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Sulfur autotrophic denitrifiers and heterotrophic denitrifiers widely exist in aquatic ecosystem, however, the response of sulfide to the microbial community structure in mixotrophic denitrification ecosystem is unknown yet. In this study, the denitrification performance and microbial community were explored by changing the molar ratio of influent C/N/S. From the level of genus, the joint action of Thauera, Pacacoccus, Fusibacter Pseudoxanthomonas, Thiobacillus, Sulfurovum and Sulfurimonas brought about the efficient denitrification performance in the mixotrophic system. Thauera increased from from 0.97% to more than 13%, and the relative abundances of Thiobacillus and Sulfurimonas were about 4.14% and 3.89% separately after adding S

Anammox and sulfide-dependent autotrophic denitrification (ASDAD) coupling system can improve the nitrogen removal, but high sulfide concentration will affect the activity of anaerobic ammonia-oxidizing bacteria (AnAOB). Gel immobilization technology can enhance the survivability of microorganisms in unsuitable environments. Therefore, in this investigation, gel immobilization technology was applied into the ASDAD coupling system to explore the removal performance and microbial communities. The results showed that the optimal S

This study investigated the shock resistance and the stability of a novel sulfide-dependent autotrophic denitrification (SDAD) and anaerobic ammonium oxidation (Anammox) coupling process for simultaneous removal of sulfide and nitrogen-containing wastewater in a single reactor. Results show that the total nitrogen (TN) removal efficiency reached 86.7% at a nitrogen loading rate (NLR) of 1.52 kgN m−3 d−1. Sulfide was fully oxidized, achieving the removal efficiency of 100% throughout the whole process. Batch tests suggest that Anammox remained dominant with the cooperation of partial SDAD (PSDAD) and could always compete over short-cut SDAD (SSDAD) for nitrite. High-throughput sequencing analysis revealed that Anammox bacteria remained active despite a relatively lower abundance and diversity than denitrifying bacteria. Candidatus Kuenenia might be the main contributor to Anammox, while Thiobacillus and Sulfurimonas were closely related to SDAD.

This work focuses to investigate the impact of lignin content on chemical compositions, crystallinity, surface characterizations, cellulase adsorption profiles and hydrolysability of Hybrid Pennisetum (HP) after alkaline sulfite pretreatment (ASP). For the HP with lower lignin content, the increase of the cellulose content by ASP was more obvious than raw HP. ASP decreased total lignin content and surface lignin content of HP substrates. HP with lower lignin content (e.g., ∼15%) is suitable for ASP, because a pretty perfect glucose yield (91%) was obtained using a low dosage of enzyme loadings (5 FPU of cellulases/g dry matter). The study provides a potential strategy to efficiently produce platform sugars from HP with reduced lignin content, indicating the importance of reduction HP lignin content properly by breeding or transgenesis programs. The work could also help elucidate the mechanism of alkaline sulfite pretreatment for efficient production of fermentable sugars from lignocelluloses.

The effect of glucose on nitrogen removal and microbial communities in the anammox-denitrification systems was investigated. The optimal nitrogen removal could be achieved when the influent glucose concentration was 56.4mgL-1. The influent nitrite to ammonium ratio of 0.95-1.40 would not obviously affect the nitrogen removal due to the coexistence of anammox, denitrification and partial denitrification. The anammox activity was deteriorated with increasing glucose concentration. When the influent glucose concentration was increased to 374.9mgL-1, the average ammonium removal efficiency decreased from 97% to around 10% and anammox activity was seriously inhibited. The anammox activity quickly recovered with decreasing influent glucose and increasing influent nitrite. High-throughput sequencing analysis suggested that the predominant genus changed from Candidatus Kuenenia to Diaphorobacter with the addition of glucose and then changed to Hydrogenophaga with the decrease of glucose. It indicated that organics concentration had an effect on the microbial communities.

The impact of lignin extracted from γ-valerolactone/water (GVL/H2O) pretreatment of corn stover on the enzymatic hydrolysis of cellulose was investigated. Two lignin samples were separated and named as GL25 and GL75 according to the amounts of sulfuric acid (25 mM and 75 mM) used in the GVL/H2O pretreatment. With the addition of 2 g/L of GL25 and GL75, the glucan conversion of enzymatic hydrolysis of Avicel improved markedly from 28.0% to 37.4% and 31.3%, respectively. Moreover, the improvement of glucan conversion increased when increasing the loadings of GL25 and GL75. A similar observation was made when GVL/H2O pretreated corn stover was the substrate. The results of the cellulase adsorption experiments showed that the GLs had a lower maximum cellulase adsorption capacity and binding strength compared to that of acid-insoluble lignin. Further structural characterization of the GLs revealed that they had a low zeta-potential and hydrophobicity, but a high Syringyl/Guaiacyl ratio.

