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[Display omitted] • A co-treatment of steelmaking slag and steel pickling waste liquor was proposed. • FePO 4 was prepared during the collaborative treatment. • After leaching, the residue can be reused as flux within the steel plant. • Comprehensive utilization of metallurgical wastes can be achieved. To prepare FePO 4 and to achieve resource utilization of metallurgical wastes, a collaborative treatment of P-bearing steelmaking slag and steel pickling waste liquor (SPWL) was proposed. The utilization of SPWL as a leachant for P separation from steelmaking slag facilitates P-removal residue recycling within steel plants, while also serving as a Fe source for the FePO 4 preparation. In this study, the effects of synthetic SPWL with various Fe2+ (or Fe3+) contents and leaching parameters on the dissolution behavior of steelmaking slag were investigated. Moreover, the impacts of H 2 O 2 oxidation and pH on the precipitation behavior of FePO 4 from leachate were studied. It was found that increasing Fe2+ concentration in SPWL resulted in a marginal reduction in the P dissolution ratio; however, it was significantly influenced by the pH and solid/liquid ratio. Furthermore, the change in Fe3+ concentration within SPWL exhibited a conspicuous impact on the P dissolution ratio. After leaching, the residue containing massive Fe 2 O 3 , MgO, and MnO could be reused as a flux within the steelmaking process. The FePO 4 precipitated predominantly at pH 2.0 ∼ 3.0, and the crude FePO 4 product containing 42.6 % Fe 2 O 3 and 35.8 % P 2 O 5 was obtained, providing a new solution for the utilization of metallurgical wastes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Global gene expression analysis reveals a novel biorecognition receptor of PBDEs. • Chemoreceptor of PBDEs is an extracellular Cache domain-containing sensor protein. • Sensor protein is displayed on the cell membrane of a hydrophobic chassis cell. • Hydrophobic whole-cell biosensor provides a specific and sensitive response to PBDEs. • It provides a new approach for quality monitoring and toxicity assessing of organics. Polybrominated diphenyl ethers (PBDEs) belong to a group of persistent organic pollutants and pose a risk of causing adverse effects to human health and the environment. Detection and monitoring of these compounds therefore is of great interest and need for remediation and health risk assessment. However, no specific receptor protein can be used as a biorecognition element for the development of PBDE-detecting whole-cell biosensor until now. The lack of knowledge of PBDEs metabolic pathways of bacteria and of bacterial regulatory networks is the main limitation in the successful biosensor design. In this study, the global gene expression analysis of promoter activation as a consequence of deca-BDE exposure led to the finding of a novel sensory element, extracellular Cache domain-containing sensor protein Chr1_2466, for specific biorecognition of PBDEs. A genetically engineered hydrophobic chassis cell, Sphingobium xenophagum C1, expressing firefly luciferase in place of Chr1_2466 on the cell membrane served as a whole-cell biosensor for PBDEs detecting. This biosensor was highly specific for PBDEs and had minimal interference from their structural analogues polychlorinated biphenyls, diphenyl ether, phenol, metals, and inorganic ions. The extracellular luminescence intensity of the hydrophobic whole-cell biosensor showed a linear relationship (R2 = 0.98) from 0.05 to 6.0 µM of deca-BDE with a detection limit of 0.01 µM and a cytotoxicity threshold of 6.25 µM. Compared to the hydrophilic strain as chassis cell, such hydrophobic biosensor significantly increased the bioavailability and detection sensitivity of PBDEs. It provides a new approach for quality monitoring and toxicity assessing of hydrophobic organics. [ABSTRACT FROM AUTHOR]

