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Biosolids have been traditionally used as a beneficial resource in the agricultural industry. However, contaminants of emerging concern (CECs) threaten their reuse due to concerns of toxicity, bioaccumulation, and increased regulations on acceptable CEC concentrations in biosolids. The thermal treatment of biosolids has the potential to destroy/mineralize these contaminants as well as transform the biosolids into valuable biochar. However, the thermal processing of biosolids is highly energy intensive due to the energy costs associated with drying biosolids to the required moisture content for thermal processing. This article performs a brief review of the drying of biosolids from a physical and theoretical viewpoint. It also provides an overview of pyrolysis and gasification. It explains the impact that moisture can have on both the degradation of CECs and the products that can be obtained through the thermal treatment of biosolids. Additionally, model-based, lab-based, and pilot-scale examples of integrated drying and thermal treatment processes are reviewed. Key challenges, such as the need for co-pyrolysis and co-gasification, as well as the impact of biosolids composition on energetic viability, are identified.

Antibiotic Resistance Genes (ARGs) are contaminants of emerging concern with marked potential to impact public and environmental health. This review focusses on factors that influence the presence, abundance, and dissemination of ARGs within Wastewater Treatment Plants (WWTPs) and associated effluents. Antibiotic-Resistant Bacteria (ARB) and ARGs have been detected in the influent and the effluent of WWTPs worldwide. Different levels of wastewater treatment (primary, secondary, and tertiary) show different degrees of removal efficiency of ARGs, with further differences being observed when ARGs are captured as intracellular or extracellular forms. Furthermore, routinely used molecular methodologies such as quantitative polymerase chain reaction or whole genome sequencing may also vary in resistome identification and in quantifying ARG removal efficiencies from WWTP effluents. Additionally, we provide an overview of the One Health risk assessment framework, as well as future strategies on how WWTPs can be assessed for environmental and public health impact.

Macroalgae have many potential applications and can make important contributions to sustainability and circular economy objectives. Macroalgae are degradable high-moisture biomaterials and drying is a necessary step, but drying is an energy and capital-intensive part of their production process. This study presents convective drying curves for commercially promising fresh and saltwater species (U. ohnoi and O. intermedium), obtained over a range of industry-relevant drying gas velocities (0.3–2 m/s) and material bulk densities (33–100 kg/m3). Pragmatic diffusion-based drying models that account for the influence of drying gas velocity, material bulk density, and material shrinkage are presented. Results provide critical insights into the validity of diffusion model assumptions for compressible biomaterials and new mechanisms describing gas penetration into such materials are proposed. The drying models provided in this work demonstrate a high degree of accuracy for both species.

Dissemination of antibiotic resistance (AR) in marine environments is a global concern with a propensity to affect public health and many ecosystems worldwide. We evaluated the use of sea turtles as sentinel species for monitoring AR in marine environments. In this field, antibiotic-resistant bacteria have been commonly identified by using standard culture and sensitivity tests, leading to an overrepresentation of specific, culturable bacterial classes in the available literature. AR was detected against all major antibiotic classes, but the highest cumulative global frequency of resistance in all represented geographical sites was against the beta-lactam class by a two-fold difference compared to all other antibiotics. Wastewater facilities and turtle rehabilitation centres were associated with higher incidences of multidrug-resistant bacteria (MDRB) accounting for an average of 58% and 49% of resistant isolates, respectively. Furthermore, a relatively similar prevalence of MDRB was seen in all studied locations. These data suggest that anthropogenically driven selection pressures for the development of AR in sea turtles and marine environments are relatively similar worldwide. There is a need, however, to establish direct demonstrable associations between AR in sea turtles in their respective marine environments with wastewater facilities and other anthropogenic activities worldwide.

Microalgae are promising candidates for recycling of carbon dioxide (CO 2 ) into renewable bioproducts. However, the low biomass concentration of current suspension culture systems leads to high water requirements, inefficient harvesting and high liquid transportation costs. Despite ongoing research, these still propose a challenge to the economic viability of microalgal cultivation. Microalgal biofilms provide an alternative approach to biomass production that could resolve these challenges by growing the cells attached to a surface, surrounded by a self-produced matrix of polymers. Microalgal biofilms have much higher biomass concentrations than suspension cultures, and the attached cells are easy to separate from the cultivation medium. However, cultivating microalgal biofilms requires the development of a purposefully designed cultivation system, especially due to interactions between cells and surface, persistent gradients in the biomass and the effects of flow, which play a critical role for biofilm productivity. A range of systems has been employed for the cultivation of microalgal biofilms, with biomass productivities of up to 60 grammes dry weight (g(DW)) m −2  day −1 (dry weight per ground area) outdoors and up to 80 g(DW) m −2  day −1 under laboratory conditions, respectively. However, there is considerable variation of reported results along with experimental conditions, which limits the capability for quantitative comparisons with other systems and hinders the identification of the drivers and variables that dictate microalgal biomass formation. Development of standard conditions and representative species would be required for closing this gap and for realising the full potential of microalgal biofilm cultivation as a viable process for industrial biomass production.

Solvents are a group of compounds with many domestic and industrial applications. However, the predominant use of solvents in the fine chemical and pharmaceutical industries has been as a medium in which to dissolve reagents and influence kinetics. Unfortunately, the recovery of these compounds presents an environmental problem for the industries that use them. This study focuses on the prediction methods that are available for engineers to make a better choice of reaction solvent. Experimental and molecular dynamics techniques were used to study the effects of solvents on both reaction kinetics and liquid-liquid phase behaviour. The Diels-Alder reaction between methylacrylate and cyclopentadiene has been used as a well-known model reaction illustrating solvent effects.Examples are used to illustrate the methods and properties that are commonly used to describe solvent effects on reactions and phase equilibrium (such as Transition State theory for reactions). In particular, the forces of repulsion and attraction between solvent molecules and other solvent or solute molecules are emphasised. A review of the experimental literature for the model reaction draws on these foundations.Gas chromatography and infra-red spectrophotometry are used as complementary techniques to experimentally characterise the model reaction in two solvents. Data reconciliation allows issues such as product selectivity, reaction rate and product partitioning to be investigated. Differences between the solvent influence on kinetics and partition in dilute solutions, and the solvent influence in concentrated solutions were found. These differences are discussed in the context of choosing solvents for better process performance. Molecular simulation is also used as a unifying theory to predict the effects of solvents on these fundamental processes.A review of the literature on predicting solvent effects by molecular simulation is given. Furthermore, the incorporation of the results of quantum mechanical studies of solvent effects on the model reaction is discussed. A statistical thermodynamic model is developed to determine the relationship between molecular dynamic properties and the design parameters of interest (rate differences and activity co-efficient ratios). Model calibration and the practical implementation of the statistical thermodynamic model to compare the effects of two solvents is described. Qualitative predictions of selectivity and partition by molecular simulation are used to demonstrate the potential application of this tool for process design.