Dyestuff Wastewater Treatment Research Articles

<b>Development of Actual Dyestuff Wastewater Treatment by Ozone with Carbonaceous Materials Produced from Waste Fiber</b>

<b>Development of Actual Dyestuff Wastewater Treatment by Ozone with Carbonaceous Materials Produced from Waste Fiber</b>

Dyestuff wastewater treatment by combined SDS-CuO/TiO2 photocatalysis and sequencing batch reactor

Combined technology of SDS-CuO/TiO2 photocatalysis and sequencing batch reactor (SBR) were applied to treating dyestuff wastewater. Photocatalysis was carried out in a spiral up-flow type reactor as pre-treatment. SDS-CuO/TiO2 photocatalyst was prepared by modification of nano-TiO2 using CuO and sodium dodecyl sulfate (SDS). Results show that the SDS-CuO/TiO2 photocatalyst contains two kinds of crystals, including TiO2 and CuO. The band gap of this photocatalyst is 1.56 eV, indicating that it can be excited by visible light (λ<794.87 nm). And characterization also shows that there are alkyl groups on its surface. It takes 40 min to improve the biodegradability of dyestuff wastewater. Five-day biochemical oxygen demand (BOD5) and dehydrogenase activity (DHA) of wastewater reach the maximum value when dissolved oxygen is higher than 2.97 mg/L. SBR reactor was used to treat this biodegradability improved wastewater. Chemical oxygen demand (COD) and colority decline to 72 mg/L and 20 times, respectively, when the sludge loading is 0.179 kg(COD)/[kg(MLSS)·d], dissolved oxygen is 4.09 mg/L and aeration time is 10 h.

Genetic Algorithms and Neural Networks Based Optimization Applied to the Wastewater Decolorization by Photocatalytic Reaction

This paper proposes a genetic algorithm and a neural network based procedure to estimate the optimal conditions for a dyestuff wastewater treatment process consisting of a heterogeneous photocatalytic oxidation. A simulated dyestuff effluent containing the azo dye Reactive Black 5 is decolorized by a photocatalytic reaction using TiO2 P-25 as catalyst in the presence of Fe+3 and H2O2. A simple feed forward neural network with one hidden layer was projected and used to predict the evolution in time of the decolorization of this type of wastewater. The neural model was included in the optimization procedure solved with a simple genetic algorithm. The goal of the optimization is to calculate the optimal reaction conditions (illumination time and amounts of reagents) which assure an imposed value for the transmittance.

Comparison study of dyestuff wastewater treatment by the coupled photocatalytic oxidation and biofilm process

Abstract Degradation of Rhodamine B (RhB) and COD by means of the coupled photocatalytic oxidation (PCO) and biofilm systems has been studied. The coupled PCO-biofilm systems were divided into two operation systems. The one (R1) consisted of a pre-PCO and a post-biofilm reactor system and the other (R2) was a pre-biofilm and a post-PCO reactor system. In a batch experiment, the order of initial decolorization rate was photocatalytic oxidation > adsorption > photolysis. The color removal rate of RhB was decreased with an increase of the initial COD concentration. In a continuous experimental study, almost all color was removed in the PCO reactor. During 180 days, the color and COD removal efficiencies in the R2 (pre-biofilm + post-PCO) system were higher than those in the R1 (pre-PCO + post-biofilm) system. In our experimental ranges, the PCO process was superior to Fenton oxidation in the color and COD removal.

Treatment of wastewater during the production of reactive dyestuff using a spiral nanofiltration membrane system

In this study, a stage-2 spiral-wound nanofiltration (NF) system was used to further treat the permeate produced by a stage-1 tubular NF employed for treatment of dyestuff wastewater. Pilot-scale experiments were carried out to select the appropriate commercial NF membranes by investigating the TOC removal, color removal, the flux and VCR values, respectively. Compared with the Dow NF1 and Desal DL membranes, Desal DK NF membrane was selected for subsequent study. Using Desal DK NF membrane, the permeation flux could be kept at a relatively high value (>30 L.h −1.m −2) while the VCR reached 10.0. Meanwhile, the TOC values could be reduced to less than 400 ppm, which meets industrial requirements and would facilitate the subsequent bio-treatment unit. Based on the pilot-scale experiments, a full-scale system was set up, and the treatment system has been successfully implemented at a company in Thailand.

Dyestuff wastewater treatment using chemical oxidation, physical adsorption and fixed bed biofilm process

Fenton’s oxidation and activated carbon adsorption were examined as pretreatment processes for dyestuff wastewater having high salinity, colour, and non-biodegradable organic concentrations. In this work, each wastewater stream produced by individual production processes was classified as streams R1, R2, and R3. The stream having a value of BOD 5/COD lower than 0.4 was pretreated by Fenton’s oxidation or activated carbon adsorption to increase the ratio of BOD 5/COD which indicates biodegradability. For Fenton’s oxidation with one stream having a value of BOD 5/COD lower than 0.4, the optimal reaction pH was 3.0 and the minimum dosing concentration (mg l −1) of H 2O 2:FeSO 4·7H 2O was 700:3500. Stream R3, which consisted mainly of methanol was efficiently treated by activated carbon adsorption. The ratio of BOD 5/COD was also increased to 0.432 and 0.31 from 0.06 in Fenton’s oxidation and activated carbon adsorption, respectively. A biological treatment system using a fixed bed reactor was also investigated to enhance biological treatment efficiency at various hydraulic retention times, pretreatment conditions by Fenton’s reagent and salt concentrations by dyestuff wastewater. In addition, the efficiency of Fenton’s oxidation as a post-treatment system was also investigated to present a total treatment process of dyestuff wastewater. As the influent COD and salinity were increased, the effluent SS and COD were consequently increased. However, as the microorganisms became adapted to the changed influent condition, the treatment efficiency of the fixed bed reactor quickly recovered under the high COD and salinity since the microorganisms were well adapted to toxic influent conditions. A wastewater treatment process consisting of chemical oxidation, activated carbon adsorption, fixed bed biofilm process and Fenton’s oxidation as a post-treatment system can be useful to treat dyestuff wastewater having high salinity, colour, and non-biodegradable organic concentration.