Iron Shavings Research Articles

Effect of Placement Pattern and Quantity of Iron Shavings in Reactor on Biological Nutrient Removal from Domestic Wastewater

Effect of placement pattern and quantity of iron shavings in reactor on biological nutrient Removal from domestic wastewater was conducted. The results indicate that: different placement pattern had obvious effect on TP removal, but had no distinct effect on TN removal; when iron was placed beside aerator, the highest TP removal can be obtained. Adding more iron can just slightly enhance TP and TN removal when iron shaving quantity increased from 5 g to 20 g per 900 ml wastewater; iron adding restrained transfer of ammonia to nitrate by microbe and this defect should be overcome in practice; 5 g iron per 900 mL is the best choice to balance good nutrient removal and low cost.

Treatment improvement of urban landfill leachates by Fenton-like process using ZVI

The aim of the present study addresses the applicability of the Fenton-like zero valent iron (ZVI) process on the remediation of several landfill leachate samples coming from different points of an existing treatment plant: initial effluent (ERaw), after biological treatment (EPost-Bio) and depurated effluent (ETreat). The effects of pH and Fe0 concentration were determined for ERaw and ETreat. It was observed that the use of low pH values enhances the treatment efficiency. Moreover, the increase on iron load leads to higher COD removals until a certain point after which the catalyst starts to show radical scavenger effect. The low efficiency attained for ERaw (COD removal always below 8%) indicates that this methodology is not suitable for this effluent. However, final ETreat within the legal limits for discharge were attained when pH=2 was used with 38% of COD removal. The utilization of iron shavings as catalyst in the Fenton-like process showed to be a suitable and economical solution on the remediation of ETreat and EPost-Bio with high COD abatements (up to 60%) leading to streams able to be released to the municipal sewage. Since the real plant often does not comply with regulatory thresholds and according to our results, it seems advisable to implement this technology after the bio-reactor for substituting the already existing physico-chemical treatment.

Assessing the Cr(VI) reduction efficiency of a permeable reactive barrier using Cr isotope measurements and 2D reactive transport modeling

In Thun, Switzerland, a permeable reactive barrier (PRB) for Cr(VI) reduction by gray cast iron was installed in May 2008. The PRB is composed of a double array of vertical piles containing iron shavings and gravel. The aquifer in Thun is almost saturated with dissolved oxygen and the groundwater flow velocities are ca. 10-15m/day. Two years after PRB installation Cr(VI) concentrations still permanently exceed the Swiss threshold value for contaminated sites downstream of the barrier at selected localities. Groundwater δ(53/52)Cr(SRM979) measurements were used to track Cr(VI) reduction induced by the PRB. δ(53/52)Cr(SRM979) values of two samples downstream of the PRB showed a clear fractionation towards more positive values compared to four samples from the hotspot, which is clear evidence of Cr(VI) reduction induced by the PRB. Another downstream sample did not show a shift to more positive δ(53/52)Cr(SRM979) values. Because this latter location correlates with the highest downstream Cr(VI) concentration it is proposed that a part of the Cr(VI) plume is bypassing the barrier. Using a Rayleigh fractionation model a minimum present-day overall Cr(VI) reduction efficiency of ca. 15% was estimated. A series of 2D model simulations, including the fractionation of Cr isotopes, confirm that only a PRB bypass of parts of the Cr(VI) plume can lead to the observed values. Additionally, the simulations revealed that the proposed bypass occurs due to an insufficient permeability of the individual PRB piles. It is concluded that with this type of PRB a complete and long-lasting Cr(VI) reduction is extremely difficult to achieve for Cr(VI) contaminations located in nearly oxygen and calcium carbonate saturated aquifer in a regime of high groundwater velocities. Additional remediation action would limit the environmental impact and allow to reach target concentrations.

Investigation of a sewage-integrated technology combining an expanded granular sludge bed (EGSB) and an electrochemical reactor in a pilot-scale plant

A sewage-integrated treatment system (SITS) for the treatment of municipal wastewater, consisting of an expanded granular sludge bed (EGSB) reactor to remove soluble organic matter and an electrochemical (EC) reactor to oxidize the NH 3–N, was evaluated. The performance of the EGSB reactor was monitored for 12 months in a pilot-scale plant. Iron shavings were added to the EGSB reactor on the sixtieth day to improve the removal efficiency of the chemical oxygen demand (COD), suspended solids (SS) and total phosphorus (TP). After the iron shavings were added, the effluent COD, SS and TP decreased from 104 to 46 mg L −1, 21 to 8.6 mg L −1 and 3.62 to 1.36 mg L −1, respectively. Moreover, in the EC reactor, which was equipped with IrO 2/Ti anodes, the NH 3–N and total nitrogen (TN) concentrations decreased from 25 to 12 mg L −1 and 29 to 15 mg L −1, respectively. The NH 3–N was directly oxidized to N 2, resulting in no secondary pollution. The results demonstrated the possibility of removing carbon and nutrients in a SITS with high efficiency. The system runs efficiently and with a flexible operation, making it suitable for low-strength wastewater. The results and parameters presented here can provide references for the practical project.

