Electrolytic treatment of wastewater containing n-phenyl-n '-1,3-dimethylbutyl-p-phenylenediamine

This study investigated the effects of electrolytic treatment using Dimensionally Stable Anode (DSA, 70%TiO2/30%RuO2) type electrodes in simulated wastewater containing aromatic amine n-phenyl-n'-1,3-dimethylbutyl-p-phenylenediamine (Flexzone 7P). A low direct current density of 0.025 A cm(-2) was applied for periods up to 60 minutes and a 52.6% decrease in Flexzone 7P concentration was observed. Ultraviolet-visible spectra, gas chromatography, toxicity and biodegradation tests were carried out with the aim of verifying the toxic by-products that were formed. Ultraviolet-visible spectra of simulated wastewater exhibited changes in the aromatic amine's molecular structure. Additionally, based on the S. cerevisiae toxicity test, it was observed that detoxification of the wastewater occurred after 15 minutes of electrolysis. It was also observed that five minutes of treatment were sufficient to improve the biodegradation rate, determined through the respirometric Bartha method.

Electrolytic treatment of wastewater from a fowl slaughterhouse using cast-iron electrodes

A viability study of an electrolytic process for the transformation of organic matter and free sulphide contained in wastewater from a fowl slaughterhouse in order to minimise odours was carried out Cast iron and aluminium electrodes were tried at 7.09 mA/cm2, under strong agitation, at 297 K. Conductivity, pH, chemical oxygen demand (COD), amount of settleable solids, and sulphide content were monitored with electrolysis duration. The cast iron electrodes were found to be viable for the elimination of soluble sulphides in the wastewater, leading to the elimination of its strong odour after short times of electrolysis. A significant decrease in COD was also attained.

Production of CGTase by a bacillus Alkalophilic CGII strain isolated from wastewater of a manioc flour industry

GCTase production by a new strain of Bacillus alkalophillc CGII isolated from Brazilian wastewater of manioc flour industry was examined. The growth medium used was composed by 1.5% starch, 1.5% nitrogen and 1% Na 2CO3. Higher activity was obtained with starch, maltodextrin and galactose. When glucose was added to the medium, no enzyme production was observed. High enzyme activity and growth were reached when aeration was increased (88.6 U/mL). The enzyme characterization showed an optimum pH and temperature 8.0 and 55°C for starch hydrolyses, respectively. Mg+ and Ca++ showed small activation; however, Hg + and Cu+ showed a strong enzyme inhibition.

Production and partial characterization of keratinase produced by a microorganism isolated from poultry processing plant wastewater

A Streptomyces was isolated from poultry plant wastewater, showed high keratinolytic activity when cultured on feather meal medium. Optimum keratinolytic activity was observed at 40°C and pH 8.0. The enzyme also showed to be stable between 40 and 60°C. The keratinolytic activity was not inhibited by EDTA, DMSO and Tween 80. On the other hand, CaCl2, ZnCl2, and BaCl2 slightly inhibited the keratinolytic activity. The Streptomyces isolated might be useful in leather, keratin waste treatment, animal feeding industry, and also cosmetic industry. © 2008 Academic Journals.

Constructed wetland in wastewater treatment

Physical and chemical variables of soil and water were measured to determine the effectiveness of a constructed wetland for wastewater treatment. Eight different macrophyte species, namely Eichhornia crassipes, Alternanthera philoxerodos, Heteranthera reniformis, Hydrocotyle umbeliferae, Lidwigia elegan, Ludwigia sericea, Myriophyllum aquaticum and Thypha domingensis, were transplanted. Inlet water and outlet water were the two sampling sites evaluated. There were significant differences (p < 0,05) when limnological characteristics between inlet and outlet water from the constructed wetland were compared. In general, dissolved oxygen was over 4 mg L-1, and conductivity was high, above 80 μS cm-1. Chlorophyll-a levels generally tended to decrease at the wetland outlet and were higher during the rainy period (fish growth period). Results show that ammonia, total phosphorus, BOD5, phosphorus and organic mattel in the sediment removals in the constructed wetland were higher, indicating that macrophytes played an important role in removing these variables. The use of constructed wetland is a viable technology for the biological treatment in aquaculture and swine wastewater.

