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The mixture of copper and iron often results in materials with favorable properties. The material production processes involving these metals including electroplating produce hazardous wastewater. In this study, the Fluidized Bed Homogeneous Crystallization (FBHC) process was applied to treat iron and copper-containing wastewater. The initial iron copper particles were successfully recovered from synthetic wastewater with [Fe] 0 :[Cu] 0 of 2:1, the total metal concentration of 3 mM, at effluent pH = 7.75 ± 0.75, with the upflow velocity (U) of 1.76 m/h. The agglomerates hardening process is a crucial step for initial particle synthesis. The SEM analysis reveals the spherical particle's densified crust and porous core. The particle formation mechanism which includes the formation of the nucleus, attachment of precipitate flakes, and densification of particles was proposed after microscopic observation. The initial particles synthesized were used to initiate the treatment of synthetic wastewater at the operating condition pH = 7.75 ± 0.5, [Fe] 0 :[Cu] 0 of 2:1, the total metal concentration of 3 mM, [CO 3 2−] 0 :[M] 0 = 1.2:1, and U of 28.66 m/h which results in the total metal removal of 99% and crystallization ratio of 90% and 88% for iron and copper respectively. The conditions were then applied to treat electroplating wastewater and resulted in the total metal removal of 99% for both iron and copper and a crystallization ratio of 83% and 79% for iron and copper, respectively. The treatment provided advantages in terms of treating larger amounts of sludge while eliminating the need to provide seed thus yielding a higher purity of product. [Display omitted] • High-purity Fe–Cu particles were recovered from wastewater. • A total metal removal of 99% was achieved for both synthetic and real wastewater. • Cost reduction of up to 88% compared to conventional chemical precipitation. [ABSTRACT FROM AUTHOR]

This study aims to explore the reusability of wastewater treatment by-product for photo-Fenton process to treat an organic pollutant model. The optimal condition, reactive oxygen species (ROS), and kinetic approach in photo-Fenton process was discussed. The Metal oxide crystal pellets from are a by-product of the Fluidized-Bed Crystallization (FBC) process and can be used as a catalyst in the Photo-Fenton process. Electroplating wastewater containing iron and copper was treated via the FBC process using granulated Al(OH) 3 as carrier seeds. The binary oxide of FeOOH and Cu 2 O on the Al(OH) 3 surface (Fe 0.66 Cu 0.33 @Al(OH) 3) was identified as the FBC by-product after characterization using FTIR and XPS analysis. In the photo-Fenton process, visible light from a fluorescence lamp with a wavelength of 400–610 nm was chosen as an irradiation source. Oxalic acid was added as chelating agent to form photosensitive iron oxalate species and hydrogen peroxide was applied as oxidant to generate active radical to decolorize and mineralize RB5 synthesized solution (100 mg/L). The operating conditions including the oxalic acid to pollutant ratio ([OA] 0 /[RB5] 0) of 4.5–13.0, reaction pH (pHr) of 3–7 and initial to theoretical hydrogen peroxide molar ratio [H 2 O 2 ] 0 /[ H 2 O 2 ] theoretical of 35%–120% were optimized. Under the optimal conditions, pH r = 5.0; [H 2 O 2 ] 0 /[RB5] 0 at 75% stoichiometric and [OA] 0 /[RB5] 0 = 9, the RB5 is almost completely decolorized after 210 min of operation and the mineralization efficiency is 58%. The contribution of •OH, O 2 •-, and O 2 1 to the Photo-Fenton system was determined using ESR analysis with the addition of DMPO and TEMP as spin trap agents. The kinetic analysis reveals the observed rate constants k RB5 , k OA and k R from fitting are 0.0120, 0.0054 and 0.0001 M−1s−1, respectively. [Display omitted] • The binary oxide of by-product from FBC process is useful for organics treatment. • Treatability of azo dye RB5 by visible light-assisted photo-Fenton was investigated. • RB5 was completely degraded and mineralized of 55% using a 75% stoichiometric dosage of H 2 O 2 with the addition of oxalic acid at pH 5. • Up to 55% of TOC was mineralized mainly by O 2 •- and O 2 1. • Rate modeling of RB5 and TOC removal were explained using consecutive kinetics. [ABSTRACT FROM AUTHOR]

