An overview of the recent research works and trends in the design and fabrication of microfluidic devices and microfluidics-integrated biosensors for pollution analysis and monitoring of environmental contaminants is presented in this paper. In alignment with the tendency in miniaturization and integration into “lab on a chip” devices to reduce the use of reagents, energy, and implicit processing costs, the most common and newest materials used in the fabrication of microfluidic devices and microfluidics-integrated sensors and biosensors, the advantages and disadvantages of materials, fabrication methods, and the detection methods used for microfluidic environmental analysis are synthesized and evaluated.

Given the energy crisis and climate change due to pollution, and given that the largest emissions of greenhouse gases are produced by the energy industry, we must turn our attention to the efficient use of solar energy, which is the cleanest and most abundant of all renewable energies. In this paper, based on an analysis of the specialized literature, we studied the effect of dust accumulation on the surface of photovoltaic modules on some performance characteristics and on the efficiency of these panels and modules compared to the efficiency of clean modules. We analyzed the cause of dust accumulation and the influence of the tilt angles of the photovoltaic panels on the dust deposition rate. We highlighted the influence of atmospheric temperature, solar radiation, wind speed, and relative humidity depending on the density of the dust deposited on the surface of the photovoltaic panel, and we found a decrease in the efficiency of the panel based on the increase in dust density for slightly high values of solar radiation, wind speed, and relative humidity. We highlighted the reduction in CO₂ emissions by replacing electricity from fossil fuels with solar energy. The efficient use of solar energy is a solution for the decarbonization of the energy sector.

Considering the increase in the amount of sewage sludge as a result of the development of urbanization, and the pollution of the environment through the storage of this sludge, the objective of this paper is to analyze the effects of the action of different doses of urban sewage sludge as a fertilizer for agricultural soil. Starting from the legislative recommendations regarding the use of urban sewage sludge in agriculture, we analyzed the sludge resulting from the sewage treatment plant in the Municipality of Alexandria, Romania. This sewage treatment plant, with two technological lines of water and sludge treatment, produces urban sewage sludge without pathogenic bacteria. We highlighted that by applying sewage sludge doses of 15 t/ha and 25 t/ha to agricultural soils, on which we planted soybean and wheat crops. We obtained high yields, and the concentration of heavy metals in the roots, stems and grains of soybean and wheat crops did not exceed the maximum standard limits allowed. Having a high content of organic matter and nutrients important for plants such as nitrogen, ammonium, potassium and zinc, sewage sludge has improved the fertility, physical, chemical and biological properties of the soil, and is able to be used as a fertilizer for degraded soils.

In the current context of the increase in the amount of municipal solid waste as a result of the development of urbanization, in this paper we have analyzed the impact of the use of fly ash obtained from the incineration of municipal solid waste in agriculture on the development of plants as an improver of acidic soils due to the nutrients it contains. We presented ash treatment methods to reduce the content of heavy metals and salts. Based on the studies in the literature, it was found that by adding certain concentrations of fly ash to degraded soils, the quality, porosity, and texture of the soil are improved; the yield of certain crops increases; the water retention capacity of the soil and soil aeration are improved; the density of the soil bulk; the compactness of the soil is reduced; the pH value is optimized; the electrical conductivity of the soil is increased; the crust formation is reduced; and it provides micronutrients to the soil. In the context of the circular economy, by using fly ash as an organic fertilizer in agriculture, the amount of chemical fertilizers harmful to agricultural crops is reduced, the problem of ash storage is solved, and thus it no longer pollutes the environment.

This paper presents an analysis of the literature that studies the possibility of sewage sludge being used in the cement industry to reduce carbon dioxide emissions from cement production and thus solve the problem of disposing of sewage sludge so that it is no longer stored, avoiding soil pollution with heavy metals, and reducing pressure on the environment. The ash of sewage sludge is a good pozzolanic material, because when it is finely ground, it can be used as a partial substitute for Portland cement. This reduces waste storage costs. Sewage sludge ash was mixed with cement, and it was analyzed to determine whether the paste obtained could be used as a raw material in the cement industry. The presented results are on the hydration characteristics of the sewage sludge ash, the compressive strength of the cement determined after different days, the workability of the cement, and the porosity of the cement paste and the ash.

Polycyclic aromatic hydrocarbons (PAHs) are considered hazardous pollutants due to their negative impact on the environment and human health. PAHs can accumulate and be retained in the soil, so PAH pollution is a worldwide problem. This review paper highlights the sources of PAH soil pollution, factors affecting the bioavailability of PAHs in soil, and soil bioremediation methods, as well as the advantages and limitations of the application of these methods. Aspects regarding the impact of the application of surfactants are presented in order to obtain good bioavailability during PAH bioremediation. Bioremediation techniques of soil polluted by these hydrocarbons are addressed: phytoremediation, rhizoremediation, composting, vermiremediation, micoremediation, and electrokinetic bioremediation of PAH-polluted soils. A comprehensive overview of bioremediation technologies for PAH-polluted soils is needed so that the right soil remediation technology is chosen. It has been observed the bioremediation of contaminated soils through rhizoremediation proved to be an effective process, the future of organic pollutants in interaction with plants and microbes must be researched. Vermiremediation, electrokinetic bioremediation, and microcomposting are effective processes for treating soils in situ. Phytoremediation is a sustainable and ecological method of PAH depollution. It improves soil fertility by releasing different organic matter in the soil, and it can be applied on a large scale.