Plastic waste is one of the biggest environmental threats since it is produced in large quantities and seriously harms both the environment and human beings. Plastic garbage generated on land frequently finds its way into water bodies, killing aquatic life and overloading the marine ecosystem. The main causes of this enormous mass of plastic garbage are a lack of technical expertise in handling hazardous waste, inadequate infrastructure development for recycling and recovery, and, most importantly, a lack of knowledge of the laws and regulations. The severity of plastic pollution harms the ecology as a whole. In this paper, a thorough investigation of the production of plastic garbage and its impact on humans and the environment are explored in terms of source identification concerning industrialized and developing nations. The article presents a thorough analysis of the current waste-to-energy and product conversion strategies. Additionally, this study clarifies sustainable waste management practices and pinpoints the major obstacles to implementing practical solutions to reduce the harmful effects of plastic trash.

This paper presents the application of sodium aluminate, directly or after small adjustments in concentration and purity, in some other valuable intermediary products. Sodium aluminate is an intermediary product in Bayer technology applied by Alum SA Tulcea production of alumina and alumina products. Mainly, sodium aluminate is a carrier of aluminum hydroxide between important manufacturing stages in the Bayer process, bauxite processing, and aluminum hydroxide crystallization. After a short investigation of the uses of sodium aluminate, it was decided to choose and study the possibility of converting this secondary product into ecological material for the treatment of natural or industrial wastewater. Actually, on the market, products similar to sodium aluminate from Alum SA Tulcea provide treated waters with high purity and reasonable quality, excellent coagulation rates, rapid flotation, and sedimentation, and in addition, significant side effects, such as excellent removal of phosphorus and silica from treated water. Treatments do not require lime or hydroxide to control alkalinity, and chemical sludge remains at a minimum volume and mass. The test performed with sodium aluminate from Alum SA Tulcea was comparable with other tests with Al2(SO4)3 and FeCl3. The maximum removal yields of global organic load expressed by chemical oxygen demand (COD) and biochemical oxygen demand (BOD5), chromium (Cr VI), and total suspended solids (TSS) were: 83%COD, 71% BOD5, 99.7% Cr VI and 93% TSS.

Rapid industrial development causes environmental contamination of land, water, and air with heavy metals which pose a significant threat to human survival. This study aims to remove antimony from wastewater using tea leaves and tea fiber (Camellia sinensis) as an adsorbent to curb the environmental decay posed by industrialization. The FTIR study presents significant vibration frequencies that correspond to –OH, C-H, and C=O in both the leaves and fibers which impact the adsorption. The adsorption study was performed by the batch adsorption method, varying different parameters including pH, adsorbent dosage, temperature, initial concentration, and contact time to find best-suited conditions for the removal of antimony from aqueous media. The results show an equilibrium condition at pH 5 and 30 minutes for both tea leaves and fibers whereas for tea leaves the equilibrium concentration was obtained at a dosage of 2g, and 3g for the fiber. From the adsorption model, the sorption of antimony by tea leaves follows the Langmuir model (R2 = 0.783), whereas that of tea fiber follows Freundlich (R2 = 0.827). From Kinetic studies, the sorption of antimony by both plant parts follows second-order kinetics with approximate R2 values of 1. From the adsorption capacity, it is no exaggeration to consider tea leaves and fibers as an excellent biosorbent for the sorption of antimony.

A continuous population and industrialization growth have enhanced the production of chemical compounds as well as their structural chemical diversification. Unfortunately, they have become an increasing burden for the environmental sustainability and biodiversity. The need for producing and using environmentally friendly products become increasingly evident in the current context of environmental concerns. It is crucial to develop new products and technologies that reduce their overall harmful environmental impact and promote its sustainability. In this study, the citrus peels waste was transformed into a potential antibacterial and antifungal extract by hydrodistillation. The efficacy of orange peels hydro distillation process in obtaining plant extracts was improved by a pre-enzyme-assisted extraction step. Enzymes such as cellulase and pectinase improved the breakdown of cellulose and pectin structures, which led to an increased extraction yield of bioactive compounds and antimicrobial activity.

The present study was carried out to evaluate the efficiency of a municipal wastewater treatment plant (WWTP) that uses biological treatment processes with activated sludge. The WWTP monitoring was carried out at the end of 2023, after the expansion and modernization stage, achieved during the period 2018-2023. The wastewater samples were collected from three important points of the wastewater treatment plant for four weeks, between October and November 2023. The physical-chemical parameters analyzed were: pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), volatile suspended solids (VSS), total nitrogen (TN), ammonia nitrogen (N-NH4+), nitrates (N-NO3-), total phosphorus (TP). The obtained results were beneficial for checking the performance parameters of the sewage treatment plant.

The investigation of photochemical degradation of chemical components in pharmaceutical wastewater by use of ultraviolet (UV) irradiation, UV in combination with sodium hypochlorite (UV/NaOCl), and Fenton’s reagent (UV/H2O2/Fe2+) was performed. Objective of this study was to determine the best alternative to the conventional wastewater treatment or pre- / post-treatment in combination with biological treatment to one of the four effluent source outlets. The effect of the advanced oxidation treatments provided varying degree of COD reduction for all four effluents. The results showed UV/H2O2/ Fe2+ treatments provided maximum chemical oxygen demand (COD) reduction of the anaerobic system outlet effluent. The combination of UV/H2O2/ Fe2+ (750 mg/L FeSO4+7500 mg/L H2O2) provided reduction in COD up to 75% upon three-hour UV exposure. The initial effluent COD was about 22000 mgO2/L and the treated effluent BOD5 /COD ratio was 0.50 showing greater amenability to biological processes. Sodium hypochlorite dosages between 3000 and 10000 mg/L achieved the results with little variation as compared to UV/H2O2/ Fe2+. Additionally, comparison was made of the UV exposure time required to reach the maximum reduction of COD value and the necessary effective oxidant dose to achieve the desired COD reduction, which could provide predictive model for the treatment of wastewater processes.

This paper presents the remediation of polluted soils with chlorinated pesticides (HCH, DDX) by zerovalent iron technology (ZVI). We performed soil remediation tests with iron (two grinding sizes), three doses, with iron and acetic acid (two doses for each dose of iron and for each type of grinding iron size). In the study was applied 99 tests (samples). The diminishing of HCH and DDX concentrations in treated samples is more significant with the increasing of iron and acetic acid doses, for the same contact time: 99% HCH and 91% DDX for large iron particles and 95% HCH and 82% DDX for small iron particles.

The atmosphere of urban localities is polluted by a number of pollutants emitted from industrial activities, car traffic and the activities of individual households. This study presents an assessment of the air pollution level in two cities (Galati and Tulcea), both of them being situated in eastern Romania. The correlation between air pollution and pollution sources and also between the causes that lead to high levels of air pollution in the studied cities were analyzed. Three air quality monitoring points were selected in the two cities, with the following pollutants: total suspended dust, PM10 dust, nitrogen dioxide, sulfur dioxide, and carbon monoxide. The pollution in the monitoring points was mainly influenced by the emissions from road traffic, the burning of methane gas for the production of heating agent, the industrial and agricultural activities performed in the monitoring area. Based on the result, it can be concluded that in the smaller city, Tulcea, the air pollution level was lower than in the Galat municipality, mainly due to the lower intensity of road traffic and polluting activities, but also the geographical positioning, close to the Danube Delta, a large area with green space, which presents a smaller pollution contribution. In areas characterized by lower population densities, specifically in small cities, there is a correlation between reduced population density and lower levels of atmospheric pollution.