This paper presents the results obtained for the effluent dewatering properties of anaerobic digestion of secondary sludge （SS） and anaerobic co-digestion of mixture of this sludge with the distillery wastewater （D...This paper presents the results obtained for the effluent dewatering properties of anaerobic digestion of secondary sludge （SS） and anaerobic co-digestion of mixture of this sludge with the distillery wastewater （DW） under thermophilic （55±1 ℃）, 5 L of working volume, three parallel lab-scale conditions. Its mixtures were prepared with a DW content of 25%and 50% and the C/N ratios of mixtures are 13.1 and 17.6, respectively. The effluent dewatering properties were evaluated under stable conditions which the biogas yield and the effluent pH were steady. The natural settleability, biogas yield, centrifugal dewatering, centrifugal supernatant turbidity and specific resistance filtration （SRF） were investigated. The results showed that the effluent dewatering properties of anaerobic co-digestion of mixtures between SS and DW were better than that of anaerobic digestion of SS alone. In the anaerobic digestion system with the feed were SS, mixture of SS and a DW content of 25%and 50% in order, the net biogas yield of secondary sludge in ADSA,ADSB and ADSC were 0.42 0.507 and 0.511 m3 biogass/kg.VS.d ; compared with the biogas yield in anaerobic digestion system A （ADSA）, the biogas yield in anaerobic digestion system B （ADSB） and anaerobic digestion system C （ADSC） had been increased by more than 20% respectively; the SRF of three digested sludge are（were） from 6.8×10^13, 1. 1×10^13 to 5.1×10^12 m/Kg, natural settling rates of 12 h are 26, 37 and 56% and that of 24 h are 32%, 45% and 59% respectively; the centrifugal dewatering rate of 3 min at speed of 1000 rpm were 16%, 31% and 51% respectively; the turbidity of centrifugal supernatant were 804, 754 and 678FTU simultaneously.展开更多
Nitrate is the leading cause of eutrophication worldwide and is one of the most challenging pollutants for restoration of polluted surface waters such as lakes, rivers and reservoirs. We report herein a new architectu...Nitrate is the leading cause of eutrophication worldwide and is one of the most challenging pollutants for restoration of polluted surface waters such as lakes, rivers and reservoirs. We report herein a new architecture of iron nanoparticles for high-efficiency denitrification by selective reduction of nitrate (NO3-) to dinitrogen (N2). The iron nanoparticles are doped with nitrogen (FeN) and encapsulated within a thin layer of nitride-carbon (NC). The nanoparticles have high pyrrolic N content (17.4 at.%) and large specific surface area (2040 m2/g). Laboratory experiments demonstrated high N2selectivity (91%) and nitrate removal capacity (6004 mg N/g Fe) for treatment of nitrate-containing water. This iron-based nanomaterial overcomes shortcomings of conventional catalysts by eliminating the use of precious and toxic heavy metals (e.g., Pd, Pt, Cu, Ni) and minimizing the generation of undesirable byproducts (e.g., ammonia) from the reactions with nanoscale zero-valent iron (n ZVI). The multiple electron transfers process from NO3- to N2can be fine-tuned by adjusting the NC shell thickness. Superior electrocatalytic perfor- mance, low cost and minimal environmental impact of the iron-derived nanocatalyst offer promising prospects for water purification, waste treatment and environmental remediation.展开更多
Sediment-water interfaces are important interfaces for lakes,which are related to most environmental and ecological problems.Wind-induced waves cause secondary pollution via sediment resuspension.Since the coupling me...Sediment-water interfaces are important interfaces for lakes,which are related to most environmental and ecological problems.Wind-induced waves cause secondary pollution via sediment resuspension.Since the coupling mechanism of water,resuspended sediments,and phosphorus affects the release of phosphorus(P)near the interface,a coupled model was explored for two sediment types with different adsorption-desorption capabilities to examine sediment resuspension and P release.The relationships among wind speed,wave characteristics,sediment distribution and P concentration were obtained.For different sediments,the unit sediment desorption release is negatively correlated with wind speed.When sediments are resuspended under low or moderate wind speed,the P concentration in the overlying water increases abruptly,hampering diffusion.P release exhibits the characteristics of concentrated release in a small region and changes the water environment rapidly.展开更多
