Journal of Environmental Engineering

During the oxidative degradation of nonbiodegradable Orange IV by means of ${\mathrm{H}}_2{\mathrm{O}}_2{/\mathrm{Fe}}^{\mathrm{III}}{\mathrm{F}}^{2+}/\mathrm{R}$ oxidation method (${\mathrm{Fe}}^{\text{III}}{\mathrm{F}}^{2+}$ complex supported on cationic exchange resin as a catalyst), the binding energy of the $\mathrm{Fe}({2\mathrm{p}}_{3/2})$ region for X-ray photoelectron spectroscopy (XPS) spectra increased with the reaction time during the initial 2.5 h and then decreased continuously. The electron paramagnetic resonance (EPR) signal for hydroxyl radical (OH) spin trap adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) also increased with the reaction time within a certain period of time. These results confirmed that ferryl (IV) (${\mathrm{Fe}}^{\mathrm{IV}}\mathrm{F}={\mathrm{O}}^{+}/\mathrm{R}$) species was generated along with the formation of OH radicals at the beginning of the reaction. The formed ferryl (IV) species enhanced the DMPO-OH signal compared with the catalyst of ${\mathrm{Fe}}^{\text{III}}{\mathrm{F}}^{2+}/\mathrm{R}$. The addition of $t$-butanol did not significantly reduce the reaction rate, which increased with reaction time in the process of ferryl (IV) catalytic decomposition of ${\mathrm{H}}_2{\mathrm{O}}_2$. This indicated that there was a more reactive species than ferryl (IV), which cannot be scavenged by $t$-butanol, and it was likely to be Fe (V). A possible mechanism for a resin-supported thermal Fenton-like oxidation reaction is proposed to better understand the process in the presence of iron complex catalysts.

Proper control of phytosterols in pulp mill effluents is necessary before disposal into receiving environments because they have been suspected to be hormonally active to aquatic life. This study provides an insight into the adsorptive behavior of sterols and the role of secondary sludge in their removal during secondary treatment. The kinetics of sterol adsorption, extent of sterol adsorption onto inactivated secondary solids, adsorptive capacity of secondary solids, and the relative contribution of the adsorption mechanism in the overall removal of sterols during secondary treatment have been investigated in this study. Isotherm modeling revealed two different adsorption regimes for each sterol. The results show that adsorption plays a major role in the secondary treatment of pulp mill effluents and that secondary sludge serves as an efficient adsorbent to remove phytosterols. The obtained information is important to improve system design and optimize the operation of pulp mill effluent treatment facilities.

The prediction of stream water quality (WQ) is essential to understand and quantitatively describe water quality parameters (which include physical characteristics, inorganic metallic, and nonmetallic concentrations) and their structure, watershed health, biodiversity, and ecology of a basin. The spatial variability and temporal randomness of stream water quality parameters makes the problem a complex modeling task by ordinary statistical regression methods. The determination of water quality parameters and their spatial and temporal description in stream networks is even more complex due to the stochastic nature of water flow, atmospheric conditions, meteorological patterns, and nonlocal effects of precipitation and temperature. In this paper, a statistical, geographic information system (GIS) and a neural network based water quality model is developed to study stream water quality parameter structure in a geographic framework in the United States of America (USA) consisting of stream network, watershed, and a variety of different land-use practices. Also, a novel way of representing land use in the form of land-use factor (LUF) is formulated for modeling purposes.

Aging of refuse-derived fuel (RDF) fly ashes was investigated in a long-term laboratory experiment. Aging affected the chemical stability of RDF fly ash in terms of leaching behavior, ANC, and mineralogical transformations. The design of experiment model evaluation showed that the use of RDF ashes in a top cover liner construction has the following advantages: most of the investigated hazardous elements like Pb, Cl, Cr, Cu, etc., will not be released from the ashes, and their buffer capacity will increase with time. However, aging has the disadvantage that leaching of Zn and ${\mathrm{SO}}_4$ is likely to increase. The multivariate data analysis of the coefficients of variation did not reveal any systematic errors in the performance of the experiment. However, batch leaching test not always reflect the real situation in the landfill top cover environment.

The potential effects of persulfate in situ chemical oxidation (ISCO) on metals and on long-term groundwater quality is an important issue because of the potential risks to public health and to the environment. Application of persulfate and its activation amendments to soil and groundwater can lead to complex interactions, altering geochemical conditions and processes, thereby affecting metals mobility. The mobility of cadmium sorbed on three soils varying in physical–chemical properties was investigated after chemical oxidation by unactivated and activated persulfate using mixed batch reactors. Each of the three soils was treated with two different concentrations of persulfate, 2.1 mM and 42 mM, and different activation amendments that included Fe(II), Fe(II)-EDTA, and high pH. Resulting solutions were analyzed for soluble cadmium after 48 h and 6 months. Results show that cadmium mobilization varied with the persulfate activation method and the soil type. The maximum amount of cadmium was mobilized with Fe(II)-EDTA activation and the least amount of cadmium was mobilized with high pH activation. In addition to Fe(II)-EDTA activation, cadmium was more mobile in soil with low soil organic carbon and low mineral content. Enhanced cadmium desorption at low pH and formation of soluble cadmium-EDTA complexes are the main mechanisms of cadmium mobilization from soils with persulfate ISCO.

