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Rainwater Electro-Galvanic Alkalization (EGA) was performed using copper and magnesium (1:1) electrode. Efficiently removal of pollutants without external energy consumption was carried out, in addition essential ions were dosed for alkalization of rainwater. The optimal system conditions were obtained using response surface methodology (RSM) by considering the following operating variables: flow rate and concentration of the supporting electrolyte (NaCl and CaCl 2 ). Furthermore, the maximum efficiency of nitrate, ammoniacal nitrogen, colour, and turbidity removal was evaluated. The results showed that the response variables were mainly sensitive to the type of supporting electrolyte used and the flow rate. Under experimental conditions of 0.009 M (NaCl) and 20 mL min -1 , the removal rate was 74.19%, 72.49%, and 81.43% for nitrates, colour, and turbidity, respectively, and the lowest concentration of ammoniacal nitrogen ( 0.99 mg L - 1 ) was obtained. The kinetic models for nitrate and colour were fitted to zero-order models with k = 0.33 mg L - 1 mi n - 1 and k = 0.933 Pt - Co , respectively. In addition, turbidity was fitted to a first-order model ( k = 0.1661 mi n - 1 ) , and ammoniacal nitrogen was fitted to a second-order model ( k = 0.0217 L m g - 1 mi n - 1 ) . The concentration increases of minerals such as Ca and Mg, which rises the rainwater alkalinity after treatment (pH shift from 6.1 to 8.91), was determined by inductively coupled plasma (ICP) analysis.

The goal of this research is to apply an electrocoagulation process in continuous flow for the defluoridation of drinking water. Two sampling sites were studied, Temascalcingo (T), Mexico state and Jerecuaro (J), Guanajuato, with fluoride (F - ) concentrations above the norms (2.3 mg L -1 and 4.5 mg L -1 , respectively). In addition, a second Temascalcingo sample was enriched (T E ) to 9.2 mg L -1 F - to study the effect of the F - concentration. A response surface design was proposed through a Box-Behnken model, and the variables studied were electrode system, flow-rate and current intensity. 51 experiments were performed with T-site to determine the best operating conditions for the system. These conditions were applied to the J-site. The experiments for T, Al/Al system achieves an F - concentration within permissible limits (0.72 mg L -1 F - ) at 10 min of treatment, 0.2 A (Current density j 48.78 A m -2 ) and 10 mL min -1 with a removal efficiency of 68.69%, and after 160 min, the removal increased to 99.56%. AlMg/AlMg needs 10 min to achieve a concentration of 0.75 mg L -1 F - at 0.2 A ( j 25 A m -2 ), 16 mL min -1 with a removal efficiency of 67.39%, and after 100 min, the removal is increased to 92.17%. An important and novel advantage is the use of AlMg allows an acceptable removal of F - (<1.5 mg L -1 ) at high and low concentrations in short periods of time; this also allows save energy costs and the effluent is free of residual aluminum, avoiding side effects.

Drinking water contaminated with As and [Formula: see text] is increasingly prevalent worldwide. Their coexistence can have negative effects due to antagonistic or synergistic mechanisms, ranging from cosmetic problems, such as skin lesions and teeth staining, to more severe abnormalities, such as cancer and neurotoxicity. Available technologies for concurrent removal include electrocoagulation ~ adsorption > membranes > chemical coagulation > , and among others, all of which have limitations despite their advantages. Nevertheless, the existence of competing ions such as silicon > phosphate > calcium ~ magnesium > sulfate > and nitrate affects the elimination efficiency. Mexico is one of the countries that is affected by As and [Formula: see text] contamination. Because only 10 of the 32 states have adequate removal technologies, more than 65% of the country is impacted by co-presence problems. Numerous reviews have been published concerning the elimination of As or [Formula: see text]. However, only a few studies have focused on the simultaneous removal. This critical review analyzes the new sources of contamination, simultaneous physicochemical behaviors, available technologies for the elimination of both species, and future trends. This highlights the need to implement technologies that work with actual contaminated water instead of aqueous solutions (55% of the works reviewed correspond to aqueous solutions). Similarly, it is necessary to migrate to the creation of pilot, pre-pilot, or prototype scale projects, because 77% of the existing studies correspond to lab-scale research., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Samples of drinking water were taken during a year from two wells; all samples were tested for pH, temperature, electric conductivity, dissolved solids, dissolved oxygen, acidity, alkalinity hardness, chloride, nitrites, nitrates, sulfates, phosphates, Ca, Mn, Mg, Na, K, and Si. The analysis showed that the concentration of manganese in one well was higher than the official regulations. Qualitative and quantitative models were applied to determine the stability of water and the corrosion indexes were determined; the results indicated that water was aggressive or corrosive. Manganese was removed from drinking water by using a sodium modified zeolitic tuff; the kinetic equilibrium was reached in 48 h. 10 mL/20 mg ratio was enough to remove the excess of manganese from aqueous solutions and 10 mL/60 mg ratio for natural water. This method is useful to remove manganese from drinking water. [ABSTRACT FROM AUTHOR]

Abstract: The removal of fluoride ions from aqueous solutions and drinking water with aluminum and lanthanum modified natural materials was studied. Drinking water containing naturally 5.87mg of fluoride ions per liter was characterized. The hematite, zeolitic tuff and calcite were aluminum modified by an electrochemical method. Hematite and a zeolitic tuff were lanthanum modified by ion exchange. The results show that the electrochemical method is useful to modify these materials with aluminum. The presence of this element improves the sorption efficiencies for fluoride ions from drinking water and synthetic solutions. The fluoride adsorption capacities increase with increasing the concentration of the aluminum in the samples. The sorption capacities for hematite 3A-2h (containing 11.92% of Al) and hematite-La (containing 1.24% of La) with drinking water were 0.53mg/g and 0.36mg/g respectively and the sorption capacities for zeolite 3A-3h (containing 34.74% of Al) and zeolite-La (containing 7.15% of La) were 0.56mg/g and 0.36mg/g respectively. The aluminum modified hematite is more effective than aluminum modified zeolitic tuff, the presence of iron may be responsible for this behavior. The presence of lanthanum in hematite and zeolitic tuff improves their sorption efficiencies for fluoride ions, but they are lower than the efficiencies found for aluminum modified materials. [Copyright &y& Elsevier]