Anaerobic treatment of wastewater from coffee pulping in upflow anaerobic sludge blanket (UASB) in two stages

In this work, the efficiency of two-stage upflow anaerobic sludge blanket (UASB) reactors was evaluated in bench scale, for treating a liquid effluent from coffee pulping. Hydraulic detention times (HDT) were 4.0; 5.2 and 6.2 days, resulting in organic loading rates (OLR) of 5.8; 3.6 and 3.0g total COD per (L-d) in the first reactor (Rl) and HDT of 2.0; 2.6 and 3.1 days with OLR of 5.8; 0.5 and 0.4 g total COD per (L-d) in the second reactor (R2). The medium values of total COD affluent varied from 15.440 to 23.040 mg O 2/L, and in the effluent to the reactors 1 and 2 were from l.lOO to 11.500 mg 0 2/L and 420 to 9.000 mg O 2/L, respectively. The medium values of removal efficiencies of total COD and TSS varied from 66 to 98% and 93 to 97%, respectively, in the system of treatment with the UASB reactors, in two stages. The content of methane in the biogas varied from 69 to 89% in the Rl and from 52 to 73% in the R2. The maximum volumetric methane production of 0.483 m 3 CH 4per (m 3 reactor d) was obtained with OLR of 3.6 g total COD per (L reactor d) and HDT of 6.2 days in the Rl. The volatile fatty acids concentration was kept below 100mg/L with HDT of 5.2 and 6.2 days in the Rl and HDT of 2.6 and 3.1 days in the R2.

Chlorine disinfection of dye wastewater: Implications for a commercial azo dye mixture

Azo dyes, the most widely used family of synthetic dyes, are often employed as colorants in areas such as textiles, plastics, foods/drugs/cosmetics, and electronics. Following their use in industrial applications, azo dyes have been found in effluents and various receiving waters. Chemical treatment of effluents containing azo dyes includes disinfection using chlorine, which can generate compounds of varying eco/genotoxicity. Among the widely known commercial azo dyes for synthetic fibers is C.I. Disperse Red 1. While this dye is known to exist as a complex mixture, reports of eco/genotoxicity involve the purified form. Bearing in mind the potential for adverse synergistic effects arising from exposures to chemical mixtures, the aim of the present study was to characterize the components of commercial Disperse Red 1 and its chlorine-mediated decoloration products and to evaluate their ecotoxicity and mutagenicity. In conducting the present study, Disperse Red 1 was treated with chlorine gas, and the solution obtained was analyzed with the aid of LC-ESI-MS/MS to identify the components present, and then evaluated for ecotoxicity and mutagenicity, using Daphnia similis and Salmonella/microsome assays, respectively. The results of this study indicated that chlorination of Disperse Red 1 produced four chlorinated aromatic compounds as the main products and that the degradation products were more ecotoxic than the parent dye. These results suggest that a disinfection process using chlorine should be avoided for effluents containing hydrophobic azo dyes such commercial Disperse Red 1. © 2012 Elsevier B.V..

Electrochemical oxidation of wastewater containing aromatic amines using a flow electrolytic reactor

Aromatic amines are environmental pollutants and represent one of the most important classes of industrial and natural chemicals. Some types of complex effluents containing these chemical species, mainly those originated from chemicals plants are not fully efficiently treated by conventional processes. In this work, the use of electrochemical technology through an electrolytic pilot scale flow reactor is considered for treatment of wastewater of a chemical industry manufacturer of antioxidant and anti-ozonant substances used in rubber. Experimental results showed that was possible to remove between 65% and 95% of apparent colour and chemical oxygen demand removal between 30 and 90% in 60 min of treatment, with energy consumption rate from 26 kWh m-3 to 31 kWh m-3. Absorbance, total organic carbon and toxicity analyses resulted in no formation of toxic by-products. The results suggest that the presented electrochemical process is a suitable method for treating this type of wastewater, mainly when pre-treated by aeration. Copyright © 2013 Inderscience Enterprises Ltd.