文摘This paper presents the results obtained for the effluent dewatering properties of anaerobic digestion of secondary sludge （SS） and anaerobic co-digestion of mixture of this sludge with the distillery wastewater （DW） under thermophilic （55±1 ℃）, 5 L of working volume, three parallel lab-scale conditions. Its mixtures were prepared with a DW content of 25%and 50% and the C/N ratios of mixtures are 13.1 and 17.6, respectively. The effluent dewatering properties were evaluated under stable conditions which the biogas yield and the effluent pH were steady. The natural settleability, biogas yield, centrifugal dewatering, centrifugal supernatant turbidity and specific resistance filtration （SRF） were investigated. The results showed that the effluent dewatering properties of anaerobic co-digestion of mixtures between SS and DW were better than that of anaerobic digestion of SS alone. In the anaerobic digestion system with the feed were SS, mixture of SS and a DW content of 25%and 50% in order, the net biogas yield of secondary sludge in ADSA,ADSB and ADSC were 0.42 0.507 and 0.511 m3 biogass/kg.VS.d ; compared with the biogas yield in anaerobic digestion system A （ADSA）, the biogas yield in anaerobic digestion system B （ADSB） and anaerobic digestion system C （ADSC） had been increased by more than 20% respectively; the SRF of three digested sludge are（were） from 6.8×10^13, 1. 1×10^13 to 5.1×10^12 m/Kg, natural settling rates of 12 h are 26, 37 and 56% and that of 24 h are 32%, 45% and 59% respectively; the centrifugal dewatering rate of 3 min at speed of 1000 rpm were 16%, 31% and 51% respectively; the turbidity of centrifugal supernatant were 804, 754 and 678FTU simultaneously.
基金This work was financially supported by the National Natural Science Foundation of China(51978488,41772243 and 41673096).
文摘Nitrate is the leading cause of eutrophication worldwide and is one of the most challenging pollutants for restoration of polluted surface waters such as lakes, rivers and reservoirs. We report herein a new architecture of iron nanoparticles for high-efficiency denitrification by selective reduction of nitrate (NO3-) to dinitrogen (N2). The iron nanoparticles are doped with nitrogen (FeN) and encapsulated within a thin layer of nitride-carbon (NC). The nanoparticles have high pyrrolic N content (17.4 at.%) and large specific surface area (2040 m2/g). Laboratory experiments demonstrated high N2selectivity (91%) and nitrate removal capacity (6004 mg N/g Fe) for treatment of nitrate-containing water. This iron-based nanomaterial overcomes shortcomings of conventional catalysts by eliminating the use of precious and toxic heavy metals (e.g., Pd, Pt, Cu, Ni) and minimizing the generation of undesirable byproducts (e.g., ammonia) from the reactions with nanoscale zero-valent iron (n ZVI). The multiple electron transfers process from NO3- to N2can be fine-tuned by adjusting the NC shell thickness. Superior electrocatalytic perfor- mance, low cost and minimal environmental impact of the iron-derived nanocatalyst offer promising prospects for water purification, waste treatment and environmental remediation.
基金supported by the Strategic Priority Research Program of the National Key R&D Program of China(Grant Nos.201BYf,CJ505500,and 201BYFCI505504)the National Natural Science Foundation of China(NSFC)(Grant Nos.11802313,and 12032005).
文摘Sediment-water interfaces are important interfaces for lakes,which are related to most environmental and ecological problems.Wind-induced waves cause secondary pollution via sediment resuspension.Since the coupling mechanism of water,resuspended sediments,and phosphorus affects the release of phosphorus(P)near the interface,a coupled model was explored for two sediment types with different adsorption-desorption capabilities to examine sediment resuspension and P release.The relationships among wind speed,wave characteristics,sediment distribution and P concentration were obtained.For different sediments,the unit sediment desorption release is negatively correlated with wind speed.When sediments are resuspended under low or moderate wind speed,the P concentration in the overlying water increases abruptly,hampering diffusion.P release exhibits the characteristics of concentrated release in a small region and changes the water environment rapidly.
