The increasing focus on sustainability and the circular economy has brought waste-to-energy technologies to the forefront of renewable energy research. However, the environmental impacts and management of contaminants associated with these technologies remain critical issues. This article comprehensively reviews the environmental impacts of converting sewage sludge into energy and fertilizers, focusing on managing potential contaminants and assessing the implications and ecological risks. It also highlights the latest trends in waste-to-energy technologies, waste-to-soil amendment, and their integration into circular economy frameworks. The discussion encompasses challenges and opportunities in optimizing these processes in wastewater treatment plants to minimize pollutants and enhance sustainability. Addressing these challenges is essential for ensuring the long-term viability and acceptance of waste-to-energy solutions, making this topic highly relevant and timely.

Environmental contamination with microplastics and trace pharmaceuticals is an increasing ecological and health concern. This study aimed to investigate the effects of low-temperature cold plasma on polyethylene (PE) microplastic particles and to assess the potential for degradation of pharmaceuticals adsorbed onto their surfaces. Two types of PE samples were prepared: suspended in distilled water and in treated wastewater. All samples were exposed to cold plasma. In the second stage, PE particles were saturated with selected pharmaceuticals (diclofenac, sulfamethoxazole, trimethoprim) and then subjected to plasma treatment. Pharmaceutical concentrations were measured using high-performance liquid chromatography (HPLC). Particle morphology was analyzed via light microscopy (after Nile red staining) and scanning electron microscopy (SEM). The results showed that cold plasma treatment leads to agglomeration of PE particles, with the extent increasing with longer plasma exposure time. Pharmaceuticals adsorbed to the PE surface in the range of 20–70% of the applied dose. Cold plasma demonstrated the ability to remove pharmaceutical contaminants, particularly diclofenac (>98%), sulfamethoxazole (99.99%) and trimethoprim (>98%). These findings indicate that cold plasma has promising potential as a supportive technology for removing both microplastics and pharmaceutical residues from wastewater and aquatic environments.

The presence of microorganisms in water and wastewater is of significant importance for public health. Bacteria from the Enterobacteriaceae family, such as E. coli and Salmonella sp., pose a serious health risk. Their presence in treated wastewater and drinking water is absolutely unacceptable. The aim of the study was to evaluate the effectiveness of the bactericidal properties of low-temperature atmospheric plasma. The research involved treating water and wastewater samples containing suspended bacteria with plasma for varying durations(ranging from 5 seconds to 30 minutes). The plasma stream was generated using a pulsed atmospheric plasma arc, with air as the working gas. The samples contained both microorganisms that naturally occur in wastewater treatment plants and laboratory-cultured strains (in water). The results showed that low-temperature atmospheric plasma effectively eliminates microorganisms, although the required exposure time depends on microbial origin. Laboratory-cultured bacteria were eliminated within 30 seconds of plasma treatment, whereas naturally occurring wastewater microorganisms required up to 20 minutes for effective inactivation. The efficiency of the process depended on many factors such as contact time and microorganism type . In addition to its strong bactericidal and fungicidal properties, low-temperature atmospheric plasma also impacts physicochemical parameters , including pH and electrical conductivity. However, these changes tend to stabilize within 24 hours, particularly in wastewater samples. Overall, cold plasma presents a promising method for water and wastewater disinfection.

Reusing wastewater in agriculture is essential due to water scarcity but requires treatment technologies that preserve soil biological integrity. This study evaluated the impact of irrigation with wastewater treated by cold atmospheric plasma (CAP; 60 min exposure) on the soil microbiome during Festuca rubra L. and Sinapis alba L. cultivation. The experimental design included various CAP-wastewater dilutions evaluated in two replicates (n = 2), with microbial shifts assessed via 16S rRNA gene sequencing. CAP treatment reduced non-purgeable organic carbon (NPOC) while enriching the water with nitrogen, which significantly stimulated S. alba root growth. Metagenomic analysis confirmed high microbiome stability. Dominant phyla (Proteobacteria and Actinobacteriota) remained stable, and beta-diversity indices showed no statistically significant ecological shifts (R² = 0.420, p = 0.121). Furthermore, CAP-treated irrigation promoted beneficial taxa, specifically the genus Bacillus. These findings demonstrate that CAP wastewater treatment is a safe, environmentally responsible strategy for wastewater reclamation. It successfully supports nutrient cycling and agricultural production without compromising soil microbial homeostasis or health, offering a viable solution aligned with the principles of a circular economy.