Most river sediments are contaminated with organic and inorganic pollutants and cause significant environmental damage and health risks. This research is evaluated an in-situ sediment remediation method using ultrasound and ozone nanobubbles to remove organic and inorganic chemicals in contaminated sediments. Contaminated sediment is prepared by mixing synthetic fine sediment with an organic (p-terphenyl) and an inorganic chemical (chromium). The prepared contaminated sediment is treated with ultrasound and ozone nanobubbles under different operating conditions. For the samples with the maximum initial concentration of 4211 mg/kg Cr and 1875 mg/kg p-terphenyl, average removal efficiencies are 71% and 60%, respectively, with 240 min of sonication with 2-min pulses, whereas 97.5% and 91.5% removal efficiencies are obtained for the same, respectively, as a single contaminant in the sediment. For the same maximum concentrations, the highest removal of p-terphenyl is 82.7% with 127.2 J/ml high energy density, and for Cr, it is 77.1% using the highest number of the treatment cycle and ozone usage with 78.75/ml energy density. The Cr highest removal efficiency of 87.2% is recorded with the reduced initial concentration of 1227 mg/kg with the highest treatment cycles. The Cr removal efficiency depends on the availability of oxidizing agents and the number of washing cycles of sediments, whereas P-terphenyl degradation is most likely influenced by the combined effects of oxidation and ultrasound-assisted pyrolysis and combustion of organics.

We compared the carapace shape and thickness as well as the energy density of Ovalipes trimaculatus inhabiting areas comprising a gradient of marine pollution: high, moderate and undetected, in the Nuevo gulf (Patagonia Argentina). The carapace shape was evaluated by means of individual asymmetry scores (=fluctuating asymmetry) whereas the carapace thickness was assessed by measuring the carapace dry weight. The energy density was analyzed through its negative relationship with water content in muscle tissue. The individual asymmetry scores as well as the percentage of water content in muscle tissue were proportional to the marine pollution gradient, whereas the carapaces thickness did not differ among sampling sites. Our results are consistent with previous findings and demonstrate the direct effect of marine pollution on other taxa different from gastropods, cephalopods and polyplacophora and add to long-standing concerns about detrimental effects caused by marine pollution on the benthic community of the Nuevo gulf.

This study evaluated the effects of the temperature and pressure used when compacting banana leaves on viscoelastic properties and briquette quality. Banana leaves with 12.4% of humidity were milled at two ranges of average particle size. The briquetting was carried out in a cylinder-piston device coupled to a universal mechanical test machine, under different compacting temperatures (30 and 120 °C) and pressures (20, 40 and 60 MPa). Several parameters, including compacting module, porosity index, final density, critical density, compacting energy, compression ratio, higher heating value, and energy density, were investigated. The banana leaf particles smaller than 1.7 mm performed better during compaction, with low compacting resistance. Temperature showed less influence on final density than pressure. The increase of pressure contributed to decreasing the compacting module and to achieving denser briquettes. It was not necessary to apply high temperature to obtain briquettes with high final density and energy density. The optimum briquetting process parameters identified can be used to produce briquettes from banana leaves at an industrial scale with an extruder. Briquetting adds value to banana leaf waste and reduces environmental pollution.

The concept of this paper was to explore the comparative advantage of polymer composite in the formation of a critical part of electrodes, separators, and electrolytes. These parts largely determine the overall performance of new evolving supercapacitors (SC) as against many other existing storage devices. Polymer materials are reputed for their low weight and life-cycle flexibility which makes supercapacitors unique in their functions. In this paper, application and classification of SCs were undertaken to take into consideration the peculiarities of polymer composite suitable for each class of SCs identified in this work. Part of the rationale of this review paper was to bridge the existing gap identified in many storage devices using salient properties inherent in light-weight materials. This paper also discussed the potential threats to SCs, which require further research works. It is expected that this paper would assist other researchers in evolving SCs devoid of low cell voltages, lower energy density, and reduction of production cost.

The effect of char addition on the digestion of animal by-products was evaluated as a way for enhancing the performance of the process. Two different types of carbonaceous materials were tested as carbon conductive elements to improve biological treatment. One was derived from a torrefaction process intended for increasing the energy density of lignocellulosic biomass, and the other was obtained from a hydrothermal carbonisation process. In this research, batch digestion systems of animal waste samples were evaluated at a volatile solid (VS) ratio of 1:1 inoculum–substrate (where the content of the substrate in the system was 1.69 ± 0.2 g). The system reported a baseline methane yield of 380 L CH₄ kg VS⁻¹ which increased on average to 470 L CH₄ kg VS⁻¹ following to the addition of char. The presence of char allowed a faster degradation of the lipid and protein material, reducing inhibitory interactions. The use of Fourier transformed infrared spectroscopy was applied for elucidating the predetermination of the degradation process and bring an insight into the greater degradation potential attained when carbon materials are used for enhancing microbial performance.

