Ni, Cu, and Ni-Cu metal oxides supported on granular activated carbon (GAC) were synthesized and used in catalytic ozonation of heavy oil produced water. The effect of preparation conditions on their catalyst composition, catalyst structure, and catalytic activity was investigated. The catalyst structure was characterized by X-ray power diffraction (XRD). The results revealed that the Ni-Cu/GAC has the highest catalytic activity, followed by Cu/GAC and Ni/GAC. Metal oxide loading rate depended on impregnation process, whereas dispersion of metal oxides was controlled by calcination process. The XRD analysis showed that the principal active phase was Cu₂O for Cu/GAC and Ni-Cu/GAC catalyst and NiO for Ni/GAC catalyst. The most active plane was Cu₂O₍₂₀₀₎ and then followed by Cu₂O₍₁₁₀₎ and Cu₂O₍₁₁₁₎ for Cu-supported catalysts. Higher calcination temperature and time favored the generation of Cu₂O but increased the crystalline diameter. It also suggested that promoting the generation of NiO and Cu₂O phase and reducing the crystalline diameter could improve the catalytic activity. During Ni-Cu/GAC preparation, existence of Ni(NO₃)₂ could accelerate the adsorption of Cu(NO₃)₂, promoting the generation of Cu₂O, and improve the dispersion of Cu₂O phase. Graphical Abstract ᅟ

Pig slurry contains sufficient amount of nitrogen, phosphorus, and potassium for plant growth. If appropriately administered, this could substitute significant amounts of fertilizer. However, excessive fertilization with slurry causes environmental problems. To reduce environmental issues, solid-liquid separation or anaerobic digestion is needed to obtain a better distribution of nutrients. Solid-liquid separation produces a solid fraction rich in phosphorus and a liquid fraction containing ammonia, potassium, and high water content. Therefore, further concentration of ammonia is desired for any practical use. In this study, ammonia membrane stripping was carried out using polypropylene membranes and the impact of temperature, flow velocities, and liquid fraction pretreatment on the membrane contactor performance was tested. Sieved liquid effluents from a decanter centrifuge, a screw press, an AL-2 system (flocculation and filtration), and an anaerobic digester were tested. Since the properties of these liquid effluents vary, they might affect ammonia recovery. Thus, it is essential to investigate which effluent is most suitable as a feed for a membrane contactor and what is the cost of preprocessing. The mean ammonia mass transfer coefficient at 30 °C was found to be equal to 17 ± 2 × 10⁻³ m h⁻¹. At 50 °C, it was found to be equal to 29 ± 2 × 10⁻³ m h⁻¹ for all the tested effluents. This means that sieving after slurry separation or anaerobic digestion alleviates the influence the solid-liquid separation has on ammonia membrane stripping. However, the cost evaluation showed that solid-liquid separation using a decanter centrifuge followed by sieve draining is the cheapest of the methods investigated.

This work is dedicated to study the potential application of char byproducts obtained in the gasification of rice husk (RG char) and rice husk blended with corn cob (RCG char) as removal agents of two emergent aquatic contaminants: tetracycline and caffeine. The chars presented high ash contents (59.5–81.5%), being their mineral content mainly composed of silicon (as silica) and potassium. The samples presented a strong basic character, which was related to its higher mineral oxides content. RCG char presented better textural properties with a higher apparent surface area (144 m² g⁻¹) and higher micropore content (V ₘᵢcᵣₒ = 0.05 cm³ g⁻¹). The alkaline character of both chars promoted high ecotoxicity levels on their aqueous eluates; however, the ecotoxic behaviour was eliminated after pH correction. Adsorption experiments showed that RG char presented higher uptake capacity for both tetracycline (12.9 mg g⁻¹) and caffeine (8.0 mg g⁻¹), indicating that textural properties did not play a major role in the adsorption process. For tetracycline, the underlying adsorption mechanism was complexation or ion exchange reactions with the mineral elements of chars. The higher affinity of RG char to caffeine was associated with the higher alkaline character presented by this char.

