Simulated Wastewater Effluent Research Articles

Electrochemically assisted photocatalytic degradation of contaminants of emerging concern in simulated wastewater using WO3 – Elucidation of mechanisms

In this work, the performance of a photoelectrochemical cell to degrade a mixture of contaminants of emerging concern (CECs) in distilled water and simulated wastewater effluents (SWWE) was assessed. The CECs mixture included trimethoprim (TMP), diclofenac (DFC), sulfamethoxazole (SMX) and carbamazepine (CBZ) (100 μg·L−1 each). WO3 nanoplate-like structures synthesized on fluorine tin oxide coated glass (FTO) were used as the photoanode with Pt or carbon gas diffusion electrodes (GDE) as the counter electrode. The most efficient degradation of the CECs was obtained with the WO3-GDE combination. Significant degradation of the CECs was observed under visible only radiation. Even under visible radiation, reasonable rate constants 5.67·10-3, 5.35·10-3, 2.9·10-3 and 4.35·10-3 min−1 were obtained for TMP, SMX, CBZ and DFC degradation. The degradation mechanism at the cathode and the photoanode was elucidated using a two-compartment cell, which allowed the identification of reactive species generated at each electrode. Photogenerated holes were the main responsible for CEC degradation in SWWE. With the carbon GDE, a high Faradaic efficiency (55 %) for H2O2 production was observed.

Treatment of Wastewater Effluent with Heavy Metal Pollution Using a Nano Ecological Recycled Concrete

Water pollution exacerbates water stress and poses a great threat to the ecosystem and human health. Construction and demolition waste (CDW) due to rapid urbanization also causes heavy environmental burdens. A major proportion of CDW can be effectively converted into recycled aggregates, which can be reused in many fields, including environment remediation. In this study, a nano ecological recycled concrete (nano-ERC) was produced with recycled aggregates and copper oxide nanoparticles (nCuO) to remove heavy metals (HMs) from a simulated wastewater effluent (SWE) for further treatment. Recycled aggregates were obtained from CDW, thereby simultaneously reducing the treatment cost of the SWE and the environmental burden of solid waste. The adsorption capacity of nano-ERC was presumed to be significantly enhanced by the addition of nCuO due to the unique large surface-to-volume ratio and other properties of nanoparticles. The SWE containing five common HMs, arsenic (As), chromium (Cr), cadmium (Cd), manganese (Mn) and lead (Pb), was filtered through a control ERC and nano-ERCs, and the concentrations of these HMs were determined with ICP-MS in the SWE and the filtrates. Results showed the nano-ERCs could significantly remove these HMs from the SWE compared to the control ERC, due to the enhanced adsorption capacity by nCuO. The relative weighted average removal percentage (RWAR%) was in the range of 53.05–71.83% for nano-ERCs and 39.27–61.65% for control ERC. Except for Cr, concentrations of these HMs in the treated wastewater effluent met the requirements for crop irrigation or scenic water supplementation; the Cr may be removed by multiple filtrations. In conclusion, nano-ERC can serve as a cost-effective approach for the further treatment of wastewater effluent and may be applied more widely in wastewater treatment to help relieve water stress.

Kinetics and equilibrium studies for methylene blue removal from simulated wastewater effluents using agricultural waste, Parthenium hysterophorus L.

Batch adsorption experiments have been carried out for the removal of cationic dye, methylene blue from aqueous solutions by using Parthenium hystrophorous L . as biosorbent. The effect of major variables such as p H, initial concentration, adsorbent dose and contact time has been investigated for the sorption of methylene blue on the low cost adsorbent. Equilibrium data were fitted in Freundlich, Langmuir and Temkin isotherm models and their constants are determined. The data could best be explained by Freundlich isotherm with maximum adsorption capacity (q o ) of 40.79mgg -1 . Kinetic modeling for methylene blue adsorption is done using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. It is found that the pseudo-second-order kinetic model most appropriately described the adsorption kinetics. The result indicates that the weed biomass can effectively be used for methylene blue removal from simulated aqueous solutions.

Cellulosic adsorbent functionalized with macrocyclic pyridone pentamer for selectively removing metal cations from aqueous solutions

Metal selective adsorbent (MCPP-SA-MCC) was synthesized by the reaction of macrocyclic pyridone pentamer (MCPP) with succinic acid anhydride modified microcrystalline cellulose (SA-MCC). Selectivity of the tailor-made adsorbent to metal cations was studied by measuring its competitive adsorption ability to nine metal cations (Ba2+, Pb2+, Cd2+, Mn2+, Cu2+, Co2+, Ni2+, and Cr3+). It was found that MCPP-SA-MCC exhibited a patterned recognition of metal cations remarkably correlated with the metal cation radius. In the simulated wastewater effluent containing nine metal cations, MCPP-SA-MCC dominantly adsorbed Ba2+, which has a larger ion radius than others, and 75% of Ba2+ was removed while others less than 18%. These features indicated the promise of MCPP-SA-MCC as a candidate to remove heavy metal cations from aqueous solution selectively.

