摘要 : The key conditions and inhibition mechanism in nitrification process were analysed by using different sludge sources and anoxic/aerobic ratios of intermittent aeration process under mainstream conditions. The results showed that nitrite accumulation was difficult to obtain in partial nitrification system relying only under low-dissolve oxygen (DO) and intermittent aeration. When coupled with anammox process, NO3--N concentration in effluent decreased from 41.64mg/L to 11.54mg/L under the same NH4+-N conversion environment, and the nitrification process was significantly inhibited. The quantitative analysis shows that Nitrate-oxidizing bacteria (NOB) had strong adaptability in the environment of low-DO and intermittent aeration, with a maximum increase of 2.9 times after 15days of operation, while in a mixed system with anammox bacteria, the maximum increase was only 1.4 times. The results of microbial community structure change showed that in low DO coupled intermittent aeration environment, the abundance of NOB inoculated in mixed sludge system increased faster than that in nitrification sludge system. Therefore, strengthening nitrite utilization and reducing its exposure concentration in aerobic stage is a key condition for achieving NOB inhibition in intermittent aeration process.

摘要 : Municipal sewage sludge was used as raw substrate for hydrothermal treatment in order to obtain soluble organic polymers (SOP), which can be modified to aggregation media. The characteristics of SOP were investigated under various hydrothermal conditions with different temperatures (150, 175, 200 and 225 °C), reaction times (0.5, 1 and 1.5 h) and amounts of alkaline additives. The results showed that the SOP yield decreased gradually with increasing temperature and reaction time, from 28.5% (150 °C-0.5 h) to 14.73% (200 °C-0.5 h). The alkali addition boosted the SOP yield, besides, NaOH had a better effect than Na2CO3. Elemental analysis demonstrated that the increase of temperature led to the decrease of O/C and H/C of SOP, which meaned the increase of humification and aromatization. Results of infrared spectroscopy and X-ray photoelectron spectroscopy indicated that the increase in temperature led to a decrease in the oxygen-containing functional groups. Thus, the hydrothermal conditions at 150 °C, 0.5 h, and NaOH dosing of 10% (w/w of dry weight ) were optimal to obtain SOP as precursors for aggregation media preparation. This study can provide a reference for the reuse of sewage sludge.

摘要 : Decentralized treatment of wastewater in rural areas usually has several challenges, which include large fluctuations in pollutant concentration and water quantity, complicated operation and maintenance of conventional biochemical treatment equipment, resulting in poor stability and a low compliance rate of the wastewater treatment process. In order to solve the above problems, a new integration reactor is designed, which uses gravity and aeration tail gas self-reflux technology to realize the reflux of sludge and the nitrification liquid, respectively. The feasibility and operation characteristics of its application for decentralized wastewater treatment in rural areas are explored. The results demonstrated that, under constant influent, the device showed strong tolerance to the shock of pollutant load. The chemical oxygen demand, NH 4 + -N, total nitrogen and total phosphorus fluctuated in the ranges of 95–715 mg/L, 7.6–38.5 mg/L, 9.32–40.3 mg/L and 0.84–4.9 mg/L, respectively. The corresponding effluent compliance rates were 82.1%, 92.8%, 96.4% and 96.3%, respectively. When the wastewater discharge was non-constant and the maximum single-day Q max / Q min reached 5, all indicators of the effluent met the relevant discharge standard. The integrated device also demonstrated high phosphorus enrichment levels in its anaerobic zone; the concentration of phosphorus reached a maximum of 26.9 mg/L, which created a good environment for phosphorus removal. The microbial community analysis showed that sludge digestion, denitrification, and phosphorus-accumulating bacteria all played an important role in pollutant treatment.

摘要 : The formation of dominant phosphate-accumulating organisms (PAOs) is essential for the high enrichment of phosphate in biofilm sequencing batch reactors (BSBR) for phosphorus recovery. The dominant PAOs in the biofilm process have not been isolated and purified, and the key metabolic pathways that promote the formation of dominant PAOs are still unclear. In this study, four strains of highly-efficient PAOs were obtained by an innovative isolation procedure. The relationship between the abundance of highly-efficient and dominant PAOs and the phosphate removal ability was compared. We found that the abundance of PAOs was positively correlated with the phosphate removal efficiency in vitro pure culture and complex biofilm process. Metagenomics analysis revealed that compared with highly-efficient PAOs cultured in vitro, dominant PAOs in biofilms had unique key metabolic pathways, F-ATPases and N-Acyl homoserine lactones (AHLs). F-ATPases are important for maintaining the proton motive force (PMF) required for the uptake of carbon sources by PAOs, and AHLs are participating in phosphate metabolism through quorum sensing (QS) mediated secretion of extracellular polymeric substance (EPS). The formation of dominant PAOs was promoted by optimizing carbon source uptake and phosphate metabolism. This study revealed that the difficult isolation of dominant PAOs was due to the AHLs-mediated QS, and we identified the key pathways regulating the formation of dominant PAOs in biofilms through genomics analysis. Our findings provide insights in enhancing phosphate enrichment in BSBR by modulating the components of microbial community under the low concentration of carbon source consumption.

