Journal of Environmental Engineering

In this study, a modification is proposed to the Soil and Water Assessment Tool (SWAT) to enable identification of areas where the implementation of best management practices would likely result in the most significant improvement in downstream water quality. To geospatially link potential locations to individual land owners, a land-use layer that incorporated specific crops and crop rotations needed to be developed. Model results obtained using the new land-use layer are compared to those obtained using a more conventional land-use layer. Results indicate that water flow and nutrient loadings are similar at the basin outlet, confirming the overall consistency of the approach. Water flow results at upland subbasin outlets appear similar; however, nutrient loadings are different since the crop distributions in the alternative approach are more representative of actual practice in the basin. These results suggest that the alternative, crop-rotation-specific method can be used to provide additional information for spatially resolved decision making regarding nutrient loading and downstream nutrient concentrations.

Pressure loss ($\mathrm{\Delta }P$) is a key parameter for estimating biofilter energy consumption. Accurate predictions of $\mathrm{\Delta }P$ as a function of air velocity ($V$) are, therefore, essential to assess energy consumption and minimize operation costs. This paper investigates the combined impact of medium particle size and shape on the $V\text{-}\mathrm{\Delta }P$ relationship. The $V\text{-}\mathrm{\Delta }P$ measurements were performed using three commercially available materials with different particle shapes: crushed granite (very angular particles), gravel (particles of intermediate roundness), and lightweight clay aggregrate (almost spherical particles). A total of 21 different particle-size fractions, with particle sizes ranging from 2 to 14 mm, were considered for each material. As expected, $\mathrm{\Delta }P$ decreased with increasing particle size in agreement with earlier findings. The value of $\mathrm{\Delta }P$, however, also showed a tendency to decrease with increasing particle roundness especially for fractions containing smaller particles. A new model concept for estimating $V\text{-}\mathrm{\Delta }P$ across different particle-size fractions and shapes was proposed. This model yielded improved prediction accuracy in comparison with existing prediction approaches.

To better plan for potential changes to stream water quality under climate change, an integrated approach to simulate paired streamflow and water quality under a range of climate scenarios is developed. Several stochastic nonparametric simulation techniques are integrated to create an end-to-end approach for comprehensive planning, with three steps: (1) develop a relationship between streamflow and water quality, (2) simulate streamflow ensembles under climate change scenarios, and (3) simulate water quality ensembles using the streamflow ensembles in conjunction with the developed relationship. The framework is demonstrated on a municipal water provider developing a new water supply source—but variations of salinity concentrations with streamflow pose limits to its use. For the current climate, the simulations accurately reproduce all of the relevant distributional and threshold statistics of flow and water quality, providing confidence in their use in long-term planning. Under climate change, reduced streamflow scenarios result in ensembles with higher salinity concentrations, which can be used in risk management and impact assessments. The approach is general and extends to other water quality variables associated with hydroclimate.

Landfill gas (LFG) is generated in municipal solid waste (MSW) landfills because of the decomposition of degradable components. Gas pressure within the landfilled MSWs is of importance as cover or landfill stability may be affected by gas pressure. This paper presents a one-dimensional transient analytical solution for gas pressure profiles in a MSW layer. This solution considers the variation of the LFG generation rate with respect to depth and decay of the LFG generation rate with time. The authors used the specified outward gas flux bottom boundary condition to simulate horizontal LFG collection systems and basal leachate collection systems serving dually as LFG collection systems. The presented solution also gives the outward gas flux from the MSW layer surface, which may be used to assist in the prediction of air quality near landfills. An application of the presented solution shows that averaging the LFG generation rate throughout the MSW layer results in a remarkable overestimation of gas pressure.

Mechanochemistry is of greater interest at present because of its application in the transformation of waste. In this study, an innovative application is proposed, namely to mechanochemically treat blast furnace slag so that it can be recycled into a low-cost adsorbent. In particular, the way this industrial waste adsorbs methylene blue present in aqueous solutions has been dealt with in detail. To this end, the slag was treated in a planetary mill at different charge ratios, rotational speeds and milling times, and then characterized by laser granulometry, porosimetric, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. These investigations shed light on the interrelationships between milling conditions and the physico-chemical characteristics of the slag. Next, the most interesting samples to submit to the following adsorption equilibrium and kinetic tests were chosen. These runs were conducted at different dye initial concentrations and adsorption times, and the results were interpreted according to the previously analyzed characteristics of the slag. Furthermore, adsorption data was postprocessed to obtain values for the equilibrium and kinetic constants, the separation factor, the removal efficiency, the initial adsorption rate, and the characteristic adsorption times.