Assessment of different iron species as activators of S2O82- and HSO5- for inactivation of wild bacteria strains

This work assesses the potential activation of peroxymonosulfate (PMS, HSO5−) and persulfate (PS, S2O82−) by different homogeneous iron species, FeSO4 and Fe(III)-citrate and heterogeneous Fe2O3 and nano zero valent iron particles (nZVI), to generate sulfate radicals for inactivation of wild bacteria strains (Escherichia coli and Enterococcus sp.) spiked in simulated wastewater effluents. The effectiveness of each iron source as activator was studied in combination with UV-A radiation at natural pH of water (≈ 7.2) using millimolar doses of oxidants (0.5 mM) at different oxidant:iron molar ratio (1:1 and 1:2). In all cases, the addition of iron enhanced the efficiency of the treatments compared to those carried out without it (PMS/UV-A and PS/UV-A); however, significant differences were evidenced depending on the type of bacteria, oxidant and iron specie. For instance, Escherichia coli was reduced (5-log) below the limit of detection (1 CFU/mL) within 2–15 min by activation of PMS and PS with all the iron species evaluated By contrast, under analogous operating conditions the efficiency was notably lower for Enterococcus sp. In this case, it is worth mentioning the notable efficiency through the use of Fe(III)-citrate, which allowed to attained a 3.50-log removal of Enterococcus sp. after 90 min, in contrast to the low reduction (1.8-log) attained with FeSO4. On the other hand, heterogeneous iron species showed an efficiency for bacteria inactivation comparable in most cases to that of homogeneous iron sources. Taking into consideration the potential advantages of heterogeneous catalysts, as for example the recovery and reuse of the catalyst thus reducing the operating costs, the obtained results are encouraging. For instance, E.coli population was removed below the detection limit (5-log) in less than 5 min with both Fe2O3 and ZVI, whereas a 2-log decrease of Enterococcus sp. was attained after 90 min of treatment, even without PMS. Finally, it was assessed the recovery and re-use of ZVI particles. According to X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis, the reaction conditions induced a progressive fading of the core-shell structure of nZVI particles, with a decrease of the efficiency for bacteria inactivation in subsequent uses. As an example, E.coli is reduced in 5-log in 15 min in the first use, and 4.70-log in 90 min with the third use of ZVI.

Microfluidic reactor for Pb(II) ion extraction and removal with an amide derivative of calix[4]arene supported by spectroscopic studies

Removal of Pb(II) ion over several other metal ions with 25,26,27,28-tetrakis(N,N-diethylaminocarbonylmethoxy)-5,11,17,23-tetrakis(1,1,3,3-tetramethylbutyl)calix[4]arene (EATOC) from nitric acid media was investigated in a solvent extraction system. Pb(II) ion was selectively extracted over Fe(III), Co(II), Zn(II), Cu(II) and Ni(II) in the competitive model system. Further, Pb(II) ion was easily stripped from the metal-laden EATOC complex with distilled water as stripping agent. However, Pb(II) extraction and stripping in the batch system took 90 min, 24 h, respectively, to reach an equilibrium in a batch system, but it was only 2.00 s with using droplet microfluidic reactor system, which is remarkable. A rapid and selective removal of Pb(II) from a simulated wastewater effluent was also achieved. Pb(II) complexation mechanism with EATOC was investigated by using ultraviolet, Fourier transform-infrared and proton nuclear magnetic resonance spectroscopies. It was found that the complexation between Pb(II) and EATOC takes place in 1:1 stoichiometric ratio through solvation mechanism. The carbonyl oxygen atoms and phenoxy oxygen atoms of EATOC played a pivotal role in Pb(II) complexation.

Production of Flocculant from Thermomechanical Pulping Lignin via Nitric Acid Treatment

There is a growing need to utilize lignin (i.e., wasted material) from the pulping industry in the production of value-added products and to develop cost-effective and environmentally friendly processes for removing dyes from wastewater effluents. In this context, lignin can be modified to gain anionic charges, which can successfully remove cationic dyes from wastewater. In this study, lignin was extracted from thermomechanical pulp (softwood) via periodate treatment, and then the extracted lignin was oxidized using 30 wt % nitric acid concentration at 80 °C for 1.5 h, which resulted in oxidized lignin with the charge density and solubility of 3.02 mequiv/g and 97% (at a 1 wt % lignin concentration), respectively. The oxidized lignin was used for removing ethyl violet and basic blue cationic dyes from simulated wastewater effluents. It was observed that the dye removals were in the ranges of 70–80 wt % for ethyl violet and of 80–95 wt % for basic blue, while the COD removals were in the ranges of 60–70% f...