Based on the wire-tube dielectric barrier discharge (DBD) reactor, this study investigated the effects of the materials and configurations of high-voltage pole, insulating medium layer and grounding pole on the discharge power, power factor, and ozone concentration of the reactor, respectively. The DBD reactor had the best discharge power and power factor and the highest ozone concentration when the high-voltage pole was the linear copper wire, the insulating medium material was quartz tube, and the grounding pole was the copper wire winding. Based on this optimized DBD reactor, the effect of energy density on the treatment efficiency and ozone concentration of H₂S exhaust gas was further investigated. At the energy density of 2143.1 J L⁻¹, the H₂S exhaust gas treatment efficiency reached 100% and the residual ozone concentration decreased to 0 g m⁻³.

The production of pellets from residual biomass generated monocropping by Brazilian agribusiness is an environmentally and economically interesting alternative in view of the growing demand for clean, low-cost, and efficient energy. In this way, pellets were produced with sugarcane bagasse and coffee processing residues, in different proportions with charcoal fines, aiming to improve the energy properties and add value to the residual biomass. The pellets had their properties compared to the commercial quality standard. Artificial neural networks and multivariate statistical models were used to validate the best treatments for biofuel production. The obtained pellets presented the minimum characteristics required by DIN EN 14961–6. However, the sugarcane bagasse biomass distinguished itself for use in energy pellets, more specifically, the treatment with 20% of fine charcoal because of its higher net calorific value (17.85 MJ·kg⁻¹) and energy density (13.30 GJ·m⁻³), achieving the characteristics required for type A pellets in commercial standards. The statistical techniques were efficient and grouped the treatments with similar properties, as well as validated the sugarcane biomass mixed with charcoal fines for pellet production. Thus, these results demonstrate that waste charcoal fines mixed with agro-industrial biomass have great potential to integrate the production chain for energy generation.

Ultraviolet (UV) disinfection of wastewater is adversely affected by the presence of particle-associated bacteria. Earlier studies have shown that disrupting these particles by ultrasonic cavitation can enhance the UV disinfection of wastewater. However, the use of ultrasound as a pretreatment technology for UV disinfection is hindered by its high energy demand. In this work, the addition of several organic solutes, including 1-propanol, 1-hexanol, and pentyl acetate, to promote the cavitation process and to improve the breakage of wastewater particles was examined. It was found that the enhancement in the cavitation and the breakage efficiency of particles was positively related to the hydrophobicity of surfactant. In addition, particle breakage was a function of the concentration of surfactant as well as the delivered ultrasound energy density. Sonication of wastewater samples containing small amounts of 1-hexanol (16 mM) or pentyl acetate (12 mM) increased the UV disinfection efficiency and decreased the required UV dose to achieve the disinfection target by a factor of more than 2.5.

Briquetting is a technology with the potential to convert agricultural wastes into solid biofuels with improved handling, transport, storage, and energy efficiency characteristics. It is important to study the variables related to the briquetting process and the raw material because these parameters can affect the quality of the final product. Thus, the objective of this study was to investigate the influence of particle size on the physico-mechanical and energy properties of briquettes produced with coffee husks. Three particle size fractions were obtained: particles larger than 1.8 mm, in the range of 1.8–1.2 mm, and smaller than 1.2 mm. The coffee husk briquettes were prepared in a densification system at 120 °C and 15 MPa for 15 min. The physical, mechanical, and energy characteristics such as apparent density, volumetric expansion, compressive strength, abrasion resistance, and energy density were determined. A combustibility test was also carried out. The results showed that particle size influenced the apparent density, compressive strength, and energy density of the briquettes. However, there was no significant difference in the volumetric expansion or abrasion resistance of the densified products among the treatments. In general, the briquettes made with particles smaller than 1.2 mm had better physico-mechanical and energy characteristics.

This paper provides an assessment of energy density and energy efficiency and creates an important indicator of environmental performance. This article applied two mathematical models and econometric techniques to obtain detailed and specific results. The DEA and the non-normative account aggregation mean a collective aggregation to form a mathematical aggregation tool to create an environmental index for the BRICS countries (Brazil, Russia, India, China, and South Africa) based on available data from 2011 to 2016. The advantage of the proposed approach is to manage the irregularities of the data and follow the desired properties of the index number. The current paper is relevant for the broad scope of construction, the environmental index, and the evolution of the rankings of countries based on multiple indicators. Our results indicate that Brazil and Russia have the highest values of the Environmental Performance Index, which range between 67.44 and 60.70, respectively. India has a minimum value of 30.57 of the environmental index. The analysis shows that Brazil, Russia, and South Africa have the best scores and that these countries have the best results, while China and India also have the best results. This study can help form a valuable political tool for the development and development of the country’s politics.