Preventive strategies for reuse and recycling of wastewater within the HDG production.

The hot-dip galvanizing consumes raw materials, supplies, and influence in the quantity/quality of wastewater, opening advantage for its segregation, reuse, and recycling. Therefore, the aim was to establish strategies for segregation, recycling, and preventives process of wastewater from a hot dip galvanizing enterprise (>10,000 t/year of galvanizing steel or gs). A mass balance (inputs-outputs by 1 t gs), Sindex considering organic and inorganic parameters for segregation/recycling, and Water Pinch (Zn, COD, TDS) for reuse opportunities were determined. Flow diagrams were based on three scenarios that combine segregation/reuse/recycling, comparing saving water, energy, costs, and carbon dioxide equivalent (CO2-eq) emissions. Results (mass balance) demonstrated that the water consumption in the rising phases (2,355.2 L/t gs) corresponding to 95% of the total water demand. The best scenario combined reuse, segregation and recycling, which decreased up to 36% of treated wastewater, up to 40% of chemicals consumption, about 41% of treatment cost, close to 38% of energy consumed, and up to 17% of CO2-eq emissions by wastewater treatment. Therefore, taking preventive measures without the need of technological changes (treatment) can achieve on efficient water management within of the hot-dip galvanizing production in developing countries.

Comparative acute toxicity of glyphosate-based herbicide (GBH) to Daphnia magna, Tisbe longicornis, and Emerita analoga.

The aim of this work was to know the differential composition of the dissolved fraction of a glyphosate-based herbicide (GBH), commercialized as GLIFOPAC, when reaches different aquatic environments and its ecotoxicological effects on crustaceans species living in them. Daphnia magna, Tisbe longicornis, and Emerita analoga were exposed to glyphosate herbicide called GLIFOPAC (480 g L-1 of active ingredient or a.i.) at concentrations between 0.5 and 4.8 g a.i. L-1. Acute toxicity in D. magna (48 h-LC50), E. analoga (48 h-LC50), and T. longicornis (96 h-LC50) was studied. Chromatographic analysis of the GBH composition used and water (freshwater/sea water) polluted with GLIFOPAC were evaluated. Results reported acute toxicity (48-96 h-LC50) values for D. magna, E. analoga and T. longicornis of 27.4 mg L-1, 806.4 mg L-1, and 19.4 mg L-1, respectively. Chromatographic evaluation described around 45 substances of the GLIFOPAC composition, such as from the surfactant structures (aliphatic chain with esther/ether group), metabolites (AMPA), and other substances (glucofuranose, glucopyranoside, galactopyranose). This study evidenced differences in the GLIFOPAC composition in freshwater and marine water, which may differentiate the toxic response at the crustacean-level in each aquatic environment.