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The rapid economic development in China places a large demand for energy, and as a result, thermal power plants in China are producing an enormous amount of coal fly ash (CFA) which causes severe environmental pollution. This paper briefly describes the current production and utilization status of CFA in China and identifies the challenges confronting sustainable CFA utilization as the Chinese economy is being transformed. These issues include a regional imbalance in supply and demand, reducing demand in the real estate industry as well as stricter laws for environmental protection. Viable directions for future CFA utilization are proposed, for example, production of CFA-based ceramic tiles, recovery of elemental resources, agricultural melioration, treatment of wastewater and flue gas, and production of high-volume CFA concretes. This paper has some guiding significance for sustainable and cleaner utilization of CFA in China and even worldwide. Graphical abstract

Countries face a serious problem due to the generation and management of higher volumes of waste. Large-scale production of waste has promoted the establishment of various operations (collection, transport, treatment and disposal) for its management. When a MSW management system is implemented, it can generate different impacts or consequences (internal or external impacts). Generally, external impacts (social and environmental impacts) are not reflected in MSW economic analysis or taken into consideration in decision-making processes in regard to MSW management options. For this reason, the objective of this paper is present a methodology with which is viable to conduct the technical-economic analysis of municipal solid waste management projects based on social cost-benefit analysis (sCBA) as it considers internal and external impacts. Its main objectives are to determine the total benefits (the difference between revenues and costs) generated by a project and to reduce uncertainty and risk of investing in particular MSW management system. Finally, a case study was carried out to verify the validity of the methodology through analysis and valuation of different impacts of a light packaging waste and bulky waste facility. Through the application of the methodology, it has been possible to visualize that this facility is viable operationally (B P  = 42.94 €/ton) as economically (B T  = 87.73 €/ton).

Banana is one of the most important agricultural products of Ecuador. It relies on intensive monoculture cropping systems with a large volume of standing biomass and large amounts of residual biomass that can be used for carbon sequestration. This study was performed (1) to quantify the yearly residual biomass generation, (2) to quantify the carbon stock of standing banana biomass, (3) to estimate the carbon sequestration potential by using the residual biomass generated yearly, and (4) to propose a biomass prediction model for banana crops in Ecuador. The study was conducted between March 2018 and January 2019 in the three main banana-producing provinces of Ecuador (Los Ríos, Guayas, and El Oro). Samples of rachis, pseudostem, leaves, and flowers from 36 banana plants of the variety Musa AAA Cavendish were taken for laboratory tests. Physical measurements such as height, circumferences, number of leaves, and weights were determined for the 36 plants. Results showed an average residue-to-product ratio of 3.79 and a country’s yearly biomass generation of 2.65 Mt on a dry basis. The carbon stock of the standing biomass was estimated as 4.18 ± 1.02 Mg/ha, 5.44 ± 0.96 Mg/ha, and 5.13 ± 1.11 Mg/ha for Los Ríos, Guayas, and El Oro, respectively. The estimated carbon abatement capacity of the residual biomass is 3.92 MtCO 2 /year. Three biomass estimation models were developed in Python®, using the data collected in this study and least squares fitting for exponential models of the form: Y = AX n + C . The models showed good prediction capacity for Ecuadorian banana plants, with R 2 up to 0.85. It is expected that this study could serve as the basis for studies on developing sustainable conversion processes of banana residual biomass.

As water scarcity has become a serious global issue, seawater reverse osmosis (SWRO) is considered as a promising technique to expand traditional water supplies. However, the reject brine from SWRO systems is still a major environmental concern. In this research, the monovalent selective electrodialysis (S-ED) was used to separate and recover one of the primary components, i.e., sodium chloride, from the SWRO brine, thereby avoiding the direct discharge of the brine and achieving the brine valorization. The permselectivity of selective ion-exchange membranes (IEMs) was elucidated by comparing with the standard IEMs in structure-property via membrane characterization techniques. Results indicated that the permselectivity of Selemion CSO membrane was attributed to the positive-charged layer with a low sulfonate/ammonium ratio of 1.28. Whereas the permselectivity of Selemion ASV membrane resulted from the highly cross-linked layer, according to the similar content of the fixed quaternary amines and the shift of the C‑N absorption peak. In addition, the effects of the current density and temperature on the membrane performance were studied, including permselectivity ( P Mg 2 + Na + and P SO 4 2 − Cl − ), Na + recovery, and specific energy consumption ( E SEC ). Finally, the NaCl-rich brine with the total dissolved solid (TDS) value of 167.5 ± 3.3 g/L was obtained using SWRO brine with the initial TDS of 76.8 g/L. The Na + /Mg 2+ mass ratio of the concentrate was 222.4, compared with the initial value of 9.7 in SWRO brine.