Silver-impregnated ceramic water filters (CWFs) are a simple and sustainable low-cost technology that has shown promise in improving household drinking water quality and reducing incidences of early childhood diarrhea in a variety of settings. Despite this promise, lower reservoir contamination is thought to be a contributing factor to the decline in the effectiveness being seen over time. A novel silver-impregnated ceramic torus that can be placed in the lower reservoir was designed to minimize this contamination. This study uses a one-year randomized trial to compare the relative effectiveness of the $\mathrm{CWF}+\mathrm{torus}$ design with a standard CWF and point-of-use chlorination. The effectiveness of each technology was measured at project inception and subsequently after six and 12 months. Results indicate that the toruses, as designed, are not able to consistently maintain lower-reservoir silver concentrations above those of the simple CWF design and are hence unable to prevent contamination. Furthermore, after six months, only 65% of households that used point-of-use chlorination maintained sufficient chlorine levels above the $0.2\mathrm{mg}/\mathrm{L}$ needed to be effective. All three technologies showed statistically equivalent log removal efficiencies for total coliform bacteria and all three declined in effectiveness over the first six months. Combined average log removal efficiencies for all three technologies ranged from $2.22\pm 0.21$ initially but declined to $1.45\pm 0.35$ after six months and to $1.42\pm 0.29$ after one year.

Landfills and tailing impoundments contain barrier layers that prevent the migration of contaminants into groundwater by slowing down the water flow through the structures. Many materials used in hydraulic barrier layers also have sorption properties, which could be utilized to reduce environmental risks. The adsorption of Ni(II) and Cd(II) on peat was studied using a single metal column test. Two samples with different dry unit weights, low-density (LD) and high-density (HD) peat, were tested. A batch test was made for comparison. Both samples in the column test adsorbed the metals well; peat adsorbed $\mathrm{9,500}\mathrm{mg}/\mathrm{kg}$ of nickel and $\mathrm{11,200}\mathrm{mg}/\mathrm{kg}$ of cadmium. The adsorption was twice as high in the column test as in the batch test. Cadmium adsorbed strongly on the top layers of the sample, whereas the adsorption profile of nickel was more even through the sample. The density of the peat did not affect the maximum adsorption capacity. In HD peat, the heavy metals adsorbed more on the top layers of the sample, and in LD peat, the metals migrated deeper. In a hypothetical field impoundment, the liquid/solid ratio of the column experiment would represent a time period of 38–59 years and the structure would adsorb 99% of both metals. A 50-cm layer of HD peat would have the capacity to adsorb 1.96 kg of cadmium and 1.66 kg of nickel per square meter.

Evaluating the pretreatment conditions and fouling behavior is a prerequisite to the effective implementation of the coagulation-ceramic membrane hybrid processes for surface water treatment. Little is known about the performance of the hybrid processes; previous studies have dealt mainly with polymeric membranes. A coagulation-ceramic microfiltration system performed better in the treatment of select U.S. surface waters than a polymeric counterpart in terms of relative pressure in a constant-flux mode and normalized flux in a constant-pressure mode. The operating pressure for the filtration of river waters with the ceramic membrane system was 2.1–2.8 times the pressure for pure water, while it was 3.7–5.6 times with the polymeric membrane system, and the normalized flux in a constant pressure mode was higher with the ceramic membrane system (0.54 and 0.44 for ceramic and polymeric systems, respectively). Less severe fouling and higher cleaning efficiency observed in the ceramic hybrid system suggest that the coagulation would be a robust pretreatment option for the application of ceramic filtration for the surface water treatment.

Nano-NaX zeolite was synthesized by the microwave heating method and its application for the removal of heavy metal ions such as lead [Pb(II)], copper [Cu(II)], and cobalt [Co(II)] from aqueous solutions was investigated. The effect of adsorption variables including contact time, initial concentration, and temperature on adsorption efficiency by the nano-NaX zeolite was studied in a batch mode. The prepared NaX zeolite nanoparticles were characterized by the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET), and X-ray fluorescence (XRF) analysis. Based on the results, the homogeneous zeolite nanoparticles with the average diameter and surface area of 95 nm and $536{\mathrm{m}}^2{\mathrm{g}}^{-1}$, respectively, were obtained. The adsorption selectivity of lead, copper, and cobalt ions by the nano-NaX zeolite was in the order of $\mathrm{Pb}(\mathrm{II})>\mathrm{Cu}(\mathrm{II})>\mathrm{Co}(\mathrm{II})$. The pseudo-first-order, pseudo-second-order, and double exponential kinetic models were used to describe the kinetic data. The equilibrium data were also analyzed using isotherm models. The maximum monolayer capacity of the NaX zeolite was found to be 461.61, 144.9, and $125.3\mathrm{mg}{\mathrm{g}}^{-1}$ for the Pb(II), Cu(II), and Co(II) ions, respectively, at a temperature of 313 K. Finally, the thermodynamic parameters were evaluated to obtain the nature of the adsorption process by the nano-NaX zeolite. The results achieved were comparable with other prepared zeolites but with the advantage of requiring a much shorter preparation time.

In view of their toxicity, the presence of endocrine disrupters such as phthalates in surface waters requires the setup of new wastewater treatment processes. Previous studies demonstrated the efficiency of ozone $({\mathrm{O}}_3)/\text{activated}$ carbon (AC) coupling in removing micropollutants such as phthalates in batch conditions. The aim of the present work was to study the removal of diethylphthalate (DEP) from water by ${\mathrm{O}}_3/\mathrm{AC}$ coupling in continuous flow on a pilot scale. Comparison of the results obtained with ${\mathrm{O}}_3/\mathrm{AC}$ coupling (both DEP removal and ozone mass transfer) to those of conventional methods shows its great potential and the influence of experimental conditions such as pH and ozone gas concentration. The process reached a steady state with a high pollutant removal and an efficient ozone mass transfer. Moreover, it extends the AC lifetime by ensuring the in situ renewal of the adsorbent. By estimating the microporous volume occupied by the adsorbent material at different times during the treatment, it is also shown that no significant modification in the AC textural and chemical properties occurs during its regeneration by oxidative species.