Ecotoxicological evaluation of wastewater from 2.4.6-TNT production

During the manufacture of explosives, large amounts of water are used to remove unwanted by-products generated. This water in turn, ends up in wastewater treatment plants or water bodies. The aim of this study was to evaluate the toxic potential of effluent generated by 2.4.6-Trinitrotoluene (TNT) production, yellow water, red water and mixture of yellow and red water, produced from a plant located in the Paraiba Valley, Sao Paolo state, Brazil. Daphnia similis, Danio rerio, Escherichia coli, Pseudomonas putida and Pseudokircheneriella subcaptata were used as test organisms. Physicochemical parameters such as color, pH, conductivity, total dissolved solids, dissolved oxygen, chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were evaluated. Effluent from 2.4.6-TNT production was extremely toxic to all test organisms. The physicochemical parameters evaluated showed high levels of conductivity (from 41.533 to 42.344 mu S /cm) and chemical oxygen demand (COD of 8471 to 27.364 mg/L) for the effluents analyzed.

Optimization of in situ derivatization SPME by experimental design for GC-MS multi-residue analysis of pharmaceutical drugs in wastewater

This paper presents the development of a procedure, which enables the analysis of nine pharmaceutical drugs in wastewater using gas chromatography-mass spectrometry (GC-MS) associated with solid-phase microextraction (SPME) for the sample preparation. Experimental design was applied to optimize the in situ derivatization and the SPME extraction conditions. Ethyl chloroformate (ECF) was employed as derivatizing agent and polydimethylsiloxane-divinylbenzene (PDMS-DVB) as the SPME fiber coating. A fractional factorial design was used to evaluate the main factors for the in situ derivatization and SPME extraction. Thereafter, a Doehlert matrix design was applied to find out the best experimental conditions. The method presented a linear range from 0.5 to 10 mu g/L, and the intraday and interday precision were lower than 16%. Applicability of the method was verified from real influent and effluent samples of a wastewater treatment plant, as well as from samples of an industry wastewater and a river.

HEPATOTOXICITY ASSESSMENT OF THE AZO DYES DISPERSE ORANGE 1 (DO1), DISPERSE RED 1 (DR1,) AND DISPERSE RED 13 (DR13) IN HEPG2 CELLS

During the dyeing process in baths approximately 10 to 15% of the dyes used are lost and reach industrial effluents, thus polluting the environment. Studies showed that some classes of dyes, mainly azo dyes and their by-products, exert adverse effects on humans and local biota, since the wastewater treatment systems and water treatment plants were found to be ineffective in removing the color and reducing toxicity of some dyes. In the present study, the toxicity of the azo dyes disperse orange 1 (DO1), disperse red 1 (DR1), and disperse red 13 (DR13) was evaluated in HepG2 cells grown in monolayers or in three dimensional (3D) culture. Hepatotoxicity of the dyes was measured using 3-(4,5-dimethylthiazol-2yl)2,5-diphenyltetrazolium (MTT) and cell counting kit 8 (CCK-8) assays after 24, 48, and 72 h of incubation of cells with 3 different concentrations of the azo dyes. The dye DO1 only reduced the mitochondrial activity in HepG2 cells grown in a monolayer after 72 h incubation, while the dye DR1 showed this deleterious effect in both monolayer and 3D culture. In contrast, dye DR13 decreased the mitochondrial activity after 24, 48, and 72 h of exposure in both monolayer and 3D culture. With respect to dehydrogenase activity, only the dye DR13 diminished the activity of this enzyme after 72 h of exposure in both monolayer and 3D culture. Our results clearly demonstrated that exposure to the studied dyes induced cytotoxicity in HepG2 cells.

Characteristics of WWTP sludge after drying in greenhouse for agricultural purposes

The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitoria, Espirito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.

Evaluation of tropical water sources and mollusks in southern Brazil using microbiological, biochemical, and chemical parameters

