Respirometric Monitoring for the Determination of Effective Height and Reaction Rate Constant in Up-Flow Autotrophic Denitrification Reactor Packed with Sulfur

A novel technology for the removal of nitrogen from wastewater, autotrophic denitrification process with sulfur particle, has been developed. A respirometer was employed for the monitoring of nitrogen gas produced in the reactor. It was found that the autotrophic denitrification studied by gas production rate and nitrate depletion rate followed a first order reaction from the relationship. The reaction rate constant based on effective volume, k_N was ranged from 2.67 to 3.07 h^–1. The effective height was around 23.8 and 50% of the total height for 11.8 and 5.9 h of packed bed contact time, respectively. It was assumed that the reaction rate constants were similar in each experimental condition, PBCT = 11.9 and 5.9 h because there was little gradient of biomass concentration within 50% of the total height. The respirometry was found to be a simple and fast way to monitor the denitrification process. The method was especially useful for the determination of kinetic parameters.     

Use of quadrupole GC-MS and ion trap GC-MS-MS for determining 3-hydroxy fatty acids in settled house dust: relation to endotoxin activity

Gas chromatography-mass spectrometry (GC-MS) using a quadrupole instrument and GC-tandem MS (GC-MS-MS) using an ion trap instrument were applied to determine 3-hydroxy fatty acids (3-OH FAs) with 10-18 carbon chain lengths, specific components of the endotoxin (lipopolysaccharide, LPS) of Gram-negative bacteria, in 30 house dust samples. The two methods provided similar detection sensitivity for methyl ester/trimethylsilyl derivatives of the 3-OH FAs and allowed these acids to be distinguished from co-eluting 2-OH FA derivatives. The correlation coefficients between endotoxin activity (Limulus test) and the combined amounts of 3-OH C10, 3-OH C12, and 3-OH C14 were 0.60 and 0.61 when using GC-MS and GC-MS-MS, respectively. The superior selectivity of GC-MS-MS was illustrated in analyses of sub-milligram amounts of dust, where the chromatograms achieved by GC-MS were difficult to interpret due to a high background and several closely eluting compounds. GC-MS-MS is therefore preferable to GC-MS for determining 3-OH FAs in minute (sub-milligram) amounts of dust.     

Effects of Asian dust events on atmospheric bacterial communities at different distances downwind of the source region

Aeolian dust particles arising from arid and semiarid zones are known to carry microbes by air currents. The effect of wind-borne bacteria on atmospheric bacterial population at various downwind distances from the dust source regions must be clarified, but has not yet been reported. This study monitored the bacterial abundance and community composition in outdoor aerosol samples in Beijing, China, which is close to the Asian dust source regions, and compared them with the results obtained in a distant region(Osaka, Japan).The Asian dust collected in Beijing contained(4 ± 3) × 10~4 bacterial cells/m~3, approximately~4 times higher than in Osaka. On 15 April 2015, Beijing experienced severe Asian dust events with a 1000-fold increase in bacterial abundance, relative to non-Asian dust days. Dominant bacterial phyla and classes in Asian dust collected in Beijing were Actinobacteria, Bacilli and Acidobacteria, and the bacterial community composition varied more widely than in Osaka.The bacterial community compositions differed between the Beijing and Osaka dusts, even for the same Asian dust events. These results indicated that aerosol bacterial communities nearer the dust source are more affected by eolian dust than their distant counterparts.     

Study to improve the reactivity of magnesium cations to CO2 for carbon capture and utilization technology using edible salt manufacturing plant wastewater

Journal of Material Cycles and Waste Management - This study aims to improve the formation of MgCO3 via inorganic carbon capture utilization (CCU) technology using industrial wastewater from an...     

Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

Journal of Material Cycles and Waste Management - Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process....     

Recovery of iron oxide and calcium chloride from an iron-rich chloride waste using calcium carbonate

Journal of Material Cycles and Waste Management - The ilmenite-chloride process has used for the production of TiCl4 from the ilmenite (FeTiO3) ore, which produces cyclone dust containing mostly...     

Reduction of tar using cheap catalysts during sewage sludge gasification

Solid-fuel conversion or gasification study of sewage sludge and energy recovery has become increasingly important because energy recovery and climate change are emerging issues. Various types of catalysts, such as dolomite, steel slag and calcium oxide, were tested for tar reduction during the sewage sludge gasification process. For the experiments on sewage sludge gasification reactions and tar reduction using the catalysts, a fixed bed of laboratory-scale experimental apparatus was set up. The reactor was made of quartz glass using an electric muffle furnace. The sewage sludge samples used had moisture contents less than 6%. The experimental conditions were as follows: sample weight was 20 g and reaction time was 10 min, gasification reaction temperature was from 600 to 800°C, and the equivalence ratio was 0.2. The quantity of catalysts was 2–6 g, and temperatures of catalyst layers were 500–700°C. As the reaction temperature increased up to 800°C, the yields of gaseous products and liquid products increased, whereas char and tar products decreased, showing effects on gas product compositions. These results were considered to be due to the increase of the water-gas reaction and Boudouard reaction. In the case of experiments with catalysts, dolomite (4 g), steel slag (6 g) and calcium oxide (6 g) were used. When the temperature of catalysts increased, the weight of the tar produced decreased with different cracking performances by different catalysts. Reforming reactions were considered to occur on the surface of dolomite, steel slag and calcium oxide, causing cracking of the hydrocarbon structure, which eventually showed reduced tar generation.     

Design and modeling of optimal distillation sequence for recovery of valuable components from a waste photoresist stripper

Currently, waste photoresist stripper from the semiconductor industries is generally incinerated at high temperatures or processed as a high-calorie fuel, which can have adverse effects on the environment and economy. Recovery of valuable solvents from waste photoresist strippers is, therefore, very important for thin flat transistor-liquid crystal display (TFT-LCD) manufactures to reduce the production costs and protect the environment against industrial waste. In the present work, systematic laboratory-scale distillation experiments were carried out to regenerate the organic solvents from the waste photoresist stripper and determine if they are feasible to recycle for commercial TFT-LCD grade chemicals: in particular, 1-hydroxyethylpiperazine and methyl diglycol were mainly tried to retrieve. Based on the experiment results, possible alternative distillation sequences were examined through intensive techno-economic analysis using a rigorous process simulator. As a result, an optimal distillation sequence and condition were drawn to separate valuable organic solvents from waste photoresist stripper for a commercial purpose recovery process.