Evaluation of the hybrid system combining electrocoagulation, nanofiltration and reverse osmosis for biologically treated textile effluent: Treatment efficiency and membrane fouling

The efficiency of the hybrid electrocoagulation-nanofiltration-reverse osmosis (EC-NF-RO) system for the treatment of biologically treated textile effluent was investigated. The treatment performances and membrane fouling behaviours of nanofiltration (NF) and hybrid EC-NF systems were compared. EC process was evaluated concerning mitigate the membrane fouling and increasing the removal efficiencies. Besides, the treated wastewater with the hybrid EC-NF process was finally processed using RO process for reuse purpose in the textile industry. The EC treatment was applied using Fe and Al electrodes at various conditions; pH:4-10, current density:0.5-17 mA/cm2 and operating time:30-180 min. Fe electrode showed better performance in terms of higher removal efficiencies (76% COD, 96% DFZ436), lower energy (21.1 kWh/m3) and electrode consumptions (3.7 kg/m3) for the optimum conditions. Scanning Electron Microscopy-Energy Dispersive Index (ESEM-EDX) and Fourier-Transform Infrared Spectroscopy (FTIR) analyses were carried out for EC sludge samples obtained with Fe and Al electrodes. Desal 5 DL and NF 270 membranes were tested in terms of removal efficiency and membrane fouling for NF and hybrid EC-NF process of textile wastewater. Membrane fouling was evaluated with flux values, resistance-in-series model results as well as Atomic Force Microscopy (AFM), FTIR and contact angle measurements. NF 270 membrane achieved better chloride (28%) and conductivity (41%) removal efficiencies for NF treatment. EC pretreatment did not result in any noticeable improvement in rejections except for chloride (48%) and conductivity (59%) for the hybrid EC-NF process with NF 270. The ratios of Rc decreased to 40% for NF 270 and 42% for Desal 5DL after EC pretreatment. NF270 membrane indicated high permeate flux and low membrane fouling considering cake resistance distribution, surface roughness, hydrophilicity and chemical structure variation. >93% COD, 99% conductivity, 97% chloride, and 91% TDS removal efficiencies were obtained with the hybrid EC-NF-RO process. Finally, the obtained high quality water by RO after the EC + NF 270 hybrid process could be used for all textile finishing process

Baker's yeast wastewater advanced treatment using ozonation and membrane process for irrigation reuse

This study focused on the advanced treatment of biologically treated baker's yeast wastewater for the purpose of irrigation reuse. The effects of pH (3, 7.5, 9, 11) and temperature (25 degrees C, 35 degrees C, 45 degrees C) on the removal efficiencies were investigated for ozonation process. Ozone utilization rates were determined at different pH and temperature levels. There were not significant changes in pollutant removal efficiencies at the temperature of 25 degrees C-45 degrees C for ozonation process. 96-98% color, 56% COD, 67% UV254, 10% conductivity, 33% chloride, and 29% total hardness removals were obtained with ozonation process at pH 7.5 and 25 degrees C. NF 90 and BW 30 membranes were used to improve the quality of treated wastewater. Relatively lower flux decline caused from membrane fouling (18%) was occurred for BW 30 membrane. Although higher permeate qualities were achieved with both membranes, the chloride and conductivity values as 35 mg/L and 530 mu s/cm were relatively lower for BW 30 permeate. As a result, the treated wastewater using ozonation and membrane process met the quality of class B regarding pH, biological oxygen demand (BOD5), suspended solids (SS) and fecal coliform parameters. Also, II. class irrigation water was obtained considering SAR parameter for degree of restriction on irrigation use. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Recovery of baker's yeast wastewater with membrane processes for agricultural irrigation purpose: Fouling characterization

Increasing water demands for both industrial and public uses as well as more restrictive laws make the industrial wastewater recovery necessary. In this study, it was aimed to propose membrane treatment process for recovery of biologically treated baker's yeast wastewater to the degree of agricultural irrigation water quality. In addition to water recovery, membrane fouling mechanism was investigated. Membrane selection was carried out using FM UP020, FM UP005, NF 270, NF 90 and Desal 5DL membranes. Desal 5DL membrane was selected as appropriate membrane for baker's yeast wastewater treatment according to relatively higher rejection performance, lower flux declines and lower increase in contact angle. The effects of pH, temperature, and transmembrane pressure (TMP) were investigated on Desal 5DL membrane fouling. In addition, atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy measurements were used for fouling characterization. NF 90 membrane was determined as suitable membrane to increase the quality of composite permeates obtained from Desal 5DL membrane. As a conclusion, the treated baker's yeast wastewater by two-step nanofiltration (NF) process was classified as class B in terms of pH, biological oxygen demand (BOD5), suspended solids (SS) and fecal coliform parameters. II. Class irrigation water was achieved for degree of restriction on irrigation use. (C) 2014 Elsevier B.V. All rights reserved