The application of a surface response methodology in the solar/UV-induced degradation of dairy wastewater using immobilized ZnO as a semiconductor

An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 m of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process. © 2013 Gisella R. Lamas Samanamud et al.

Performance of UASB reactors in two stages followed by post-treatment with activated sludge in wastewater batch of wet-processed coffee

In this study it was evaluated the efficiency of the treatment of wet-processed coffee wastewater in upflow anaerobic sludge blanket (UASB) reactors in two stages, in bench scale, followed by post-treatment with activated sludge in batch. The first UASB reactor was submitted to an hydraulic retention time (HRT) of 6.2 d and organic loading rates (OLR) of 2.3 and 4.5g CODtotal (L d)-1, and the second UASB reactor to HRT of 3.1 d with OLR of 0.4 and 1.4g CODtotal (L d)-1. The average values of the affluent CODtotal increased from 13,891 to 27,926mg L-1 and the average efficiencies of removal of the CODtotal decreased from 95 to 91%, respectively, in the UASB reactors in two stages. The volumetric methane production increased from 0.274 to 0.323L CH4 (L reactor d)-1 with increment in the OLR. The average concentrations of total phenols in the affluent were of 48 and 163mg L-1, and the removal efficiencies in the UASB reactors in two stages of 92 and 90%, respectively, and increased to 97% with post-treatment. The average values of the removal efficiencies of total nitrogen and phosphorus were of 57 to 80% and 44 to 60%, respectively, in the UASB reactors in two stages and increased to 91 and 84% with the post-treatment.

Anaerobic-aerobic treatment of swine wastewater in uasb and batch reactors in series

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Influence of Municipal Treated Wastewater on Morpho-Physiological Characteristics of Eucalyptus Plants

The effects of municipal-treated wastewater on growth and gas exchange characteristics were studied in eucalyptus plants cultivated in a greenhouse under continuous sub irrigation with 70 % Long Ashton solution as a control, 100 % treated wastewater, and treated wastewater diluted 50 % with tap water. Irrigation with wastewater resulted in a reduction of total dry matter per plant and the shoot-to-root ratio and increased specific leaf mass, irrespective of the dilution. The gas exchange characteristics were adversely affected by the irrigation with wastewater, with photosynthetic rates been negatively affected. Total chlorophyll and carotenoids content were reduced in plants grown under treated wastewater. The results demonstrated that when the eucalyptus plants were grown under treated wastewater as the only source of mineral nutrients they were able to produce nearly 50 % of the dry matter produced by the plants grown under appropriate mineral nutrient supply, irrespective of the dilution. Therefore, the contribution of mineral nutrients and organic matter from the treated wastewater used as agricultural irrigation will be significant in lower the fertilizer rates without reducing dry matter production per plant.

Daily photosynthesis, water relations, and ion concentrations of uuonymus irrigated with treated wastewater

Euonymus japonica Thunb. (euonymus) plants were submitted for 9 months to two irrigation treatments using water from different sources: a control (C) water with electrical conductivity (EC) less than 1.2 dS.m(-1) and reclaimed wastewater (RW) with EC approximate to 4 dS.m(-1). At the end of the experiment, no differences in the total dry weight were observed between treatments, whereas the leaf dry mass increased (to the detriment of the root part in RW plants). Throughout the day, the stem water potential (Psi(stem)) of the RW plants was lower than in C, whereas stomatal conductance (g(S)) was slightly reduced in RW from 0800 HR to 1200 HR, but no significant variation in photosynthesis (P-n) or energy conversion efficiency (F'(v)/F'(m)) in photosystem II was detected through the effect of salinity. Gas exchange and fluorescence showed a tendency to increase after midday in plants treated with RW. The photosynthetic behavior and fluorescence of RW plants may have been related to the nitrogen and chlorophyll content of the leaves, confirming the resistance of the photosynthetic mechanism to salinity in this species in these conditions. The toxic effects produced by high concentrations of boron (B), sodium (Na+) and chloride (Cl-) were offset by the effect of other ions like magnesium (Mg2+), potassium (K+), and phosphorus (P) in plants irrigated with RW, thus improving their physiological status without decreasing their ornamental value.