Eggshell ash was used as an adsorbent to remove phosphorus from wastewater. Adsorbent dose, initial phosphorus concentration, and contact time were investigated to determine the optimum conditions. Results indicate that 5 g of eggshell ash adsorbent with 1.5 mg L⁻¹ of initial phosphorus concentration removed over 90% of the phosphorus. When the temperature was increased, phosphorus removal potential also increased. Specific surface area, morphological features, and structure of the adsorbent were characterized by Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy with energy dispersive X-ray spectrometer (SEM-EDS), and X-ray diffraction (XRD). Results showed prominent calcium, magnesium, and phosphorus in the eggshell ash surface after adsorption. The elemental composition of eggshell ash surfaces before adsorption did not contain phosphorus, revealing that calcium carbonate-based eggshell ash was co-precipitated with calcium phosphate. The adsorption mechanism was studied by applying Langmuir and Freundlich isotherm models. Experimental data fit well with the Langmuir model, which indicates monolayer adsorption. Eggshell ash was also applied as an adsorbent in wastewater at Srinakharinwirot University dormitories, resulting in 80% phosphorus removal within 2 h. These findings indicated that eggshell ash could be applied as an adsorbent for phosphorus treatment and removal from domestic and industrial wastewater.

In this work, two recyclable phosphotungstic acid salts/reduced graphene oxides were successfully prepared. The prepared samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA), Raman spectroscopy, and photoluminescence spectroscopy (PL). The structure and catalytic performance of two composites were comparatively investigated, and the reduced graphene oxide mass ratios in K₃[PW₁₂O₄₀]/reduced graphene oxide (denoted as KPW-RGO) and (NH₄)₃[PW₁₂O₄₀]/reduced graphene oxide (denoted as NH₄PW-RGO) were optimized and their roles in them were explored. The results indicate that the Keggin structures of KPW and NH₄PW are still kept after being anchored on the RGO surface, but their morphologies change a lot in composites. The photocatalytic activities of KPW-3RGO (0.01989 min⁻¹) are 5.42 times than that of KPW (0.00367 min⁻¹), and NH₄PW-1RGO (0.0184 min⁻¹) is 2.26 times than that of NH₄PW (0.00814 min⁻¹). The enhanced photocatalytic activity is mainly ascribed to photo-induced interfacial charge transfer on the heterojunction between RGO and NH₄PW or KPW and strong adsorption ability of RGO towards MO. Moreover, NH₄PW-1RGO and KPW-3RGO had much better photocatalytic activity, good recyclable ability, and stability compared to HPW-RGO, which cannot be recycled.

Uncertainty in future availability of irrigation water and regulation of nutrient amount, management strategies for irrigation and nitrogen (N) are essential to maximize the crop productivity. To study the response of irrigation and N on water productivity and economic return of maize (Zea mays L.) grain yield, an experiment was conducted at Water Management Research Center, University of Agriculture Faisalabad, Pakistan in 2015 and 2016. Treatments included of full and three reduced levels of irrigation, with four rates of N fertilization. An empirical model was developed using observed grain yield for irrigation and N levels. Results from model and economic analysis showed that the N rates of 235, 229, 233, and 210 kg ha⁻¹ were the most economical optimum N rates to achieve the economic yield of 9321, 8937, 5748, and 3493 kg ha⁻¹ at 100%, 80%, 60%, and 40% irrigation levels, respectively. Economic optimum N rates were further explored to find out the optimum level of irrigation as a function of the total water applied using a quadratic equation. The results showed that 520 mm is the optimum level of irrigation for the entire growing season in 2015 and 2016. Results also revealed that yield is not significantly affected by reducing the irrigation from full irrigation to 80% of full irrigation. It is concluded from the study that the relationship between irrigation and N can be used for efficient management of irrigation and N and to reduce the losses of N to avoid the economic loss and environmental hazards. The empirical equation can help farmers to optimize irrigation and N to obtain maximum economic return in semi-arid regions with sandy loam soils.