Spent ion exchange resins have become a crucial radioactive solid waste from the nuclear industry. Developing effective and safe disposal methods as alternatives to the present cementation method remains challenging. This investigation demonstrates the treatment of a mixed resin (sulfonated and quaternary ammonium polystyrene beads with a weight ratio of 40%:60%) by the electro-Fenton process. Mesh-type titanium metal that was coated with IrO 2 /RuO 2 (Ti-DSA) was used as the anode and a stainless steel net was used as the cathode. The conversion of resins to soluble fragments and the removal of total organic carbon reached 92% and 99.4%, respectively, under conditions of solid loading = 40g L −1 , pH 2, applied current = 2 A, H 2 O 2 flow rate = 1.2 mL min −1 , FeSO 4 = 20 mM at 85 °C. A pseudo first-order kinetic model of consecutive reactions specified that the efficacy of the electro-Fenton depended strongly on the slowly generated styrene in the aqueous phase by H 2 O 2 and strong acid, which was rapidly mineralized by the hydroxyl radicals. The electro-Fenton process with reused iron catalyst was effective for treating ion exchange resin for at least for three runs, greatly reducing the volume of waste resin liquid. [ABSTRACT FROM AUTHOR]

This work demonstrated the removal of lead (Pb) from aqueous solution using fluidized-bed crystallization (FBC, using silica sand as seeds) and fluidized-bed homogeneous crystallization (FBHC, without seeds) systems. Synthetic lead wastewater with concentrations of 10, 40 and 200 ppm were treated. The results thus obtained indicated that effluent pH was an essential parameter in determining the efficiency of FBC and FBHC. A comparison between theoretical solubility and residual Pb in effluents revealed that FBHC in the predictable metastable region of pH 6.5–8.5 guaranteed 99% Pb removal and a crystallization ratio of 95% (CR%). XRD analysis suggested that the lead carbonate of FBHC products comprised either a cerussite (PbCO 3 ) or a hydrocerussite (Pb 3 (CO 3 ) 2 (OH) 2 ) phase, depending on pH. FBHC was proven to be effective in remediating lead wastewater under optimal hydraulic conditions (initial molar ratio of [Na 2 CO 3 ]/[Pb] > 1.2, upflow velocity = 25–35 m h −1 and pH e = 7.2 ± 0.4), which were all similar to those in FBC. The cross-section loading (L, kg m −2 L −1 ) depended on the input Pb level; L was controlled at 0.15 kg m −2 h −1 for treating 10 ppm-Pb and was increased to 5.73 kg m −2 h −1 for 40 and 200 ppm-Pb, optimizing the FBHC and FBC processes. Without the addition of seed materials, FBHC recovered purer lead carbonate than did FBC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfide-containing synthetic wastewater was treated by fluidized-bed homogeneous crystallization. • Fluidized bed homogeneous crystallization technology does not need to add the heterogeneous seeds. • The crystallization efficiency of sulfide recovered as zinc sulfide particles reached 97.8%. • Supersaturation is calculated to determine the optimum condition of sulfur crystallization. Sulfide wastewater that is anthropogenically generated from industrial activities is highly corrosive, hazardous, and harms the natural ecosystem. This study uses a novel fluidized-bed homogeneous crystallization (FBHC) method to remove sulfide ions from an aqueous solution. Zinc is used as a precipitant to crystallize ZnS homogeneously in the FBHC reactor to reduce the sludge, which is commonly produced in a conventional chemical precipitation process. The optimal pH value, [Zn2+] 0 /[S2-] 0 M ratio, sulfide cross-sectional surface loading (L, kg-S/m2.hr), and hydraulic retention time (HRT) for the system are established, to optimize the sulfur removal efficiency. The maximum crystallization ratio and the total removal efficiency for sulfur are 97.7% and 98.8%, respectively, at pH = 5.4, a [Zn2+] 0 /[S2-] 0 M ratio of 1, a cross-sectional surface loading of 2.2 kg-S/m2.hr, and an HRT number of 6 with an initial sulfur concentration of 320 mg/L. The solid products are collected and identified as zinc sulfide (wurtzite) using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

