Journal of Environmental Engineering

The quality of wastewater varies between catchments due to variation in urbanisation, sewer system properties, and pollution levels. This study was conducted to identify wastewater quality parameters that could be normalized to estimate levels of infiltration/inflow (I/I) in selected catchments and to investigate the geographic origins of metals entering sewer systems. Two sampling campaigns were conducted in the five catchments of the Gothenburg area focusing on 14 water quality parameters. Data from a reference study on domestic wastewater quality to normalize the mass flows associated with pure domestic wastewater was applied. The level of dilution due to I/I in wastewater entering Rya Wastewater Treatment Plant, estimated using Tot-N and Tot-P as indicators, provided the closest fit among the water quality parameters with results obtained by established methods for the two campaigns. The results from the study also indicated which catchments generated nondomestic wastewater with higher mass flows of specified metals.

The objectives of this work were first to evaluate the effect of coupling a zero-valent side filter to anaerobic fluidized bed bioreactors (HFBB) versus bioreactors without the zero-valent filter, also called methanogenic fluidized bed bioreactors (MFBB); and second to study the diversity of the microbial community in both types of bioreactors. At the end of operation (in the last 75 d), the HFBB reached a 95% removal of the incoming tetrachloroethylene, whereas the MFBBs without filter achieved a removal of 88%. Genera such as Dehalobacter spp., Desulfurospirillum spp., Desulfitobacterium spp., and Dehalococcoides spp., and Methanosarcina were found at the end of the treatment. Coupling zero-valent filters to bioreactors (HFBB) fed with high tetrachloroethylene concentration improved reactor performance [high tetrachloroethylene removal and reduction of concentrations of vinyl chloride (VC) and dichlorethylene (DCE)]. This performance was consistent with significant higher concentrations of dehalogenating bacteria found in the HFBB.

In this study, the electrochemical oxidation (EO) process was implemented and optimized to effectively decolorize and degrade wastewater containing Acid Yellow 23 (Y23). The experiments were carried out in a laboratory-scale batch cell reactor, with monopolar configuration of electrodes, made of graphite (anode) and titanium (cathode). The response surface methodology (RSM), coupled with Box-Behnken experimental design (BBD), was used to evaluate the single and interactive effects of different variables of the EO process on (1) degradation percentages of both chemical oxygen demand (%DCOD) and color (%DC) and (2) energy consumption (EC). Thus, the following experimental factors were considered: initial dye concentration ($40–100\mathrm{mg}/\mathrm{L}$), current density ($10–20\mathrm{mA}/{\mathrm{cm}}^2$), and conductivity ($\mathrm{1,000}–\mathrm{4,000}\mathrm{\mu S}/\mathrm{cm}$). Thus, the subsequent conditions were found to be optimal for decolorization and degradation of Y23: initial dye concentration = $100\mathrm{mg}/\mathrm{L}$; current density = $20\mathrm{mA}/{\mathrm{cm}}^2$; and conductivity = $\mathrm{4,000}\mathrm{\mu S}/\mathrm{cm}$. At these conditions, the EO process allowed to reach approximately 99% of color degradation and 76% of COD degradation. Because NaCl was used as an electrolyte, chorine formation was monitored, and its effect on %DC and %DCOD was also evaluated.

