摘要 : The regulation of the accumulation of NO 2 - -N in the partial nitritation system with low ammonia concentration by enhanced light is of great significance for coupling with anammox to form a completely autotrophic biological nitrogen removal process. In this study, the effects of different light wavelengths on the nitrogen conversion performance and functional microbial community in partial nitritation system were investigated. The results indicated that all wavelengths of light can promote the conversion of NH 4 + -N, among which blue light had the most obvious promoting effect. Both blue light and UVA had stable inhibitory effects on the activity of nitrite-oxidizing bacteria (NOB), leading to an increase in the accumulation of NO 2 - -N. Microorganisms alleviated the oxidative stress exerted by different light wavelengths on the system by increasing the secretion of extracellular polymeric substances (EPS) and the activity of antioxidant enzymes. Notably, both EPS concentration and catalase activity were found to be highest in the blue light treatment. The relative abundances of the nitrosifying bacterial genera Ellin6067 and Nitrosomonas were enhanced by all light wavelengths, whereas the nitrifying bacterial genus Nitrospira constituted only 0.14% in the blue light reactor. The relative abundances of the DNA damage repair gene unrA, the electron transport chain functional gene coxA, and the photosensitive receptor protein gene bluF in the partial nitritation system were found to be upregulated by blue light. Blue light enhanced the stable operation of the partial nitritation system and can be used as the optimal light for regulating NO 2 - -N accumulation in the algal-bacterial symbiotic system.

摘要 : Thiourea can significantly inhibit the aerobic ammonia oxidation process, yet it can also serve as a multi‐electron donor in denitrification. Understanding the perturbational influence of thiourea on nitrogen removal in anaerobic ammonium oxidation (Anammox) systems is crucial for its application in treating high NH4+-N wastewater containing thiourea. Therefore, the present inquiry investigated its effects on nitrogen degradation pathways and microbial metabolism in Anammox systems. The findings reveal that when the influent thiourea concentration remains below 139.7 mg/L, both sulfur-oxidizing autotrophic denitrifiers (SOB) and their heterotrophic denitrifiers residing in the Anammox reactor fully metabolize this compound. They use NO2--N/NO3--N as electron acceptors, converting thiourea into SO42- and NH4+-N. The activity of Anammox bacteria (AnAOB) was not significantly affected. However, the activity of the associated ammonia-oxidizing bacteria (AOB) was significantly inhibited, and nitrite-oxidizing bacteria (NOB) took over to mitigate the dissolved oxygen toxicity in the influent. The denitrifying microbial community in the Anammox system, originally dominated by AnAOB, shifted toward a multifunctional denitrifying community dominated by heterotrophic denitrifiers, SOB, and AnAOB. As thiourea concentrations increase, denitrifying microorganisms struggle to grow synergistically, leading to thiourea accumulation. Oxidative stress in the system rises, and catalase (CAT) activity is inhibited, resulting in cellular damage. Accumulated thiourea reduced the relative abundances of core genes hzs and hdh in AnAOB and sqr in SOB. Although the relative abundances of fccA/fccB in SOB and nirS in denitrifiers were upregulated, these potential functional changes could not counteract thiourea toxicity. AnAOB activity is restricted and cannot be restored in the short-term. Thiobacillus and Candidatus_Brocadia, as functional genera of SOB and AnAOB, respectively, exhibit abundance that varies with changes in nitrogen-sulfur transformation performance. Enhancing sulfur-autotrophic and heterotrophic denitrification to prevent thiourea accumulation is a key strategy for alleviating the denitrification stress imposed on the Anammox system.

摘要 : This study systematically investigated the phosphorus (P) adsorption and release behaviors of biofilm extracellular polymeric substances (EPS) in a sequencing batch biofilm reactor (SBBR). Batch experiments, enzyme activity assays, P forms, and spectral characterizations (3D-EEM, FTIR, XPS) were integrated to elucidate the independent role of EPS in biofilm P metabolism. The results quantified the independent P adsorption and release capacities of EPS as 1.68 mg/g and 2.46 mg/g, respectively. Different from cell-dependent biological P metabolism, EPS-mediated P transformation was insensitive to dissolved oxygen variation and carbon addition, and was mainly dominated by physicochemical adsorption. EPS-derived orthophosphate (Orth-P) and polyphosphate (Poly-P) contributed over 67% and less than 12% to the total Orth-P and Poly-P metabolism of biofilms, respectively. Although polyphosphate kinase (PPK) and polyphosphate hydrolase (PPX) activities were detected in EPS, the lack of effective carbon utilization capacity restricted their involvement in Poly-P transformation. Metal-mediated complexation served as the core immobilization pathway, in which Ca2+ and Mg2+ bound with phosphate groups, as well as carboxyl and amino functional groups of tryptophan- and tyrosine-rich proteins in EPS. Beyond the inherent physicochemical adsorption properties of EPS, microbial cells further regulated EPS content by aerobic biosynthesis and anaerobic biodegradation. Such microbial regulation synergistically optimized the P adsorption-release performance of EPS, verifying that EPS acts as the dominant functional component responsible for P transformation in biofilm systems. This study clarifies the intrinsic mechanisms underlying EPS-mediated P adsorption and release, and provides a theoretical basis for the development of low-carbon and high-efficiency P recovery technologies.

