Contaminated Water Streams Research Articles

Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes

Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg2+ as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S>CNT-I>CNT-OX>CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams.

Innovative Green Technology and Products Meeting Geo-Environmental Challenges

Abstract Climate change issues have a significant impact on our environment. In this paper, development and use of innovative green technology products to meet the current pressing geo environmental challenges are presented. The environments addressed include contaminated water streams, landfills, challenging foundations, recycling wastes, highway slope failures and manufactured aggregates. Green technology develops and supports a strategy to address sustainability in the environment.

Evaluation of anthropogenic dose distribution amongst building walls at the Metlino area of the upper Techa River region

This paper presents the results of an effort to evaluate anthropogenic doses in bricks from old buildings located on the banks of the Techa River. The river area was contaminated in 1949-1956 as a result of radioactive waste releases by the Mayak plutonium facility (Southern Urals, Russia). Absorbed doses were determined by luminescence measurements of quartz extracted from the near-surface layers of bricks sampled in 1991-1997 from three remained buildings (a mill, a granary and a church). These buildings are located in the former residence area of Metlino, which was the settlement located closest to the release site (residents of Metlino were relocated from the contaminated river in 1956). The measured anthropogenic dose in the three buildings was found to be comparable: minimum values were equal to 0.5-0.9 Gy and maximum values amounted to about 3-4 Gy. Unfortunately, the geometry of gamma-exposure of the brick samples changed significantly in 1956 as a result of creation of an artificial reservoir downstream of the Metlinsky pond. Since luminescence data provide absorbed dose in the investigated samples accumulated over the whole period of irradiation, for interpretation of the data obtained it is important to know the exposure geometry for the period of maximal exposure, which was in the early 1950s. In 2005, archival data describing configuration of contaminated water streams and shorelines (which were the main sources of gamma-irradiation) were published. Comparison of these data with the results of the luminescence study presented here showed that the bricks with the highest thermoluminescence (TL)-based doses faced contaminated shores and were located close to them. In contrast, the bricks with lower values of measured dose were opposite to contaminated shores and/or being shielded. This demonstrates that the luminescence method allowed reconstruction of the anthropogenic dose distribution in the former settlement center. The obtained results suggest new options for further luminescence studies in Metlino aimed at the reconstruction of the external exposures of the affected population.

Photocatalytic Decolorization of Methylene Blue with Two Photoreactors

AbstractMost of dyes are considered as non - biodegradable substances and because this, they have became in an environmental problem. Commercial dyes are used in paper and textile industries, and their by-products contaminate surface water sources. Titanium dioxide - based photocatalysis can be an alternative for treatment of dye - contaminated water streams before dumping, because this process can generate powerful oxidant species as hydroxyl free radicals (•OH). In this study, the photocatalytic decolorization of methylene blue was carried out in a compound parabolic collector (CPC) and tubular collector (TC; no reflectors) using the radiation provided by a set of six UV black-lamps. The experimental tests corresponding to a central-composite experimental design were carried out during three hours, whereas the tests for optimal conditions were carried out during 315 min. The decolorization of the dye was measured indirectly with UV- visible absorbance. The optimal region could be determined using the Response Surface Methodology, and for CPC reactor the results were 70.8% for optimal degradation at 0.44 g/L of TiO

Treatment of zinc-contaminated water using a multistage ferrihydrite sorption system

Previous studies demonstrated the environmental and economic benefits of treating lead(II)-contaminated water streams with ferrihydrite in multiple equilibrium sorption stages. In this work, multistage ferrihydrite sorption systems were evaluated for their effectiveness in reducing single-solute zinc(II) (Zn(II)) concentrations in contaminated water streams to very low levels. As for lead(II) (Pb(II)), experimental data and modeling results indicate that a multistage sorption system can significantly reduce Zn(II) effluent concentrations for the same total amount of sorbent or, alternatively, dramatically lower total sorbent consumption for the same effluent Zn(II) concentration. Compared to Pb(II), however, Zn(II) removal requires on the order of 10 times more sorbent to achieve the same target effluent concentration for the same pH and number of stages. Model predictions were made using a steady-state, multistage, equilibrium adsorber model that was previously developed for and integrated into OLI Systems' Environmental Simulation Program (ESP). The modified triple-layer model was used to simulate Zn(II) surface-liquid equilibria within the adsorber model. Engineering screening evaluations again indicate that a 2- to 3-stage sorption process can provide significant economic savings when compared to a 1-stage process operating with the same target effluent Zn(II) concentration. Additional equilibrium stages beyond 2 or 3 provide diminishing economic returns. The major economic driver for multiple contacting stages is reduced capital investment and operating costs for sludge handling, dewatering, and disposal.

Lead sorption onto ferrihydrite. 3. Multistage contacting.

Few studies have demonstrated the practical application of surface complexation models, calibrated with fundamental macroscopic and spectroscopic metal sorption data, in helping to solve industrial trace metal emissions problems. In this work, multistage ferrihydrite sorption systems are evaluated for their effectiveness in reducing single-solute lead(II) [Pb(II)] concentrations in contaminated water streams to very low levels. Experimental data and modeling results indicate that a multistage sorption system can significantly reduce Pb(II) effluent concentrations for the same total amount of sorbent or, alternatively, dramatically lower total sorbent consumption for the same effluent Pb(II) concentration. Model predictions were generated using a steady-state, multistage, equilibrium adsorber model that was specifically developed for and integrated into 0LI Systems' Environmental Simulation Program. The modified triple-layer model was used to simulate Pb(II) surface-liquid equilibria within the adsorber model. Engineering screening evaluations indicate that a 2-3-stage sorption process can provide significant economic savings when compared to a 1-stage process operating with the same target effluent Pb(II) concentration. Additional equilibrium stages beyond 2 or 3 provide diminishing economic returns. The major economic driver for multiple contacting stages is reduced capital investment and operating costs for sludge handling, dewatering, and disposal.

A new process for electrocoagulation

For water providers needing to make the most of scarce resources, a new electrocoagulation system treats contaminated supplies effectively and economically.An innovative electrocoagulation process has been shown to be effective in treating raw water sources for the production of potable water. The process is a boon to water reuse because it has the capability to remove heavy metals from contaminated water streams and to treat leachates from mining and landfill sites. Study results showed bacteria (i.e., E. coli) were typically reduced by a factor of log 4.17 to concentrations below the detection limit. Molybdenum was reduced from 9.95 to 0.006 mg/L in leachate at a mining site, and iron was reduced from 130 to 0.015 mg/L in leachate from a landfill site. In the new process, coaxial electrodes permit continuous flow at rates up to 225,000 L/min (5.944 × 104 gpm) and above. The technology has no moving parts and operates at a fraction of the cost of other water treatment systems. Because the flocculent produced is chemically inert and does not leach back contaminants, it is readily disposable. In addition to describing the electrocoagulation process, the author discusses the critical role water electrolysis intermediate radicals play in removing bacteria.

Design and construction of a mobile activated carbon regenerator system

Activated carbon adsorption has become a standard treatment for the cleanup of contaminated water streams. To facilitate such cleanups, mobile carbon a The adaptation of adsorption systems to a mobile base suggested that regeneration systems could be similarly adapted. A program was undertaken to asses A system was designed and built based on technology developed for the fabrication of a laboratory-sized regenerator. Housed in a standard van-type trai Test runs using spent carbon from treatment of a spill were quite successful. The carbon was returned to essentially 100% activity, with an 88% volume