Nitrate reduction by Fe(II) species was previously known to occur only in ${\mathrm{Cu}}^{2+}$-catalyzed and alkaline conditions or at high temperatures. In this study, a reactant system consisting of nitrate, iron oxide particles, and Fe(II) (in different forms) was used to study possible reactions between nitrate and Fe(II). At near-neutral pH, nitrate could not be reduced by aqueous Fe(II) species or by $\mathrm{Fe}{(\mathrm{OH})}_2$ gel. In the presence of magnetite (${\mathrm{Fe}}_3{\mathrm{O}}_4$) particles, however, a significant amount of ${\mathrm{Fe}}^{2+}$ could be adsorbed onto an ${\mathrm{Fe}}_3{\mathrm{O}}_4$ surface at $\mathrm{pH}=7.3$ and became surface-bound ${\mathrm{Fe}}^{2+}(\mathrm{S.B.}{\mathrm{Fe}}^{2+})$, which could react with nitrate via the reaction: $12\mathrm{S.B.}{\mathrm{Fe}}^{2+}+{\mathrm{NO}}_3^{-}+13{\mathrm{H}}_2\mathrm{O}\to 4{\mathrm{Fe}}_3{\mathrm{O}}_4\downarrow +{\mathrm{NH}}_4^{+}+22{\mathrm{H}}^{+}$. The reaction stopped when pH decreased to $<6.8$. Introducing trace amount of ${\mathrm{O}}_2$ or ${\mathrm{Fe}}^{3+}(\mathrm{aq})$ into the nitrate-${\mathrm{Fe}}^{2+}$ reactant system was as effective as seeding magnetite particles in triggering the nitrate-Fe(II) reaction, suggesting that lepidocrocite ($\gamma \text{-}\mathrm{FeOOH}$) is a precursor for initiating the nitrate-Fe(II) reaction. Hematite and Kaolinite particles could also serve as the reactive sites for the nitrate-Fe(II) reaction upon surface transformation by $\mathrm{S.B.}{\mathrm{Fe}}^{2+}$. The observed abiotic nitrate reduction by Fe(II) could be an important link between the nitrogen cycling and the Fe(II)/Fe(III) redox couple in the biosphere or geosphere.

To demonstrate the feasibility of photocatalysis for the removal of polycyclic aromatic hydrocarbons (PAHs) from offshore-produced water (OPW), the effects of water matrix were studied by comparing the performance of ${\mathrm{TiO}}_2$-induced photocatalysis in distilled water and OPW media. The effects of salinity, insoluble particulate matter, and organic composition were evaluated. The results showed the strong improvements with the addition of catalysts but the enhancement of photocatalysis was restricted by OPW media. The photocatalytic degradation of PAHs with high molecular weights was more sensitive to the variations of salinity and insoluble matter due to their lower solubility. The overall degradation of PAHs was strongly restricted by the organic composition in OPW particularly the aromatic compounds. The aromatic compounds played an important role as ultraviolet-photon absorbents and competed with the photodegradation of PAHs. Because of their abundance in OPW, these species had the most significant effect on the photocatalytic degradation of PAHs.

This study investigates the effect of low levels of hydrogen peroxide (${\mathrm{H}}_2{\mathrm{O}}_2$) on photo-oxidation of pharmaceuticals and personal care products (PPCPs) present in secondary effluent of a municipal wastewater treatment plant (WWTP). Experiments were conducted using two types of flow-through reactor systems: (1) three ultraviolet light (UV) reactors connected in series without a ${\mathrm{H}}_2{\mathrm{O}}_2$ addition, and (2) a UV reactor with a ${\mathrm{H}}_2{\mathrm{O}}_2$ addition. In the first part of this study, 38 PPCPs detected in secondary effluent were examined based on their degradability by UV in the presence and absence of ${\mathrm{H}}_2{\mathrm{O}}_2$. For the PPCPs that were not degraded to or below their detection level, the pseudo first-order photo-oxidation rate constants, k (${\mathrm{s}}^{-1}$), were determined using a mathematical model developed for three continuously stirred tank reactors in series. The second part of the study investigated the kinetics of the selected PPCPs in the $\mathrm{UV}/{\mathrm{H}}_2{\mathrm{O}}_2$ reactor. The effect of low concentrations of ${\mathrm{H}}_2{\mathrm{O}}_2$ on the photo-oxidation rate of PPCPs was quantified by the power function expression.