• Extremely high concentrations form denser sludge instead of suspended particulates. • A preliminary experiment formed atypical flake-like CaF 2 particles. • Various flow regimes can be crucial to CaF 2 granulation. • A 2.0-mm glass-bead bed enhances the over-all granulation efficiency. • CaF 2 homogenous granulation is achieved with 98% removal and granulation. Excessive and industrial advances have increased fluoride quantity in the effluents. However, the environmental carrying capacity for fluoride is relatively slim immediately affecting both aquatic and terrestrial animals while its transport can further contaminate the water source. To protect the public and the environment, different environmental agencies globally set their respective effluent standard restricting F- concentration to 15 mg/L as the median value. However, various processes from previous investigations have mostly been limited in treating 100–1000 mg F-/L with secondary pollution commonly overlooked. Re-assessing the available defluoridation technologies, chemical precipitation has still been the most feasible among the technologies, especially extremely high fluoride concentrations. In this study, fluoride removal through chemical precipitation was investigated using conventional precipitation and fluidized-bed homogeneous crystallization. Parameters such as a wide range of initial concentrations from 100 to10,000 mg/L and pH 2.0–11.0 under conventional precipitation were varied and analyzed. To reduce high water content sludge, a 550-mL cylindrical glass was modified to simulate a fluidized-bed reactor to investigate homogenous crystallization varying influent concentration, bed-support size, and fluid flow. Results showed that chemical precipitation could effectively remove fluoride even at very high fluoride concentrations ranging from 1,000 to 10,000 mg/L. Alternatively in the fluidized-bed granulation process, an initial very low flow without recirculation flow was required to initiate particle formation. The predominant size of the recovered particle was < 0.2 mm which was relatively heavy atypically not reaching the upper region of the reactor. Under the observed optimum condition with an initial fluoride concentration of 450 mg/L, both total removal and crystallization ratio could reach ∼ 98% efficiency lowering fluoride concentration to < 15.0 mg F-/L within 7 days. [ABSTRACT FROM AUTHOR]

• Cu/Ni electrodes were successfully prepared using electrodeless method. • Depositing time affected the morphology and crystal facet distribution of Cu. • The Cu{1 1 1} facet played a significant role on nitrate reduction. • Nitrogen selectivity was 55.6% at >−0.6 V vs. Hg/HgO. • Complete nitrate reduction occurred at <−0.6 V vs. Hg/HgO. Cu/Ni composite electrodes were prepared and studied for the electrochemical reduction of nitrate in aqueous solutions. Electrodeless plating technique, with tartrate as chelatant and formaldehyde as reducing agent, enabled the in-situ incorporation of Cu nanoparticles into the open-pore structured Ni foam to form Cu-Ni composite electrodes. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) revealed that the crystal facet and grain morphology of Cu nanoparticles was closely controlled by the plating time and played a significant role in nitrate reduction and nitrogen selectivity. Cyclic voltammetry provided information on the electron transfer between surface nitrogen species and Cu/Ni electrodes. Electrochemical nitrate reduction was initiated at the onset potential of Cu(0)/Cu(I) redox reaction over a potential window of −0.6 V to −1.2 V. The preferential Cu{1 1 1} facet orientation improved the electron transfer process. Batch kinetics studies at constant current and potential showed that specific adsorption of nitrate and nitrite on the Cu{1 1 1} facet was critical to efficient electrochemical nitrate reduction. Moreover, the conversion of nitrogenous byproduct was potential-dependent. Results showed that N 2 selectivity was high (55.6%) at low overpotential (i.e., ⩾ −0.6 V vs. Hg/HgO. At high overpotential (i.e, <−0.6 V) there was complete of NO 3 − reduction with NH 4 + as major byproduct. [ABSTRACT FROM AUTHOR]

