The disposal of cyanogenic residues from the processing of cassava, during the flour production in certain regions of the Brazilian northeastern, has been a cause of concern in recent years, since this practice may lead to environmental imbalances. The results obtained in this work show a possible impact caused by the release of this kind of waste into water bodies, as well as its potential use as biofertilizer, mainly due to its high nutrient content. Humic substances (HS) from water and soil showed high interaction with cyanide ions (CN⁻), being the main responsible for the bioavailability of these ions into the environment. Furthermore, studies in microcosms propose viable and low-cost alternatives to decrease the levels of CN⁻ions in the liquid waste (called “manipueira”), as well as its potential use as biofertilizer.

Magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites were prepared by the facile citrate-gel thermal decomposition process. Their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and vibrating sample magnetometer (VSM). The as-prepared magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites were characterized with about 8-nm grains, specific surface area of 119.3 m²/g, and magnetization of 38.7 Am²/kg. The adsorption kinetics and adsorption isotherms of methyl blue (MB) and As(V) onto the magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites at room temperature were investigated. Adsorption kinetics of MB and As(V) onto the magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites have been researched using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, the statistic results show that the pseudo-second-order kinetic model is fitted well to describe the MB and As(V) adsorption process. The adsorption equilibrium data of MB and As(V) onto the magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites at room temperature were analyzed with Langmuir, Freundlich, and Temkin models, and the adsorption isotherms was more effectively described by the Freundlich model based on the values of the correlation coefficient. Figure The magnetic 0.8Ni₀.₅Zn₀.₅Fe₂O₄/0.2SiO₂ nanocomposites were prepared by the citrate-gel thermal decomposition process. They show high adsorption capacities for methyl blue (MB) and arsenic(V) in aqueous solution, and the adsorption kinetics and isothermals were analyzed.

The culture of Trametes gibbosa sp. white-rot fungi (WRF) 3 under mesophilic conditions can lead to the degradation of azo dye compounds. This ability of T. gibbosa sp. WRF 3 is attributed to the released enzymes that are able to catalyze the structural degradation of the azo dye compound. The effect of environmental factors such as carbon sources, nitrogen sources, and pH of growth medium were investigated in this research. The addition of 20 g/L glucose (carbon source) and yeast extract (nitrogen source) at pH 5 of growth medium enhanced the decolorization of Reactive Black 5 (RB5) dye up to 87.07 % within 30 days of incubation. The decolorization of RB5 can be analyzed using UV–vis spectroscopy and differential pulse cathodic stripping voltammetry (DPCSV). The maximum absorbance of RB5 was at 597 nm and decreased after the dye was treated with T. gibbosa sp. WRF 3. In the voltammetric analysis, we examined the effect of pH of Britton–Robinson buffer (BRB) medium on the detection of bis-azo compound of RB5. A stock solution of RB5 was used in the study, and it showed two reduction peak potentials at −0.5 and −0.7 V which attributed to the bis-azo bond, whereas the metabolic product showed one reduction peak at −0.6 V. The GC-MS mass spectrum confirmed the formation of metabolites at tR4.63 min and m/z of 73 after 30 days of incubation which was sec-butylamine.

In allocating the waste load of a river basin, the first priority is to achieve a given water quality goal for that river by utilizing several water quality management methods. Minimizing the waste load abatement cost within the river basin through appropriate, efficient water quality management is an important aspect of this process. In the past, it was common to concentrate on economic factors when constructing a waste load allocation (WLA) model. However, environmental resources (e.g., sub-basin area, population, wastewater flow, etc.) vary in each region of a river, and the fairness in the distribution of the treatment efforts among waste dischargers must be considered. The WLA model in this study was constructed as a multi-objective optimization problem and was established to achieve the economic goal of minimizing waste load abatement and to consider the inequality among waste dischargers. Two types of inequality were introduced into the WLA model. The first type is the inequality in the waste load discharge regarding the environmental resources in each region was computed with the environmental resource-based Gini coefficient. The second type of inequality is the fairness in the distribution of the treatment efforts among waste dischargers. The suitability of this WLA model was verified with its application in a heavily polluted total maximum daily load subject river in South Korea. Furthermore, Pareto-optimal solutions drawn from the multi-objective genetic algorithm were analyzed to infer the least cost solution, the least inequality solution, and the compromise solutions and to verify critical pollution sources.

The variability of levels of fecal indicator bacteria (FIB) and a human-associated genetic marker (HF183) during wet and dry weather conditions was investigated at two urban coastal watersheds in Southern California: Santa Monica Canyon channel (SMC) and Ventura Harbor, Keys, and Marina. Seventy-eight to 86 % of the samples collected from SMC sites exceeded standard water quality standards for FIB (n = 59 to 76). At SMC, HF183 was present in 58 % of the samples (n = 78) and was detected at least once at every sample site. No individual site at SMC appeared as a hotspot for the measured indicators, pointing to a likely chronic issue stemming from urban runoff in wet and dry weather. In Ventura, the Arundell Barranca, which drains into Ventura Harbor and Marina, was a source of FIB, and HF183 was most frequently detected off of a dock in the Marina. Rainfall significantly increased FIB levels at both SMC and Ventura; only at Ventura did HF183 detection increase with wet weather. Sample locations that were high in FIB were geographically distinct from the sites that were high in HF183 in Ventura, which supports the importance of measuring host-associated parameters along with FIB in chronically impaired watersheds to guide water quality managers in pollution remediation efforts.

