The physical-chemical characteristics of surface waters in the management of quality in clearwater rivers in the Brazilian Amazon

The study of water quality in the Amazon region is important for understanding the functioning of ecological mechanisms. The standard that governs water quality in Brazil, including the Amazon, is Resolution CONAMA 357/05, which uses criteria inspired by standards from other countries. However, this resolution does not consider characteristics of Amazonian aquatic ecosystems, and this can lead to incorrect interpretation of the data. Furthermore, there are few studies on the physical-chemical characteristics of clearwater rivers in the Amazon and the influence of the forest-water interface. Therefore, water samples were collected from four clearwater tributary watersheds of the Amazonas and Tapajós Rivers during the dry season in the city of Santarém, Pará. Most of the points were collected in pristine areas in order to capture the natural physicochemical characteristics of clearwater rivers, as well as to show the importance of ecoregional aspects in water quality management. All samples were below pH 6.0, which represents non-compliance with the CONAMA resolution. Statistical tests yielded negative correlations between pH and conductivity (r = −0.87, p < 0.05), Therefore, the rivers of lower ionic load are influenced by the type of surrounding vegetation, which are characteristics that have been widely reported for blackwater rivers.

Fluoride Polluted Groundwaters in Calabria Region (Southern Italy): Natural Source and Remediation

Excessive ingestion of fluoride through the consumption of F--rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical characterization was performed to define the source of natural pollution of two groundwaters (samples Pc and Bg) coming from deep crystalline aquifers located in the Calabria region (southern Italy) and to define and optimize the most appropriate water treatment strategy. The samples were classified as a F- enriched NaHCO3 type of water. In particular, the F- concentrations observed were 30 mg/L and 8.9 mg/L for the Pc and Bg samples, respectively. Based on the acquired geochemical characterization knowledge, the groundwaters were treated by two thin-film composite NF membranes, namely SPR 10113 and SPR 10114 which have so far not been used for water defluoridation. It was found that the SPR 10114 membrane was able to guarantee water permeates with F- contents lower than the threshold value of 1.5 mg/L for both treated waters, whereas the fluoride content remained above the threshold value when the Pc sample was treated using the SPR 10113 membrane. The obtained permeates were characterized by a low ionic load and were not suitable for long-term consumption as drinking water. However, all of the produced waters did not need any further re-mineralizing processes for agricultural irrigation or other purposes.

Removal of Cu2+ and Zn2+ from aqueous medium using ionic polyacrylamides

<p>The wastewater produced by the galvanoplasty industry is a serious environmental problem due to the high concentrations of heavy metals. In this study polymers were used in ionic flocculation to treat synthetic wastewater containing metals, applying four types of polyacrylamides with different ionic loads as agents to remove copper and zinc. Metal removal efficiency was assessed considering the influence of polymer concentration, ionic load and pH. Selectivity (Cu²⁺/Zn²⁺) at different polymer concentrations was also evaluated. The results confirm that polyacrylamide is efficient in treating wastewater containing heavy metals. These experiments exhibited removal efficiency of around 40% and pH= 4,5; however, efficiency was more than 80% with pH= 7.0 under the same conditions, when polyacrylamides with average ionicity were used.</p>

Estimation of Ionic Load Effect on the Oxidizing Activity of the Microbial Population in the Heap Bioleaching Process at Escondida Mine

The design of the industrial copper bioleaching plant at Escondida mine involves the recycling of the solutions in the system, with a consequent increase of ionic solutes in the raffinate solution and Pregnant Leach Solution (PLS). It is known that elevated concentrations of solutes in these solutions have a negative effect on the microbial population leading to decrease the dissolution of copper containing ore. To study the effect of the ionic load on the microbial oxidizing activity, a regression model was built using the systematic data obtained for the concentrations of sulfate, aluminum, chloride and manganese in solutions, during five years of operation. Then, this model was used to support a design of experiment (DOE). The DOE revealed an important effect on the microbial activity produced by sulfate and/or aluminum, decreasing the activity to minimum values, but the effect of chloride and manganese were not significant on the microbial oxidizing activity. This work highlights the importance of determining operational limits for the ionic load of biomining solutions in order to prevent future inhibitions of the microbial oxidizing-activity.