A mixture of coal processing agents, namely crude-MCHM (primarily 4-methylcyclohexanemethanol) and stripped-PPH (primarily dipropylene glycol phenyl ether and propylene glycol phenyl ether) spilled into the Elk River near Charleston, West Virginia in January 2014. The spill resulted in a do-not-use ban on drinking water for up to 10 days. Studies were undertaken to determine the potential for aerobic biodegradation of crude-MCHM and PPH in the riverine system and in the sewage treatment plant postflushing of affected water lines. Complete biotransformation of crude-MCHM occurred only when MCHM was initially $<6\mathrm{mg}{\mathrm{L}}^{-1}$. When both PPH and crude-MCHM were present, biotransformation of both compounds only occurred when MCHM was initially $<2.3\mathrm{mg}{\mathrm{L}}^{-1}$ and PPH was $<3\mathrm{mg}{\mathrm{L}}^{-1}$. Limited conversion of PPH was typically observed ($<40\%$). Estimated maximum specific biodegradation rates were 0.087 mg cis-MCHM ${(\mathrm{mg}\text{biomass}\mathrm{h})}^{-1}$ and 0.23 mg trans-MCHM ${(\mathrm{mg}\text{biomass}\mathrm{h})}^{-1}$. The estimated half saturation constants were 2.7 mg cis-MCHM ${\mathrm{L}}^{-1}$ and 10.5 mg trans-MCHM ${\mathrm{L}}^{-1}$. Toxicity studies with agar diffusion plates and ToxTrac indicate both MCHM and PPH exhibit toxicity to Elk River microcosm cultures and that microbiological degradation of MCHM and PPH may generate more toxic products. Phylogenetic analysis of sediments and biodegradation microcosm cultures identified methanotrophs, methylotrophs, and organisms associated with xenobiotic biodegradation, acid mine drainage, and sulfidic mine tailings. These studies can be used to understand the likelihood of biological degradation of MCHM and PPH in environmental and treatment systems.

To gather further data about metal mobility in accumulated sediments in stormwater treatment facilities, metal mobility in sediments from sedimentation tanks, gully pot sediment traps, and sedimentation ponds was investigated using the sequential extraction procedure. This method allows distinguishing the metal speciation between ion-exchangeable, carbonate-associated, reducible, organic matter/sulfide-associated, and residual fractions. The metal fractionation reveals that, for all treatment facilities, the majority of Cd, Cu, Pb, and Zn and a significant amount of Ni were in potentially mobile forms. Cd, Pb, and Zn are, to a large extent, associated with Fe-Mn oxides while Cu is commonly present as Cu–organic matter complexes. The metals in these potentially mobile fractions may represent a potential environmental hazard, e.g., due to release during maintenance (sediment removal) when the chemical phase distribution might change.

The main objective of this study is to present a first demonstration of the potential of aged powdered activated carbon (PAC) to remove micropollutants during batch tests. Three PACs of varying ages (0, 10, and 60 days) were added ($1\mathrm{g}/\mathrm{L}$) in settled and preozonated settled water, in which a mixture of 10 micropollutants had been spiked at environmentally relevant concentrations. Under these operating conditions, direct competition with natural organic matter was not evidenced when decreasing absorbability of the organic matter through ozonation. All the micropollutants were rapidly adsorbed on the three PACs, and removals superior to 95% were reached within 5 min of contact time for all the micropollutants investigated. PAC aging decreased the adsorption kinetics of atrazine, deethylatrazine, and caffeine. PAC age is thus expected to reduce significantly the process performance at contact times less than 15 min. This study demonstrates that aged PAC suspensions allowing the removal of ammonia and dissolved organic carbon also have the potential to efficiently remove a wide variety of micropollutants by adsorption and comply with current World Health Organization guideline values for microcystin-LR ($1\mathrm{\mu g}/\mathrm{L}$) and atrazine ($2\mathrm{\mu g}/\mathrm{L}$).