Florianopolis, a city located in the Santa Catarina State in southern Brazil, is the national leading producer of bivalve mollusks. The quality of bivalve mollusks is closely related to the sanitary conditions of surrounding waters where they are cultivated. Presently, cultivation areas receive large amounts of effluents derived mainly from treated and non-treated domestic, rural, and urban sewage. This contributes to the contamination of mollusks with trace metals, pesticides, other organic compounds, and human pathogens such as viruses, bacteria, and protozoan. The aim of this study was to perform a thorough diagnosis of the shellfish growing areas in Florianopolis, on the coast of Santa Catarina. The contamination levels of seawater, sediments, and oysters were evaluated for their microbiological, biochemical, and chemical parameters at five sea sites in Florianopolis, namely three regular oyster cultivation areas (Sites 1, 2, and oyster supplier), a polluted site (Site 3), and a heavily polluted site (Site 4). Samples were evaluated at day zero and after 14 days. Seawater and sediment samples were collected just once, at the end of the experiment. Antioxidant defenses, which may occur in contaminated environments in response to the increased production of reactive oxygen species (ROS) by organisms, were analyzed in oysters, as well as organic compounds (in oysters and sediment samples) and microbiological contamination (in oysters and seawater samples). The results showed the presence of the following contaminants: fecal coliforms in seawater samples (four sites), human adenovirus (all sites), human noroviruses GI and GII (two sites), Hepatitis A viruses (one site), JC Polyomavirus in an oyster sample from the oyster supplier, Giardia duodenalis cysts, and Cryptosporidium sp oocysts (one site). Among organochlorine pesticides, only DDT (dichlorodiphenyltrichloroethane) and HCH (hexachlorocyclohexane) were detected in some sediment and oysters samples in very low levels; site 4 had the highest concentrations of total aliphatic hydrocarbons. PAHs, and linear alkylbenzenes (LABs) found either in oysters or in sediment samples. The major concentration of fecal sterol coprostanol was found at site 4, followed by site 3. After 14 days of allocation in the four selected sites, there was a significant difference in the enzymes analyzed at the monitored spots. The detection of different contaminants in oysters, seawater, and sediment samples in the present study shows the impact untreated or inadequately treated effluents have on coastal areas. These results highlight the need for public investment in adequate wastewater treatment and adequate treatment of oysters, ensuring safe areas for shellfish production as well as healthier bivalve mollusks for consumption.

EX-SITU BIOREMEDIATION OF BRAZILIAN SOIL CONTAMINATED WITH PLASTICIZERS PROCESS WASTES

The aim of this research was to evaluate the bioremediation of a soil contaminated with wastes from a plasticizers industry, located in Sao Paulo, Brazil. A 100-kg soil sample containing alcohols, adipates and phthalates was treated in an aerobic slurry-phase reactor using indigenous and acclimated microorganisms from the sludge of a wastewater treatment plant of the plasticizers industry (11gVSS kg(-1) dry soil), during 120 days. The soil pH and temperature were not corrected during bioremediation; soil humidity was corrected weekly to maintain 40%. The biodegradation of the pollutants followed first-order kinetics; the removal efficiencies were above 61% and, among the analyzed plasticizers, adipate was removed to below the detection limit. Biological molecular analysis during bioremediation revealed a significant change in the dominant populations initially present in the reactor.

Hydrodynamic evaluation of a mechanical flocculation pilot unit

This work focused on the hydrodynamic research aiming at the short-circuiting evaluation for five different outlet configurations through the compartments of a vertical paddle flocculation pilot unit. The tests were carried out with variable and constant velocity gradients, including alternative rotation direction of the paddles. The research pointed out that the relevance of outlet configuration increases with the reduction of the number of compartments. In opposite, the velocity gradient and the rotation direction of paddles seem less significant features. These results open the perspective of viable increasing of performance, with low financial investments, mainly for flocculation units with three or two compartments installed in overloaded water treatment plants.

ESTIMATING REACTION CONSTANTS BY AB INITIO MOLECULAR MODELING: A STUDY ON THE OXIDATION OF PHENOL TO CATECHOL AND HYDROQUINONE IN ADVANCED OXIDATION PROCESSES

Molecular modeling is growing as a research tool in Chemical Engineering studies, as can be seen by a simple research on the latest publications in the field. Molecular investigations retrieve information on properties often accessible only by expensive and time-consuming experimental techniques, such as those involved in the study of radical-based chain reactions. In this work, different quantum chemical techniques were used to study phenol oxidation by hydroxyl radicals in Advanced Oxidation Processes used for wastewater treatment. The results obtained by applying a DFT-based model showed good agreement with experimental values available, as well as qualitative insights into the mechanism of the overall reaction chain. Solvation models were also tried, but were found to be limited for this reaction system within the considered theoretical level without further parameterization.

