Addition Of FeSO4 Research Articles

Improvement Effect of FeSO4·7H2O on Flotation Separation of Scheelite from Fluorite.

In this study, FeSO4·7H2O was used as an auxiliary depressant to improve the selective depression effect on fluorite. Microflotation tests using oleic acid as the collector showed that the pre-addition of FeSO4·7H2O and subsequent addition of sodium silicate (SS) resulted in a stronger selective depression effect on fluorite compared with SS alone. Addition of FeSO4·7H2O reduced the required dosage of SS and had little negative effects on scheelite recovery. The selective depression mechanism of FeSO4·7H2O was investigated in detail. X-ray photoelectron spectroscopy indicated that the difference in the number of surface active sites was the mechanism for improved differential flotation of scheelite from fluorite. The improved depression of fluorite was attributed to both ferrous and sulphate ions. The pre-adsorption of ferrous species increased the number of active sites, enhancing the adsorption of silicate species on the fluorite surface. Simultaneously, sulfate ions were selectively adsorbed on the fluorite surface to form hydrophilic calcium sulfate, reducing the floatability of fluorite.

Pretreatment of Olive Mill Wastes for the Extraction of Residual Oil and High Added Value Compounds

A novel extraction method for recovering the residual oil from olive mill wastes (OMW) from II-phase olive mills was developed in this study. The new acidification/hydrolysis method is based on the addition of sulphuric acid and ferrous sulphate heptahydrate. A range of water dilutions and extraction temperatures were tested. Experimental runs were carried out according to a central composite design taking into consideration all the most important factors that affect the extraction process such as the solid to liquid ratio (w/v), the addition of H2SO4 (% v/w), the addition of FeSO4·7H2O (% w/w) and temperature (°C). The optimum residual oil yield was 47.7 mg/g OMW dry basis (db) at 0.25 w/v solid to liquid ratio, 1.4% v/w H2SO4, 0.6% w/w FeSO4·7H2O and 70 °C. Moreover, the extraction kinetics of the residual oil from OMW were examined at the optimum conditions and were well fitted by using second order kinetics. Analysis of the residual oil showed similar fatty acid profile with the virgin olive oil. Finally, characterisation of the aqueous phase following the residual oil extraction process demonstrated a high content of phenolic compounds and especially tyrosol and hydroxytyrosol.

Determination Number Of Magnesium Nutritions From MgSO4.7H2O AND IRON FROM FeSO4.7H2O on Tetraselmiss chuii Cultivation To The Maximum Lipid Contact

This study discusses the effect of adding magnesium nutrients from MgSO4.7H2O and iron from FeSO4.7H2O to obtain maximum lipid levels in Tetraselmis chuii microalgae. The nutritional variations used were 0, 4, 6, 8 gr / L MgSO4.7H2O and 0, 24, 30, and 36 µM / L FeSO4.7H2O. Microalgae was cultivated with a photobioreactor filled with 1 L microalgae culture with a ratio of microalgae and sea water 3: 7, namely 300 ml of microalgae and 700 ml of sea water with salinity of 30 ppt. The light intensity is 2000 lux. The study began with culturing microalgae with variations in these nutrients. Then, the cell density is observed every 3 hours until the optimum time is obtained where the cell density is high. Then the microalgae is harvested and extracted so that the lipids are obtained. The extraction process was carried out using diethyl ether solvents. After obtaining the lipid mass, the microalgae lipid levels were calculated. The results showed that the highest lipid levels in Tetraselmis chuii microalgae were obtained by the addition of MgSO4.7H2O 6 gram and the addition of FeSO4.7H2O 36 µM which was 20,175%.

Plant-wide model-based analysis of iron dosage strategies for chemical phosphorus removal in wastewater treatment systems