摘要 : Capturing the abundant organic matter residing in wastewater can not only reduce the emission of CO 2 from the source, but the enriched organics can also be used for anaerobic fermentation to generate and offset energy consumption in wastewater treatment processes . The key is to find or develop low-cost materials that can capture organic matter. Herein, sewage sludge-derived cationic aggregates (SBC-g-DMC) were successfully prepared via a hydrothermal carbonization process coupled with a graft copolymerization reaction for recovering organic matter from wastewater. Based upon preliminary screening of synthesized SBC-g-DMC aggregates regarding grafting rate, cationic degree, and flocculation performance, SBC-g-DMC 2.5 aggregate prepared with 60 mg of initiator, DMC-to-SBC mass ratio of 2.5:1, 70 °C, and 2 h of reaction time was selected for further characterization and evaluation. Results showed that SBC-g-DMC 2.5 aggregate has a positively-charged surface over a wide pH range of 3–11 and a hierarchical micro-/nano-structure, endowing it with an excellent organic matter capture efficiency (97.2% of pCOD, 68.8% of cCOD, and 71.2% of tCOD). Meanwhile, SBC-g-DMC 2.5 exhibits inappreciable trapping ability for the dissolved COD, NH 3 –N, and PO 4 3−, guaranteeing the regular running of subsequent biological treatment units. Electronic neutralization, adsorption bridging, and sweep coagulation between cationic aggregates surface and organic matter were identified as the primary mechanisms for SBC-g-DMC 2.5 to capture organics. This development is expected to provide a theoretical reference for sewage sludge disposal, carbon reduction, and energy recovery during municipal wastewater treatment.

摘要 : In this paper, the effects of ammonia concentration in synthetic sewage on the phosphorus (P) enrichment performance, P uptake and release rate of biofilm were investigated in an anaerobic/aerobic polyphosphate accumulating organisms biofilm reactor. The results showed that an increase of ammonia from 15mg-N/L to 30mg-N/L stimulated the P uptake rate of denitrifying polyphosphate accumulating organisms while weaken the PAOs, which resulted in the phosphate uptake rates (PUR) of 11.25mg-P/(L·h), and phosphate release rate (PRR) of 12.02mg-P/(L·h) for the biofilm system. The P concentration in enriched stream reached 52mg-P/L. The uptake and release of P mainly depended on DPAOs when further increase of ammonia to 40mg-N/L, whereas the PAOs metabolism was almost suppressed. As a consequence, the P concentration in enrichment stream was only 40mg-P/L with 8.65mg-P/(L·h) of PUR and 8.81mg-P/(L·h) of PRR. Stoichiometric analysis showed the Prel/HAcupt(the P released per organics uptake) of the biofilm system witnessed a rising and decent trend, with an increase of ammonia from 15mg-N/L to 40mg-N/L. The average values of Prel/HAcuptunder different ammonia concentrations were 0.06, 0.11and 0.07P-mmol/C-mmol, respectively. The adverse effect of ammonia (40mg-N/L) can be eliminat by decrease the volume ratio of sewage stream and enrichment stream (from 3:1 to 1.5:1). Specifically, the PUR and PRR of biofilm reached 16.25mg-P/(L·h) and 15.60mg-P/(L·h) respectively, resulting in a enrichment stream of 70mg-P/L. Meanwhile, the Prel/HAcupt rised up to 0.29P-mmol/C-mmol. The resuls of present study showed that the P enrichment performance in PAOs-biofilm was not affected by ammonia (< 40mg-N/L), also, the nitrogen removal efficiency reached 95%. Therefore, PAOs-biofilm-based technology is of great potential in simultaneous P enrichment and nitrogen removal from sewage.