The environment is affected by agricultural, domestic, and industrial activities that lead to drastic problems such as global warming and wastewater generation. Wastewater pollution is of public concern, making the treatment of persistent pollutants in water and wastewater highly imperative. Several conventional treatment technologies (physicochemical processes, biological degradation, and oxidative processes) have been applied to water and wastewater remediation, but each has numerous limitations. To address this issue, treatment using bimetallic systems has been extensively studied. This study reviews existing research on various synthesis methods for the preparation of bimetallic catalysts and their catalytic application to the treatment of organic (dyes, phenol and its derivatives, and chlorinated organic compounds) and inorganic pollutants (nitrate and hexavalent chromium) from water and wastewater. The reaction mechanisms, removal efficiencies, operating conditions, and research progress are also presented. The results reveal that Fe-based bimetallic catalysts are one of the most efficient heterogeneous catalysts for the treatment of organic and inorganic contamination. Furthermore, the roles and performances of bimetallic catalysts in the removal of these environmental contaminants are different. Image 1 • Bimetallic catalysts possess different physicochemical properties than those of monometallic catalysts. • Bimetallic catalysts have remarkable catalytic properties and functions, and exhibit high reducibility. • Organic and inorganic pollutants in water and wastewater can be treated using bimetallic systems. [ABSTRACT FROM AUTHOR]

Heavy metal removal is a significant task that protects our water resources. Fluidized-bed homogeneous granulation process (FBHGP) was used to treat nickel containing wastewaters by recovering nickel in the form of nickel carbonate hydroxide granules with low moisture content rather than soft sludge. This study investigated nickel removal and recovery through HFBGP by determining the effects of varying influent nickel concentrations, [CO 3 2− : Ni 2+ ] molar ratios, and pH of the precipitant. This was conducted in a continuous process using a laboratory scale fluidized-bed reactor that determined the effects driven by supersaturation. The best operating conditions that resulted in a 98.8% nickel removal and 97.8% granulation efficiency were 200 mg L −1 influent nickel concentration, 2.0 M R of [CO 3 −2 :Ni +2 ], and 10.7 pH of precipitant. Based on SEM analysis, the granules formed have sizes between 0.50 mm and 0.15 mm. EDS results showed that the atomic percentages of nickel carbon, and hydrogen were ∼50%, ∼9–12%, and ∼35% respectively, representing the nickel carbonate compound. The XRD results showed the low symmetry of the granules formed that confirmed the characteristics of nullaginite mineral of Ni 2 (CO 3 )(OH) 2 . [ABSTRACT FROM AUTHOR]

Chemical oxo-precipitation (COP), which combines treatment with an oxidant and precipitation using metal salts, was developed for treating boron-containing water under milder conditions (room temperature, pH 10) than those of conventional coagulation processes. The concentration of boron compounds was 1000 mg-B L-1. They included boric acid (H3BO3) and perborate (NaBO3). Precipitation using calcium chloride eliminated 80% of the boron from the perborate solution, but was unable to treat boric acid. COP uses hydrogen peroxide (H2O2) to pretreat boric acid, substantially increasing the removal of boron from boric acid solution by chemical precipitation from less than 5% to 80%. Furthermore, of alkaline earth metals, barium ions are the most efficient precipitant, and can increase the 80% boron removal to 98.5% at [H2O2]/[B] and [Ba]/[B] molar ratios of 2 and 1, respectively. The residual boron in the end water of COP contained 15 ppm-B: this value cannot be achieved using conventional coagulation processes. [ABSTRACT FROM AUTHOR]