Advanced treatment of pulp and paper mill wastewater by nanofiltration process: Effects of operating conditions on membrane fouling

In this study, the application of two-step nanofiltration (NF) process was investigated in the purification of biologically treated pulp and paper wastewater for the purpose of reuse. In the first step, the effect of operating conditions such as pH, temperature, transmembrane pressure and volume reduction factor (VRF) on the membrane fouling was investigated using FM NP010 membrane. Membrane fouling was minimized by optimizing the operating conditions using Taguchi experimental design method. The smaller-the-better signal-to-noise (S/N) ratio was used to analyze the results of experiments. Flux decline caused by fouling was selected as response parameter. The best results were obtained at third level of pH (10), first level of temperature (25 degrees C), first level of transmembrane pressure (12 bar) and third level of VRF (4) which provided minimum flux decline caused by fouling (11%). Based on the analysis of variance (ANOVA), the results indicated that transmembrane pressure has significant effect on membrane fouling, while VRF shows very little effect on membrane fouling. Membrane fouling was further examined in terms of atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis. Under the optimized conditions, 91% chemical oxygen demand (COD), 92% total hardness and 98% sulphate removal were achieved using FM NP010 membrane. Also the obtained permeate is colorless and free from suspended solids. However, chloride and conductivity were partially removed. In the second step, FM NP030 membrane was used to provide better permeate quality like actual process water. Membrane fouling was also investigated in terms of flux decline, contact angle measurements and SEM analysis in this step. As a conclusion, the water produced by two step NF treatment of biologically treated pulp and paper industry meets the quality of actual process water. (c) 2010 Elsevier B.V. All rights reserved

Treatment of Pulp and Paper Mill Wastewater Using Utrafiltration Process: Optimization of the Fouling and Rejections

Treatment of pulp and paper mill wastewater using ultrafiltration (UF) membranes was investigated in this study. A Taguchi experimental design was implemented for design of the experiments to investigate optimum operating conditions that achieve higher removal of pollutants and lower membrane fouling. Four factors at three different levels were considered for the experimental design, namely, pH, temperature, transmembrane pressure, and volume reduction factor (VRF). Under the optimized conditions (pH 10, temperature 25 degrees C, transmembrane pressure 6 bar, and VRF 3), a 35% flux decline caused by fouling occurred. Higher rejections were observed for total hardness (83%), sulfate (97%), spectral absorption coefficient (SAC(254)) (95%), and chemical oxygen demand (COD) (89%), but not for conductivity (50%), under these conditions. From the analysis of variance (ANOVA), it was determined that the factor of pH made the greatest contribution to response parameters. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses showed that membrane fouling occurring on the membrane surface and within pores decreased by optimizing the operating conditions. The Taguchi method was successfully applied to find the optimum conditions for the treatment of pulp and paper mill wastewater using the UF process

Optimization of filtration conditions for CIP wastewater treatment by nanofiltration process using Taguchi approach

In this study, the nanofiltration of cleaning-in-place (CIP) wastewater was studied using a two-step nanofiltration (NF) process. In the first step, the effects of operating parameters including pH, temperature, and transmembrane pressure on the membrane fouling were investigated using a loose NF membrane. Also, Taguchi method was applied in order to design the experiments and optimize the experimental results. The optimum conditions providing the lowest flux decline were estimated. L(9) (3(4)) orthogonal array for experimental planning and the smaller-the-better response category was selected to obtain optimum conditions. Analysis of variance (ANOVA) was used to determine the most significant parameters affecting the flux decline caused by membrane fouling. The optimum conditions were found as the second level of pH (7), first level of temperature (25 degrees C) and first level of transmembrane pressure (12 bar). Under these conditions, flux decline caused by membrane fouling was predicted as 24% that was within the range of confidence limit of the observed value of 20%. Transmembrane pressure was found to be the most important factor on the flux decline. The effect of pH on the membrane fouling was also investigated with scanning electron microscopy (SEM) and contact angle measurements. It was found that pore plugging was dominant at pH 4. In the first step of the treatment; 97% chemical oxygen demand (COD), 100% sulphate, 50% chloride and 38% conductivity removal was obtained under the optimized conditions. In the second step, the quality of permeate obtained from the first step was improved using a tight membrane at 20 and 30 bar. Even better rejections were achieved especially for chloride and conductivity in the second step at 30 bar. (C) 2009 Elsevier B.V. All rights reserved

Removal of Cu(II), Ni(II) and Zn(II) from aqueous solutions using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) gel: sorption kinetics and characterization