The rice husk ash (RHA) was used as an alternative source of silica for the synthesis of the functionalized mesoporous material, which was used in the removal of the PAHs naphthalene (Nap), benzo[b]fluoranthene (B[b]F), benzo[k]fluoranthene (B[k]F), and benzo[a]pyrene (B[a]P) from aqueous media. The PABA-MCM-41 (RHA) was characterized using FTIR, TGA, SAXS, and N₂ adsorption–desorption analyses. Removal experiments were performed to determine the initial concentrations, individual adsorption in comparison with the mixture of the PAHs, PABA-MCM-41 (RHA) amount, pH, time, and temperature, and the results obtained were statistically analyzed. The PABA-MCM-41 (RHA) presented the SBET, VT, and DBJH values of 438 m² g⁻¹, 0.41 cm³ g⁻¹, and 3.59 nm, respectively, and good thermal stability. The qₑ values found in the kinetic equilibrium for the PAHs mixture followed increasing order: Nap < B[a] P < B[k]F < B[b]F, with removal percentages of 89.08 ± 0.00, 93.85 ± 0.28, 94.54 ± 0.10, and 97.80 ± 0.05%, respectively. Graphical abstract

Better cotton is introduced with the aim of a reduction in the use of environmentally detrimental farm inputs in order to attain sustainable cotton production. The present study is designed to assess the environmental and economic effects of better cotton in Pakistan using panel data comprising of two cropping seasons, 2015 and 2016. Panel methods were used in the present study. Findings show that better cotton increases the gross margin by 37% and yield by 9%, whereas it results in decreasing seed rate by 6%, fertilizers by 7%, pesticides by 7%, and irrigation by 14%. Since better cotton involves more labor use due to higher yield, labor increases by 3%. The study concludes that better cotton is more economically and environmentally sustainable than conventional cotton. The study suggests that public private partnership will be a good strategy to diffuse better cotton technologies among the farming communities.

A growing body of research has investigated the vital effects of urban greening. However, the green space on campus, also recognized as an important element of urban greening and providing many benefits to college students, has gained very limited attention. In developing China, after nearly 20 years of campus construction climax, the speed of expansion has dropped significantly and the focus of a sustainable and optimized green campus has emerged. Improving the accessibility, availability, and attractiveness is a control determining if the green spaces can realize their values. Therefore, this study, taking a case, aims to explore and better understand students’ usage conditions, perceptions, and demands about campus green spaces. On Yijin campus in Hangzhou, China, through the questionnaire among 590 students, and accessibility analysis based on Space syntax theory, we have revealed that the negative usage condition of green spaces: most students rarely or occasionally visit the green space, and the visit time is concentrated in the afternoon and after class but rarely in the morning. Besides, students’ gender and growth surroundings have little influence on the perception of campus green space, but the plant configuration, seasonal color richness, and facilities required at different spaces will affect. In addition, the ranking of accessibility analyzed by Space syntax theory is similar to campus convenience considered by students. In the conclusions, suggestions are made about how to fulfill students’ requirements and improve the attractiveness and accessibility of campus green spaces so that they may inform to the growth of emerging colleges and universities in other cities and countries undergoing campus construction climax.

Most sulfonamides, widely used around the world, are excreted via feces and urine along with their metabolites in humans and animals. Therefore, understanding the potential removal pathway of sulfonamides and their metabolites in wastewater treatment systems is of importance. The occurrence and fate of four sulfonamides and their acetyl metabolites in wastewater and sludge in a biological aerated filter in Xiamen city were evaluated. Six of the target compounds were detected in wastewater, but only parent compounds were detected in sludge. The highest concentration in wastewater was acetyl-sulfamethoxazole (Ac-SMZ) with a concentration of 75.2 ng/L. Removal efficiency and mass load in wastewater treatment systems were calculated. In terms of the overall removal efficiency, they ranged from 24.4 to 100%. The removal efficiencies of sulfamerazine (SM1), sulfamethazine (SM2), and sulfadiazine (SD) were up to 100% while N-acetyl sulfamerazine (Ac-SM1) showed the lowest removal efficiency. Biodegradation was the dominant remove pathway according to the mass balance analysis while SD and SM2 were sludge adsorption. The results can provide an insight into the fate of target sulfonamides in BAF systems and provide data to assess their potential ecological risks.