Soil colloids play critical roles during the fate and transport of micropollutants (e.g., pesticides and hormones) due to their high sorption affinity and mobility. In this study, the authors developed a centrifugation and mass balance–based methodology for studying sorption of testosterone to soil colloids of different size fractions (DSFs). The method should allow one to conduct the sorption tests with the whole soil first and then separate soil colloids of DSFs to evaluate their contributions to sorption. Results indicate the colloids diameter ranges (i.e., 900–600, 600–400, and 400–200 nm) can be controlled by a group of series centrifuge conditions (i.e., speed and time). The sorption affinity of soil colloids for testosterone is three times higher than that of the bulk soil and increases significantly with decreasing diameter size because of the difference of specific surface area and organic carbon content. The authors propose that the centrifuge condition of 2,844 relative centrifugal force $(\mathrm{RCF})+30\min$ is required to separate the dissolved ($d_{\text{nano}}<200\mathrm{nm}$) and particle-associate phases to ensure the error of sorption results less than 2%. One may use the methodology to develop a framework to study the sorption of micropollutants on soil colloids of DSFs with whole soils or sediments as testing material media.

This paper deals with an upflow anaerobic sludge blanket (UASB) reactor’s effluent post treatment under aerobic conditions. The kinetics of stripping and oxidation of sulfides (${\mathrm{H}}_2\mathrm{S}$, ${\mathrm{HS}}^{-}$ and ${\mathrm{S}}^{2-}$) and purgeable organic compounds are determined. The effects of dissolved oxygen (DO) and temperature on stripping and oxidation kinetics are also investigated. Batch results indicate that the effluent quality [sulfide, chemical oxygen demand (COD) and purgeable organic carbon (POC)] can be improved by 50% with aeration at $6\mathrm{mg}/\mathrm{L}$ DO and at hydraulic retention time (HRT) of 30 min. The results obtained in the batch studies were confirmed in full size reactors. Moreover, it was observed that sulfides in absence of dissolved oxygen are removed by stripping rather than oxidation.

This study investigated the efficiency and cost-effectiveness of electrocoagulation (EC) parameters using aluminum (Al) electrodes to remove cadmium (Cd) from synthetic and real industrial mining wastewater (MWW) discharged by the Tunisian Chemical Group (TCG), which poses serious ecological hazards. Based on individual examinations of each operation parameter, the best removal of Cd was obtained at a current density of $7.35\mathrm{mA}{\mathrm{cm}}^{-2}$, an initial pH of 7, and a sodium chloride (NaCl) dose of $2\mathrm{g}{\mathrm{L}}^{-1}$ corresponding to a conductivity of $5.3\mathrm{mS}{\mathrm{cm}}^{-1}$. The effects of initial concentrations, the Faradic efficiency, the state of the Al plates, the electrical energy consumption, and the operating cost were examined in detail. These optimum conditions enabled the achievement of a largely efficient removal in a relatively short treatment time of 30 min, with a significantly low operating cost of 0.2 Tunisian national dinars $(\mathrm{TND}){\mathrm{m}}^{-3}$; a low energy consumption of $0.5\mathrm{kWh}{\mathrm{m}}^{-3}$ yielded the total removal of Cd. In addition, an application of all the optimum EC parameters together was carried out; a total removal was achieved not only of Cd, but also of other pollutants, at the same time. The investigation of EC processes carried out in this work provides evidence for a highly cost-effective wastewater treatment method if compared to other widely used technologies such as coagulation and precipitation.