The alarming increase in the average temperature of the planet due to the massive emission of greenhouse gases has stimulated the introduction of electric vehicles (EV), given transport sector is responsible for more than 25% of the total global CO 2 emissions. EV penetration will substantially increase electricity demand and, therefore, an optimization of the EV recharging scenario is needed to make full use of the existing electricity generation system without upgrading requirements. In this paper, a methodology based on the use of the temporal valleys in the daily electricity demand is developed for EV recharge, avoiding the peak demand hours to minimize the impact on the grid. The methodology assumes three different strategies for the recharge activities: home, public buildings, and electrical stations. It has been applied to the case of Spain in the year 2030, assuming three different scenarios for the growth of the total fleet: low, medium, and high. For each of them, three different levels for the EV penetration by the year 2030 are considered: 25%, 50%, and 75%, respectively. Only light electric vehicles (LEV), cars and motorcycles, are taken into account given the fact that batteries are not yet able to provide the full autonomy desired by heavy vehicles. Moreover, heavy vehicles have different travel uses that should be separately considered. Results for the fraction of the total recharge to be made in each of the different recharge modes are deduced with indication of the time intervals to be used in each of them. For the higher penetration scenario, 75% of the total park, an almost flat electricity demand curve is obtained. Studies are made for working days and for non-working days.

Herein we synthesized a novel structure of mesoporous TiO 2 decorated on 1D ZnO nanorods for environmental remediation. The effect of mesoporous TiO 2 over 1D nanorods were investigated. The phase transitions of nanocomposite were confirmed by powder diffraction analysis. The morphological investigation of synthesized TiO 2 /ZnO catalyst revealed that the TiO 2 are in porous in nature which covered the surface of 1D nanorods. The size of mesoporous TiO 2 nanoparticles was about 10–15 nm. The chemical composition and elemental mapping results clearly evident that the presence of ZnO and TiO 2 is distributed uniformly on ZnO nanorods. TiO 2 /ZnO nanocomposite shows enhanced activity which degrades in 14 min under visible light irradiation. TiO 2 /ZnO catalyst with 5 wt % exhibited the high photocatalytic activity (0.1882 min −1 ). It is proposed that a synergistic interaction between ZnO and TiO 2 leads to a charge separation which leads to the enhanced activity.

There are some peculiarities in instrumental observation over snow cover characteristics in Belarus and those of neighboring countries. Maximum snow water equivalent varies around Belarus from 107 mm in Brest to 207 mm in Novogrudok. It differs significantly in terms of years, which is proved by high values of variation coefficients ( C v ). Maximums are observed in the south and south-west of Belarus. Minimum values are typical for central and north-eastern parts of Belarus with a stable snow cover. There is a distinct correlation between snow water equivalent and the stations’ altitude. We observe a space-time variability of SWE in Belarus’ river catchments. Changes in SWE are of cyclic nature. They correlate with current climate fluctuations. In certain parts of Belarus, there is a trend in reduction of SWE up to 8–10 mm in 10 years. This research determines the amount of water that forms spring flood runoff in the catchments of Belarus’ big rivers. Possible daily snow melting is calculated in the research as well. It reaches 26 mm in its maximum and 5–6 mm on average. The amount of river runoff water, which is formed within Belarus, is 58 km 3 . The amount of melt water is 11 km 3 , which accounts for 19%. In particularly extreme years, melt water reaches 29 km 3 , which is over a half of all annual river runoff.

