Effects of Water Injection Arrangement on The Performance of a Venturi Scrubber

The effect of three different arrangements of two water manifold injection systems on the performance of a venturi scrubber was studied. Velocities ranging from 23.4 to 49.7 m/sec were used with aerosol diameters of 0.8, 1.6, 2.9 and 5.0 microns. Scrubber efficiency was found to be larger than predicted theoretically with the larger particles, and smaller than predicted theoretically with the smaller particles. The spacing, diameter, and location of the injection orifices were found to have an effect on scrubber efficiency.     

Droplet Size and Surface Tension in Venturi Scrubbers

Droplet sizes in venturi scrubbers using water, water and detergent, and water-propan-1-ol mixtures have been measured using a stroboscopic-photographic method. Droplet sizes for water and water-detergent systems are not significantly different, although much smaller droplets are formed when water-propanol mixtures are used. The better particle collection claimed for water-detergent systems is probably due to the subsequent break-up of bubbles found in the water-detergent system into microdroplets, or better particle-droplet adherence. The classical Nukiyama-Tanasawa equation commonly used for predicting the Sauter mean diameter of droplets (and in turn, collection efficiency) in venturi scrubbers, which has surface tension as a critical parameter, is only approximately applicable to water and water-alcohol mixtures and not to water-detergent mixtures.     

Size distribution of polycyclic aromatic hydrocarbons in a roadway tunnel in Lisbon, Portugal

Atmospheric aerosols of four aerodynamic size ranges were collected using high volume cascade impactors in an extremely busy roadway tunnel in Lisbon (Portugal). Dust deposited on the tunnel walls and guardrails was also collected. Average particle mass concentrations in the tunnel atmosphere were more than 30 times higher than in the outside urban background air, revealing its origins almost exclusively from fresh vehicle emissions. Most of the aerosol mass was concentrated in submicrometer fractions (65%), and polycyclic aromatic hydrocarbons (PAH) were even more concentrated in the finer particles with an average of 84% of total PAH present in sizes smaller than 0.49 μm. The most abundant PAH were methylated phenanthrenes, fluoranthene and pyrene. About 46% of the total PAH mass was attributed to lower molecular weight compounds (two and three rings), suggesting a strong influence of diesel vehicle emissions on the production of local particulate PAH. The application of diagnostic ratios confirmed the relevance of this source of PAH in the tunnel ambient air. Deposited dust presented PAH profiles similar to the coarser aerosol size range, in agreement with the predominant origin of coarser aerosol particles from soil dust resuspension and vehicle wear products.     

Size fractionated speciation of nitrate and sulfate aerosols in a sub-tropical industrial environment

Size fractionated chemical speciation of acidic aerosols were performed for ammonium sulfate, other sulfates, ammonium nitrate and other nitrates in a sub-tropical industrial area, Bina, India during December 2003 to November 2004. Analysis of variance (ANOVA) revealed highly significant temporal variations (p > .001) in the concentrations of nitrate and sulfate aerosols in all the three size fractions (fine, mid-size and coarse). Winter demonstrated utmost concentrations of ammonium sulfate, which ranged from 3.2 to 26.4 microg m(-3) in fine particles and 0.20-0.34 microg m(-3) in coarse particles. Ammonium sulfate was chiefly in fine mode (43.77% of total particulate sulfate) as compared to coarse particles (28.60% of total particulate sulfate). The major fraction Ammonium sulfate existed in different forms in atmospheric aerosols, for example NH4Fe(SO4)2, (NH4)2SO4, (NH4)3H(SO4)2 in fine particles, and (NH4)4(NO3)SO4+ in coarse particles. Other sulfate concentrations were also higher during winter ranging from 1.89 to 14.3 microg m(-3) in fine particles and 0.12-0.65microg m(-3) in coarse particles. Ammonium nitrate constituted the major fraction of total particulate nitrate all through the year and was principally in fine particles (the highest concentration in January i.e. 14.2 microg m(-3)). Other nitrates were mainly distributed in the fine particles (highest concentration in January i.e. 11.2 microg m(-3)) All the sulfate and nitrate species were mainly distributed in fine mode and have significant impact on human health.     

Copper chelation in discharged groundwater via EDTA addition: a real world application.

The Water Effects Ratio allows regulators to modify the water quality criteria of metals based on the knowledge that complexing a metal generally reduces its toxicity. Using this logic, the Alameda Corridor Transportation Authority was granted a temporary variance based on bioavailable metal concentration for groundwater discharged into the L.A.-Long Beach Harbor in California. Chelex-labile copper, used as a surrogate for bioavailable copper, was measured using Chelex-100 resin combined with graphite furnace-atomic absorption spectrophotometry (CRC-GFAAS). Ethylendiaminetetraacetic acid (EDTA) was added on-site to a concentration of 10-60 mg L(-1) in order to reduce the bioavailable fraction to non-detectable levels, however unexpectedly only approximately 50% of the available copper was chelated. This partial complexation of the copper was due to high iron concentrations in the industrial mixture of EDTA used for the project, whereas pure EDTA was shown to fully chelate the copper. This technique may hold promise for similar short-term projects.     

Nitrogen removal via the nitrite pathway during wastewater co-treatment with ammonia-rich landfill leachates in a sequencing batch reactor

The biological treatment of ammonia-rich landfill leachates due to an inadequate C to N ratio requires expensive supplementation of carbon from an external carbon source. In an effort to reduce treatment costs, the objective of the study was to determine the feasibility of nitrogen removal via the nitrite pathway during landfill leachate co-treatment with municipal wastewater. Initially, the laboratory-scale sequencing batch reactor (SBR) was inoculated with nitrifying activated sludge and fed only raw municipal wastewater (RWW) during a start-up period of 9 weeks. Then, in the co-treatment period, consisting of the next 17 weeks, the system was fed a mixture of RWW and an increasing quantity of landfill leachates (from 1 to 10 % by volume). The results indicate that landfill leachate addition of up to 10 % (by volume) influenced the effluent quality, except for BOD₅. During the experiment, a positive correlation (r ²?=?0.908) between ammonia load in the influent and nitrite in the effluent was observed, suggesting that the second step of nitrification was partially inhibited. The partial nitrification (PN) was also confirmed by fluorescence in situ hybridisation (FISH) analysis of nitrifying bacteria. Nitrogen removal via the nitrite pathway was observed when the oxygen concentration ranged from 0.5 to 1.5 mg O₂/dm³ and free ammonia (FA) ranged from 2.01 to 35.86 mg N-NH₃/dm³ in the aerobic phase. Increasing ammonia load in wastewater influent was also correlated with an increasing amount of total nitrogen (TN) in the effluent, which suggested insufficient amounts of assimilable organic carbon to complete denitrification. Because nitrogen removal via the nitrite pathway is beneficial for carbon-limited and highly ammonia-loaded mixtures, obtaining PN can lead to a reduction in the external carbon source needed to support denitrification.     

Removal of dye using peroxidase-immobilized Buckypaper/polyvinyl alcohol membrane in a multi-stage filtration column via RSM and ANFIS

Environmental Science and Pollution Research - The feasibility and performance of Jicama peroxidase (JP) immobilized Buckypaper/polyvinyl alcohol (BP/PVA) membrane for methylene blue (MB) dye...     

The in situ catalytic oxidation of sulfamethoxazole via peroxydisufate activation operated in a NG/rGO/CNTs composite membrane filtration

Environmental Science and Pollution Research - Metal-free carbonaceous composite membranes have been proven to effectively drive novel in situ catalytic oxidation for the degradation of organic...