Stringent phosphorus discharge standards (i.e. 0.15–0.3 g P.m−3) in the Baltic area will compel wastewater treatment practice to augment enhanced biological phosphorus removal (EBPR) with chemical precipitation using metal salts. This study examines control of iron chemical dosing for phosphorus removal under dynamic loading conditions to optimize operational aspects of a membrane biological reactor (MBR) pilot plant. An upgraded version of the Benchmark Simulation Model No. 2 (BSM2) with an improved physico-chemical framework (PCF) is used to develop a plant-wide model for the pilot plant. The PCF consists of an equilibrium approach describing ion speciation and pairing, kinetic minerals precipitation (such as hydrous ferric oxides (HFO) and FePO4) as well as adsorption and co-precipitation. Model performance is assessed against data sets from the pilot plant, evaluating the capability to describe water and sludge lines across the treatment process under steady-state operation. Simulated phosphorus differed as little as 5–10% (relative) from measured phosphorus, indicating that the model was representative of reality. The study also shows that environmental factors such as pH, as well operating conditions such as Fe/P molar ratios (1, 1.5 and 2), influence the concentration of dissolved phosphate in the effluent. The time constant of simultaneous precipitation in the calibrated model, due to a step change decrease/increase in FeSO4 dosage, was found to be roughly 5 days, indicating a slow dynamic response due to a multi-step process involving dissolution, oxidation, precipitation, aging, adsorption and co-precipitation. The persistence effect of accumulated iron-precipitates (HFO particulates) in the activated sludge seemed important for phosphorus removal, and therefore solids retention time plays a crucial role according to the model. The aerobic tank was deemed to be the most suitable dosing location for FeSO4 addition, due to high dissolved oxygen levels and good mixing conditions. Finally, dynamic model-based analyses show the benefits of using automatic control when dosing chemicals.

EFECTO DE DECOLORACIÓN POR PLASMA NO TÉRMICO EN COLORANTES TEXTILES DISUELTOS: NEGRO ÁCIDO 194

In this work, we show that cold plasma (electrical discharge) acting on the liquid–atmosphere interface can change some macroscopic and microscopic parameters of wastewater with dissolved dyes, a process characterized by the study of physical and chemical variables, such as the voltage and current of the electrical discharge, temperature, volume, absorbance, electrical conductivity, pH, chemical oxygen demand (COD), and total organic carbon (TOC). The dye used is Acid Black 194 (AB194) in a water solution (250 mL) with a concentration of 0.1 mM and the addition of FeSO4 at 1.0 mM. The initial values of pH and electrical conductivity were 2.54 and 1.55 mS/cm, respectively, at a temperature of 21.5°C. Nonthermal plasma was generated with a DC power supply at a potential of 700 V and 133 mA, which was maintained throughout the process, until an exposure time of 45 min. This physicochemical method is environmentally friendly because it does not generate polluting waste.

Effect of Fenton-like oxidation reagent on hydrophobicity and floatability of chalcopyrite and molybdenite

A fundamental study is provided in this work to understand the effect of Fenton-like reagent made by the addition of FeSO4 in H2O2 aqueous solution on surface hydrophobicity and floatability of chalcopyrite (CuFeS2) and molybdenite (MoS2). Contact angle measurements were performed to assess the surface hydrophobicity. The contact angle results showed that Fenton-like reagent could alter the surface hydrophobicity of chalcopyrite at lower concentration of H2O2 aqueous solution compared to that of using H2O2 aqueous solution. On the other hand, molybdenite surface remained hydrophobic after the oxidation treatments using Fenton-like reagent and H2O2 aqueous solution. Surface characterizations using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) shows that the chalcopyrite surface covered with a thicker layer of oxidation products after the oxidation treatment using Fenton-like reagent, indicating a stronger surface oxidation. Flotation results were in agreement with contact angle results, showing that Fenton-like reagent could depress the floatability of chalcopyrite at lower concentration of H2O2 aqueous solution. On the other hand, molybdenite recovery remained high under various oxidation treatments owing to low surface oxidation.

The Soil Amendments to Improve the Efficiency of the Intercropping System of Pteris vittata and Morus alba

Intercropping of arsenic (As) hyperaccumulator Pteris vittata and cash crop Morus alba could improve the As concentration in the hyperaccumulator but decrease As concentration in the intercropped crop. The effects of several amendments on the transfer of As were investigated to determine an enhancement strategy for the intercropping system of P. vittata and M. alba. Phosphorus, in the form of Ca(H2PO4)2, promoted the release of As to the soil solution and apparently increased the As removal from the soil by 42% compared with the untreated variant. The addition of FeSO4 and CaCO3 decreased As concentration in the soil solution and the uptake of As by both plant species. The As levels in the mulberry leaves remained under the threshold limits of feedstuffs in China. Intercropping was confirmed as an applicable strategy to manage contaminated soil. Hence, under the condition that all treatments produced safe mulberry leaves, Ca(H2PO4)2 was the appropriate amendment to achieve the highest As removal rate, whereas FeSO4 could lower the risk of As to further migrate to another medium.

