Industrial wastewater treatment using magnesium electrocoagulation in batch and continuous mode.

In the present study, the electrocoagulation (EC) performance of a Mg-Mg system was applied for the industrial wastewater treatment, from an industrial park that covers different activities such as: food, automotive, pharmaceutical, chemistry and cosmetics, after primary clarification. The effects of major operating parameters such as pH, reaction time, and current density were investigated for chemical oxygen demand (COD), color, and turbidity removal efficiency. The batch system was found convenient, achieving 63.52% COD, 96% color, and 99.32% turbidity removal at optimized operating conditions of pH 7.12, reaction time of 75 min, and current density of 201.5 A/m2. On the other hand, for continuous EC, the process removed approximately 46.58%, 95.96%, and 87.19% of the COD, color, and turbidity respectively, at 90 min of retention time, current density 440 A/m2, and a rate of 20 mL/min. Additionally, concerning nutrient removal (N and P), the EC system with Mg electrodes was highly efficient; batch treatment removed 97% of total phosphorus and 67% of ammoniacal nitrogen, whereas the continuous treatment removed 98.5% of total phosphorus and 83% of ammoniacal nitrogen. The sludge characterization before and after EC treatment was made by SEM, EDS, Fluorescence spectroscopy, IR spectroscopy. Minerals such as chlorite, crossite, richterite, pyroaurite, langbeinite as weel as aliphatic and polysubstituted aromatics compounds, sulfates and phosphates inorganic ions, and organic phosphorus were reduced. The energy cost in the batch EC is US$0.05/m3. A numerical CFD model was used to estimate the velocity fields and guarantee the presence of turbulent kinetic energy within a continuous flow reactor.

Hydrogeochemical Characterization and Assessment of Contamination by Inorganic and Organic Matter in the Groundwater of a Volcano-Sedimentary Aquifer.

The chemical composition of groundwater is a product of the evolution and transformation of major ions, which come from natural hydrogeochemical processes or from anthropogenic interference. The objective of this study was to identify the hydrogeochemical processes and the influence of anthropogenic activity on the variation of chemical composition in Toluca Valley groundwater. The type of water in the zone is fundamentally Mg-Ca-HCO3. Three groups with different evolutionary tendencies were identified: one within a local recharge zone and two others in an intermediate region with anthropic activity. The latter, which show contamination by inorganic matter (fertilizers) and organic matter (urban or industrial wastewater). The content of N-NO3- (0.024-0.219 mEq L-1), N-NH4+ (0-0.022 mEq L-1), Porg (0.03-1.02 mEq L-1) and PO43- (0.0-0.28 mEq L-1) indicated contamination coming from inorganic and organic matter. These chemical compounds were identified by way of a 3D fluorescence technique. The results of this study demonstrate that the main processes that affect and control the chemical composition of the water in the Toluca Valley aquifer are weathering of silicates, the ion exchange and a mixture process generated by a source of anthropic contamination.

Chemical activity relation of phosphorus and nitrogen presence in trace elements incorporation into underground water.

Anthropogenic activities can deteriorate the quality of groundwater destined for human use and consumption due to the fact that human activities cause changes in groundwater chemistry. The changes are induced by chemical species coming from industrial waste, which interacts with rocks and minerals. These trigger agents (phosphorus and nitrogen nutrients) which can incorporate trace elements (As, Fe, Mn, Pb, Cd, Ni, Zn). The main objective of the present work was to study the phosphate ions' and nitrogenous species' effects on the incorporation of trace elements into groundwater used for human consumption and to determine the physicochemical processes that participate in the incorporation of trace elements. The physicochemical analysis and elemental analysis by ICP of the groundwater that supplies the study area showed that the phosphorus (P) activity contributes in the incorporation of trace elements into the water. Significant correlations between the activities of P and Fe (0.516), Mn (0.553), Pb (0.756), and As (- 0.747) as well as the correlation of NH4+ with As indicate that the presence of chemical species such as PO43- (2.50-32.20 mg L-1), NO3- (0.89-30.80 mg L-1), and NH4+ (0.2-12.70 mg L-1) are triggering agents that favor the dissolution and mobility of As (0.014-0.020 mg L-1), Fe (0.020-1.14 mg L-1), Mn (0.007-0.254 mg L-1), Ni (0.002-0.0141 mg L-1), Zn (0.009-0.459 mg L-1), and Pb (0.009-0.0170 mg L-1), species with adverse health effects because they are considered carcinogenic. Adequate control of the nitrogenous and phosphated material prevents the dissolution and mobility of trace elements into the water.