Ex-situ bioremediation of Brazilian soil contaminated with plasticizers process wastes

The aim of this research was to evaluate the bioremediation of a soil contaminated with wastes from a plasticizers industry, located in São Paulo, Brazil. A 100-kg soil sample containing alcohols, adipates and phthalates was treated in an aerobic slurry-phase reactor using indigenous and acclimated microorganisms from the sludge of a wastewater treatment plant of the plasticizers industry (11gVSS kg-1 dry soil), during 120 days. The soil pH and temperature were not corrected during bioremediation; soil humidity was corrected weekly to maintain 40%. The biodegradation of the pollutants followed first-order kinetics; the removal efficiencies were above 61% and, among the analyzed plasticizers, adipate was removed to below the detection limit. Biological molecular analysis during bioremediation revealed a significant change in the dominant populations initially present in the reactor.

Estimating reaction constants by ab initio molecular modeling: a study on the oxidation of phenol to catechol and hydroquinone in advanced oxidation processes

Molecular modeling is growing as a research tool in Chemical Engineering studies, as can be seen by a simple research on the latest publications in the field. Molecular investigations retrieve information on properties often accessible only by expensive and time-consuming experimental techniques, such as those involved in the study of radical-based chain reactions. In this work, different quantum chemical techniques were used to study phenol oxidation by hydroxyl radicals in Advanced Oxidation Processes used for wastewater treatment. The results obtained by applying a DFT-based model showed good agreement with experimental values available, as well as qualitative insights into the mechanism of the overall reaction chain. Solvation models were also tried, but were found to be limited for this reaction system within the considered theoretical level without further parameterization.

Characterization of Immobilized Biomass by Amplified rDNA Restriction Analysis (ARDRA) in an Anaerobic Sequencing-Batch Biofilm Reactor (ASBBR) for the Treatment of Industrial Wastewater

The performance of an anaerobic sequencing-batch biofilm reactor (ASBBR-laboratory scale- 14L) containing biomass immobilized on coal was evaluated for the removal of elevated concentrations of sulfate (between 200 and 3,000 mg SO4-2.L-1) from industrial wastewater effluents. The ASBBR was shown to be efficient for removal of organic material (between 90% and 45%) and sulfate (between 95% and 85%). The microbiota adhering to the support medium was analyzed by amplified ribosomal DNA restriction analysis (ARDRA). The ARDRA profiles for the Bacteria and Archaea domains proved to be sensitive for the determination of microbial diversity and were consistent with the physical-chemical monitoring analysis of the reactor. At 3,000 mg SO4-2.L-1, there was a reduction in the microbial diversity of both domains and also in the removal efficiencies of organic material and sulfate.

Application of Electrochemical Degradation of Wastewater Composed of Mixtures of Phenol-Formaldehyde

The industrial wastewater from resin production plants contains as major components phenol and formaldehyde, which are traditionally treated by biological methods. As a possible alternative method, electrochemical treatment was tested using solutions containing a mixture of phenol and formaldehyde simulating an industrial effluent. The anode used was a dimensionally stable anode (DSAA (R)) of nominal composition Ti/Ru0.3Ti0.7O2, and the solution composition during the degradation process was analyzed by liquid chromatography and the removal of total organic carbon. From cyclic voltammetry, it is observed that for formaldehyde, a small offset of the beginning of the oxygen evolution reaction occurs, but for phenol, the reaction is inhibited and the current density decreases. From the electrochemical degradations, it was determined that 40 mA cm(-2) is the most efficient current density and the comparison of different supporting electrolytes (Na2SO4, NaNO3, and NaCl) indicated a higher removal of total organic carbon in NaCl medium.

Characterization of immobilized biomass by amplified rDNA restriction analysis (ARDRA) in an anaerobic sequencing-batch biofilm reactor (ASBBR) for the treatment of industrial wastewater

The performance of an anaerobic sequencing-batch biofilm reactor (ASBBR- laboratory scale- 14L )containing biomass immobilized on coal was evaluated for the removal of elevated concentrations of sulfate (between 200 and 3,000 mg SO4-2·L-1) from industrial wastewater effluents. The ASBBR was shown to be efficient for removal of organic material (between 90% and 45%) and sulfate (between 95% and 85%). The microbiota adhering to the support medium was analyzed by amplified ribosomal DNA restriction analysis (ARDRA). The ARDRA profiles for the Bacteria and Archaea domains proved to be sensitive for the determination of microbial diversity and were consistent with the physical-chemical monitoring analysis of the reactor. At 3,000 mg SO4-2·L-1, there was a reduction in the microbial diversity of both domains and also in the removal efficiencies of organic material and sulfate.