Wastewater Treatment Plants (WWTPs) play a crucial role in maintaining ecological balance, a cornerstone of environmental health for thriving biodiversity and undisturbed natural processes. This balance is crucial for the sustainability of ecosystems, directly influencing human health, biodiversity, and the overall quality of our natural environment. WWTPs contribute to this equilibrium by efficiently removing pollutants and harmful substances from wastewater, thus averting the degradation of water bodies that are essential for numerous ecological processes. WWTPs encompass multiple stages of wastewater and sludge treatment and are significant energy consumers globally, especially in secondary treatment, particularly the activated sludge method which is the most common method. With an upcoming directive from the European Union aiming to reduce energy consumption in WWTPs, this paper focuses on a literature review examining global practices implemented across all stages of WWTP treatment processes. It summarizes the key points of each study, focusing primarily on the outcomes of each application. This document concludes with an in-depth review of each study and provides general conclusions for each group of studies. The objective is to identify methods that have effectively reduced energy consumption and enhanced the overall energy efficiency of WWTPs. The main conclusions indicate that the studies encompass a wide range of applications that achieve significant reductions in energy consumption. However, additional testing of these applications in more diverse operating environments through trials could further enhance their reliability and increase acceptance among WWTP operators.

Growing concerns over public health and environmental safety have intensified the focus on minimizing harmful disinfection byproducts (DBPs) in water treatment. Traditional methods like chlorination, while effective against pathogens, often lead to the formation of DBPs, which pose significant risks. This paper explores alternative strategies to reducing DBP formation while ensuring effective disinfection. The methodology involved a bibliographic study conducted through the Scopus platform, using appropriate keywords. The initial search yielded 9576 articles from the period 2020 to 2024. The key approaches identified include advanced oxidation processes (AOPs) such as UV/H₂O₂ and ozone, which mineralize natural organic matter (NOM) and minimize chemical use and sludge production; membrane-based filtration systems, like reverse osmosis, effectively removing contaminants without chemical disinfectants, reducing DBP risks. Furthermore, conventional processes, such as coagulation and filtration, serve as crucial pretreatment steps to lower NOM levels before disinfection. Additionally, optimizing chlorine dosing, using non-chlorine disinfectants, and employing post-disinfection methods like adsorption and biological filtration further mitigate DBP formation. Finally, the integration of artificial intelligence in process optimization is emerging as a promising tool for enhancing treatment efficiency and safety. This research contributes to the development of safer, more sustainable water treatment solutions, addressing regulatory demands and public health objectives.

This study presents an overview about the arsenic (As) contamination and its sources in two European countries. Arsenic is a highly toxic element in its inorganic form and it is carcinogenic to human seven in low concentrations. The occurrence of As in surface water, stream and marine waters, groundwater, bottled water, sediment, soil, mines, and seafood, its environmental origin, and its impacts on human health are discussed. The classes of Geoaccumulation Index for As in Greece ranges from practically uncontaminated to extremely contaminated, and in Cyprus varies between practically uncontaminated and heavily contaminated. In many cases, the As contamination reaches very high concentrations and the impacts may be crucial for the human health and ecosystems. Physicochemical properties, regional climate and geological setting are controlling the occurrence and transport of As. In Greece and Cyprus, the geology, lithology, and ore-deposits are the most important factors for the variation of As contents in water, soil, and sediment. The dominant As species are also determined by the location and the redox conditions. The findings of this paper may be useful for scientists and stakeholders monitoring the studied areas and applying measures for protection of the human and terrestrial ecological receptors (plants, avian, mammals).

Rainwater Harvesting system (RWHs) can be considered as an alternative water resource in the era of the climate crisis. This research aims to study the effectiveness of a RWHs for domestic non-potable use and the water demand of the community in a Mediterranean site (Chios island, Greece). A water balance model is applied to simulate the behavior of a rainwater tank and calculate the daily water savings. The analysis correlates rainwater tank capacity, catchment area and population. The operation of the rainwater collection system has been calculated for seven years. In order to assess the investment risk regarding the application of the RWHs, the financial ratio of PayBack (PB) period was determined. The multifaceted character of Rainwater Harvesting (RWH) practice in the three-dimensional concept of sustainability is discussed. This study concludes that RWH contributes to the greening of society, dealing with water scarcity in urban areas.

Natural pesticides are in the forefront of interest as ecofriendly alternatives to their synthetic ancestors. In the present study, we evaluated the nematicidal activity of seven Greek Lamiaceae species and discerned among principal components for activity according to GC-MS analysis. Care was taken that all botanicals used were easily prepared without employing elaborate procedures and toxic solvents. We established the in vitro EC₅₀ values of the hydrosols of Origanum vulgare L., Mentha piperita L., and Melissa officinalis L. and the water extracts of Origanum vulgare, Τhymus vulgaris L., Thymus citriodorus (Schreb), Rosmarinus officinalis (Spenn), and Ocimum basilicum L. against Meloidogyne javanica (Treub) and Meloidogyne incognita (Kofoid & White). Furthermore, we amended nematode-infested soil with powdered leaves and flowers of O. vulgare to assess for efficacy. According to in vitro studies, the most active botanical preparations against both nematode species was O. vulgare, as regards its hydrosol and water extract. Thymus citriodorus was proved very potent against M. javanica, provoking 100% paralysis at 4 μL/mL after 96 h, but was only nematostatic against M. incognita since the second-stage juveniles (J2s) recovered movement 48 h after immersion in test solutions. Interestingly, O. vulgare was also proved nematicidal in pot bioassays but at test concentrations over 50 g/kg was phytotoxic for tomato plants. According to GC-MS analysis, the principal components sustaining activity of O. vulgare are carvacrol and thymol. The nematicidal activity of O. vulgare seems promising in the forms of essential oil leftovers (i.e., hydrosol), self-prepared water extract that can be of consideration as α “basic substance”, and powder for soil amendment.

This article delves into the enduring self-governing nature of a traditional irrigation system in a rural community in Greece through the lens of the social–ecological system (SES) framework. The aim is to analyze the variables and interactions that have sustained this community-based governance structure over a century. This study underscores the critical role of social capital, where social networks and effective communication facilitate self-governance in the management of this common pool resource. The findings reveal how actors coordinate social and physical capital when performing daily activities, enabling them to collectively solve common dilemmas. By examining the institutional arrangements and operational dynamics of the irrigation system, the study illuminates the community-led social processes that drive its sustainability. This analysis enhances the understanding of the importance of integrating social and physical capital in governance through collective action to achieve resilience. This study provides insights into alternative pathways for building resilience and discusses an irrigation system as a communal autonomous space that prioritizes social equity, democratic decision-making, and social–ecological contacts.