This paper investigates the feasibility of the application of scrap tire and swine manure to produce a sustainable alternative for bituminous asphalt used in pavement construction. Biobinder is produced from swine manure by using a thermochemical conversion process; biobinder is then blended with crumb rubber and asphalt binder (PG 64-22) to produce biomodified rubber (BMR) asphalt. In addition to offering a renewable alternative for petroleum-based binder, BMR can be a hybrid environmental solution for the management of swine manure and scrap tire. To study the merit of application of BMR in the asphalt industry, this paper compares the rheological properties of BMR with a crumb rubber–modified (CRM) binder commonly being used in the United States. The authors found that BMR has comparable properties with the CRM binder. In addition, the authors found that the introduction of the biobinder to the CRM binder was beneficial in improving the low temperature property of the CRM binder while also reducing the CRM binder’s overall viscosity. In turn, this would allow for lower mixing and compaction temperatures of CRM asphalt while alleviating crumb rubber’s stiffening effect and enhancing the CRM asphalt’s pumpability. A lower mixing and compaction temperature will reduce the greenhouse gas emission during application of the CRM binder in pavement construction.

The objective of this study was to assess the feasibility of various chemical wet oxidation techniques to remove azo dyes from wastewater. The performances of three different catalytic wet oxidation techniques were evaluated: catalytic wet air oxidation (CWAO), catalytic wet peroxide oxidation (CWPO), and hydrogen peroxide promoted wet air oxidation (PCWAO), using activated carbon as a catalyst to evaluate the degradation and decolorization of Reactive Black 5 in aqueous solution. The experiments were also conducted to investigate the optimum operating conditions of the processes, such as temperature, pH, activated carbon loading, ${\mathrm{H}}_2{\mathrm{O}}_2$ loading, and reaction time. This investigation revealed that all of the wet oxidation techniques showed similar results and rather high removal efficiencies, but at different operating conditions. At the optimized conditions, the degradation was generally approximately 85% and decolorization was nearly 95% in each case. The operating conditions were as follows: in the CWAO process, higher temperature (70°C) and higher activated carbon loading ($0.5\mathrm{g}/\mathrm{L}$) were used; in the CWPO process, a lower temperature ($0.25\mathrm{g}/\mathrm{L}$) was used but a high amount of ${\mathrm{H}}_2{\mathrm{O}}_2$ was added ($0.1\mathrm{mL}/250\mathrm{mL}$ solution); and in the PCWAO process, a lower amount of ${\mathrm{H}}_2{\mathrm{O}}_2$ was added ($0.01\mathrm{mL}/250\mathrm{mL}$ solution) and higher temperature (70°C) was necessary to achieve the required performance.

The coagulation of oil in water is potentially cost-effective for removing oil from water. A coagulant consisting of sawdust (79.6% by volume), bentonite (15.8% by volume), and calcium hydroxide (4.7% by volume) gives coagulation efficiency of $\ge 94\%$ and coagulation time of $\le 45\mathrm{s}$. The resulting coagulated material (a semisolid) floats on water. Its oil (liquid) content, which decreases with a decreasing amount of oil originally present in the water, ranges from 69–81% by volume. This paper provides the first identification of multiple forms of oil in a coagulated material that is made from a single form of oil. The oil consists of strongly bonded oil (16% by volume, with relative dielectric constant 32) and weakly bonded oil (84% by volume, with the same relative dielectric constant of 2.0 as the original oil). The maximum and minimum volumes of oil per unit area that can be coagulated by $0.022{\mathrm{cm}}^3/{\mathrm{cm}}^2$ of coagulant volume per unit area are 0.116 and $0.052{\mathrm{cm}}^3/{\mathrm{cm}}^2$, respectively. Below the minimum amount of oil, the coagulated material sinks in water, thus hindering oil removal.

The synergistic effects of sequential ultraviolet (UV) radiation and chlorination on tailing during disinfection of Escherichia coli in secondary effluent were investigated. To accomplish this, the effects of UV and chlorination, pH, dose of chlorine and dose of UV on kinetic curves of E. coli were evaluated. Total suspended solids (TSS) were found to be responsible for tailing during disinfection, and their concentrations were linearly correlated with the overall inactivation rate. Specifically, inactivation decreased by 10 times as suspended solids increased from 6 to $85\mathrm{mg}/\mathrm{L}$. The synergistic effects of sequential UV radiation and chlorination were identified. Sequential UV radiation and chlorination substantially increased the inactivation rate by 1.08–1.25 times in the first-order region and increased the log-inactivation value by 2–2.5 times in the tailing region with respect to chlorination. Reducing pH and/or increasing chlorine and UV dose magnified the enhancements of the first-order inactivation rate and reduced the time at which the tailing region started.

A specially designed, large-scale municipal solid waste (MSW) settlement apparatus was used to conduct experiments in this study. The suction for unsaturated waste in different layers also was measured. The test results show that the deeper the sample, the more saturated it will become during testing, although the initial state of the overall sample is almost the same. The pore gas pressure was measured for different depths of the sample. It is shown that the pore gas pressure varies in different layers. Two sets of experiments were conducted to make the comparisons. For one test, water was added to the sample; for the other test, no water was added. Significant differences were observed in the quantity of gas and leachate produced during contrastive tests. A previous theoretical model was updated and extended to be suitable to new boundary conditions with a liquid supply.