This overview presents the updated physicochemical characteristics of thallium and its stable isotopes (²⁰⁵Tl/²⁰³Tl) in the context of their occurrence and fate in abiotic and biotic systems. This also deals with the thallium behavior in geochemical interactions in and between different environmental compartments and describes its natural (geogenic) and industrial sources. The particular emphasis is placed on some extreme environments, including acid mine drainage areas where oxidation processes of Tl-bearing pyrite and other sulfides lead to very high concentrations of this metal in reactive acidic waters. Many geochemical studies have also employed stable thallium isotopes to reconstruct redox conditions in different environmental systems, to fingerprint relative pollution source strengths and to evaluate mobility of this element and its geochemical interactions in the mineral-water and soil–plant systems. This is the reason why this overview also highlights the growing potential of stable Tl isotopes in solving different geologic and environmental issues.

Roof runoff is generally perceived as a relatively clean source of water and is therefore often discharged or used without any treatment. Available data from literature however show that roof runoff can be contaminated by a wide range of (micro)pollutants, and in concentrations often exceeding surface water quality and/or drinking water standards. In this review, information on more than 100 contaminants, including trace metals, polycyclic aromatic hydrocarbons, pesticides, phthalates, alkylphenols and alkylphenolethoxylates, is summarized and a meta-analysis provides quantitative proof that roof runoff is a major contributor to stormwater quality deterioration. The two prime sources of roof runoff contamination are leaching from roofing materials and atmospheric deposition. A detailed discussion on material-pollutant relationships is given and a benchmarking method is presented which ranks roofing materials based on their runoff quality. Treated wood roofing and metallic rooftops (copper and zinc) were found to have the highest impact on water quality. Atmospheric deposition is also discussed in detail and includes a summary on the concentration levels in deposition for more than 400 pollutants such as trace metals, pesticides and polycyclic aromatic hydrocarbons. As a conclusion, it can be argued that the general perception on roof runoff quality is inaccurate and that its quality aspects should not be overlooked when roof runoff is used or discharged.

Agrivoltaics (APV) combine crops with solar photovoltaics (PV) on the same land area to provide sustainability benefits across land, energy and water systems (Parkinson and Hunt in Environ Sci Technol Lett 7:525–531, 2020). This innovative system is among the most developing techniques in agriculture that attract significant researches attention in the past ten years. The objective of this mini review is to present and summarize the recent studies on the effect of PV shading on crop cultivation (open field system and greenhouses integrated PV panels), with the aim to identify a correlation between the growth indicators, crop quality (antioxidant activity, sugar content, etc.) and the characteristics of PV installation (shading degree). The alteration of microclimate parameters such as solar radiation, air temperature, humidity and soil temperature under the PV panels was highlighted. Moreover, impact of APV shading on irrigation and water saving and economic feasibility of APV was further discussed. Our main findings are that (1) the reduction in solar radiation is the main changed factor underneath the APV canopy where a reduction of more than 40% the solar radiation due to the presence of the PV panels was observed. (2) Agrivoltaic systems (PV greenhouse or ground) with cover ratio equal or lower than 25% did not show significant effects on plant growth and quality. (3) Inhibitory effects on crops growth was observed with coverage ratio of 50 to 100% except for strawberry and spinach. (4) Water use efficiency for some crops species in dry land climate was greater in the APV system. Given the findings, the research seems promising enough to support APV practices that limit PV panel shading to be lower than 25% to avoid affecting crop growth, assumed to be the priority of an agricultural operation.

Lichens are widely distributed symbiotic organisms producing unique chemical compounds with interesting biological properties. The secondary metabolites of lichens, which are tailored to live in the most extreme conditions, are highly attractive for the pharmaceutical and cosmetic industries. The need for continuing research in the identification of new metabolites, the studies of their potential and mechanisms of action as well as their large scale production requires effective and greener extraction processes. This review presents a survey of the conventional and advanced extraction technologies reported for obtaining lichen bioactives. Due to the complex lichen morphology, the influence of different strategies causing the cell degradation for aiding in the extraction of solutes are discussed.