摘要 : Current mainstream sequencing batch biofilm reactor (SBBR) processes has the problem of that the concentration of phosphate recovery liquid (P RL ) is difficult to be improved after reaching the highest. This study found that only the three-step carbon dosing strategy could increase the concentration of P RL after comparing the regulation of the dissolved oxygen (DO), hydraulic retention time (HRT), pH, P concentration in influent and temperature. After treatment with the three-step carbon dosing strategy, P RL concentration were improved by 10.23 mg/L with shorter harvest cycle and lower carbon source dosing. The COD/Prel decreased by 28.4 % in each phosphate harvest cycle, indicating that the optimal regulation strategy improved the economic benefits of phosphorus recovery by SBBR. The carbon source stimulation of the optimal regulatory strategy not only activated the enzyme activities of phosphate kinase (PPK) and exopolyphosphatase (PPX) to enhance the Poly-P metabolism of cells, but also reduced the extracellular polymeric substances (EPS) content in the anaerobic phase to facilitate the Orth-P desorption and apatite phosphorus (AP) shedding from EPS, so as to realize the simultaneous enhancement of phosphorus absorption and release of cells and EPS. This study explored the mechanism of optimal carbon source regulation strategy to improve the efficiency of phosphorus recovery, and provided regulatory guidance for the economical and efficient phosphorus recovery of biofilm process.

摘要 : The application of biofilm-based phosphorus enrichment technology has been hampered by the limited information on the performance, microbial interactions and metabolic patterns of dominant functional bacteria, especially those fed with complex carbon sources conditions. In this study, three representative carbon sources contained in real sewage, i.e., volatile fatty acids (VFAs), glucose, and amino acids were selected as the complex carbon sources. The comparison in phosphorus removal/enrichment performance, carbon utilization, and metabolic characteristics were performed during the biofilm system changed the sole carbon source (acetate sodium) feeding to complex carbon source feeding gradually. The performance reduction and instability were observed in initial stage of complex carbon source feeding, while the phosphorus removal/enrichment efficiency improved significantly after long-term acclimation by extending the anaerobic HRT. The concentration of phosphorus enrichment solution exceeded 50 mg/L, meanwhile the total nitrogen and total phosphorus removal efficiencies over 82 % and 97 %, respectively. Intriguing, intracellular organic phosphorus (OP) contents fluctuated with phosphorus uptake and release, which may be a hint of the important role of OP in PAOs energy conversion. Complex carbon sources induced the succession of biofilm community, especially the enrichment of hydrolytic fermentation bacteria, and a more intricate microbial interaction network among functional microbiota. The co-occurrence of the EMP and ED pathways during glycolysis implied more extensive carbon utilization pathways, and amino acids was speculated to complement intracellular energy metabolism via the tricarboxylic acid cycle (TCA). This study demonstrated that the biofilm systems have great potential to simultaneously achieve phosphorus removal and enrichment by using complex carbon sources in sewage wastewater.

摘要 : The treatment of high-salinity industrial wastewater challenges conventional biological processes. This study investigated the effects of high salt concentrations on anaerobic digestion (AD) and a coupled partial nitrification-anaerobic ammonium oxidation (PN/A) process using actual casing wastewater as the carrier. This process aims to achieve low-carbon denitrification and efficient energy utilization. Results showed that as the salinity increased from 1 % to 3.5 %, the degradation of tyrosine-like and tryptophan-like substances in AD was gradually inhibited, and the COD removal rate decreased from 12.0 ± 0.5 kg/(m3·d) to 5.4 ± 0.1 kg/(m3·d). The PN/A process exhibited low-promotion and high-inhibition. At 1.6 % salinity and 800 mg/L COD in AD effluent, total nitrogen removal rate (TNRR) of PN/A increased to 0.39 ± 0.02 kg/(m3·d). When salinity reached 3.5 % with 2300 mg/L COD in AD effluent, TNRR declined to 0.30 ± 0.01 kg/(m3·d). Compared with inoculated sludge, reactive oxygen species (ROS) in AD increased by 3.69 times, while PN/A only increased by 1.12 times, as it formed an effective ROS clearance system. The salt tolerance was governed by the synergistic "EPS barrier-antioxidant enzyme" mechanism. Methanobacterium has always been the dominant bacteria in AD. The abundance of Nitrosomona s first increased and then decreased, while Candidatus_Kuenenia and Candidatus_Brocadia gradually increased in PN/A.