摘要 : Municipal sewage is characterized by low temperature and low ammonia nitrogen (NH4+-N), and nitrite oxidizing bacteria (NOB) can hardly be stably inhibited for a long time, while excessive proliferation of NOB will lead to the increase of NO3--N in effluent, which will produce competitive inhibition on other functional microorganisms, thus, the nitrogen removal performance and stability of partial nitrosation-anammox (PN/A) system is reduce. Based on the dynamic parameters and growth characteristics of functional microorganisms such as ammonia oxidizing bacteria (AOB), NOB and anaerobic ammonium oxidation bacteria (AnAOB), the changes of dominant functional microorganisms under mainstream conditions were discussed. The commonly used NOB inhibition strategies, such as low soluble oxygen (DO restriction), aerobic and hypoxia alternations, bioenhancement, inhibitor injection, mud age (SRT) panning, and low nitazine, were reviewed. It was concluded that a single inhibition strategy could not inhibit NOB activity in a long-term and stablly, and the combined effects of multiple strategies should be further investigated. Then, from the aspect of performance and the complexity of the process, the reaction system widely used to realize the joint control of multiple strategies was discussed. The method of combining activated sludge model (ASM) with experiment was proposed, which could provide a new idea for facilitating the operation and regulation of mainstream PN/A process. It was also pointed out that deeping the research of basic theories and developing a new combined process to strengthen the inhibition of NOB and the stability of nitrogen removal performance would also be a feasible development direction.

摘要 : Double short-cut sulfur autotrophic denitrification (DSSADN) coupled with Anammox is of great significance in the low-carbon treatment of nitrogen-containing wastewater. In order to achieve high salinity autotrophic nitrogen removal, the effects of different salinities on the accumulation characteristics of NO2--N and S0 and microorganisms in DSSADN process were studied. The results showed that the effect of salinity on the DSSADN process could be categorized into the stimulation, stable, and inhibition. When the salinity gradually increased to 2.5 %, the highest NO2--N production rate (NiPR) and S0 production rate (S0PR) of DSSADN were 0.54 kg/(m3·d) and 1.1 kg/(m3·d) respectively. NiPR and S0PR gradually decreased as the salinity increased to more than 3 %. However, salinity had a relatively low impact on nitrite accumulation efficiency and S0 accumulation efficiency, which were 80 % and 81.5 %, respectively, when the salinity reached 5 %. Salinity has a great influence on the structure and abundance of microbial communities in the system.

摘要 : The feasibility of anaerobic membrane bioreactor (AnMBR) for the treatment of N, N-dimethylformamide (DMF)-containing wastewater was theoretically compared with the conventional activated sludge (CAS) process in this study. The electricity consumption and expenditure, bio-energy production and CO2 emission were investigated using the operational results of a lab-scale AnMBR operated in a long-term operation. The AnMBR was capable of producing bio-methane from wastewater and generated 3.45 kWh/m3 of electricity as recovered bio-energy while the CAS just generated 1.17 kWh/m3 of electricity from the post-treatment of excessive sludge disposal. The large quantity of bio-methane recovered by the AnMBR can also be sold as sustainable bioresource for the use of household natural gas with a theoretical profit gain of 29,821 US$/year, while that of the CAS was unprofitable. The AnMBR was also demonstrated to significantly reduce the carbon emission by obtaining a theoretical negative CO2 production of -2.34 kg CO2/m3 with the recycle of bio-energy while that for the CAS was 4.50 kg CO2/m3. The results of this study demonstrate that the AnMBR process has promising potential for the carbon-neutral treatment of high-strength DMF-containing wastewater in the future.

摘要 : The effects of salinity on anaerobic nitrogen and sulfide removal were investigated in a coupled anammox and short-cut sulfur autotrophic denitrification (SSADN) system. The results revealed that salinity had significant nonlinear effects on the nitrogen and sulfur transformations in the coupled system. When the salinity was <2 %, the anammox and SSADN activities increased with increasing salinity, and the total nitrogen removal rate, S0 production rate, and nitrite production rate were 0.41 kg/(m3·d), 0.37 kg/(m3·d), and 0.28 kg/(m3·d), respectively. With continuous increase of salinity, the performances of the anammox and SSADN gradually decreased, and the three indicators decreased to 0.14 kg/(m3·d), 0.22 kg/(m3·d), and 0.14 kg/(m3·d) at 5 % salinity, respectively. When the salinity reached 5 %, the nitrogen removal contribution of anammox decreased to 68.4 %, while the contribution of the sulfur autotrophic denitrification increased to 31.6 %. The coupled system recovered in a short time after alleviation of the salinity stress, and the SSADN activity recovery was faster than anammox. The microbial community structure and functional microbial abundance in the coupled system changed significantly with increasing salinity, and the functional microbial abundance after recovery was considerably different from the initial state.