A kind of reduced graphene oxide decorated with titanium-based (RGO/TiO2) composites are successfully synthesized and employed in this current study as a novel nonprecious metal catalyst for enhancing bioelectricity generation and cathodic oxygen reduction reaction (ORR) in single chamber microbial fuel cells (MFCs). Compared with commercial Pt/C, RGO/TiO2 shows obviously enhanced oxygen reduction reaction activity due to the appropriately-permeated, large electrochemical active area, enough exposure of electrocatalytic active sites of RGO/TiO2. The air-cathode MFC with RGO/TiO2-1 cathode achieves 1786.7 mW m−3 of power density, 86.7% ± 1.2% of COD removal and 31.6% ± 1.1% of CE, which are higher than commercial Pt/C. Moreover, RGO/TiO2-1 cathode exhibits high-effective electrocatalytic activity, and the power density of RGO/TiO2-1 can keep a stable level and only has a minor decline (5.35%) during 30-cycles operation. These results indicate that RGO/TiO2-1 is a potential cathode catalyst, markedly enhancing cathode ORR, wastewater treatment efficiency, and bioelectricity generation of MFC.

The impact of γ-valerolactone/water (GVL/H2O) pretreatment coupled with alkaline post-incubation on the digestibility of cellulose substrates was investigated. When Avicel was pretreated by GVL/H2O with H2SO4 as catalyst, the glucan conversion decreased from 27% (untreated Avicel) to 16% due to the esterification of cellulose after pretreatment. After incubation of GVL/H2O pretreated Avicel with 1% NaOH at 50 °C for 1 h, the glucan conversion enhanced to 20%. When corn stover (CS) pretreated by GVL/H2O with 25 mM H2SO4 was used as substrate, alkaline post-incubation removed 72% and 50% of the hemicellulose and lignin, respectively, and increased the glucan conversion by 1.9-fold consequently. Moreover, higher cellulases adsorption capacity, affinity and binding strength on GVL/H2O pretreated CS was achieved after alkaline post-incubation. These results indicated that the improved digestibility of GVL/H2O pretreated lignocellulose by alkaline post-incubation was attributed to the depletion of ester groups on cellulose and removal of hemicellulose and lignin.

Two up-flow blanket filter (UBF) reactors were employed to treat synthetic wastewater with different substrate concentrations and nitrogen load rates (NLR) for 178 days. During days 0–60, higher influent NLR of R 2 (0.21–0.58 kg·m 3 ·d) slowed down the formation of anammox sludge compared with the lower NLR of R 1 (0.18–0.31 kg·m 3 ·d). Difference in sludge color and nitrogen conversion rate indicated greater anammox activity of R 2 than R 1 . During days 61–178, R 1 and R 2 achieved the maximum nitrogen removal rates (NRR) of 1.213 and 1.684 kg/(m 3 ·d) under the NLRs of 1.924 and 2.502 kg/(m 3 ·d), respectively. Furthermore, high-throughput sequencing showed that R 2 (43.5%) had a higher proportion of anammox bacteria than R 1 (37.8%) and less species. These results showed that after going through a higher NLR acclimation process during start-up period, stronger resistant capability against high impact nitrogen load and greater anammox activity were obtained by R 2 .

Long-term performance of a two-stage partial nitritation (PN)-anaerobic ammonium oxidation (ANAMMOX) process treating mature landfill leachate was investigated. Stable partial nitritation performance was achieved in a sequencing batch reactor (SBR) using endpoint pH control, providing an effluent with a ratio of NO2(-)-N/NH4(+)-N at 1.23 ± 0.23. High rate nitrogen removal over 4 kg N/m(3)/d was observed in the ANAMMOX reactor in the first three months. However, during long-term operation, the ANAMMOX reactor can only stably operate under nitrogen load of 1 kg N/m(3)/d, with 85 ± 1% of nitrogen removal. The ammonium oxidizing bacteria (AOB) in the PN-SBR were mainly affiliated to Nitrosomonas sp. IWT514, Nitrosomonas eutropha and Nitrosomonas eutropha, the anaerobic ammonium oxidizing bacteria (AnAOB) in the ANAMMOX reactor were mainly affiliated to Kuenenia stuttgartiensis.

A novel sulfide-based denitrification and Anammox process was established for simultaneous removal of nitrogen and sulfide in a UBF reactor. The effects of the N/S ratio on reactor performance were investigated under five N/S molar ratios (4.56, 2.38, 0.96, 0.73, and 0.51). The best total nitrogen removal efficiency was 82.8% at a N/S ratio of 2.38. When the N/S ratio exceeded 0.96, Anammox contributed to more than 90% of the N loss. Sulfide was completely removed during the full operational period and S0 accumulation occurred when N/S ratio was less than 1. Thiobacillus (6.1%) and Candidatus Kuenenia (18.8%) were the main functional microorganisms when nitrate was in excess on day 12. As nitrate became limited on day 50, Thiobacillus (21.0%), Sulfurimonas (3.9%), and Candidatus Kuenenia (19.7%) became dominated. In this study, Candidatus Kuenenia was not inhibited by the sulfide.