent (NO3--N+NO2--N)/ΔNH4+-N value was less than 0.11, and the average removal rates of NH4+-N and TN (total nitrogen) increased to 63.26% and 55.71%, respectively. Moreover, high-throughput sequencing results demonstrated that the dominant microbial populations at phylum level were Chloroflexi (with a relative abundance of 50.78%), Proteobacteria (13.34%), and Planctomycetes (9.26%). The relative abundance of Nitrosomonas increased from 1.55% to 1.98%. In addition, the relative abundance of Candidatus_Brocadia and Candidatus_Kuenenia increased from 0.01% and (<0.01%) to 4.66% and 4.18%, respectively, and the relative abundance of Denitratisoma increased from (<0.01%) to 2.06%. Meanwhile, qPCR analysis showed that the amounts of ammonia-oxidizing bacteria, ANAMMOX, and denitrifying bacteria increased significantly compared with the inoculated sludge. An efficient and stable nitrogen removal rate can be achieved, and the follow-up processing cost can be reduced, by application of the SNAD treatment process for ADLSW.

Investigating adsorption performance of heavy metals onto humic acid from sludge using Fourier-transform infrared combined with two-dimensional correlation spectroscopy.

Efforts to improve sludge resource utilization have become increasingly important. In this study, humic acid (HA) was extracted from sludge samples collected from a sewage treatment plant, and then used for the adsorption of heavy metals. We used two-dimensional correlation spectroscopy (2D-COS) integrated with Fourier-transform infrared spectroscopy (FTIR) to explore the adsorption between sludge HA (HA) and three metal ions (Cu, Ni, and Pb). The resulting adsorbing data conformed to the isotherm of Langmuir adsorption. The maximum capacity values (qm) were 5.34, 1.49, and 26.29.8 mg/g for Cu, Ni, and Pb, respectively. The data from 2D-FTIR-COS analysis showed that the susceptibility of the functional group followed the order 2300 → 1130 → 1330 → 1480 → 1580 cm-1 for Cu(II) and Ni(II), and 2300 → 1130 → 1330 → 1480 → 1200 → 1580 cm-1 for Pb(II). The sludge HA with Pb(II) showed more adsorption sites than sludge HA with Cu(II) and Ni(II), and these adsorption sites could preferentially bond with Pb(II) at × 1 compared with Cu(II) and Ni(II). Our findings indicate that 2D-FTIR-COS technology has great potential for application as a useful tool for understanding the adsorption mechanism between adsorbents with heavy metals.

[Start-up of Partial Nitritation AGS-SBR and Analysis of Its Microbial Community Composition].

The mature aerobic granular sludge (AGS) was inoculated in an sequencing batch reactor (SBR) to treat the simulation wastewater with low carbon nitrogen ratio (COD/N). The start-up characteristics of partial nitritation (PN) based on gradually increasing influent ammonia concentration strategy were investigated. The reactor was operated at dissolved oxygen (DO) of 0.8 mg·L-1, pH 7.5-8.5 and 30℃.The PN was realized in the AGS-SBR within 60 days. From day 61 and onwards, the nitrite accumulation efficiency of 80% was achieved throughout the experiment. Meanwhile, the total nitrogen average removal rate was maintained at a relatively high level of 64.54%, and the effluent NO2--N/NH4+-N ratio reached 1.16, which was a suitable mixture to feed subsequent anammox. Finally, we also investigated the bacterial abundances in AGS-SBR in the PN period (PN-AGS-SBR) through Illumina 16S rRNA gene MiSeq sequencing. The dominant microbial communities at genus level were subjected to sequence analysis. The results revealed that the relative abundance of Candidate-division-TM7-norank was 68.63%, Saprospiraceae-uncultured was 8.26%, Thauera was 4.63%, Denitratisoma was 3.16%, Anaerolineaceae-uncultured was 1.63% and Anaerovorax was 1.39%, respectively. Nitrosomonas, Thauera, Denitratisoma and Bacillu were considered as the main organisms responsible for nitrogen removal. Meanwhile, various denitrification pathways, such as autotrophic denitrification, the denitrification and anaerobic ammonia oxidation of nitrogen, coexisted in PN-AGS-SBR system.