Magnetically separable spinel ferrites were created in an electrocoagulation (EC) process for removing boron from aqueous solution. Coprecipitates of NiFe 2 O 4 , CoFe 2 O 4 and CuFe 2 O 4 were obtained using sacrificial iron anodes (EC-Fe) in an electrolyte that contained transition metal salts (Ni, Co, Cu). The use of nickel chloride (NiCl 2 ) as the supporting electrolyte yielded the highest boron removal since the maximum adsorption capacity of the resulting sludge was 28.9 mg-B/g. An EC that used iron and nickel as anodes (EC-Fe/Ni) in NaCl electrolyte was then employed to form nickel ferrite by electrochemical dissolution of ferrous (Fe(II)) and nickel (Ni(II)) ions, providing comparable removal efficiency but minimizing the residual level of Ni(II) in the treated water. The saturation magnetization of the precipitate that was produced in the EC-Fe/Ni system was 50.3 emu/g which exceeded that in the EC-Fe system with nickel chloride – 21.8 emu/g, indicating its outstanding magnetic separability. EC-Fe/Ni was optimized to remove 95% of boron from solution in 60 min with an initial boron concentration of 10 ppm at pH 8 and a current density of 3.75 mA/cm 2 . [ABSTRACT FROM AUTHOR]

• Simultaneous recovery of phosphorus and potassium from urine was achieved. • Recovery of P and K reached 98.4% and 70.5%, respectively at low Mg:K ratio of 1.25. • K-struvite pellets recovered have low water content and high purity (>95%). • The fluidized bed homogeneous crystallization (FBHC) was performed without seeds. • FBHC recovery can help yield a profit of $0.26/m3-urine. Most of nutrients in municipal wastewater originate from human urine. In this study, a novel fluidized-bed homogeneous crystallization process was developed for the simultaneous recovery of phosphorus (P) and potassium (K) from synthetic human urine. The operational variables including pH, Mg:K ratios and up-flow velocity were tested in the laboratory. The total removal of P and K (TR%) reached 98.4% and 70.5%, respectively, and the crystallization ratios (CR%) were 86.5% and 62.3%, respectively, at conditions of pH 10 ± 0.2, molar ratio Mg:K = 1.25, initial concentrations 850 mg P/L and 1830 mg K/L. The SEM and XRD analyses showed that the fluidized bed homogeneous crystallization (FBHC) product was pure magnesium potassium phosphate (K-struvite) (average size = 0.85 mm; purity = 95 ± 3%). The modelling of minimum fluidization velocity (MFV) resulted in values of up-flow 1.5–2.0 times the MFV for the effective fluidization. The profit of the recovery of P and K from human urine via FBHC process could be $0.26/m3-urine. [ABSTRACT FROM AUTHOR]

• Carbon dioxide capture, utilization and storage in the form of calcium carbonate. • Calcium carbonate homogeneous granulation in a fluidized-bed reactor. • The kinetic analysis revealed that the pseudo-second order best fitted the results. • Calcium-is-to-carbonate molar ratio directly affects the granule characteristics. • High purity of calcium carbonate-aragonite granules were produced. The granulation of calcium carbonate (CaCO 3) exhibited high industrial demand due to its wider application and importance in cement, paper, glass and steel manufacturing. This paper investigated the granulation kinetics of CaCO 3 through the fluidized-bed homogeneous granulation (FBHG) process during the homogenous nucleation stage. The CaOH solution was used as source of Ca2+ reactant, while K 2 CO 3 solution as source of CO 3 2− precipitant. The mechanism followed the pseudo-second order kinetics. The calcium cation attracts the carbonate anion to form CaCO 3 through a double displacement chemical reaction. The calcium-is-to-carbonate molar ratio ([Ca2+]/[CO 3 2−]) was varied into 1.25 to 2.50, with constant values of pH = 10 ± 0.2, influent carbonate concentration = 10 mM and total influx flow rate = 60 mL min−1. The ideal [Ca2+]/[CO 3 2−] condition was found to be at 1.50 that means the precipitation of CaCO 3 grew and stayed inside the reactor. At the same condition, granules of diameter size of 1 mm to 2 mm were collected with a subrounded shape and smooth surface as shown by its surface morphology. The characterization analysis also verified the high purity of CaCO 3 -aragonite granules precipitated through the FBHG process. [ABSTRACT FROM AUTHOR]