Bench-scale and pilot-scale experiments were conducted in an outdoor environment to study the ability of some plant species in dewatering of sewage sludge collected from biological activated sludge treatment. In the bench-scale experiments, four types of plants were tested, including water hyacinth ( Eichhornia crassipes ), common reed ( Phragmites austuralis ), Samar ( Cyperus alopecuroides ), and El Nesila ( Panicum echinochloa ). Sludge dewatering in the plant reactors was compared with that in the control reactors (no plants). The bench-scale experiments were conducted in reactors with capacities of 17 L. All plants showed a growth in the sewage sludge matrix. High dewatering efficiencies of sewage sludge were obtained with the use of each type of plant, as compared with those in the controls. Among other plants tested in the current study, water hyacinth proved to have the highest dewatering efficiency and was selected for further testing in a pilot-scale experiment. Two identical drying beds were constructed as a pilot-scale, each with its own multi-layered underdrainage system. The plants were added to one of the beds while the other bed served as a control. The pilot study showed that the use of water hyacinth in conventional sludge drying beds can triple the sludge dewatering capacity of these beds. In addition, the quality of the dewatered sludge was also improved compared with that found in conventional drying beds.

Bisphenol A is a well-known endocrine-disrupting compound that is commonly detected in industrial effluents and wastewater treatment plants. It is extensively used in the production of polycarbonate and epoxy resins. It is linked to serious environmental pollution and negative effects in humans and living microorganisms, i.e., malfunction of the endocrine system through imitating or blocking natural hormones. Several bisphenol A remediation techniques have been investigated over the last decades, with many of them gradually emerging as effective ones. This article summarizes the most recent findings and progress of the highly effective and widely accepted bisphenol A elimination/degradation techniques, such as membrane separation, adsorption, advanced oxidation processes, and biodegradation, based on their beneficial and optimistic aspects, namely, ease of operation, excellent bisphenol A removal performance, and cost-effectiveness. The operational specifications affecting the elimination efficiency and concerning mechanisms of the processes are summarized. The prominent remarks from this article are as follows. (i) Reverse osmosis, membrane distillation, and nanofiltration-based membrane separation processes particularly eliminated ~100% of bisphenol A from the contaminated aqueous solutions; however, the durability and force resistance frame integrity of the membranes need to be increased. Combining the membrane separation techniques with other oxidation/biodegradation techniques can lower the major issues of each technique; i.e., integrating the membrane separation and electrochemical oxidation can reduce the fouling and mass transfer limitation issues of both the techniques, respectively. (ii) Numerous conventional and nonconventional adsorbents can effectively eliminate bisphenol A from effluents; however, the higher adsorbability and rapid adsorption rates need to be addressed. (iii) Mono/bimetal ion-loaded catalysts could significantly degrade bisphenol A via photocatalysis; however, variation in reaction rates, catalyst deactivation owing to fouling, complex structures, intricate fabrication methods, and uncontrollable morphology of metal-based nanocatalysts remain the core issues. (iv) Numerous bacterial species/fungi/fungal enzymes and microalgae can effectively biodegrade bisphenol A with comparatively higher efficiencies. Finally, prominent remarks and perspectives from this paper provide perception and future investigation directions to address existing problems of bisphenol A-contaminated wastewater treatment.

The world is facing environmental pollution and is in an alarming situation due to industrialization and urbanization. Especially, industrial wastewater discharge is causing serious pollution in the environment (water, soil, and air) and has become a challenge for researchers and scientists. Wastewater contains heavy metals like Cu, Ni, Cr, Pb, and Ar and causes toxicity in living beings and the environment. In this review, the sources of heavy metals and their toxicological effects on the environment have been reviewed. Various remediation techniques such as reverse osmosis, chemical precipitation, and ultrafiltration are being used for the treatment of wastewater, but still are limited in their efficiencies, residues, cost, and versatility. In this study, the most promising wastewater treatment technique, the physic-chemical technique, has been reviewed along with its working mechanism and efficiency. Further, the pros and cons of this technique and sub-techniques have also been reviewed to provide a basic understanding to beginners and a pathway to experts in the selection of better techniques.