Alexandre Andrade Cerqueira

ELECTROFLOCCULATION FOR TEXTILE WASTEWATER TREATMENT

Abstract - This work reports on the viability of the electroflocculation (EF) process for chemical oxygen demand (COD), turbidity and color removal from a raw effluent originated from a particular textile industry related to hemp manufacture. Firstly, the following operational parameters were optimized: current density; initial pH; electrolysis time; material of the electrode (iron, aluminum or iron-aluminum); and interelectrode distance. Additionally, the effects of these parameters on specific electrical energy consumption (SEEC) were studied under the optimum conditions. The best removal efficiencies obtained were 93% for color, 99% for turbidity and up to 87% for COD using an aluminum electrode, the initial pH was 5, the cell time operation was 30 min and current density was 15 A/m 2 . These results indicate that, under the studied operational conditions, electroflocculation of these efluents may constitute a viable alternative for COD, turbidity and color removal. Keywords : Textile effluent; Dye; Electroflocculation.

Electrolytic Treatment of Wastewater in the Oil Industry

Due to the negative environmental impacts of exploration and production of oil, new more restrictive environmental laws and regulations have been issued. It is estimated that in the United States alone, the oil industry will need to invest about 160 billion dollars in actions to protect the environment over the next 20 years to meet environmental legislation more demanding than currently adopted in Brazil [4].

Avaliação do processo eletrolítico em corrente alternada no tratamento de água de produção

The main objective was to study the treatment of wastewater generated by the oil industry. This work consisted of tests of electroflocculation with alternate current (AC), and chemical coagulation. The removal efficiencies of organic load were evaluated by the removal of oils and greases, color and turbidity. The parameters investigated were the change in alternate current frequency, the initial pH, the distance between electrodes, the applied potential and time lapse. From the results, one may conclude that the electroflocculation process is potential applicability to the effluent studied, while chemical coagulation was not successful.

Oilfield water treatment by electrocoagulation-reverse osmosis for agricultural use: effects on germination and early growth characteristics of sunflower.

ABSTRACT This study aims to evaluate the effects of oilfield water (OW), treated by a hybrid process of electrocoagulation and reverse osmosis (EC–RO), on seed germination and early growth characteristics of sunflower (Heliantus annus L.). In the EC step, tests were conducted with 28.6 A m−2 current density and 4 min. reaction time. In the RO step, the system was operated with 1 L min−1 constant flow and 2 MPa, 2.5 MPa and 3 MPa feed pressures. In all feed pressures, RO polymeric membranes achieved very high removals of chemical oxygen demand (up to 89%) and oils and greases (100%) from EC-treated effluent. In best feed pressure (2.5 MPa), turbidity, total dissolved salts, electrical conductivity, salinity, toxic ions and sodium adsorption ratio values attained internationally recognized standards for irrigation water. Using EC–RO (feed pressure:2.5 MPa) treated OW, germinated sunflower seeds percentage (86 ± 6%), speed of germination (30 ± 2) and biomass production (49 ± 5 mg) were statistically similar to control (distilled water) results. Vigor index average values obtained using OW treated by EC–RO (3871)were higher than that obtained by OW water treated by EC (3300). The results of this study indicate that EC–RO seems to be a promising alternative for treatment of OW aiming sunflower crops irrigation, since the use of this treated effluent did not affect adversely seed germination and seedling development, and improved seedling vigor. Furthermore, OW treatment by EC–RO reduces sodium levels into acceptable standards values avoiding soil degradation.

Use of reverse osmosis as a polish for the cationic surfactant after electro-oxidative treatment: Acute and chronic toxicity assessment

The main purpose of this work was to evaluate the performance of a commercial reverse osmosis (RO) membrane regarding selectivity (rejection) and productivity (permeate flux) of the treatment of quaternary ammonium compounds (QAC) after electro-Fenton (EF) treatment. Pollutants treated after the EF process should be investigated for ecotoxicity, since excess ions and high conductivity are harmful to aquatic and terrestrial biota. The use of the membrane system after EF treatment acts as final polishing since some electro-oxidative treatments leave the sample with high conductivity. In this study, RO was operated with a constant flow of 1 L min-1 and feed pressures of 1 MPa, 2 MPa and 3 MPa to reject ions (sodium and iron) and to decrease the level of toxicity using representative species from different taxonomic groups: freshwater algae (Pseudokirchneriella subcapitata), microcrustaceans (Daphnia similis) and lettuce seeds (Lactuca sativa). Experiments carried out at different pressures showed that increased pressure caused a rise in rejection and permeate flux. At the applied pressure of 3 MPa, after 180 min, conductivity removal efficiency of 83% was obtained, 85% for sodium and 99% for iron at a flow of 13.87 L/h m2. In all bioassays, the use of the membrane was efficient to decrease the toxicity by rejecting the ions. The microcrustacean tested was the most sensitive organism, while alga was the most tolerant organism. The germination of lettuce seeds and the relative growth rate of the radicle after the combined EF+RO process was satisfactory.

Preliminary Study of Trace Metals by Environmental Quality Criteria in Sediments from a Mangrove Forest inSaco do Mamanguá(Ilha Grande Bay, Rio de Janeiro, Brazil)

Urban and industrial activities are major sources of pollution to mangrove forests. Mangrove sediments can act as sink and reservoir for a wide range of contaminants, including heavy metals. The aim of this study was to investigate the contents of trace metals (Cu, Ni, Pb and Zn) in sediment samples from a potentially unpolluted mangrove ecosystem in the south of Rio de Janeiro state, Brazil. Determination of pH, Eh, organic carbon, nitrogen, phosphorus and particle size were also performed. In accordance to the international criteria of quality of sediment, the results indicate anthropogenic influence since some metals reached excessive values, which can affect the balance of the ecosystem studied. According to the results, the area cannot be considered a trace metal non-polluted area. Despite not having a significant source of metals inside the Bay nowadays, Ilha Grande Bay harbors a shipyard, an oil terminal, and a commercial port, as well as two thermonuclear power plants, all of which indirectly influence the study area. Palavras-chave: Trace metals; contamination; sediments; mangrove. * Universidade do Estado do Rio de Janeiro, Laboratório de Tecnologia Ambiental, Instituto de Química, Rua São Francisco Xavier 524, Maracanã, CEP 20550-900, Rio de Janeiro-RJ, Brasil. Tel.: +55 21 23340563. monicamarques@uerj.br DOI: 10.5935/1984-6835.20130067