摘要 : Realizing the full-scale treatment of aged landfill leachate with high NH 4 + -N, low carbon-to‐nitrogen (C/N) ratio and containing a large amount of refractory organic matter is an urgent problem to be solved. Constructed a partial denitrification/anammox (PD/A)-partial nitrification/anammox (PN/A)-alternating electrochemical oxidation/denitrification process to explore the feasibility of efficiently utilizing all organic carbon source of raw water to achieve aged landfill leachate full-scale treatment. The results show that the PN/A system could efficiently remove NH 4 + -N from wastewater without relying on carbon sources. Meanwhile, it utilizes biodegradable organic matter (BOD) in raw water to convert the NO 3 − -N produced into NO 2 − -N for reuse by anammox. When BOD/TN is 0.5, the total nitrogen (TN) removal rate of PD/A-PN/A system reaches >90 %. Under the conditions of a pH of 7 and a current density of 40 mA/cm 2, the BOD5/COD ratio of refractory organic matter was further increased through electrochemical oxidation, achieving deep denitrification removal of nitrogen from PD/A-PN/A effluent, and reducing COD and TN to approximately 100 and 20 mg/L, respectively. The low-consumption and high-efficiency treatment of aged landfill leachate is achieved without the addition of organic matter or the discharge of concentrated liquid.

摘要 : The simultaneous nitrification-denitrification (SND) process has been widely studied for cost-effective nitrogen (N) removal. However, integrating SND with the phosphorus (P) enrichment process in the one-stage system remains challenging due to the conflicting conditions (low vs. high DO) and design principles. Herein, we demonstrated this integration in a single biofilm reactor under alternating anaerobic/aerobic conditions, achieving 94 % of NH4+-N and 93 % of TN removal under high-DO operation (5–6 mg/L) and obtaining 75.7 mg/L P-enriched solution in the anaerobic stage. The dynamic test in situ and stoichiometric evaluations showed that SND was the main N removal pathway at high DO conditions, which was rate-limited by the nitridation process. The ex-situ denitrification batch tests revealed that NO 3 −-N was the primary electron acceptor in the aerobic denitrification process, which was mainly attributed to the DGAOs using the intracellular carbon source, as well as the DPAOs. The latter cooperated with the APAOs and contributed to P removal. The macro-genome sequencing further revealed that DGAOs ( Pseudoxanthomonas and Sulfuritalea et al. ) were the dominant denitrifiers in the P enrichment system due to a series of denitrifying genes' high expression. That implied the DGAOs have a higher tolerance to high DO concentration, which was crucial to performing SND in the P enrichment system. These findings shed light on the positive roles of DGAOs in the denitrification process and lay an experimental basis for developing a new feasible technical route for simultaneous N removal and P enrichment in a single-stage system.

摘要 : This study investigated the impact of different operational sequences on phosphorus removal and enrichment in biofilm phosphorus enrichment system. The research com-pared two distinct operational modes, analyzing phosphorus uptake and release characteristics in cells and extracellular polymeric substances (EPS) over a single cycle, while also examining microbial community composition and associated functional genes. After long-term acclimation, the Ae/An system achieved higher phosphorus concentration (120 mg/L) than the An/Ae system (65 mg/L). However, the An/Ae system showed stronger phosphorus uptake and release capabilities due to higher phosphorus load during the aerobic phase. In both systems, Mg-P and Ca-P dominated in cells and EPS. Compared to the Ae/An system, the An/Ae system stored phosphorus mainly in EPS, with higher orthophosphate content. However, EPS-associated phosphorus is more easily released, explaining the An/Ae system's higher aerobic phosphorus load but lower overall storage capacity. Microbial analysis revealed higher abundance of phosphorus accumulating organisms (PAOs) in the An/Ae system (25.99 % vs. 19.69 %), while glycogen accumulating organisms (GAOs) showed the opposite trend. Candidatus Competibacter was abundant in both systems and correlated with phosphorus metabolism genes. The An/Ae system expressed the pst system more, whereas the Ae/An favored the pit system, suggesting that transfer system variations affect enrichment solution concentration. Lower expression of polyphosphate kinase ( ppk1 ) in the An/Ae system may explain its unsatisfied phosphorus enrichment performance. Mantel analysis confirmed connections among environmental factors, kinetic parameters, phosphorus metabolism genes, and phosphorus morphology in EPS, demonstrating their combined influence on enrichment solution concentration.

摘要 : A high phosphate (P) recovery concentration was achieved in pilot-scale biofilm sequencing batch reactor (BSBR) with a low carbon source (C) cost. Especially, a high-abundance glycogen-accumulating organisms (GAOs) (13.93–31.72%) was detected that was accompanied by a high P recovery concentration of BSBR. High-abundance GAOs obtain additional C through various C compensation pathways (split tricarboxylic acid cycle (TCA cycle), glyoxylate shunt and gluconeogenesis), thus reducing the need to compete with polyphosphate-accumulating organisms (PAOs) for C and weakening the adverse effects on P recovery by PAO cells. Under the action of N -acyl homoserine lactones (AHLs)-mediated quorum sensing (QS), GAOs promoted the secretion of a large amount of extracellular polymeric substances (EPS), which helped to realize the P recovery of EPS-dominated biofilms (68.02%–96.89%). This study provides a low-carbon technology for the recovery of high concentration P from municipal wastewater, and improves the ecological theory of P recovery in collaboration with GAOs and PAOs.