Analysis on GNSS receiver with the principles of signal and information

In the paper, principles of signal and information were introduced to the design of GNSS receiver. Analyze Antenna and radio frequency (RF) front-end with the perspective of transmission link, Understand the baseband processing though signal modulate and demodulate, design the navigation calculation utilized the information pick-up and disposal, and research the receiver system by the inherent connection between signal and information. New ways and means would be developed though these researches. © (2013) Trans Tech Publications, Switzerland

Operation of a sequencing batch reactor for cultivating autotrophic nitrifying granules

The granulation of nitrifying sludge in a sequencing batch reactor (SBR) fed with NH4 +-N-laden inorganic wastewater was investigated. After 120-day operation spherical and elliptical granules with an average diameter of 0.32 mm were observed. The hydrophobicity surface, settling velocity and specific gravity of the matured granules increased with the processing of sludge granulation. Spatial distribution of bacterial species within the autotrophic granules was analyzed with fluorescence in situ hybridization. Both ammonia- and nitrite-oxidizing bacteria were observed in the granular sludge. The Michaelis-Menten equation was used to describe their NH4 +-N utilization rate, and the kinetic coefficients were calculated to be vm = 18.0 mg/g-VSS/h and Km = 36.7 mg/l. Taking into account the NH4 +-N utilization rate and removal efficiency together, an NH4 +-N concentration range of 100-250 mg/l was found to be favourable for the operation of the SBR to cultivate nitrifying granules. © 2009 Elsevier Ltd. All rights reserved.postprin

Biodegradation and biotransformation of wastewater organics as precursors of disinfection byproducts in water

Laboratory experiments were carried out to investigate wastewater organics as the precursors of disinfection byproducts (DBPs) in drinking water supply. The focus was on the change in wastewater DBP precursors during biological degradation under simulated natural conditions. The wastewater and its treated secondary effluent were characterized for DBP formation potential (DBPFP) and DBP speciation profile, including trihalomethanes, haloacetic acids, chloral hydrate, and nitrogen-containing DBPs. Several model organic compounds, including humic acid, tannic acid, glucose, starch, glycine, and bovine serum albumin (BSA), were used to represent the different types of organic pollutants in wastewater discharge. The results show that the DBPFP of wastewater decreased after biodegradation, but the remaining organic matter had a greater DBPFP yield with chlorine. Different model organics displayed different changes in DBPFP during biodegradation. The DBPFP remained largely unchanged for the glycine solution, decreased greatly for the tannic acid and BSA solutions, and increased nearly 3-fold for the glucose and starch solutions after 10d of biodegradation. Meanwhile, the DBPFP yield increased from 3 for glycine to 51μg DBP mg-1 C for its degradation residue, and from 1 for glucose and starch to 87 and 38μg DBP mg-1 C for their organic residues, respectively. Although biodegradation may effectively remove some DBP precursors, biotransformation during the process produces new DBP precursors in the form of soluble microbial products (SMPs). The experimental results reveal that SMPs may be an important source of wastewater-derived DBP precursors in natural waters. © 2010 Elsevier Ltd.postprin

Concurrent photocatalytic hydrogen production and organic degradation by a composite catalyst film in a two-chamber photo-reactor

A novel visible light-driven photocatalyst film, MoS2/Ag/TiO2, was synthesized on a glass-fiber membrane. The composite catalyst film had a multi-layer structure with Ag as nanoconjunctions between the MoS2 and TiO2 layers. The catalyst film performed well for both photocatalytic hydrogen production and organic degradation in a two-chamber photo-reactor under either solar or visible light. Hydrogen was produced in the cathode side chamber while the model organic was decomposed in the anode side chamber. The specific hydrogen production rate went through a maximum of 85 mmol/m2-h with an energy conversion efficiency of 0.85%, while the maximum specific organic carbon removal for formic acid under solar light reached 1,520 mg/m2-h. It is apparent that Ag between the TiO2 and MoS2 layers allowed the transfer of photo-excited electrons via TiO2 → Ag → MoS2 for organic degradation and H+ reduction (e.g. hydrogen evolution) in two different chambers.postprin

Photocatalytic hydrogen generation with simultaneous organic degradation by a visible light-driven CdS/ZnS film catalyst

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Aerobic sludge granulation facilitated by activated carbon for partial nitrification treatment of ammonia-rich wastewater

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Effect of the food-to-microorganism (F/M) ratio on the formation and size of aerobic sludge granules

Laboratory experiments were carried out to investigate the effect of the sludge loading, or the food-to-microorganism (F/M) ratio, on the rate of aerobic granulation and the size of the granules in biological wastewater treatment. Four column batch reactors were used with a similar sludge suspended solids (SS) concentration of around 2000 mg/L. The reactors were fed with a glucose-based wastewater at different chemical oxygen demand (COD) concentrations, resulting in F/M ratios from 0.3 to 1.1 g COD/g SS-d. A higher F/M ratio appeared to promote faster formation of larger granules and a lower F/M ratio led to slower formation of smaller granules. Upon complete granulation, the granules became rather stable in size, and the mean diameter of the granules in different reactors increased from 1.2 to 4.5 mm linearly with the F/M ratio applied. Molecular analysis of the sludge did not show the domination of any particular bacterial species during the granulation process. It is apparent that applying different F/M ratios in different granulation stages, e.g., a higher F/M in the early stage and a reduced F/M in the later stage, can be an effective start-up strategy to facilitate rapid granule formation and sustain small and healthy granules in bioreactors. © 2011 Elsevier Ltd. All rights reserved.postprin

Surface coating with Ca(OH)2 for improvement of the transport of nanoscale zero-valent iron (nZVI) in porous media

A novel thermal deposition method was developed to coat Ca(OH)2 on the surface of nanoscale zero-valent iron (nZVI). The nZVI particles with the Ca(OH)2 coating layer, nZVI/Ca(OH)2, had a clear core-shell structure based on the transmission electron microscopy observations, and the Ca(OH)2 shell was identified as an amorphous phase. The Ca(OH)2 coating shell would not only function as an effective protection layer for nZVI but also improve the mobility of nZVI in porous media for its use in environmental decontamination. A 10% Ca/Fe mass ratio was found to result in a proper thickness of the Ca(OH)2 shell on the nZVI surface. Based on the filtration tests in sand columns, the Ca(OH)2-based surface coating could greatly improve the mobility and transport of nZVI particles in porous media. In addition, batch experiments were conducted to evaluate the reactivity of Ca(OH)2-coated nZVI particles for the reduction of Cr(VI) and its removal from water.postprin

Synthesis Of A Sulfur-graphene Composite As An Enhanced Metal-free Photocatalyst

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