A paramagnetic solid-phase nanoextractant, L-Cysteine functionalized ${\mathrm{Fe}}_3{\mathrm{O}}_4/{\mathrm{SiO}}_2$ (FSAC), was assembled for separating ${\mathrm{Pb}}^{2+}$ from wastewater. L-Cysteine molecules were fixed on the surface of ${\mathrm{Fe}}_3{\mathrm{O}}_4/{\mathrm{SiO}}_2$ nanoparticles by aminopropyl-silane. The properties of the nanoextractant were characterized by Fourier transform infrared spectroscopy (FTIR), a transmission electron microscope (TEM), and a vibrating sample magnetometer (VSM). It was shown that FSAC particles are sphere-like, are 20 nm in size, and have good paramagnetic properties. The FSAC nanoextractant shows good adsorption, excellent adsorption kinetics, wide acidic resistance, and high saturated adsorption capacity beyond $234\mathrm{mg}·{\mathrm{g}}^{-1}$, reached within 30 min. The applied nanoextractant can be completely recovered in a 1.0-M HCl/0.5% thiourea mixing solution within 5 min, but maintain over 92% adsorption when recycled 6 times.

This study aims to determine the concentration of particulate matter (PM) produced from construction sites focusing on concrete and masonry works in terms of the fractions of total suspended particles (TSP) and Particulate Matter 10 μm (PM10) and their chemical elements. The experimental study was conducted at five building construction sites over a period of 11 work days for 8 h each day, and on one day when the sites were inoperative (on Sunday). Portable air samplers were used to collect the particulate matter, sticky pads were used to collect settleable dust, and a portable meteorological station was used to determine the meteorological variables. The variation of the average for TSP fraction for 8 h was between 108 and $483\mathrm{\mu g}/{\mathrm{m}}^3$, and for PM10 fraction for 8 h was between 46 and $214\mathrm{\mu g}/{\mathrm{m}}^3$. This study contributes to a better understanding of the behavior and composition of PM at construction sites in that particular phase of construction activity, the meteorological variables and the construction activities that most influence its concentration, and the factors that interfere with the results of the collection. This paper provides a valuable knowledge for various real situations and provides a basis for improving the methodology of collecting PM on construction sites.

This study determined the effectiveness of pilot-scale tertiary sedimentation and filtration systems on lowering phosphorus, biochemical oxygen demand (BOD), and pharmaceutical levels in municipal secondary wastewater effluent. Secondary effluent was diverted into five pilot-scale tertiary treatment systems. The systems used alum and a polymer during coagulation and flocculation, after which sedimentation was used to remove settleable solids, and filtration was used to remove nonsettleable solids. The filtration units following sedimentation were (1) continuous backwash upflow sand filtration following conventional sedimentation, (2) dual-media granular filtration following microsand ballasted sedimentation, (3) dual-media granular filtration following magnetite ballasted sedimentation, (4) ultrafiltration following microsand ballasted sedimentation, and (5) ultrafiltration following magentite ballasted sedimentation. Total phosphorus was $1.11\mathrm{mg}/\mathrm{L}$ in the secondary effluent and decreased to $0.015\mathrm{mg}/\mathrm{L}$ after sedimentation and ultrafiltration. BOD was $9.9\mathrm{mg}/\mathrm{L}$ in the secondary effluent and decreased to $<1\mathrm{mg}/\mathrm{L}$ after the five systems. The pharmaceutical concentrations found in the secondary effluent were $211\mathrm{ng}/\mathrm{L}$ trimethoprim, $323\mathrm{ng}/\mathrm{L}$ carbamazepine, and $901\mathrm{ng}/\mathrm{L}$ sulfamethoxazole. The range of concentrations following tertiary treatment were $160–255\mathrm{ng}/\mathrm{L}$ trimethoprim, $302–335\mathrm{ng}/\mathrm{L}$ carbamazepine, and $482–792\mathrm{ng}/\mathrm{L}$ sulfamethoxazole. Overall, the tertiary sedimentation and filtration systems did not provide enhanced pharmaceutical removal. The results from this study corroborate other research findings, suggesting that rapid rate sand filtration and ultrafiltration may be inadequate for removing trace concentrations of water soluble pharmaceuticals, although phosphorus and BOD removal was $>96\%$ and $>91\%$, respectively, comparing secondary and tertiary effluent.