Selective flotation of chalcopyrite and molybdenite using H2O2 oxidation method with the addition of ferrous sulfate

Hydrogen peroxide (H2O2) has been used as an oxidizing agent in the selective flotation of chalcopyrite and molybdenite. However, this method required relatively high concentration of H2O2 to deliver flotation results (i.e., mineral grades and recoveries) comparable to those obtained by the conventional copper-molybdenum (Cu-Mo) ores flotation using sodium hydrosulfide (NaHS). Therefore, further improvements are needed to reduce the consumption of H2O2 reagent. In this study, ferrous sulfate (FeSO4) was used to enhance the oxidation performance of H2O2 through Fenton-like reactions. Flotation results showed that the consumption of H2O2 reagent could be reduced by the addition of FeSO4 without losing the flotation selectivity. The reason might be caused by increasing of oxidation performance as indicated by the increasing concentration of dissolved oxygen after the addition of FeSO4 into the H2O2 aqueous solution. Surface analysis using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) images showed that the surface of chalcopyrite was covered by more hydrophilic precipitates after the oxidation treatment using H2O2 aqueous solution with the addition of FeSO4, thus more hydrophilic surface and lower floatability. On the other hand, the surface of molybdenite was slightly oxidized and its surface remained hydrophobic as confirmed from contact angle results. Flotation tests using Cu-Mo bulk concentrate demonstrated that selective flotation might be possible using a mixture of FeSO4 and H2O2 aqueous solution. Moreover, this new method could be used as an alternative to copper depressant in Cu-Mo selective flotation, replacing the NaHS reagent.

Phosphorus removal by in situ generated Fe(II): Efficacy, kinetics and mechanism

The application of in situ electrochemical generation of ferrous (Fe(II)) ions for phosphorus (P) removal in wastewater treatment was investigated with attention to the efficacy, kinetics and mechanism. At concentrations typical of municipal wastewater, P could be removed by in situ Fe(II) with removal efficiency higher than achieved on addition of FeSO4 and close to that of FeCl3 under both anoxic and oxic conditions. The generation of alkalinity due to water electrolysis at the cathode created much higher pH conditions compared to FeSO4 dosing thereby resulting in very different pathways of Fe solid phase formation and associated P removal mechanisms. The remarkably similar dependence of P removal on accumulated Fe for all investigated currents, initial P concentrations and DO conditions indicated that kinetic aspects did not play a role in P removal during in situ Fe(II) dosing. Thermodynamic modelling was undertaken to investigate possible solid phase formation pathways under anoxic conditions and these insights were extended to oxic conditions. The exclusive formation of ferrous hydroxide during anoxic in situ Fe(II) dosing implied that P removal occurred via coprecipitation and adsorption. Under oxic conditions, the high pH conditions would have resulted in rapid Fe(II) oxidation and formation of ferric oxyhydroxides with associated coprecipitation and adsorption effecting P removal in a similar pattern to that observed under anoxic conditions. In situ Fe(II) dosing represents a versatile option for chemical P removal with the precise control of Fe dosage to optimize FeP forms for possible P recovery.

Tannin-based adsorbents from green tea for removal of monoaromatic hydrocarbons in water: Preliminary investigations

ABSTRACTIn this study, we report the adsorption of benzene and toluene from water using rarely reported tannin adsorbents. Tannin gel and tannin powder were synthesized by adding formaldehyde to green tea extract, while iron nanoparticles were synthesized by the addition of FeSO4 · 7H2O. The surface morphology of the synthesized adsorbents was determined using SEM and FTIR prior to application to contaminated water. The results show up to 88% removal of benzene and toluene in a batch system after 30 min of reaction time, with a higher rate of removal of toluene compared to benzene. A low pH value of 2 had an adverse effect on the tannin gel, reducing the total adsorption of benzene to approx. 37.5%. On the other hand, iron nanoparticles were least affected by the pH with an adsorption of 62.9% for benzene and 83.3% for toluene.

Effects of ferrous sulfate amendment and water management on rice growth and metal(loid) accumulation in arsenic and lead co-contaminated soil.

