Waste Disposal & Sustainable Energy最新文献

Municipal wastewater sludge can be pyrolyzed as biochars to better use nutrients and stabilize carbon compared with other typical technologies, such as landfill and incineration. However, sludge-derived biochars might contain large amounts of potentially toxic elements (PTEs), such as Zn, Cu, Cr, Ni, Pb, and As. The stability of PTEs in biochars might be improved by higher pyrolytic temperatures, which can be further improved by different modifications. Herein, PO₄-modification at 300 °C and Cl-modification at 700 °C were carried out, respectively, to enhance the stability of PTEs. Various leaching tests have been performed to assess the stability of PTEs in biochars, including the synthetic precipitation leaching procedure (SPLP), toxicity characteristic leaching procedure (TCLP), diethylenetriamine pentaacetate (DTPA) extraction, and in vitro simple bioaccessibility extraction test (SBET). The morphological structure, elemental mapping, and mineral formation of the pristine and modified biochars were studied by scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) and X-ray diffraction (XRD). Our results suggested that the leachability, mobility, plant-availability, and bioaccessibility of most PTEs were decreased by pyrolysis, yet the total contents of PTEs were elevated, especially at 700 °C. Generally, modification by phosphates and MgCl₂ enhanced the stability of PTEs in biochars. Nevertheless, it should be noted that higher bioaccessibility of PTEs was observed in biochars of P-modification than Cl-modification, which is associated with the dissolution of phosphate precipitates under acidic conditions (pH<2). Additionally, Cl-modification leads to higher plant-available Zn and Cu and bioaccessible Zn compared with the unmodified biochar produced at 700 °C.

Wastewater from the spray absorption treatment of sludge drying gas is a kind of refractory wastewater with poor biodegradability. In this study, the free radicals generated from the double dielectric barrier were  innovatively used for the degradation of simulated spray wastewater. The effects of residence time, input power, initial pH, aeration rate, and discharge area on the degradation rate and COD (chemical oxygen demand) removal rate were investigated. The optimal conditions were as follows: residence time=120 min, input power=170.0 W, initial pH=5.54, aeration rate=0.9 mL/min, discharge area=10.8 cm², and the initial concentrations of NH₃, H₂S, methanethiol, trimethylamine, benzene and toluene were 250, 250, 50, 50, 50 and 100 mg/L, respectively. Meanwhile, it was also found that hydroxyl radical (left( { cdot {text{OH}}} right)) played an important role in the degradation process.

Antibiotics and their metabolic byproducts are found in wastewater and natural water as a result of increased consumption, posing a major threat to humans and other living organisms. One of the most promising methods for their removal is adsorption using biochar because it offers excellent adsorption potential and is both affordable and environmentally beneficial. However, raw biochar frequently has a low adsorption capacity due to its limited pore structure and unfavorable surface characteristics. Biochar surface modifications using modifiers such as H₃PO₄, KOH, and NaOH have improved the surface area and thereby the adsorption capacity. Experimental methods for assessing the effectiveness and adsorption mechanism of modified biochar are costly and time-consuming. Density functional theory (DFT) was used to investigate the interfacial interactions and adsorption mechanism of tetracycline (TC), a widely used antibiotic for personal care and veterinary medication, on unmodified and modified biochar. The DFT calculations showed that the adsorption energy of TC on unmodified and modified biochar is in the following order: KOH-modified biochar (− 2.38 eV)<NaOH-modified biochar (− 2.20 eV)<unmodified biochar (− 1.56 eV)<H₃PO₄-modified biochar (5.48 eV). The lower adsorption energy is associated with a stronger and more stable interaction between the adsorbent and the contaminant. This suggests that the adsorption of TC on KOH-modified biochar is more prolific and stable compared to the other biochar. This study provides an understanding of the mechanism underlying the adsorption of TC by modified biochar and can be used as a guide to screen for biochar with promising adsorption potential prior to experimental efforts.

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Pharmaceutical is one of the noteworthy classes of emerging contaminants. These biologically active compounds pose a range of deleterious impacts on human health and the environment. This is attributed to their refractory behavior, poor biodegradability, and pseudopersistent nature. Their large-scale production by pharmaceutical industries and subsequent widespread utilization in hospitals, community health centers, and veterinary facilities, among others, have significantly increased the occurrence of pharmaceutical residues in various environmental compartments. Several technologies are currently being evaluated to eliminate pharmaceutical compounds (PCs) from aqueous environments. Among them, adsorption appears as the most viable treatment option because of its operational simplicity and low cost. Intensive research and development efforts are, therefore, currently underway to develop inexpensive adsorbents for the effective abatement of PCs. Although numerous adsorbents have been investigated for the removal of PCs in recent years, biochar-based adsorbents have garnered tremendous scientific attention to eliminate PCs from aqueous matrices because of their decent specific surface area, tunable surface chemistry, scalable production, and environmentally benign nature. This review, therefore, attempts to provide an overview of the latest progress in the application of biochar for the removal of PCs from wastewater. Additionally, the fundamental knowledge gaps in the domain knowledge are identified and novel strategic research guidelines are laid out to make further advances in this promising approach towards sustainable development.