Energy is a foundation for a city to create economic wealth, satisfy people’s desires, and achieve benefits. However, the increasing mismatch between energy supply and demand and the worsening of environmental pollution have highlighted the importance of improving urban energy performance, so the number of studies related to urban energy performance evaluation is increasing. Based on describing the authors, numbers, regional sources, and themes of these studies, this paper reviews and analyzes the conceptions, evaluation indicators, influencing factors, evaluation methods, and evaluation systems related to urban energy performance. Most countries have expressed concern about this topic. Researchers in China, Belgium, and the USA have had the most achievements and collaborations. The concept of urban energy performance further extends to a comprehensive performance. It is measured based on an input-output process. In addition to the original evaluation indicators, new desirable outputs and undesirable outputs are included. Industrial structure, energy price, population density, home car ownership, climate factors, Gini coefficient, health expenditure level, and unemployment rate are regarded as influencing factors. Therefore, a new framework of evaluation indicators and influencing factors is constructed. Stochastic frontier analysis (SFA) and data envelopment analysis (DEA) are commonly used to evaluate. With changes in conceptions, evaluation indicators, and influencing factors, the evaluation method should rather focus on measuring multiple input-output variables, determining the evaluation results and the impacts of factors at the same analysis stage, and highlighting policy orientations. As an important management tool, the evaluation system would continue to be studied and developed.

In this study, the alginate-based biosorbent produced from seaweed Sargassum sp. was used in biosorption of Ni²⁺ and Cu²⁺ ions from synthetic solutions and real electroplating effluents. Biosorption kinetics, isotherms, pH effect, thermodynamic parameters, and sorption/desorption cycles were also evaluated. Kinetic studies show the sorption equilibrium can be obtained within 180 min for Ni²⁺ ions and 360 min for Cu²⁺ ions, and the adsorption kinetics data are well described by the pseudo-second order and diffusion in spherical adsorbents. Langmuir model can be well used to describe the biosorption isotherm data. The maximum sorption capacity (qₘₐₓ) and Langmuir constant (b) were up to 1.147 mmol g⁻¹ and 1.139 L mmol⁻¹ for Ni²⁺ ions and 1.640 mmol g⁻¹ and 4.645 L mmol⁻¹ for Cu²⁺ ions. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) showed that the biosorption of Ni²⁺ and Cu²⁺ ions are predominantly a chemical phenomenon of endothermic nature, favorable, and spontaneous at the temperature ranges of 293–313 K. Partial desorption of the Ni²⁺ and Cu²⁺ ions on the biosorbent was achieved using acidic and saline eluents, allowing the biosorbent to be used in new sorption/desorption cycles. EDX analysis suggests an ion exchange mechanism between calcium ions on the biosorbent and target metals. Biosorption of Ni²⁺ and Cu²⁺ from real electroplating effluents with high concentrations of light metals becomes highly competitive, decreasing the amount of Ni²⁺ and Cu²⁺ ions biosorbed due to the ionic strength effect.

In industrial sites, historically contaminated by coal tar (abandoned coking and manufactured gas plants), other families of organic pollutants than the 16 PAHs (polycyclic aromatic hydrocarbons) classified by the US-EPA can occur and induce potential risk for groundwater resources. Polar PACs (polycyclic aromatic compounds), especially oxygenated and nitrogenated PACs (O-PACs and N-PACs), are present in the initial pollution and can also be generated over time (i.e., O-PACs). Their aqueous solubilities are much greater than those of the PAHs. For these reasons, we need to increase our knowledge on polar PACs in order to better predict their behavior and the potential on-site risk. Batch leaching tests were carried out under various conditions of temperature, ionic strength, and availability of pollutants to determine the mechanisms and key parameters controlling their release. The results show a release of low-molecular-weight PAHs and polar PACs mainly by dissolution, while higher molecular weight PAHs are mainly released in association with colloids. Aging mainly controls the former mechanism, and ionic strength mainly controls the latter. Temperature increased both dissolution and colloidal mobilization. The Raoult law predicts the PAC equilibrium concentration for soils presenting high pollutant availability, but this law overestimates PAC concentration in aged soils (low pollutant availability). This is mainly due to limitation of PAC diffusion within coal-tar particles with aging. The most soluble PACs (especially polar PACs) are the most sensitive to aging. For better prediction of the PAC behavior in soils and water resources management, aging needs to be taken into account.