The increase in demand for food due to the rapid population growth in recent years has raised the use of fertilizers, particularly phosphate salts. This fact has contributed to the excess amount of phosphorus species in aquatic systems. This is due to the leaching of these species present in the fertilizers applied to the soil to aquatic environments and may lead to eutrophication in these environments. Substances capable of interacting with the phosphate in the aquatic environment are promising for the reduction on the environmental impact. The humin, an insoluble fraction of humic material, has potential for phosphate retention, behaving like a chelating resin. Thus, the purpose of this research was to study the interaction between humin and phosphate. The equilibrium time between humin and phosphate was 15 min, where hydrogenionic potential (pH) 4.0 was the most effective in the interaction process. In this pH, the humin retained 33% of phosphate added. The complexing capacity of the humin-phosphate system was 11.53 mg g⁻¹. The adsorption studies indicated that the system follows a kinetic pseudo-second-order model. The Freundlich model was the most suitable to describe the phosphate adsorption process in humin. To evaluate the humin application in real systems, humin was added to the domestic wastewater. Sixteen percent of the total phosphate was adsorbed by the humin. Based on these results, humin has the potential to phosphate retention in domestic wastewater and could be used as a chelating resin minimizing environmental impact.

The purpose of this research was to evaluate the biodegradation extent of petroleum hydrocarbons by Phormidium ambiguum strain TISTR 8296 in the presence of inorganic nutrients and heavy metals as co-contaminants. In this context, waste motor oil served as a source of petroleum hydrocarbons. Strain TISTR 8296 grew actively with waste motor oil at 0.5–2.0% (v/v) concentrations and also exhibited good biodegradation potential at this concentration range. Meanwhile, its growth and biodegradation capacity fell down with increasing oil concentration to 3.0 and 4.0%. Strain TISTR 8296 adapted quickly to pH changes, showing good growth ability and biodegradation capability at a pH range of 4.0–9.0 with an acidic pH of 4.0 and 5.0 appearing to decelerate its biodegradation efficiency. The addition of PO₄ ³⁻ and NO₃ ⁻ exerted a strong stimulatory effect on growth and biodegradation efficiency, while a slight promoting effect was observed for NO₂ ⁻. By contrast, amendment of NH₄ ⁺ as well as heavy metals caused a substantial inhibitory effect on growth and biodegradation efficiency with NH₄ ⁺ and Mn(II) appearing to show a weak suppressing effect. GC-MS analyses indicated that strain TISTR 8296 could transform and degrade both aliphatic and aromatic compounds.

Volatilization is a critical pathway for herbicide loss from agricultural fields, and subsequently deposited downwind from the edge of the field. To better understand the volatilization process, field-scale turbulent volatilization fluxes of metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide) were quantified for 13 consecutive years using a combination of herbicide concentration profiles and eddy diffusivities derived from turbulent fluxes of heat and water vapor. Site location, type of herbicides, and agricultural management practices remained unchanged during this study in order to evaluate the effect of soil moisture on metolachlor volatilization. Twenty gravimetric surface soil moisture samples (0–5 cm) were collected immediately after herbicide application and then at 0430 hours each morning to determine the impact of surface moisture on herbicide volatilization. Five days after application, cumulative herbicide volatilization ranged from 5 to 63% of that applied for metolachlor. Metolachlor volatilization remained an important loss process more than 5 days after application when the soil surface was moist. Conversely, if the soil surface was dry, negligible volatilization occurred beyond 5 days. Furthermore, the total amount of metolachlor volatilized into the atmosphere increased exponentially with surface soil water content during application (r ² = 0.78). Metolachlor volatility was found to be governed largely by surface soil moisture.