A novel high-capacity phosphate removal adsorbent of graphene nanosheets (GNS) supported lanthanum hydroxide (LaOH) is prepared. The phosphate adsorption performance for GNS-LaOH is examined by a batch adsorption method from aqueous solutions. The Freundlich and Langmuir models are used to simulate the sorption equilibrium, which reveal that the Langmuir model has a better correlation with the experimental data. The maximum adsorption capacity is calculated to be 41.96 mg/g. The kinetic data from the adsorption of phosphate is suggested as the pseudo-second-order model, and the multi-linearity adsorption process is observed in the intraparticle diffusion model, indicating that a chemisorption process is dominant in the adsorption of phosphate. The phosphate adsorption mechanism is explored by analyzing the Fourier transform infrared spectroscopy (FT-IR) and the relationship between the adsorption amount and the pH value of phosphate solution. Ligand exchange and electrostatic and Lewis acid–base interactions are determined to be three main factors for phosphate adsorption.

Different cases of bioremediation technique were experimentally investigated here for decontaminating light non-aqueous phase liquid (LNAPL)-polluted groundwater collected from Panipat oil refinery situated in Haryana, India. Natural biodegradation of toluene, the selected LNAPL, was studied first under different varying substrate concentrations at room temperature (21.6 ± 0.3 °C). Biostimulation was then studied by mixing the polluted groundwater with a primary treated domestic wastewater for providing nutrients and other supplementary components to the native microbial population. For studying the remaining cases, small-scale wetland having plants of Canna generalis was developed in the laboratory with and without the presence of toluene in the rhizosphere. The wetland system in the presence of toluene was used here for developing the pre-grown microbial cultures to enhance the degradation rate of the LNAPL (bioaugmentation). The plant-assisted biostimulation was studied in the third case by adding the polluted groundwater with the root zone water of the wetland system developed without the presence of toluene. In the fourth case, the biostimulation was coupled with the bioaugmentation strategy by mixing the groundwater with the root zone water of the wetland system developed in the presence of toluene. A comparative account of these four different bioremediation techniques was prepared for their respective rates of biodegradation, duration of lag phases, and the total time of degradation. It was observed that the plant-assisted bioremediation techniques had better performance over the natural biodegradation and biostimulation methods of the considered LNAPL. The plant-assisted biostimulation coupled with the bioaugmentation technique needed almost no acclimatization time and accelerated the rate of degradation almost twofold compared to the natural bioremediation and, hence, is proved to be the best one among the other bioremediation techniques for decontaminating the LNAPL-polluted groundwater. The results of the conducted experiments can be used to obtain vital information on framing the engineered bioremediation planning for LNAPL-contaminated sites.

US National Ambient Air Quality Standards (NAAQS) are based on quantitative linkages between ambient air concentrations and an effects indicator. Critical loads (CLs) can provide quantitative information on safe levels of atmospheric deposition to aquatic systems, but CLs cannot be directly used in the NAAQS context because they are not expressed in terms of atmospheric concentrations. Here, we describe the aquatic acidification index (AAI) model that incorporates CL concepts and relates atmospheric nitrogen and sulfur concentrations to an acid neutralizing capacity (ANC) effects indicator (Fig. 1). The AAI estimates the potential surface water ANC associated with a set of atmospheric concentrations of nitrogen and sulfur and a region's biogeochemical and hydrological attributes by combining steady-state CL modeling with air quality modeling outputs. Initial applications of the AAI model yielded results consistent with well-recognized spatial patterns of acid-sensitive aquatic systems. Furthermore, the response of AAI predictions to future year changes in NO ₓ and SO ₓ emissions suggest that planned national emission reduction strategies designed to reduce ozone and particulate matter air pollution will produce increases in surface water ANC.

While most waste foundry sands (WFSs) are not hazardous, regulatory agencies are often reluctant to permit their beneficial use in agricultural and geotechnical applications due to concerns over metal leaching. The objective of this study was to quantify total and Toxicity Characteristic Leaching Procedure (TCLP) metals in 16 waste sands from Brazilian ferrous foundries then assess their potential to leach to groundwater using a probabilistic model. Total and TCLP metal concentrations in the non-hazardous sands fell within ranges as reported in the literature, although some of the leachate concentrations were found to exceed drinking water and groundwater maximum contaminant levels (MCLs). Leachate values above the MCLs were then used in the model to estimate groundwater concentrations at hypothetical wells up to 400m downgradient from a land application unit. A conservative scenario of 1 ha of land applied WFS, and high annual rainfall totals (low evaporation) suggested that groundwater concentrations of Ba, Hg, Mn, Ni, and Pb could potentially exceed health-based MCLs at most wells. While a wet climate can exacerbate the transport of metals, land application of WFSs in areas with moderate rainfall totals or high rainfall, high evaporation was predicted to be protective of groundwater quality and human health.

The issue of air pollution has become the focus of the world because of its significant influence to the economic development and public health. This paper proposes an interval dual stochastic-mixed integer programming (IDSIP) approach for regional air quality management. The IDSIP approach can be effectively communicated into the optimization processes and resulting solutions, which is formulated through integrating interval-parameter integer programming (IIP) within a two-stage stochastic programming (TSP) joint chance-constrained programming (CCP) and could deal with uncertainties expressed as not only probability distributions but also interval values. Moreover, the left-hand-side (LHS) constraints with stochastic variables could be handled at different risk levels with varied reliability scenarios. In the modeling formulation, penalties are imposed when expected policies are violated. The results indicate that reasonable solutions for air quality management system have been generated, which can help decision makers draw up productive strategies taking into account the trade-off between system economy and air quality under uncertainty.