Crop contamination with organic pollutants is an important food safety concern. Since organic pollutants are highly toxic, human consumption of contaminated crops can harm human health. Thus, understanding the mechanisms of how organic pollutants are accumulated in crop plants can aid the development of strategies for safer crop production. It is well known that the Cucurbitaceae family accumulates organic pollutants in its fruits at high concentrations. Previous studies have described the organic pollutant-uptake mechanisms of the Cucurbitaceae family. However, an integrated understanding of organic pollutant uptake by Cucurbitaceae is still lacking. In this review, we discuss the uptake mechanisms from the perspective of plant molecular biology. We clearly show that major latex-like proteins identified from the Cucurbitaceae family play a crucial role in the uptake of organic pollutants. This is the first review to describe the mechanisms underlying the accumulation of organic pollutants in the Cucurbitaceae family across the entire uptake pathway.

In order to address freshwater scarcity, seawater desalination technologies have been widely studied in recent years. However, the disposal of desalination brine which contains an even higher concentration of salts than seawater can potentially damage the surrounding environment. Therefore, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. Three resources that can be recovered have been studied in this paper, which are minerals, freshwater and energy. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques. The water recovery techniques employ mainly membrane/thermal integrated hybrid processes, while the energy recovery techniques such as pressure retarded osmosis (PRO) and reverse electrodialysis (RED) utilize the salinity gradient energy (SGE) to generate energy. The valuable mineral products have also been reviewed in this paper in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na₂SO₄), lithium salts (LiCl, Li₂CO₃), magnesium salts (struvite, Mg(OH)₂, MgSO₄, MgO), calcium salts (CaSO₄, CaCO₃) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.

The number of studies dealing with tertiary ozonation to remove trace organic contaminants (TrOCs) in effluents originating from wastewater treatment plants (WWTPs) is increasing due to the need for upgrading the WWTPs overall performance. To follow-up TrOCs removal in real-time during ozone-based treatment, online surrogate measurements are necessary, of which mainly spectroscopic surrogates (i.e. UV–VIS absorbance and fluorescence) are the emerging techniques in literature. This paper summarizes and reflects on the state-of-the-art as retrieved from more than 100 peer-reviewed studies published between January 2007 and December 2020 and dealing with (1) surrogate correlation models for the prediction of TrOCs removal in secondary effluent and (2) control strategies to adjust the ozone dose during (full-scale) operation. Next to the flow and load proportional ozone dosing strategies, controlling the ozone dose solely based on the characteristics of the effluent entering the ozonation unit, also a differential control strategy based on the change in characteristics due to ozonation of the WWTP effluent is highlighted. The latter seems the best option as flow and load proportional ozone dosing do not consider the amount and/or reactivity of the matrix constituents. The presence of organic and inorganic scavengers of ozone and radicals in the effluent matrix has a significant impact on the TrOCs removal efficiency. This effluent quality can differ in time and between WWTPs, hence the surrogate correlation models should be widely applicable. At the end of the review, recommendations are made for future research and implementation of an effective control strategy for (full-scale) applications.

Volatile fatty acids (VFAs) are key platform chemicals used in a multitude of industries including chemicals, pharmaceuticals, food and agriculture. The current route for VFA production is petrochemical based. VFAs can be biologically produced using organic wastes as substrate, therefore directly contributing to a sustainable economy. This process is commonly known as acidogenic fermentation (AF). This review explores the current research on the development of AF processes optimized for VFA production. Three process steps are considered: feedstock pretreatment, fermentation, and primary product recovery with a focus on in situ recovery. Pretreatment is required for recalcitrant feedstocks, especially lignocellulosic substrates. Different pretreatment techniques for AF application have not been studied in depth. The operational parameters of AF (temperature, pH, hydraulic retention time, substrate concentration, etc.) highly influence microbial activity, VFA yields and product distribution. Optimum conditions are ultimately dependent on substrate composition, however, there is indication that certain operational ranges are beneficial for most feedstocks. VFA recovery and purification are necessary for chemical applications. When recovery is performed in situ, it can help relieve product-induced inhibition and keep alkalinity levels stable enabling further waste degradation. Many techniques have been tested, but none are directly compatible with the fermentation conditions tested. Bio-VFAs have the potential to aid in developing a circular economy, but further development is required. Processes need to be developed with the product market in mind, considering both process integration and systematic process optimization.