Reactive transport modelling of Cr(VI) treatment by cast iron under fast flow conditions

Abstract The Cr(VI) reduction behaviour of five different types of grey cast iron shavings meant for construction of a permeable reactive barrier (PRB) in Thun, Switzerland, was investigated by performing batch and column experiments. Closed system batch experiments clearly demonstrated that the largest shavings also containing the largest spherical C inclusions, were best qualified for the PRB due to their fast Cr(VI) reduction rate. However, the column experiment performed with this type of material revealed that a complete and long term Cr(VI) treatment by the planned PRB was questionable due to the site-specific high groundwater flow velocities and the almost O 2 and CaCO 3 saturated aquifer conditions. The experimentally observed Cr(VI) breakthrough is explained as a result of a decline of reactivity provoked by a strong passivation by observed Fe hydroxides (FeOOH-polymorphs) and carbonates (calcite and aragonite). The column experiment was simulated using the reactive transport modelling code CrunchFlow. Iron cycling and intra-aqueous reactions were incorporated into a previously described reaction network in order to model the strong decline in reactivity of grey cast iron. All key parameters like aqueous species concentrations and mineralogical evolution of the column were successfully modelled. The modelling results confirmed that the observed Cr(VI) breakthrough was caused by surface passivation of the Fe shavings. Complete oxidation of the initially present mass of shavings is not predicted to occur during the expected PRB lifetime of several decades. The model seems to be robust, and it is expected that an application of the calibrated model in 2D to field sites will allow a quantitative evaluation for the performance of planned PRB’s in such environments.

Assessment of Long-Term Performance and Chromate Reduction Mechanisms in a Field Scale Permeable Reactive Barrier

An innovative full-scale implementation of a permeable reactive barrier, consisting of a double-row of cylinders filled with zerovalent iron shavings, for chromate remediation was monitored over four years. Solid samples were analyzed to elucidate (i) the relevant corrosion mechanisms and products, (ii) the pathways of chromate reduction and immobilization, and (iii) the long-term performance of the barrier situated in a hydrological and geochemical complex groundwater regime. Sampling and analysis of groundwater and reactive material revealed an oxidative iron corrosion zone evolving in the inflow and a zone of anaerobic iron corrosion in the center and outflow of the barrier. Chromate reduction was mainly confined to the inflow region. The formation and thickness of corrosion rinds depended on sampling time, position, and depth, as well as on the size, shape, and graphite content In the inflow, the corrosion rinds mostly consisted of goethite and ferrihydrite. X-ray absorption fine structure spectroscopy revealed two distinct Cr(III) species, most likely resulting from homogeneous and heterogeneous redox reaction pathways, respectively. The longevity and long-term effectiveness of the PRB appears to be primarily limited by reduced corrosion rates of the ZVI-shavings because of the thick layers of Fe-hydroxides.

Enhanced Biological Treatment of Industrial Wastewater With Bimetallic Zero-Valent Iron

ADVERTISEMENT RETURN TO ISSUEPREVFeatureNEXTEnhanced Biological Treatment of Industrial Wastewater With Bimetallic Zero-Valent IronThe technical and economic feasibility of iron shavings is evaluated in a series of experiments from benchtop to full-scale facility.Luming Ma and Wei-xian ZhangView Author Information Tongji University (China) Lehigh UniversityCite this: Environ. Sci. Technol. 2008, 42, 15, 5384–5389Publication Date (Web):July 30, 2008Publication History Published online30 July 2008Published inissue 1 August 2008https://doi.org/10.1021/es801743sCopyright © 2008 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views39662Altmetric-Citations147LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Hydrocarbons,Iron,Redox reactions,Wastes,Water treatment Get e-Alerts

Dechlorination of Trichloroethylene (TCE) by Zero-Valent Iron

Dechlorination of TCE was done using zero-valent iron in two forms: powder and shavings. A simulated TCE solution of initial concentration 5 ppm was mixed with iron powder, finer than 100 mesh, in 120-mL serum bottles. The pH of the solution was varied at 5, 7 and 9; the amount of iron powder was at 10, 12.5 and 15 mg per mL of TCE solution; and the water used was distilled de-ionized water. On the other hand, 50 grams of iron shavings were used as materials packed in a glass column passed with simulated TCE solutions. Two thicknesses of the shavings were used (1 mm and 1.5 mm). The iron shavings were subjected to different preparations: pretreated with 0.1 M NaCl solution and untreated; and the water used was de-oxygenated, de-ionized distilled water. Samples taken at different intervals were analyzed for TCE and chloride ion concentrations. Results showed a decrease in the concentration of TCE, accompanied by the formation and increase in chloride ion concentration over time, thus confirming the dechlorination of TCE. Degradation was possible when the pH of the solution was 7 and below, while better dechlorination was observed with the thinnest iron shavings possible and with the said shavings subjected to pretreatment with the NaCl solution.

Reduction Annealing for Cast Iron Powder and Its Effect on Sintered Antifriction Material Properties

The effect of reduction annealing for powder obtained from cast iron shavings on powder specimen properties is studied. An approximate mechanism is suggested for the oxidation-reduction process during annealing of cast iron powder. An increase in annealing temperature leads to an increase in carbon gasification rate and change in absolute powder weight. Prior reduction annealing for cast iron powder improves its compactability, and increases the mechanical properties of sintered material. The best mechanical properties were obtained for specimen made from cast iron powder reduced at 1000°C. Alloying an iron-cast iron charge with 3 mass% of nickel-chromium alloy leads to a marked improvement in the mechanical properties of a sintered composite.

Production of powders of cast iron shavings and special features of production of components from these powders. III. Structure and strength of heat-treated alloys

Quenching the specimens from 800°C does not lead to the redistribution of the carbide in the volume of the alloys of the iron-cast iron system. The most homogeneous structure of the alloys is formed only in quenching from 900°C. However, quenching from 1000°C increases the size of voids and causes supinating of the alloys, although their homogeneity increases.

Silica Removal With Iron Shavings

Silica Removal With Iron Shavings