Organic waste management is an important concern for both industries and communities. Proper management is crucial for various reasons, such as reducing greenhouse gas emissions, promoting sustainability, and improving public health. Composted manure is a valuable source of nutrients and organic matter that can be used as a soil amendment in agriculture. Some important benefits of using composted manure in agriculture include: improves soil fertility, enhances soil structure, reduces soil erosion, suppresses plant diseases, and reduces reliance on synthetic fertilizers. Composted manure represents one of the most effective methods of organic waste valorization. Its macronutrients and micronutrients content can increase plant yield, without any reported negative or toxic effects on the soil and plants at various application rates. However, improper use of farmyard manure can have negative effects on the environment, such as air pollution from greenhouse gas emissions, soil acidification, and contamination of surface water and groundwater by nitrates and phosphates. The properties of the soil, including aeration, density, porosity, pH, water retention capacity, etc., can be improved by the structure and composition of manure. The slow-release source of nutrients provided by the nutrient content of compost can determine proper plants growth. However, it is crucial to use compost in moderation and regularly test soil to prevent excessive nutrient application, which can have adverse effects on plants and the environment.

In the present study, heavy metal concentrations (Cu, Zn, Pb, As) from former industrial areas were analyzed in soil and the plant species Phragmites Australis (common reed), a plant species found in shallow river banks. The objectives of the study were to determine the accumulation, translocation, and enrichment capacity of soils and plants (root, stem, leaf, and flower) with heavy metals, and to evaluate the potential of the plant species Phragmites Australis (common reed) in the phytoremediation of heavy-metal-polluted soils. The sediments and plants investigated were particularly rich in heavy metals such as Cu, Zn, Pb, and As, and Pb and Zn concentrations were determined to be of phytotoxic level. The highest transfer coefficient of heavy metals from the soil to the root of the plant species Phragmites Australis (common reed) was for the metals Cu and Zn. The transfer of heavy metals from the root of the plant species Phragmites Australis (common reed) to the aerial part of the plant was lowest for Cu. A very low enrichment factor value was recorded for the metal As. The mobility of heavy metals was generally higher from the sediment to the plant roots, with the order of the average transfer coefficient values being Cu > Zn > Pb > As for all three areas analyzed. The translocation of heavy metals from the root to the upper aerial part of the plant was in the form of As > Pb > Zn > Cu in the plant species Phragmites australis (common reed). According to the average values obtained for the three coefficients, the accumulation, translocation, and enrichment capacity of heavy metals in soil and the plant species Phragmites Australis (common reed), it can be stated that the plant species Phragmites Australis (common reed) is very suitable for use in the process of soil remediation by phytoremediation.

In the current global context of the natural resource crisis and the need for environmental protection, sustainable economy strategies are becoming imperative. These strategies aim to optimize wastewater treatment processes, with a particular focus on the removal of biological and chemical quality indicators such as BOD, COD and TSS. By developing and implementing advanced technologies and effective resource management methods, this article explores ways the industry can reduce its negative environmental impact and contribute to a sustainable future. The proposed research investigates the impact of 40% ferric chloride on the purification processes of domestic wastewater using biological contactors. The study evaluates the efficiency of pollutant removal through measurements such as biochemical oxygen demand over 5 days (BOD), chemical oxygen demand (COD) and total suspended solids (TSS). Through the statistical analysis of the obtained results, the research identifies opportunities for innovative strategies in the sustainable economy, thus contributing to the optimization of purification process efficiency and significantly reducing pollution’s impact on the environment. In conclusion, this research highlights the use of 40% ferric chloride as an effective and sustainable method to improve the efficiency of wastewater treatment processes, focusing on BOD, COD and TSS removal. The findings demonstrate significant pollutant reduction and environmental impact mitigation, underlining its potential for Sustainable Development Goals. The study supports innovative strategies for optimizing water quality and recommends further evaluation of long-term impacts on human and environmental health.

In the context of ever-increasing water demand and pressures on natural resources, efficient water management is becoming a major priority for contemporary society. Since nitrogen and phosphorus, as essential nutrients, play a crucial role in the dynamics of aquatic ecosystems, but excessive concentrations can cause eutrophication of receptors, they need to be eliminated as completely as possible while respecting the principles of a sustainable economy, efficiency, and quality. In this study, the efficiency of optimizing the technological process of wastewater treatment by dosing FeCl₃ 40% solution to reduce nitrogen and phosphorus concentrations in treated water was investigated. The results obtained revealed that the use of this type of flocculant resulted in an increase in the efficiency of the removal process of total N by an average of 35.57 mg/L and total P by an average of 3.89 mg/L. Also, the results, which are interpreted by mathematical modeling, show that the optimal use of FeCl₃ 40% solution leads to a significant reduction in pollutants, well below the maximum permitted values (according to Romanian regulations, the maximum value for total phosphorus is 2 mg/L and total nitrogen is 15 mg/L for localities with a population between 10,000 and 100,000 inhabitants). This technical approach not only improves the quality of treated water but also contributes to minimizing the impact on aquatic ecosystems and promotes the principles of circular economy in water resource management. By optimizing the dosage of FeCl₃ 40% solution in the treatment process, the efficiency of the coagulation and flocculation processes is maximized, thus providing a viable and sustainable solution for reducing the environmental impact of nitrogen and phosphorus and promoting responsible and sustainable water resource management.

This study highlighted the potential for greywater reuse in irrigation of olive trees. An experimental field was set up in a household of Soukra, located northwest of Tunis City, to test the performance of vertical greywater treatment. Treated greywater (TGW) was used for the irrigation of two olive tree varieties (Chétoui and Picholine) during five years. The results show high performance of the treatment, as reflected by the good quality of TGW. The chemical and biological parameters of this TGW are under the threshold values of the Tunisian Norms of Treated Wastewaters for agriculture use (NT106.03). The BOD₅ average decreased from 160.44 mg O₂/L for UGW (Untreated greywater) to 15.32 mg O₂/L for TGW. The COD average recorded a high reduction from 290.15 mg O₂/L for UGW to 49.58 mg O₂/L for TGW. The average removal rate was 90% for BOD₅ and 83% for COD, proving the high performance of the treatment. The average increases in height, diameter, and olive production are significantly high for the two varieties of olive trees irrigated with treated greywater (ITGW), compared to those not irrigated and under natural conditions. In this regard, the present study has shown promising potentials for the reuse of TGW in agriculture.

Passenger cars differ in their levels of emitted noise and mileage, which can have a negative impact on the environment and humans. This was confirmed by the results of this study on the noise levels generated by passenger cars that have the same parameters, or are of one type. The loudest place in the tested vehicles turned out to be the combustion engine compartment, with the average noise level exceeding 90 dB and exhibiting a noticeable, significant increase alongside an increase in the mileage of the vehicles. This value of noise intensity is classified as dangerous for the human body. As a result of the conducted tests, it can be concluded that an engine cover is an important element in damping the sounds emitted by an internal combustion engine after the use of an aluminum heat shield to increase noise absorption. In the future, the environmental problem of noise emission from cars can be solved by encouraging the use of quieter, electric vehicles.