Solid waste management is a severe challenge in India due to massive and rapid growth in waste generation rates, environmental difficulties, and financial constraints for proper treatment. Poorly managed municipal solid waste (MSW) has substantial negative consequences for society, including financial and aesthetic harm, contamination of natural resources, environmental pollution, and severe health danger. Both qualitative and quantitative factors are required to select the appropriate solid waste treatment and disposal technologies. Multi-Criteria decision-making tools helped in analyzing solid waste in terms of qualitative and quantitative factors. In this paper, seven criteria and their sub-criteria are selected for ranking solid waste treatment and disposal technology using fuzzy-analytic hierarchy process. The results showed that composting is the most suitable option for solid waste treatment and disposal technology, followed by refuse-derived fuel. The incineration and sanitary landfills are the least preferred  MSW management alternatives. The sensitivity analysis reveals a high consistency, robustness, and stability level.

Empty fruit bunch (EFB) is an industrial waste that is abundantly available in Malaysia. Traditionally, EFBs were burned and dumped on the plantation site, resulting in global warming pollution from methane and carbon dioxide. In this study, the EFB was transformed into a high-surface area of activated biochar through a microwave physicochemical approach involving the combination of steam followed by a hydroxide mixture for palm oil mill effluent (POME) treatment. It was found that BET (Brunauer–Emmett–Teller) surface area and total pore volume of activated biochar were 365.60 m²/g and 0.16 cm³/g, respectively. The surface morphology of activated biochar revealed the formation of well-developed pores that can potentially be used as adsorbents to treat POME. The removal efficiency of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of POME achieved 75%–55%, respectively. This study offers insight into the transformation of industrial waste into value-added products for sustainable environmental remediation.

Intensive land use has several detrimental effects on land function and imposes an undue burden on the environment. Continuous farming and pollution by heavy metals have negatively influenced many soils. Biochar is now gaining attention as a major research subject in the areas of agriculture, environment, and energy as an eco-friendly soil conditioner. The use of biochar for agricultural and environmental purposes has been widely studied and reviewed. Unfortunately, there are few reviews on biochar structures and other biochar uses. This review presents an overview of current developments in the effects of numerous biochar physicochemical properties and biochar uses, such as utilization as a soil microbial activity, contaminant adsorbent, ion exchange, soil amendment, gas storage and water retention. The physical, chemical and biological properties have been discussed following amendments to the soil and conditions of preparation. However, scientific observation and research are required to identify the negative effects of biochar in preparations and applications. It is envisaged that further in-depth studies of biochar amendment will lead to a deeper understanding of biochar's relationships with soils and that reviews of the negative impacts of biochar could reveal ways in which they might be mitigated.

Microwave steam pyrolysis (MSP) is an innovative thermochemical approach to converting biomass into high-quality biochar using steam to improve the dielectric heating of microwave radiation. Biochar shows high fixed carbon and carbon contents at a maximum temperature of 550 °C in 10 min. The MSP achieved a heating rate of 112 °C/min from 200 °C to 400 °C to produce biochar effectively. Furthermore, the thermal properties of biochar in microwave heating were investigated in this study to explore its potential as a microwave heat-absorbent material. Microwave is able to perform volumetric and controllable heating to the biochar. Moreover, biochar shows good microwave heat absorbency, storing and transferring heat effectively. The temperature profile of three different sizes of biochar was investigated to examine the efficiency of biochar in heat absorption from microwave radiation. It was found that the powder form of biochar showed a higher heat transfer rate of 40 °C/min and a low cooling rate of 7.5 °C/min. The presented results are useful for evaluating the application of biochar as a promising medium for heat storage systems.

Alum sludge is a typical by-product of drinking water treatment processes. Most sludge is disposed of at landfill sites, and such a disposal method may cause significant environmental concern due to its vast amount. This paper assessed the feasibility of reusing sludge as a supplementary cementitious material, which could efficiently exhaust stockpiled sludge. Specifically, the pozzolanic reactivity of sludge at different temperatures, the reaction mechanism of the sludge–cement binder, and the resistance of sludge-derived mortar to microbially induced corrosion were investigated. The obtained results indicated that 800 °C was the optimal calcination temperature for sludge. Mortar containing sludge up to 30% by weight showed comparable physical properties at a curing age of 90 days. Mortar with 10% cement replaced by sludge can significantly improve the resistance to biogenic corrosion due to the formation of Al-bearing phases with high resistance to acidic media, e.g., Ca₄Al₂O₇·xH₂O and strätlingite.

Graphical abstract

A novel selective catalytic reduction (SCR) catalyst with high catalytic activity on chloroaromatic organics at lower temperatures (160–180 ℃) is critical for municipal solid waste incineration (MSWI) plants. This study prepares a series of honeycomb-type VO_x/TiO₂ catalysts and finally develops a new low-temperature catalyst with high catalytic activity in eliminating chloroaromatic organics. Based on the conversion efficiency (CE) of 1,2-dichlorobenzene (1,2-DCB) and CO₂ selectivity, the optimal VO_x content of 4.06% (in weight) in VO_x/TiO₂ catalyst is first confirmed. By modifying CeO_x and WO_x, a novel honeycomb-type catalyst of VO_x–CeO_x–WO_x/TiO₂ achieves the highest CE (93.1%–93.6%) and CO₂ selectivity (40.9%–60.7%) at 150–200 ℃. It was found that the CeO_x and WO_x can improve the catalytic activity by enriching the surface content of V and O, increasing the proportion of V⁵⁺ and O_surf, enlarging the supply source of reactive oxygen species and their storage capacity, and accelerating the redox cycle of VO_x, CeO_x, WO_x, and reactive oxygen species. This study can guide the development of monolithic low-temperature catalysts with high catalytic activity in eliminating chloroaromatic organics in MSWI flue gas.