Arsenic (As) and lead (Pb) commonly co-exist with high concentrations in paddy soil mainly due to human activities in south of China. This study investigates the effect of ferrous sulfate (FeSO4) amendment and water management on rice growth and arsenic (As) and lead (Pb) accumulation in rice plants. A paddy soil co-contaminated with As and Pb was chosen for the pot experiment with three FeSO4 levels (0, 0.25, and 1%, on a dry weight basis) and two water managements (flooded, non-flooded). The concentrations of As and Pb in iron plaques and rice plants were determined. Application of FeSO4 and non-flooded conditions significantly accelerated the growth of rice plants. With the addition of FeSO4, iron plaques were significantly promoted and most of the As and Pb were sequestered in the iron plaques. The addition of 0.25% FeSO4 and non-flooded conditions did not significantly change the accumulation of As and Pb in rice grains. The practice also significantly decreased the translocation factor (TF) of As and Pb from roots to above-ground parts which might have been aided by the reduction of As and Pb availability in soil, the preventing effect of rice roots, and the formation of more reduced glutathione (GSH). Flooded conditions decreased the Pb concentration in rice plants, but increased As accumulation. Moreover, rice grew thin and weak and even died under flooded conditions. Overall, an appropriate FeSO4 dose and non-flooded conditions might be feasible for rice cultivation, especially addressing the As issue in the co-contaminated soil. However, further detailed studies to decrease the accumulation of Pb in edible parts and the field application in As and Pb co-contaminated soil are recommended.

Bacterial cyclic β-(1,2)-glucans sequester iron to protect against iron-induced toxicity.

Cellular iron homeostasis is critical for survival and growth. Bacteria employ a variety of strategies to sequester iron from the environment and to store intracellular iron surplus that can be utilized in iron-restricted conditions while also limiting the potential for the production of iron-induced reactive oxygen species (ROS). Here, we report that membrane-derived oligosaccharide (mdo) glucan, an intrinsic component of Gram-negative bacteria, sequesters the ferrous form of iron. Iron-binding, uptake, and localization experiments indicated that both secreted and periplasmic β-(1,2)-glucans bind iron specifically and promote growth under iron-restricted conditions. Xanthomonas campestris and Escherichia coli mutants blocked in the production of β-(1,2)-glucan accumulate low amounts of intracellular iron under iron-restricted conditions, whereas they exhibit elevated ROS production and sensitivity under iron-replete conditions. Our results reveal a critical role of glucan in intracellular iron homeostasis conserved in Gram-negative bacteria.

Effluent valorization in copper hydrometallurgy plant

Copper is commonly produced by hydrometallurgical processes. The production of this metal results in the formation of emissions (unwanted solids, liquids and gases). In this paper, an effluent from a Cu producer company is valorized by means of Fe and Cu recovery.In the current process, an effluent from the secondary solvent extraction (secondary raffinate) was sent to neutralization plant to be discharged. In this paper a modification of the process is proposed. The secondary raffinate was contacted with TP207 resin for Fe3+ and Cu recovery. Metals were eluted from the resins using another real effluent (primary raffinate, effluent from the primary solvent extraction) from the same plant.Experiments for the uptake and elution were carried out in batch and in columns. The effect of pH, resin dosing, and temperature onto metals retention are analyzed. Retention efficiencies (loading capacities) were 50.1% (8.1mg·g−1) for Cu and 54.8% (23.2mg·g−1) for Fe3+ under the optimal operational conditions (pH=0.45 and T=65°C). These values were confirmed in column tests. It is possible to recover Fe3+ and Cu from the secondary raffinate, leaving most of Fe2+ and other elements in solution. The experimental affinities that TP207 showed are: Cu>Fe3+>Fe2+>Zn.The elution of Fe and Cu was quantitatively achieved with concentrated H2SO4 solution. When acidified primary raffinate was used as eluting solution, an enriched solution containing 14.3g Cu·L−1, 20.3g Fe2+·L−1, and 18.6 de g Fe3+·L−1 was obtained. This enriched primary raffinate can be reintroduced in the process as leaching solution.So, after the modification of the process, using secondary raffinate as loading solution and acidified primary raffinate as eluting solution, the ion-exchange stage could substitute the external FeSO4 addition. In addition, 30–80kgCu·h−1 are reintroduced in the process.

