Kinetic investigation and optimization of a sequencing batch reactor for the treatment of textile wastewater

Discharging of untreated or partially treated textile wastewater is common in Ethiopia, and this has detrimental effect to the environment. It is difficult to treat textile wastewater by conventional biological processes. In this study, real textile wastewater was taken and treated using sequencing batch reactor using a biomass taken from domestic wastewater treatment plant. Cycle period, air flowrate and sludge retention time (SRT) were initially optimized using the response surface methodology. The optimum ratio of cycle period/air flowrate/SRT which gives a 57% COD removal and 54% color removal was found to be 25 h/15 L/h/16 day. Using two types of wastewater substrate concentrations and various hydraulic retention times at optimized condition, COD removal, color removal, sludge volume index (SVI) and mixed liquor suspended solid were measured. The maximum of COD removal (73%) and color removal (65.8%) was obtained at an organic loading rate of 0.078 kg COD/m3 day. SVI at the optimized condition was found to be 90–92 mL/g. Finally, a first-order kinetic model was used to represent the degradation of textile wastewater

Using Box–Behnken experimental design to optimize the degradation of Basic Blue 41 dye by Fenton reaction

Degradation of a Basic Blue 41 dye using Fenton reagent was examined at laboratory scale in batch experiments using Box-Behnken statistical experiment design. Dyestuff, hydrogen peroxide (H2O2) and ferrous ion (Fe2+) concentrations were selected as independent factors. On the other hand, color and chemical oxygen demand (COD) removal were considered as the response functions. The value of coefficient of determination (R-2) for both color and chemical oxygen demand removal with values 0.98 and 0.99 shows the best agreement between predicted value and experimental values. Perturbation plots indicated that iron dosage has the most effect on both color and COD removal. Normalized plot of residuals also indicated that the models were adequate to predict for both responses. Color and COD removal increased with increasing H2O2 and Fe2+ concentrations up to a certain level. High concentrations of H2O2 and Fe2+ did not result in better removal of color and COD due to hydroxyl radical being gradually consumed by both oxidant and catalyst. Percent color removal was higher than COD removal indicating the production of colorless compounds. The second-order polynomial model revealed optimal process factor ratio. The ratio of H2O2/Fe2+/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195 mg/L/90 mg/L/255 mg/L

Pretreatment of secondary effluents in view of optimal ozone-based AOP removal of trace organic contaminants : bench-scale comparison of efficiency and energy consumption

This study compares the performance of several ozone-based advanced oxidation processes (AOPs), in combination with filtration, in terms of trace organic contaminant (TrOC) removal efficiency and energy and cost requirement. It was shown that the hydroxyl radical ((OH)-O-center dot) scavenging rate of the secondary wastewater effluent decreased as a result of an additional pretreatment step, leading to an increase of ozone and (OH)-O-center dot exposures at the same ozone dose. Adding filtration such as sand filtration or granular activated carbon filtration (GACF) as a pretreatment increased the removal efficiency of TrOCs by all tested ozone-based AOPs and reduced the minimum effective ozone dose for TrOC elimination. When the applied ozone dose is more than this minimum effective ozone dose, the elimination of TrOCs can be observed. For example, because of the use of anion resin filtration, 17 alpha-ethinylestradiol elimination contributed by the process of ozone-based AOP increased from 34.6 to 42.1% at an ozone dose of 1.0 g O-3/g dissolved organic carbon. Ozone-based AOPs coupled with filtration as a pretreatment were found to be more cost-efficient than the single AOPs at all ozone dose levels. The energy consumption of ozone-based AOPs was decreased by more than 25% when applying GACF as a pretreatment. In comparison with other filtration techniques, the pretreatment of secondary effluents by GACF before ozonation was proven to be the most cost-effective method for TrOC elimination

Organic matter and nitrogen recovery from landfill leachate using coagulation flocculation followed by granular activated carbon and ion exchange

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How emergent self organizing maps can help counter domestic violence.

Topographic maps are an appealing exploratory instrument for discovering new knowledge from databases. During the past years, new types of Self Organizing Maps (SOM) were introduced in the literature, including the recent Emergent SOM. The ESOM is used to study a large set of police reports describing a whole range of violent incidents that occurred during the year 2007 in the police region Amsterdam-Amstelland (the Netherlands). It is demonstrated that it provides an exploratory search instrument for examining unstructured text in police reports. First, it is shown how the ESOM was used to discover a whole range of new features that better distinguish domestic from non-domestic violence cases. Then, it is demonstrated how this resulted in a significant improvement in classification accuracy. Finally, the ESOM is showcased as a powerful instrument for the domain expert interested in an indepth investigation of the nature and scope of domestic violence.

Analyzing domestic violence with topographic maps: a comparative study.

Topographic maps are an appealing exploratory instrument for discovering new knowledge from databases. During the recent years, several variations on the Self Organizing Maps (SOM) were introduced in the literature. In this paper, the toroidal Emergent SOM tool and the spherical SOM are used to analyze a text corpus consisting of police reports of all violent incidents that occurred during the first quarter of 2006 in the police region Amsterdam-Amstelland (The Netherlands). It is demonstrated that spherical topographic maps provide a powerful instrument for analyzing this dataset. In addition, the performance of the toroidal Emergent SOM is compared to that of the spherical SOM, and it turned out to be superior to that of an ordinary classifier, applied directly to the data.Topographic maps; Domestic violence; Knowledge discovery in databases; Emergent SOM; BLOSSOM;