Journal of Environmental Engineering

Novel low-cost and antifouling polyvinylchloride (PVC)–based membranes were fabricated with regular and hydrophilic nano-${\mathrm{SiO}}_2$ particles as additives. The modified membranes exhibited significant improvements in mechanical properties, surface hydrophilicities, and antifouling performances in filtration of oil extraction wastewater. The addition of two types of nano-${\mathrm{SiO}}_2$ particles increased the quantities of hydrophilic functional groups on the surface of the PVC membranes, which enhanced the resistance to adsorption of oily hydrophobic contaminants. Compared with the unmodified membrane, the membranes modified by regular and hydrophilic nano-${\mathrm{SiO}}_2$ (at optimal addition of 1.5 g) presented more steady initial fluxes and higher flux recovery ratios in every filtration cycle. Meanwhile, both modified membranes exhibited high removal efficiencies of suspended solids (more than 98%) and oil components (up to 95%). These findings indicate that PVC membranes modified with two types of nano-${\mathrm{SiO}}_2$ particles have great potential for applications in the reuse of oil extraction wastewater.

The performance of a lab-scale biotrickling filter treating ${\mathrm{H}}_2\mathrm{S}$ from biogas produced from an upflow anaerobic sludge bed reactor of the wastewater-treatment plant of a brewery was evaluated. A sulfide-oxidizing culture obtained from the anaerobic sludge of the same upflow anaerobic sludge bed reactor was immobilized on polyurethane foam. The nitrate and nitrite (final electron acceptor) depletion on the trickling medium resulted in remarkable destabilization in the performance of the system. The optimum temperature was in the range from 31 to 42°C ($\text{removal}\text{efficiency}=91.8\pm 5.5\%$). At a temperature of 22°C the removal efficiency reduced to 39% [$\text{inlet}\text{load}(\mathrm{IL})=5.3\mathrm{gS}\text{-}{\mathrm{H}}_2\mathrm{S}{\mathrm{m}}^{-3}{\mathrm{h}}^{-1}$, empty bed residence time $(\mathrm{EBRT})=2.9\min$]. Trickling liquid velocity (TLV) of 4.4, 7.4, and $11\mathrm{m}{\mathrm{h}}^{-1}$ did not affect the system at EBRT of 6.2 min ($\text{removal}\text{efficiency}=94.2\pm 1.3\%$, $\mathrm{IL}=1.86\pm 0.18\mathrm{gS}{\mathrm{m}}^{-3}{\mathrm{h}}^{-1}$). A TLV effect was observed at an EBRT of 1.6 min where the removal efficiency decreased from 50.9% ($4.4\mathrm{m}{\mathrm{h}}^{-1}$) to 33.7% ($7.3\mathrm{m}{\mathrm{h}}^{-1}$).

In this work, sodium borohydride reduced nanoscale zero-valent iron (nZVI–BR), sodium borohydride reduced nanoscale zero-valent iron–nickel (nZVIN–BR), nanoscale zero-valent iron sourced from NanoIron, s.r.o. (nZVI–Star), and nanoscale zero-valent iron sourced from Toda Kogyo Corporation (nZVI–RNIP) have been tested for the ex situ removal of aqueous uranium (U) from a bicarbonate-rich mine water effluent. Laboratory scale (2 L) batch treatment systems containing the mine water and comparator uranyl solutions were tested to compare U removal efficacy and aqueous corrosion behavior of the different nanopowders. The two commercially sourced nanopowders were also tested for the removal of U from 2,500 L batch systems to determine the nature of any differential behavior exhibited by the nanopowders when deployed at commercial scale. Analysis of aqueous samples taken at periodic intervals throughout the 96 h reaction period using inductively coupled plasma mass spectroscopy recorded $>95\%$ aqueous U removal within 15 min by the sodium borohydride reduced nanopowders in all systems studied. Similar behavior was exhibited by the commercially sourced nanopowders for the uranyl-only solutions; however, a maximum of only 30.0 and 43.2% removal was recorded for the 2 L mine water effluent by nZVI–Star and nZVI–RNIP, respectively. Similar U uptake behavior was exhibited by the commercially sourced nanopowders for the 2,500 L batch treatment systems; however, a redox and U removal gradient as a function of depth was recorded, compared to a homogenous distribution recorded for the 2 L experiments. Analysis of reacted nanoparticulate solids using X-ray diffraction determined only minor aqueous corrosion of the two commercial nanopowders whereas near-total conversion to iron (hydr)oxides was recorded for the sodium borohydride reduced nanopowders. Results therefore demonstrate that in order for effective U removal from waters containing appreciable concentrations of complexing agents, highly reactive forms of iron and iron–nickel nanoparticles are required. In addition, the performance of such materials in commercial scale applications is likely to be lower than in laboratory-scale experiments due to the significant technical challenge of homogenous mixing/dispersion of the nanopowder with the aqueous phase.

Removing phosphorus (P) from the environment is a growing priority for water resource stakeholders. Unlike prior research that focused on using adsorbents to treat wastewater discharges, urban stormwater, or agricultural runoff, several adsorbents were evaluated in this work for their ability to remove P directly from surface water. Isotherm models predicted that the capacity of Sorbtive Media, dried alum sludge, fly ash, and Bold and Gold solid adsorbents were 42.1, 21.3, 10.5, and 0.019 mg ${\mathrm{PO}}_4/\mathrm{g}$ adsorbent, respectively. Alum sludge and Sorbtive Media were further evaluated by packing 10% of the adsorbent with 90% sand (by volume) into 15-mm-diameter mini-columns that were fed surface water collected from the Econlockhatchee River near Orlando, FL. The average percent removal of P was 51% for the alum sludge column and 61% for the Sorbtive Media column. The adsorptive capacity of the columns was not exhausted after more than 1,300 h of continuous operation. This study shed light on the use of adsorbent materials for P removal from surface water and provides insight into the challenges of treating P from nonpoint sources.

Waste settlement as well as consolidation phenomena, which occur inside a landfill for municipal solid waste (MSW), can cause a decrease in waste permeability. This can lead to a reduction in conveyance of the leachate drainage system. It is therefore possible that a so-called perched leachate zone will form. Such a zone is constituted by an area in the body of the landfill where the leachate is temporarily trapped and is unable to infiltrate downward. This phenomenon is influenced by many factors, which include rain infiltration rate, waste moisture and composition, landfill height, and so on. The main aim of the paper is to elucidate the role played by landfill height in the formation of perched leachate zones using a one-dimensional (1D) mathematical model. The model allows for the simulation of the percolation fluxes throughout an MSW landfill based on mass-balance equations. The results showed a different response in terms of flow rates throughout the landfill, highlighting the important role of landfill height in the formation of perched leachate zones. Landfill height influences not only the formation of perched leachate zones but also their extension throughout the body of the landfill.

A comprehensive model was applied to simulate a laboratory microcosm study of biodegradation rates and the branched production and loss of daughter products. The aim of the investigation was to evaluate the effect of electron donors (lactate, ethanol, and natural organic matter) on 2,4,6-trinitrotoluene (TNT) biodegradation rate and pathway in historically contaminated sediments undergoing biostimulation. Simulation results show overall TNT degradation rates for lactate-amended microcosms were greater than ethanol-amended microcosms by a factor of 1.7 and 3.0 times compared with natural organic matter amended microcosms. Differences in observed biomass concentrations ($\text{lactate}>\text{ethanol}>\text{unamended}$) were thought to be a contributing factor. TNT degradation pathway modeling included determination of branching coefficients representing whether the first nitro group reduction occurred in the ortho or para position. Branching coefficients were greater for the initial reduction of para (17–27% initial TNT concentration) over ortho (3–9% initial TNT concentration) for all test conditions. However, greater degradate recovery and a different (lower para:ortho) ratio was observed for ethanol compared with lactate and unamended conditions. Given the variation in sorption parameters among degradate isomers, these results suggest that differences in pathway branching stimulated by different electron donors are potentially relevant to the long-term persistence of TNT degradation products and the ultimate success of bioremediation-based remedial strategies.

The research reported in this paper determined the effect of combined microwave irradiation and NaOH pretreatment on solubilization and biodegradation in anaerobic digestion of waste-activated sludge (WAS). Solubilization increased significantly with NaOH concentration ($20–60\mathrm{meqNaOH}/\mathrm{L}$) and microwave final temperature (100–170°C). However, the experimental trials did not adequately approximate the response surface for volatile solids reduction, cumulative biogas production, and biogas yield. Within the design boundaries, the maximum solubilization degree (72%) of WAS occurred at $60\mathrm{meq}/\mathrm{L}$ and 170°C. The highest volatile solids removal efficiency (62.4%) was achieved at $40\mathrm{meq}/\mathrm{L}$ and 170°C. Cumulative biogas production and yield were $2.3–5.7\mathrm{L}/\mathrm{L}$ and $154–393\mathrm{mL}/\mathrm{g}$ added volatile solids, respectively, and both parameters were highest at $20\mathrm{meq}/\mathrm{L}$ and 135°C.