A ToF‐SIMS investigation on correlation between grinding environments and sphalerite surface chemistry: implications for mineral selectivity in flotation

AbstractChanges in mineral surface properties during grinding play a key role in flotation performance. Time of flight secondary mass spectrometry (ToF‐SIMS) surface chemical analytical studies have shown that flotation separation of sphalerite from chalcopyrite is significantly affected by the oxidation of metal species on the surface of sphalerite. The intensity of iron oxyhydroxyl species on the surface of sphalerite has a positive correlation with poor recovery of sphalerite. Given the link between the presence of oxide species on the surface of sphalerite and a lower recovery during copper flotation, a laboratory study was initiated to evaluate the potential for sphalerite surface oxidation control and improving recovery through grinding. For the investigation, a ball mill that allowed for monitoring pulp chemistry during grinding was utilized to study the impact of grinding conditions on selective flotation of sphalerite. ToF‐SIMS was used to identify and measure the variability in sphalerite surface species as a result of the different test parameters. Variable mill parameters include two types of grinding media, aeration conditions, addition of FeSO4, and altering the pyrite content in the feed ore. ToF‐SIMS analyses of mill discharge samples identified higher intensities of iron oxyhydroxyl species on sphalerite surface subsequent to grinding with mild steel balls, in condition of aeration, use of FeSO4, and by increasing the pyrite content of the feed ore. The higher adsorption of iron oxyhydroxyl species on the surface of sphalerite should be consistent with the lower recovery. To verify this, bench‐scale flotation tests in the presence and absence of FeSO4 were performed; results correlated iron oxyhydroxyl species with the poor sphalerite recovery. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of iron sulphate on the phosphorus speciation from agro-industrial sludge based and sewage sludge based compost

Composting is considered a suitable process for organic waste management, providing stable products that can be safely utilized as fertilizers, but little is still known about the variation of phosphorous (P) extractability during the stabilization process. In this work, sequential chemical extraction (SCE) with increasing strength extractants (H2O; 0.5M NaHCO3 pH 8.5; 0.1M NaOH, 1M HCl) was applied for P speciation over 56days of composting of either agro-industrial or urban wastewater sludge with green waste treated (AICFe+; SSCFe+) or not (AICFe−; SSCFe−) with FeSO4 (2%v/v). Composting strongly reduced the H2O-P, promoting the organic-P (Po) mineralization from the labile fraction (H2O+NaHCO3 40%), in addition to the increases of NaHCO3- and HCl-extractable inorganic-P (Pi) in both AICFe− and SSCFe− (+20% on average). The FeSO4 treatment did not negatively affect the process, reducing the Po mineralization during composting by increasing the NaOH-P, also protecting this fraction from fixation in the sparingly soluble fraction. The final P fractionation (%) was in AICFe−: NaOH (41)=NaHCO3 (38)>HCl (18)>H2O (3); in AICFe+: NaOH (53)>NaHCO3 (24)=HCl (22)>H2O (2); in SSCFe−: NaOH (46)>NaHCO3 (29)>HCl (21)>H2O (4) and in SSCFe+: NaOH (66)>NaHCO3 (13)>HCl (20)>H2O (1). Composting reduced the more easily leachable fraction (labile-Po), reducing the risk of P loss by increasing the long-term available P fraction (NaOH-P). This was enhanced by the FeSO4 addition. Further investigation into soil behaviour and plant availability of P from this source is needed.

Current and future microbiological strategies to remove As and Cd from drinking water.

Current and future microbiological strategies to remove As and Cd from drinking water.

Bioremediation of benzene from groundwater by calcium peroxide (CaO2) nanoparticles encapsulated in sodium alginate

This study was conducted through batch and column experiments for remediation of benzene from groundwater (50mg/L) by encapsulated calcium peroxide (CaO2) nanoparticles and FeSO4. The results showed complete benzene removal by CaO2 capsules within 60 days, whereas, addition of FeSO4 capsules to the batch tests removed 100% of pollution after 70 days. Furthermore, the initial temperature and pH of the groundwater showed significant impacts on the remediation process. Results indicated that benzene was removed more efficiently by addition of FeSO4 and CaO2 capsules in modified Fenton (MF) reaction at lower pH (3). However, raising the pH resulted in better stimulation of microbial population due to more oxygen generation from CaO2 capsules. In addition, results revealed that CaO2 capsules are able to perform effectively for pollution bioremediation at 30°C and at lower temperatures MF reaction is performed ideally. In column experiments, MF reaction showed higher capability for benzene remediation from the effluent (100% removal after 4 days) and CaO2 capsules were successfully exploited for comprehensive treatment of the groundwater after 30 days. Results indicated that MF reaction was more potent than only CaO2 capsules for benzene removal from groundwater. Present investigation provides a considerable insight into application of CaO2 nanoparticles as reactive barriers.

