Current Issue : January - March Volume : 2019 Issue Number : 1 Articles : 5 Articles
This study examined potential microbial impacts of cyanide contamination in an aquifer\naffected by ferrocyanide disposal from nuclear waste processing at the US Department of Energyâ??s\nHanford Site in south-eastern Washington State (USA). We examined bacterial productivity and\nmicrobial cell density in groundwater (GW) from wells with varying levels of recent and historical\ntotal cyanide concentrations. We used tritiated leucine (3H-Leu) uptake as a proxy for heterotrophic,\naerobic bacterial productivity in the GW, and we measured cell density via nucleic acid staining\nfollowed by epifluorescence microscopy. Bacterial productivity varied widely, both among wells\nthat had high historical and recent total cyanide (...)concentrations and among wells that had\nlow total ....values. Standing microbial biomass varied less, and was generally greater than that\nobserved in a similar study of uranium-contaminated hyporheic-zone groundwater at the Hanford\nSite. Our results showed no correlation between 3H-Leu uptake and recent or historical cyanide\nconcentrations in the wells, consistent with what is known about cyanide toxicity with respect to iron\nspeciation. However, additional sampling of the .... affected groundwater, both in space and time,\nwould be needed to confirm that the... contamination is not affecting the GW biota....
Calculation of open water evaporation is important for hydrology, industry,\nagriculture, environment, and other fields. The available methods of calculating\nevaporation are based on field or laboratory experiments and should\nnot be used for scale-up to open water evaporation for similitude relationships\ncannot be correctly obtained. The methods are thus unjustified scientifically.\nIn addition, surface evaporation is not a local phenomenon that is a\nfunction of independent meteorological parameters. These are in fact dependent\nparameters, and the solar energy exchanged with the surface of the earth\nis the only independent variable for open water evaporation. Contrary to the\nexisting methods, meteorological records and measurements are therefore\nnot required. Many parts of the world do not have full or partial records\navailable. For these, the available methods are likely not to be useful. In addition,\nfuture meteorological records or measurements cannot be made available\nfor evaporation projection in a warming world. This may well place a limit\non using the existing methods. The work presented in this manuscript reveals\na new understanding of evaporation as a climate parameter instead and can\nbe calculated as such. Minimal to no meteorological records or measurements\nmay be required. The advantages of the proposed method are scientific justification,\nsimplicity, accuracy, versatility, low to virtually no cost, and can be\nused to map present and future evaporation in a short period of time....
Three-dimensional numerical simulations are performed to evaluate the effect of porous\nbaffles on the efficiency of water treatment contact tanks. A second-order accurate numerical model\nis employed for the solutions of unsteady flow and tracer transport through the porous baffles. The\nflow through the porous medium is characterized while using the Darcy-Forchheimer relationship.\nLarge Eddy Simulation (LES) model is used to simulate the instantaneous mixing of the tracer in\nthe chambers of the contact tank. Three different porosities are considered to evaluate the effect of\nporosity on the hydraulic and mixing efficiencies of the contact tank. Simulated time-averaged flow\nfield shows that porous baffles that are placed at the entrance of each chamber could successfully\nmitigate short-circuiting and yield plug-flow conditions through the system for low porosities. Flow\nin the contact tank becomes laminar as the flow velocities decrease due to viscous effects and inertial\nresistance in the porous zone. For this case, the tracer is transported with bulk flow through the\nsystem and leaves the contact tank with a high peak seen in the Residence Time Distribution (RTD)\nplot. Porous layer increases the hydraulic efficiency of the conventional design from â??poorâ? to\nâ??goodâ? according to the baffling factor and increases the overall efficiency from â??compromisingâ? to\nâ??goodâ? according to the AD index. Comparison of the performance of the porous layer with the\npreviously developed slot-baffle design shows that the slot-baffle design increases the efficiency of\nthe tank with increasing dispersion effects, whereas the porous design increases hydraulic efficiency\nand reduces the dispersion effects. While the porous design reduces energy efficiency by 33% due\nto a drastic increase in drag in the flow through porous zone, the slot-baffle design increases the\nenergy efficiency of the conventional design by 67%....
Compositions of dry and wet atmospheric depositions vary depending on\ngeographic locations and industrialization. Fog waters were collected from\ndifferent regions of Bangladesh along with rain, sub-surface irrigation water\nand dust particles from Gazipur and compositions were analyzed. The compositions\nof fog water varied greatly among locations. The ammonium nitrogen\n( 4 NH -N) content was the highest (36 - 37 ppm) in Gazipur district and\nthe lowest in Sylhet district (3.2 - 3.6 ppm). Phosphorus (5.2 - 5.5 mg/L), K\n(29.5 - 30 mg/L), S (11.0 - 11.5 mg/L), Zn (2.9 - 3.3 mg/L), Na (11.7 - 12.5\nmg/L), Ca (22.0 - 23.3 mg/L) and Cd (0.14 - 0.17 mg/L) contents were also\nhigher in Gazipur district. Dust particles, rain and sub-surface irrigation water\nof Gazipur district contained considerable amounts of macro and micro\nelements. We conclude that dry and wet atmospheric depositions varied depending\non locations and industrial development. Such study needs to be\ncorrelated with ecological consequences and soil fertility management....
The Rehabilitated Mudor sewage treatment plant at James Town was monitored\nover a period of 4 months (October 2017 to January 2018). This study\nanalyzed the physical, chemical and biological parameters of the raw sewage\nand the treated effluent from the plant. The result indicates that the total removal\nefficiencies were 98.8%, 91.2%, 62.8%, 28.6%, 81.7%, 43.6%, 82.5% and\n99.6% for BOD, COD, TSS, Nitrate-Nitrogen, Phosphate-Phosphorus, Ammonia-\nnitrogen, Sulphate and faecal coliform respectively. More than 13 parameters\nneeded to be met according to the Ghana Environmental Protection\nAgency (EPA) guideline were satisfactorily met whiles ammonia, total suspended\nsolids and phosphate were slightly out of range. From the results obtained,\nthe overall performance of the rehabilitated plant was satisfactory and\nhas seen some improvement with respect to the former recorded performance\nof the plant. With monitoring operation parameters for waste water plants\ndischarge guidelines becoming stringent over the past years, it could be said\nthat management of the Mudor rehabilitated treatment plant is on the right\ncause with full scale operation of the plant barely less than a year. Increase in\nthe process steps through rehabilitation resulted in several significant improvements\nin effluent quality parameters....
Loading....