Constructed wetlands are typical best management practices (BMPs) often used to reduce nutrient loads in streams. Evaluating the effectiveness of wetland design on nutrient removal is essential to assist watershed managers in optimal design of BMP dimensions and placement. In this study, we assess performance of two constructed wetland systems (comprising of nine wetlands) installed in downstream of Longhongjian Stream in Hangzhou City, China. These wetland systems are monitored and evaluated for their effects on nutrient removal, particularly TN, NO₃-N, TP, and PO₄-P. Based on wetland input–output metrics, removal efficiency (RE) is used to quantify wetland system. Results show that both wetland systems effectively removed nutrients, with RE as high as 45% of TN, 57% of NO₃-N, 78% of TP, and 86% of PO₄-P. In general, nutrient removal efficiency is seasonally dependent, with better removal efficiency occurring during warmer seasons than others. Macrophyte uptake is a primary removal process in these wetlands. We observe that more wetlands working concurrently can provide a greater level of control on nutrients in lotic environments. Wetland design parameters play an important role in removal of nutrients in streams. Increasing flow volume and surface area of wetland, designing curvilinear shoreline, and longer flow paths can be used as design criteria for wetland systems aimed at nutrient removal.

Irrigation with reclaimed water and soil amendment with sewage sludge are becoming common practices in arid and semiarid areas. When wastewater treatments do not efficiently remove all the contaminants, these contaminants can later end up in agricultural soils. These contaminated soils are a potential source of surface and groundwater pollution by leaching and runoff. In the present work, we assessed the behavior of alcohol sulfates (AS) in agricultural soil. For the experimental work, a tract of soil was irrigated with linear alcohol sulfates with 12–18 hydrocarbon chain and subsequently tested for AS concentration from November 2014 to July 2015. The highest concentrations of AS were found at the top layer of soil (29.80 to 6.23 mg kg⁻¹). The adsorption rate and the amount of surfactant adsorbed increased as the length of the hydrocarbon chain increases. AS homologues can leach up to 60 cm. A mathematical model was applied to predict the environmental behavior of AS in the agricultural soils studied. Disappearance rate constant (k) values for AS homologues were between −5.10·10⁻³ and −1.68·10⁻² h⁻¹, and average half-life values were between 37 and 135 h. Coefficients of determination (R ²) between 92.4 and 99.1% showed that the proposed model satisfactorily describes the experimental results. The present study provides a conceptual framework and essential parameters for predicting and understanding the environmental behavior of AS in agricultural soils. Graphical Abstract Behavior of alcohol sulfates in agricultural soils. A seasonal field study

Nano-enabled materials are produced at growing volumes which increases the likelihood of nanoparticles being released into the environment. Constructed wetlands (CWs) are likely to receive wastewater containing nanoparticles leaching from products during usage. Therefore, we investigate the retention of silver nanoparticles (Ag-NPs) in microcosms simulating CWs treating domestic wastewater. The effects of aeration and organic matter content on the Ag-NP removal efficiencies are studied in particular. CWs remove most of the Ag (80–90%) and the largest fraction of Ag is found in/on the biofilm. Detailed electron microscopy analyses suggest that Ag-NPs are transformed into Ag₂S in all microcosm experiments. The good correlation between total suspended solids (TSS) and the Ag concentration measured in the effluent indicates that Ag-NPs are bound to the solids in the effluent. Aeration of the microcosms does not affect the release of Ag-NPs from the systems but increasing organic matter leads to increased amounts of Ag passing the CWs, correlating with the increased release of TSS from the CWs. These results suggest that Ag-NPs are retained with the (suspended) solids in CWs and that the removal efficiency of TSS is an important factor determining the discharge of Ag-NPs from CWs.

Understanding the spatial distribution of PM₂.₅ concentration and its contributing environmental variables is critical to develop strategies of addressing adverse effects of the particulate pollution. In this study, a range of meteorological and land use factors were incorporated into a linear regression (LR) model and a logistic model-based regression (LMR) model to simulate the annual and winter PM₂.₅ concentrations. The vegetation cover, derived from a linear spectral unmixing analysis (LSUA), and the normalized difference built-up index (NDBI), were found to improve the goodness of fit of the models. The study shows that (1) both the LR and the LMR agree on the predicted spatial patterns of PM₂.₅ concentration and (2) the goodness of fit is higher for the models established based on the annual PM₂.₅ concentration than that based on the winter PM₂.₅. The modeling results show that higher PM₂.₅ concentration coincided with the major urban area for the annual average but focused on the suburban and rural areas for the winter. The methods introduced in this study can potentially be applied to similar regions in other developing countries.