Study of DNA adduct 8 hydroxy-2’-deoxyguanosine (8-OHdG) formation through fenton reaction with tert-butylhydroquinone (TBHQ) and butyl hydroxy toluene (BHT)

The research of DNA adduct formation 8-hydroxy-2’-Deoxyguanosine (8-OHdG) as a biomarker of DNA damage due to oxidative stress was carried out by reacting the DNA base 2’-deoxyguanosine-5’-monophosphate with TBHQ and BHT. The formationof 8-OHdG was carried out in various conditions, at temperature of 37° C and 60° C, pH 7.4 and pH 8.4, within 5 hours of incubation time and in the addition of FeSO4. The formation of DNA adducts profile were analyzed using reversed phase HPLC with UV detector at a wavelength of 254 nm. The results of the study showed that TBHQ and BHT can trigger the formation of 8-OHdG from the reaction of 2’-hydroxy Deoxyguanosine-5’-monophosphate in the presence of Fe (II). Meanwhile, in the addition of hydrogen peroxide, the formation of DNA adducts only occur in the test substance TBHQ. The results showed that the condition of higher temperature at 60°C and pH 8,4 affects the higher formation of DNA adducts.

Stabilization of Chromium in Synthetic Slags with FeSO4 and FeS2

In this work, the effects of the slag basicity (mass ratio CaO to SiO2) and the addition of FeSO4 or FeS2 into the slag on the stability of the mineralogical species in the slag containing chromium compounds were studied. The chemical stability was evaluated by leaching the slags with an acid solution. The main Cr-compounds in slags with low basicity (CaO/SiO2 = 1) and FeSO4 were FeCr2O4 and Ca3Cr2Si3O12, while Cr3S4 and Ca3Cr2Si3O12 were formed in slags with FeS2. The slags with high basicity (CaO/SiO2 = 2) and FeSO4 contained CaCr2O4, FeCr2O4 and Ca5(SiO4)2SO4. The slags with FeS2 and high basicity produced FeS·Cr2S3, FeCr2O4 and Ca3Cr2Si3O12. The results showed that the lowest chromium concentration levels in the leaching liquors corresponded to slags with CaO/SiO2 = 1 and high FeS2 contents, owing to the stable binding of chromium in the compounds FeCr2O4, Cr3S4 and Ca3Cr2Si3O12.

Immobilization of Heavy Metals by Solidification/Stabilization of Co-Disposed Flue Gas Desulfurization Brine and Coal Fly Ash

The coal-fired power industry in the United States faces growing needs to improve wastewater treatment and disposal practices, especially for wet flue gas desulfurization (FGD) systems. Zero liquid discharge (ZLD) treatment systems may be implemented, and one ZLD option is the coupling of brine concentration with solidification/stabilization (S/S). This S/S process could be achieved by co-disposing the concentrated FGD brines with coal fly ash (CFA) and Portland cement. S/S using bituminous CFA (BCFA) achieved good retainment (average 68–90%) of AsV, CdII, HgII, and SeIV in the toxicity characteristic leaching procedure (TCLP); however, poor retainment was observed for CrVI and SeVI. Separate experiments showed good sorption of AsV, CdII, HgII, and SeIV (average 56–100%) but poor sorption of CrVI and SeVI to S/S solids. Meanwhile, CrVI and SeVI retainment could be enhanced by addition of FeSO4 to the S/S mixture, likely due to reduction of these metals to lower oxidation states. Compared to BCFA, S/S using sub-bituminous CFA (SCFA) resulted in higher pH S/S solids and final TCLP leachate, which increased retainment of AsV, CdII, and SeVI. Apart from the pH impact on the process, AsV retainment was likely improved by the high Ca content of SCFA and SeVI retainment was improved by the incorporation of SeO42– in Friedel’s salt (AFm-Cl) by exchange with Cl–. Friedel’s salt was positively identified by X-ray diffraction in the SCFA S/S solids but not for the BCFA S/S solids. Even so, reduction of SeVI plus S/S is likely a better immobilization strategy than SeO42– substitution in the AFm phase because of higher stability under long-term landfill conditions.