Small-angle neutron scattering studies of mineralization on BSA coated citrate capped gold nanoparticles used as a model surface for membrane scaling in RO wastewater desalination.

Bovine serum albumin (BSA) coated on citrate capped gold nanoparticles (BSA-GNPs) was exposed to a simulated wastewater effluent (SSE) in order to study the mineralization and thereby mimic scaling at biofouled membranes of reverse osmosis (RO) wastewater desalination plants. RO is a leading technology of achieving freshwater quality as it has the capability of removing both dissolved inorganic salts and organic contaminants from tertiary wastewater effluents. The aim was to better understand one of the major problems facing this technology which is fouling of the membranes, mainly biofouling and scaling by calcium phosphate. The experiments were performed using the small-angle neutron scattering (SANS) technique. The nanoparticles, GNPs, stabilized by the citrate groups showed 30 Å large particles having a homogeneous distribution of gold and citrate with a gold volume fraction of the order of 1%. On the average two BSA monomers are grafted at 2.4 GNPs. The exposed BSA-GNPs to SSE solution led to immediate mineralization of stable composite particles of the order of 0.2 μm diameter and a mineral volume fraction between 50% and 80%. The volume fraction of the mineral was of the order of 10(-5), which is roughly 3 times larger but an order of magnitude smaller than the maximum possible contents of respectively calcium phosphate and calcium carbonate in the SSE solution. Considering the extreme low solubility product of calcium phosphate, we suggest total calcium phosphate and partially (5-10%) calcium carbonate formation in the presence of BSA-GNPs.

Mass Transfer Characteristics during the Removal of Dissolved Heavy Metals from Waste Solutions in Gas Sparged Fluidized Beds of Ion Exchange Resins

The paper presents experimental results concerning the removal of cupric ions from a simulated wastewater effluent consisting of copper sulphate solution in a gas sparged fluidized bed of cation exchange resin. Variables investigated were: superficial gas velocity, particle diameter, bed height and the physical properties of the solution (adding glycerol). These variables were studied with respect to their effect on the solid-liquid mass transfer coefficient. The coefficient was found to increase with increasing superficial gas velocity. Increasing both particle diameter and bed height were found to reduce the mass transfer coefficient. The experimental data can be correlated by the equation J = 0.68 (Fr Re )–0.143 (dp/d)–0.62 (dp/L)0.55valid for the following conditions: 1430 < Sc < 2488; 0.017 < Fr Re < 1.41; 6.33 × 10–3 < dp/d < 0.021 and 9.5 × 10–3 < dp / L < 0.125.

Removal of phenol from aqueous solutions by mixed adsorbents: Maghara coal and activated carbon

The removal of phenol from a simulated wastewater effluent by adsorption on a homogeneous mixture of Maghara Coal and Activated Carbon in different proportions has been carried out in a fixed bed reactor. It was noted that the adsorption capacity of activated carbon is 12.05 fold that of Maghara Coal. Variables studied were initial phenol concentration, bed height, and type of adsorbent, namely GMC, GAC, (50%GMC+50%GAC), and (25%GMC+75%GAC). The volumetric flow rate of phenol solution and the temperature were kept at 27.5 ml/min and 27°C respectively. Also the adsorption isotherm for both PMC and PAC were studied. The equilibrium data fit well in the Freundlich model of adsorption.

Mass transfer during the removal of dissolved heavy metals from wastewater flows in fluidized beds of ion exchange resins

AbstractA fluidized bed of cation exchange resin was used for the removal of cupric ions from a simulated wastewater effluent consisting of copper sulphate solution. Variables investigated were: superficial liquid velocity, particle diameter, bed height and copper sulphate concentration. These variables were studied with respect to their effect on the solid‐liquid mass transfer coefficient. The coefficient was found to increase with increasing superficial liquid velocity. Increasing particle diameter, bed height and copper sulphate concentration were found to reduce the mass transfer coefficient. The experimental data can be correlated by the equation equation image valid for the following conditions: 0.23 &lt; Re1 &lt; 2.27; 0.52 &lt; ϵ &lt; 0.87; 0.0127 &lt; dp/d &lt; 0.0417 and 0.0095 &lt; dp/L &lt; 0.125.