Considerable Amount Of Wastewater Research Articles

Electrochemical oxidation of Basic Blue 3 dye using a diamond anode: evaluation of colour, COD and toxicity removal

BACKGROUND: Textile industries generate considerable amounts of waste-water, which may contain strong colour, suspended particles, salts, high pH and high chemical oxygen demand (COD) concentration. The disposal of these coloured wastewaters poses a major problem for the industry as well as a threat to the environment. In this study, electrochemical oxidation of Basic Blue 3 (BB3) dye was studied in a bipolar trickle tower (BTT) reactor using Raschig ring shaped boron-doped diamond (BDD) electrodes in recirculated batch mode. The effects of current density, temperature, flow rate, sodium sulfate concentration (Na2SO4) as supporting electrolyte, and initial dye concentration were investigated. RESULTS: The best experimental conditions obtained were as follows: current density 0.875 mA cm−2, temperature 30 °C, flow rate 109.5 mL min−1, Na2SO4 concentration 0.01 mol L−1. Under these conditions, 99% colour and 86.7% COD removal were achieved. Toxicity tests were also performed on BB3 solutions under the best experimental conditions. CONCLUSION: Based on these results, the BDD anode was found to be very successful for the simultaneous degradation of BB3 and removal of COD. Additional toxicity test results also showed that electrochemical treatment using a BDD Raschig ring anode in a BTT reactor is an effective way of reducing toxicity as well as removing colour and COD. Copyright © 2010 Society of Chemical Industry

Integration of a small biofuel refinery in a rural context

In this work three scenarios of biomass production, conversion and utilization of different biofuels (sunflower crude oil, sunflower refined oil and sunflower methyl-ester) in a rural context are compared. The analysis is referred to the district of Pisa, in Italy. Technical feasibility was analysed by comparing process schemes and safety issues, while environmental impacts were studied by applying the methodology of life cycle assessment. Scenarios involving upgrading of crude sunflower oil (refined oil and biodiesel) require complex plants and the management of dangerous materials, and they produce considerable amounts of wastewater. These scenarios need larger plant size, more complex organization (farm cooperatives) and higher costs than the simple mechanical operations associated with crude oil production. On the other hand the use of low-quality fuels in internal combustion engines can lead to short engine lifetime and high pollutant emissions. The life cycle analysis shows that the biofuel upgrading processes (refining and transesterification) and oil transport have a low influence on the environmental impact, compared to seed cultivation, which is the most impacting step. However fuel upgrading allows a significant reduction in polluting emission during combustion; as a consequence biodiesel results the most sustainable biofuel.

Surface and Interfacial Properties of Nonaqueous‐Phase Liquid Mixtures Released to the Subsurface at the Hanford Site

Surface and interfacial tensions are key parameters affecting nonaqueous‐phase liquid (NAPL) movement and redistribution in the subsurface after spill events. In this study, the impact of major additive components on surface and interfacial tensions for organic mixtures and wastewater was investigated. Organic mixture and wastewater compositions were based on CCl4 mixtures released at the U.S. Department of Energy's Hanford site, where CCl4 was discharged simultaneously with dibutyl butyl phosphonate, tributyl phosphate, dibutyl phosphate, and a machining lard oil. A considerable amount of wastewater consisting primarily of nitrates and metal salts was also discharged. The measured tension values revealed that the addition of these additive components caused a significant lowering of the interfacial tension with water or wastewater and the surface tension of the wastewater phase in equilibrium with the organic mixtures, compared with pure CCl4, but had minimal effect on the surface tension of the NAPL itself. These results led to large differences in spreading coefficients for several mixtures, where the additives caused both a higher (more spreading) initial spreading coefficient and a lower (less spreading) equilibrium spreading coefficient. This indicates that if these mixtures migrate into uncontaminated areas, they will tend to spread quickly but will form a higher residual NAPL saturation after equilibrium than pure CCl4 With time, CCl4 probably volatilizes more rapidly than other components in the originally disposed mixtures and the lard oil and phosphates would become more concentrated in the remaining NAPL, resulting in a lower interfacial tension for the mixture. These results show that the behavior of organic chemical mixtures should be accounted for in flow and transport models.

Elimination of resin acids by advanced oxidation processes and their impact on subsequent biodegradation

Wood pulping and paper production generate a considerable amount of wastewater, containing many pollutants among them resin and fatty acids. Resin acids contribute substantially to effluent toxicity and were identified to be detrimental to microorganisms of activated sludge and in particular to bacteria in anaerobic wastewater treatment system and other forms of aquatic life. The objective of the present study was to check the applicability of the ozone and advanced oxidation processes (AOPs) to eliminate resin acids from aqueous solutions and to determine the ozone dose required. Furthermore, an investigation of the influence of the oxidation methods on subsequent biological destruction of the byproducts was performed. Aqueous solution of the resin acids: abietic, dehydroabietic and isopimaric acids with different initial composition were subjected to ozonation or AOP processes at different ozone doses. After ozonation or advanced oxidation pretreatment the model solutions were biodegraded in aerated vessels containing activated sludge. During ozonation of the resin acids aqueous solutions the resin acids were almost eliminated, however the reduction of chemical oxygen demand (COD) was rather low. The ozone dose required to obtain reduction of resin acids >90% was in the range of 0.1–0.7 mgO 3/mgCOD, depending on the composition and concentration of model solutions. The toxicity of ozonated resin acids solutions decreased with increasing applied ozone dose up to about 0.3–0.5 mgO 3/mgCOD, thereafter increased. Ozonation and other AOP processes did not increase the rate of biodegradation of resin acids model solutions in aerated activated sludge systems compared to not pretreated solutions.

Polyphenolic content in olive oil waste waters and related olive samples.

The production of olive oil yields a considerable amount of waste water, which is a powerful pollutant and is currently discarded. Polyphenols and other natural antioxidants, extracted from olives during oil extraction process, partially end up in the waste waters. Experimental and commercial olive oil waste waters from four Mediterranean countries were analyzed for a possible recovering of these biologically interesting constituents. Identification and quantitation of the main polyphenols were carried out by applying HPLC-DAD and HPLC-MS methods. Representative samples of ripe olives were also analyzed at the same time to correlate, if possible, their polyphenolic profiles with those of the corresponding olive oil waste waters. The results demonstrate that Italian commercial olive oil waste waters were the richest in total polyphenolic compounds with amounts between 150 and 400 mg/100 mL of waste waters. These raw, as yet unused, matrices could represent an interesting and alternative source of biologically active polyphenols.