The wastewater produced by the galvanoplasty industry is a serious environmental problem due to the high concentrations of heavy metals. In this study polymers were used in ionic flocculation to treat synthetic wastewater containing metals, applying four types of polyacrylamides with different ionic loads as agents to remove copper and zinc. Metal removal efficiency was assessed considering the influence of polymer concentration, ionic load and pH. Selectivity (Cu2+/Zn2+) at different polymer concentrations was also evaluated. The results confirm that polyacrylamide is efficient in treating wastewater containing heavy metals. These experiments exhibited removal efficiency of around 40% and pH= 4,5; however, efficiency was more than 80% with pH= 7.0 under the same conditions, when polyacrylamides with average ionicity were used.
This paper presents new and explicit equations to estimate aeration-related parameters such as standard oxygen requirement, daily energy consumption and total mass transfer coefficient for the diffused aeration. The proposed formulations are derived for the steady-state completely mixed activated sludge process based on the nonlinear regression analysis by using the Richardson’s extrapolation method and the Levenberg–Marquardt algorithm. The applicability of the proposed models has been investigated for a wide range of thirteen inputs consisting of the fundamental biological, hydraulic, and physical design variables, and tested against a total of 1500 additional computational scenarios. All estimations are proven to be satisfactory with very high determination coefficients (R2) between 0.961–0.965, 0.967–0.972 and 0.980–0.984, respectively, for the prediction of standard oxygen requirement, daily energy consumption and total mass transfer coefficient for diffused aeration. The proposed models offer sufficiently simple and practical mathematical formulations incorporating routinely obtainable parameters, which are readily available for all activated sludge-based treatment plants. Besides eliminating the need for additional time or computational effort typically performed in the theoretical procedure, the developed equations have simple coefficients to be easily used for manual calculations with a hand-held calculator. The statistical results clearly exhibit that the proposed equations are accurate enough to be used in estimation of the studied aeration parameters based on the practical ranges of the corresponding design variables.
V2O5-WO3/TiO2 catalysts were fabricated by a simple impregnation method. Effects of V2O5 and WO3 loadings on the catalytic performance of V2O5-WO3/TiO2 catalyst for selective catalytic reduction (SCR) of NO with NH3 were investigated. Morphology and structure of the V2O5-WO3/TiO2 catalysts were characterised by XRD, SEM, XPS, and N2 adsorption techniques. The XRD patterns of the V2O5-WO3/TiO2 catalyst are indexed to anatase-TiO2. XPS spectra analysis confirms that V, Ti, W and O species exist on the surface of V2O5-WO3/TiO2 catalyst. V2O5 species are the main active sites in the process of SCR reaction. Increasing V2O5 loading in the V2O5-WO3/TiO2 catalysts can improve their catalytic performance. Exceeding 2 wt%, the catalytic performance of V2O5-WO3/TiO2 catalyst begins to decline because high V2O5 loading on TiO2 speeds up the growth of anatase grains, which leads to the loss of catalytic activity. Appropriate WO3 species can significantly improve the catalytic performance of V2O5-WO3/TiO2 catalysts. However, as the WO3 loadings reaches 6 wt%, NO conversion decreases instead.
The present study was conducted to compare the performance of different solar photocatalytic processes (TiO2 photocatalysis, photo-Fenton, photo-Fenton coupled with TiO2 photocatalysis, and photo-Fenton coupled with TiO2/ZnO photocatalysis) for the treatment of petroleum wastewater. The removal efficiency of chemical oxygen demand (COD) is evaluated. TiO2 dosage and pH are the main factors that improve the COD removal in the TiO2 photocatalysis process while Fe+2 and H2O2 concentration are the main factors in photo-Fenton process. The photo-Fenton coupled with TiO2/ZnO photocatalysis is the most efficient process for treatment of petroleum wastewater at the neutral conditions (pH 7). Therefore, no need to adjust pH during this treatment. In acidic conditions (pH<7), the photo-Fenton process is more efficient than the TiO2 photocatalysis process while it is less efficient than the TiO2 photocatalysis process in alkaline conditions (pH>7).
The present study aims to evaluate RV-5R and RBO-3R decolourizing potential of Bacillus sp. DT9 isolated from textile effluent in Denizli (Turkey). In present study, maximum dye-decolourizing efficiency of the culture was achieved at 25 mg l-1 concentration of RV-5R and 500 mg l-1 concentration of RBO-3R. While the optimum dye-decolorizing activity of DT9 was observed at pH 7.5 and 37oC in sucrose for RV-5R (91.66% decolourization rate), 500 mg l-1 RBO-3R concentration by Bacillus sp. DT9 was decolourized at pH 9.0 and 30°C in sucrose/peptone containing medium (98.41% decolourization rate). In other step of study, DT9 was immobilized in Ca-alginate. According to immobilization results, the percentage of decolourization of RV-5R was found very similar to cell free result. But, the percentage of decolourization of RBO-3R decreased 30.0%, when DT-9 cells were immobilized in Ca-alginate. Metabolites of the RV-5R and RBO-3R biodegradation were analysed via ESI-TOF/MS analysis at the end of decolourization process, and the biotransformation and dimerization was confirmed.