Removal of Cu(II), Ni(II) and Zn(II) ions from aqueous solutions was studied by using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) gel. The gel was prepared by free radical polymerization at 60 degrees C for 24 h in the presence of the ammonium peroxodisulfate and N, N'-methylenebis( acrylamide) as the initiator and the cross-linker, respectively. The effect of initial metal ion concentration (25-100 mg/L) on the removal efficiency and the sorption process were investigated by batch method. At initial concentration of 25 mg/L, the removal efficiencies were found to be higher and too close to each other (95%-95.5%), whereas lower removal efficiencies (65.8%-72.0%) were determined at an initial concentration of 100 mg/L, for all the metal ions investigated. Sorption data of Cu(II), Zn(II), and Ni(II) ions on the gel showed good fit to the pseudo-second order type kinetics. PAMPS exhibited slightly higher selectivity for the sorption of Zn(II) from ternary solutions at higher concentrations. Characterizations of the poly(2-acrylamido-2-methyl-1-propanesulfonic acid) gel before and after the sorption process were carried out by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), environmental scanning electron microscopy (ESEM), and zeta (zeta) potential measurements. PAMPS gel was found to be charged negatively at pH values between 3 and 9

Lead removal from battery wastewater using synthesized poly(ethyleneglycol dimethacrylate-methacrylic acid) gel bead and poly(methacrylic acid) hydrogel

This study presents the synthesis and characterization of two new polymers with the aim of Pb2+ ion removal from the wastewater of a battery factory. Poly(ethyleneglycol dimethacrylate-methacrylic acid) (poly(EGDMA-MAA)) gel bead and polymetacrylic acid (polyMAA) hydrogel were prepared and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), environmental scanning electron microscopy (ESEM), swelling capacity analysis and zeta potential measurements. Both polymers showed greater negative zeta potential values in the range of pH 3-8. Poly(EGDMA-MAA) had a relatively lower swelling capacity of 0.9 g(water)/g(polymer) than polyMAA because of the crosslinking degree. The FTIR spectrum of the virgin poly(EGDMA-MAA) showed that the polymer has carboxylic groups to sorb the Pb2+ ions. The FTIR spectrum of poly(EGDMA-MAA) after sorption showed that interactions between the Pb2+ ions and carboxyl groups caused a decrease in the intensity of the C=O peak. The sorption experiments carried out under different conditions yielded optimal conditions of contact time and polymer amount. The Pb2+ adsorption capacities were found to be 1.995 and 2.047 mg g(-1) for poly(EGDMA-MAA) and polyMAA, respectively. Moreover, the sorption mechanism was studied using kinetic and thermodynamic models. The higher R-2 (0.9997 and 0.9999), lower epsilon% (1.3 and 0.8) and closer values of q(exp) and q(cal) show that the data fit well with the type (I) pseudo-second-order model. The higher positive Delta S degrees value indicated that greater structural changes occurred in polyMAA than in poly(EGDMA-MAA)

Occurence and Prioritization of Pharmaceutical Active Compounds in Domestic/Municipal Wastewater Treatment Plants

In this study, pharmaceutically active compounds (PhACs) were analyzed in the influent and effluent of a domestic wastewater treatment plant in Turkey and a municipal wastewater treatment plant in Germany and the toxicity of these wastewaters were estimated using a toxic unit (TU) approach. A total of 21 and 32 PhACs were detected in the domestic wastewater and the municipal wastewater, respectively. The TUs estimated for PhACs in municipal wastewater were higher than the TUs estimated for PhACs present in domestic wastewater. The levels of the anti-anxiety drug, oxazepam were estimated to be in the high risk category (HQ>10) in both wastewaters. In bench-scale tests with ozonation, the removals of four PhACs in the municipal wastewater were investigated. At a dose of 2mg/L ozone, 97%-98% of diclofenac and carbamazepine were removed. The lowest removal rate at 71% was observed for metoprolol

Sorption of Pb (II) from battery industry wastewater using a weak acid cation exchange resin

This study investigates the removal of Pb (II) from a real battery industry wastewater by batch and column studies using a weak acid cation (WAC) resin. Batch experiments carried out under different conditions yielded optimum conditions of t = 360 min and m = 0.1 g (2 gL(-1)). The mechanism of ion exchange was studied using kinetic and thermodynamic models. The temperature had a limited effect on the diffusion kinetics. The Gibbs free energy change (Delta G degrees) values were negative, corresponding to a spontaneous process of Pb (II) ion sorption onto the WAC resin. The plots obtained from the first loads of the column studies show the typical "S" shape of a packed-bed system with gradual breakthrough for both flow rates. Breakthrough was reached at 360 bed volume (BV) and 83 BV for flow rates of 1 m h(-1) and 3 m h-1, respectively. Capacity losses of 77% and 87% were obtained after regeneration. WAC resins were characterized based on Fourier Transform Infrared Spectrum (FTIR), thermogravimetric analysis (TGA) and Environmental Scanning Electron Microscopy (ESEM) images before and after column studies. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved