Journal of Environmental Engineering

Use of water treatment plant residuals (WTRs) in storm-water control measures (SCMs) is a sustainable alternative to landfill disposal of WTRs. However, research is needed to determine how effective WTR-amended SCMs would be in field-scale applications and what modifications can be implemented to improve performance. The modifications examined in this study were oven-drying (105°C) and baking (1,000°C) of the WTRs. Results showed that both modifications increase the hydraulic conductivity by two orders of magnitude. Dried WTRs showed no loss of phosphate removal potential compared to the as-received WTRs. Baking the WTRs lowered the phosphate removal potential but prevented manganese resuspension. The as-received WTRs, as well as both modifications, removed copper, lead, and zinc from storm-water runoff to below detection. Taken together, these results suggest that amending SCMs with modified WTRs has the potential to enhance the water quality improvement processes of SCMs while maintaining the infiltration capacity required for water quantity control.

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are common groundwater pollutants. Biological activated carbon (BAC) treatment is attractive because BTEX species are well-adsorbed on activated carbon and also easily biodegraded in the adsorber. The inoculated activated carbon columns quickly became BAC systems; they removed most of the BTEX species present in the feed. Biodegradation was primarily responsible for the overall removal of the BAC systems, and the amounts of benzene, toluene, and o-xylene removed during the 2-week treatment period were all more than their respective isotherm capacities; 1,486, 1,463, 1,537, and 1,719 mg of benzene, toluene, ethylbenzene, and o-xylene were removed in the 2.5-g BAC systems versus the available adsorptive capacities of 174, 731, 1,515, and 895 mg, respectively. The stable BAC systems were resistant to the shock loadings of higher flow and concentration and consumed less than the expected amount of dissolved oxygen. Bioregeneration enabled the long-term treatment capability of the BAC systems for removing BTEX and other pollutants without periodic carbon replacement. The coal-based activated carbon (SC) was more desirable than the coconut-based activated carbon (YK) because of its lower cost and higher degree of bioregeneration.

Infiltration is a primary functional mechanism in green infrastructure storm water controls. This study used time domain reflectometers (TDRs) to measure spatial infiltration and assess clogging dynamics of permeable pavement systems in Edison, New Jersey, and Louisville, Kentucky. In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha parking lot surfaced with three permeable pavement types (permeable interlocking concrete pavers, pervious concrete, and porous asphalt). Paired TDRs were installed at two locations in each permeable pavement type and at a depth of 0.4 m below the driving surface. The relative volumetric water content (RVWC) prior to an event had a significant negative correlation to antecedent dry period, and the peak RVWC during an event had a significant positive correlation to the peak 5-min rainfall intensity. The TDRs measured a significantly different response when water was presumably infiltrating as direct rainfall compared to rainfall combined with runoff from a contributing drainage area. The results indicated clogging progressed from the upgradient edge. Based on the lessons learned at Edison, TDRs were installed in permeable pavement strips in Louisville, Kentucky, during December 2011. The TDR placement strategy was selected to understand the spatial infiltration of runoff and to document clogging and infiltration dynamics. As contributing drainage area size and condition impacts incoming sediment load, and the runoff infiltrates along the upgradient edge of the permeable pavement surface, the ratio of drainage area to working width of permeable surface is an important design parameter to predict the rate of clogging. At Edison, the design ratio of contributing drainage area to permeable pavement width at the upgradient edge was $7.62{\mathrm{m}}^2/\mathrm{m}$. In Louisville, the ratio was about $\mathrm{3,829}{\mathrm{m}}^2/\mathrm{m}$. Because of the much larger ratio, clogging was expected to occur rapidly at the Louisville site. Responses from rainfall events during the first three months at Louisville supports the hypotheses related to surface clogging mechanisms. This paper highlights evaluation techniques, placement locations, and techniques to use TDRs to remotely monitor surface clogging, which can be used to provide guidance for maintenance scheduling.

The effectiveness of nitrogen removal in vertical-flow filters with double-layer filling composed of lightweight aggregate made of fly ashes from sewage sludge thermal treatment (FASSTT LWA) and gravel at a varying hydraulic load was determined. Synthetic wastewaters containing $47\mathrm{mg}/\mathrm{L}$ of total nitrogen (TN) were fed into 15 filter columns filled with gravel and FASSTT LWA (gravel was the bed’s lower layer, whereas the top layer of the FASSTT LWA constituted 0, 12, 25, 50, and 100% of the depth of the column) at hydraulic loads of 3, 5, and $7\mathrm{mm}/\mathrm{day}$. The study demonstrated a significant TN removal by the filters, which was accompanied by a high concentration of ${\mathrm{NO}}_3\text{-}\mathrm{N}$ in the effluent. The results point to differentiated effectiveness of ${\mathrm{NH}}_4\text{-}\mathrm{N}$ removal by both the FASSTT LWA and gravel. The highest TN removal rate reaching up to 74.93% was achieved in the filter column with 100% FASSTT LWA content, irrespective of the hydraulic load applied.

In Colombia, several communities with limited or uncertain access to drinking water services collect rainwater for various domestic uses. This paper presents the results of a water quality analysis of the rainwater runoff from roofs in Kennedy (Bogota) to evaluate the suitability of adapting this water to satisfy domestic uses in this district. Based on the high values of turbidity and biochemical oxygen demand, and on the high concentrations of total suspended solids and heavy metals found in the studied rainwater, it is concluded that the water samples are not suitable for any of the domestic uses currently employed by the citizenry. Nevertheless, a high spatial and temporal variability was detected, in addition to variability as a function of the roof material. In particular cases, the runoff water from roofs may be adapted as an alternative source for domestic uses in the district.

Polyaniline/coconut shell–activated carbon (PANI/GAC) composites were fabricated by chemical oxidative polymerization of aniline monomers with GAC as the supporting materials. These prepared PANI/GAC composites were characterized by scanning electron microscopy, ${\mathrm{N}}_2$ adsorption-desorption analysis, and Fourier transform infrared spectroscopy. The effects of various parameters, including aqueous pH, contact time, the initial concentration of Cu(II), and temperature (288–323 K) on the Cu(II)’s adsorption, were investigated in detail. Results showed that the adsorption maximum occurs at around pH 5.5 and adsorption equilibrium was achieved in 90 min at $400\mathrm{mg}{\mathrm{L}}^{-1}$ Cu(II) concentration. The adsorption process followed the pseudo second-order kinetics, and the adsorption equilibrium data fit well with the Langmuir isotherm. Thermodynamic parameters indicated that the adsorption processes were endothermic, spontaneous, and more favorable at a higher temperature.

Copper and cadmium ions were removed from aqueous solutions by adsorption onto a new organic-inorganic hybrid material. N-(aminothioxomethyl)-2-thiophen carboxamide (TAC) was covalently anchored on SBA-15 mesoporous silica. Various characterization techniques [X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, ${}^{29}\mathrm{Si}$, ${}^{13}\mathrm{C}$ nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy] have proved that the organic ligand was successfully anchored and the ordering of the inorganic support was preserved during the chemical modifications. Metal cations in aqueous solution were adsorbed onto this material with multichelating atoms by a complexation mechanism. Adsorption capacity for the divalent copper and cadmium cations were 0.74 and $0.21\mathrm{mmol}{\mathrm{g}}^{-1}$, respectively. Cu(II) was selectively eliminated from contaminated water with Cu(II) and Cd(II). TAC-functionalized silica sorbent presented a good regeneration capacity without significantly losing its adsorption capacity and could be used for the development of an in-flow wastewater purification technology.

The performance of the electrocatalytic oxidation of phenol on poly(diallyldimethylammonium chloride) (PDDA)–modified ${\mathrm{PbO}}_2$ anodes in the presence of chloride ions was studied. The objective was to elucidate the influence of NaCl dosage, current density, initial phenol concentration, and initial pH on this catalysis process in the presence of ${\mathrm{Cl}}^{-}$. The results revealed that at low current densities, the presence of ${\mathrm{Cl}}^{-}$ could greatly enhance the current efficiency by electrogenerating active chlorine, and the current density increased, but if competitive adsorption of $·\mathrm{OH}$ radicals occurred, the removal efficiency did not improve significantly and the current efficiency decreased. This indicated that the pH value had a major impact on phenol, with optimal removal observed at approximately pH 6–7. In both acidic and alkaline solutions outside this optimal pH window, the removal efficiency deteriorated. The modified anode performs well for phenol degradation for a wide range of phenol concentrations under neutral conditions with an appropriate current density ($30\mathrm{mA}/{\mathrm{cm}}^2$) and NaCl concentration (0.05 M).

Combined sewer overflows (CSOs) are a major source of contamination to urban waterways. Discharges from CSOs represent a major source of chemical oxygen demand, biological oxygen demand, nutrients, toxics, and bacteria to receiving waters. The impacts of these discharges to ecosystem health include deposition of sewer sediment on the stream bed, anoxic events, and algal blooms. A case study is presented, which analyzed in-stream dissolved oxygen and sediment oxygen demand (SOD) in an urban stream in Philadelphia, Pennsylvania, to observe short-term and long-term water-column oxygen depletion caused by CSO discharges. Multiple SOD measurements were collected at six locations in a 5.61-km reach. Continuous in-stream dissolved oxygen measurements indicate that water-column dissolved oxygen concentration in the reach is depleted as it flows through the study section. This depletion appears to be the result of elevated SOD downstream of the CSO outfalls.