Papers by Keyword: DPB

Abstract: In order to investigate the potential of sequencing batch biofilm reactor (SBBR) technology of two-sludge system for denitrifying dephosphatation (A₂ON process),we build a tab-scale experiment .Then find that the simultaneous removal of phosphorus and nitrogen in the two sludge system is possible .By the control of COD/TN ratio ,highly effective simultaneous nitrification and denitrification is achieved in the A2ON system.And the ratio of denitrification is 85%, the ratio of dephosphatation is 87%.It also demonstrates that the process is stable ,at the same time decrease the effect of dephosphorization and denitrification by the limited carbon source.

Abstract: This paper aims to study the impact of different carbon sources on phosphorus removal after the (AO)²SBR system was started successfully. Four kinds of carbon resources were used in sequence experiments to observe the impact of different carbon resources on phosphorus release at anaerobic condition, uptake aerobic condition, uptake anoxic condition and phosphorus removal of the (AO)²SBR system. And the carbon sources are sodium acetate, sodium propionate, glucose, sodium acetate + sodium propionate separately. The experiment result shows that the phosphorus release and uptake of active sludge at anaerobic/aerobic/anoxic condition was preferable with sodium acetate as carbon source. And the phosphorus removal rate of (AO)²SBR system and TP concentration in the effluent were 95% and under 0.5mg·L^-1 respectively. The phosphorus removal rate of (AO)²SBR system was only 60% with glucose as carbon resource. This study concluded that it is beneficial for the biological phosphorus removal to choose organics with short carbon chain, such as sodium acetate as carbon source.

Abstract: Based on DPBs (Denitrifying Phosphorus-removing Bacteria) obtained from a lab-scale SBR, a quinone profile system had been established to analyze quinones in sludge samples. There existed a positive correlation between the contents of UQ-8 extracted from the sludge samples and the denitrifying and phosphorus removal efficiency of the treating system. With quinone profiles taken as a new important index, it was evidently feasible to determine the removal effect.

Abstract: Abstract. The paper aims to study the fast start-up of anaerobic-aerobic-anoxic-aerobic sequencing batch reactor, with domestic sewage as treating object, to solve the problem of SBR that can be used for denitrification or dephosphorization independently and to realize simultaneous nitrogen and phosphorus removal in a single SBR system. Phosphorus accumulating organisms were enriched at the anaerobic condition for 2h/aerobic for 3h after activated sludge were inoculated. Then denitrifying polyphosphate-accumulating organisms were enriched by inserting an anoxic phase into the aerobic phase. The lengths of anaerobic time, anoxic time and aerobic time were adjusted and the nitrogen and phosphorus removal effect of (AO)2SBR system were observed. The (AO)2SBR system was started successfully with 80d of training and domesticating. The nitrogen and phosphorus removal effect was performed preferably at the condition of anaerobic(2h)-aerobic(1.5h)-anoxic(1.5h)-aerobic(0.5h). The removal rate of COD, NH4+-N, TN and TP reached 90%, 97%, 88% and 92% respectively. And 33% of energy was saved when aerobic time was shortened from 3h to 2h, while the treating effect dropped off rarely. The results show that (AO)2SBR is applicable for simultaneous nitrogen and phosphorus removal, and the effluent water quality meets the first level B criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002). The system can also reach the aim of saving energy and providing theoretical basis for the nitrogen and phosphorus removal in single SBR systems.

Abstract: The development of 3C-SiC crystals from <0001> oriented hexagonal seed has always suffered from the systematic twinning which appears during the nucleation step of the layer. Using the continuous feed – Physical Vapour Transport (CF-PVT) growth process, we succeeded in growing single domain 3C-SiC crystals. To explain that, we propose in this work, a model based on the interaction between the lateral expansion anisotropy of 3C-SiC nuclei and the step flow growth front. Depending on the step edges direction, we can obtain one 3C orientation developing simultaneously with the vanishing of the other one. This model is confirmed by cross sectional HRTEM observation of the α-β interface.

Abstract: Growing good quality SiC epitaxial layers at temperature lower than 1400°C is a challenging problem which could help reducing the costs, increasing the safety of the process or even give new perspectives. Toward this aim, liquid based growth techniques have been used. The Si-based melts should be carefully chosen considering several criteria. Furthermore, the implementation of a liquid phase for growing SiC epilayer can be performed in various manners (dipping or VLS mechanism) so that one has to choose the more appropriate technique. The discussion is illustrated with several results showing that the growth of SiC from a liquid phase at low temperature can address various important technological points such as experimental safety, ptype doping, on-axis or selective epitaxy. The recent demonstration of single-domain 3C-SiC heteroepitaxial layers on hexagonal SiC substrates confirms that liquid based growth has still unexpected qualities.