Dual role of carbon monoxide in medium-chain fatty acids production from food waste.

Upcycling biowaste into useful biochemicals, including medium-chain fatty acids (MCFAs) represents a crucial node in the transition toward a circular economy. However, the output and stability of anaerobic microbiomes for MCFAs production are strongly anchored on the effective inhibition of competing pathways, including methanogenesis, while stimulating the growth of bacteria producing MCFAs. Here, we proposed a mixotrophic chain elongation (CE) concept for producing MCFAs from food waste by exploring carbon monoxide (CO) as a methanogenic inhibitor.

Assessment of trace organic chemicals in anaerobically digested sludge and their partitioning behaviour: Simultaneous Soxhlet chemical extraction and quantification via LC-MS/MS analysis.

The increasing number of trace organic contaminants (TrOCs) detected in anaerobically digested sludge (ADS) is triggering increasing concern on its circular-economy reuse practices. A large scientific effort has been performed to define their concentration limits, partition behaviour, and innovative technologies for their removal, which require the definition of versatile and economically sustainable analytical methodologies. In this study, a Soxhlet extraction method coupled with LC-MS/MS analysis was developed to simultaneously determine 32 TrOCs in ADS, 11 of them being quantified in this matrix for the first time.

Low-intensity magnetization pretreatment to enhance biomethane generation and the abundance of key microorganisms for anaerobic digestion of sewage sludge.

This work explores the impact of static magnetic field (SMF) intensity on biomethane production from anaerobic digestion (AD) of sewage sludge. Two different SMF intensities (20 mT and 1.5 T) were applied to magnetize the sludge destined to the AD process.

Life Cycle Sustainability Assessment of municipal solid waste management systems: a review.

In the context of Circular Economy, the significance of municipal solid waste management systems (MSWMSs) has increased, as well as the need for comprehensive assessment tools of their sustainability. In the Life Cycle Thinking (LCT) framework, the Life Cycle Sustainability Assessment (LCSA), which is a methodology aiming to evaluate the environmental, economic, and social burdens throughout the various phases of waste management, has raised great interest. The paper describes the state-of-the-art of the implementation of LCT tools, with high regard to LCSA, for the evaluation of MSWMSs through their life cycle, with a deep focus on the use of both midpoint and endpoint categories.

Implementing a sustainable process for the recovery of palladium from spent catalysts at industrial scale: A LCA approach.

Due to its unique physicochemical properties, palladium is widely used in several industry applications (e.g., vehicle emission control).

Valorization of Purple Phototrophic Bacteria Biomass Resulting from Photo Fermentation Aimed at Biohydrogen Production.

This study evaluated the feasibility of contextually producing hydrogen, microbial proteins, and polyhydroxybutyrate (PHB) using a mixed culture of purple phototrophic bacteria biomass under photo fermentative conditions. To this end, three consecutive batch tests were conducted to analyze the biomass growth curve and to explore the potential for optimizing the production process. Experimental findings indicated that inoculating reactors with microorganisms from the exponential growth phase reduced the duration of the process.

Acidogenic fermentation of food waste to generate electron acceptors and donors towards medium-chain carboxylic acids production.

This study investigated the optimum pH, temperature, and food-to-microorganisms (F/M) ratio for regulating the formation of electron acceptors and donors during acidogenic fermentation to facilitate medium-chain carboxylic acids (MCCAs) production from food waste. Mesophilic fermentation at pH 6 was optimal for producing mixed volatile fatty acids (719 ± 94 mg COD/g VS) as electron acceptors. Under mesophilic conditions, the F/M ratio (g VS/g VS) could be increased to 6 to generate 22 ± 2 g COD/L of electron acceptors alongside 2 ± 0 g COD/L of caproic acid.

Microbial protein production from lactose-rich effluents through food-grade mixed cultures: Effect of carbon to nitrogen ratio and dilution rate.

Overabundant agro-industrial side streams such as lactose-rich effluents from dairy activities offer multiple valorisation opportunities. In the present study, a food-grade mixed culture of bacteria and yeasts was tested under different operational conditions for the treatment and the valorisation of cheese whey permeate (CWP), the residue of whey protein recovery, into microbial protein (MP). Under continuous aerobic fermentation settings, the carbon-to-nitrogen (C/N) ratio showed little to no influence on the system performances and MP quality as compared to dilution rates (D), leading to a final protein content as high as 76%.

Application of high-intensity static magnetic field as a strategy to enhance the fertilizing potential of sewage sludge digestate.

Anaerobic digestion (AD) is a sustainable and well-established option to handle sewage sludge (SS), as it generates a methane-rich biogas and a digestate with potential fertilizing properties. In the past, different strategies have been proposed to enhance the valorization of SS. Among these, the application of a static magnetic field (SMF) has been poorly evaluated.

Composting of Organic Solid Waste of Municipal Origin: The Role of Research in Enhancing Its Sustainability.

The organic solid waste of municipal origin stands as one of the residual streams of greatest concern: the great amounts continuously produced over time as well as its biochemical and physical characteristics require its proper handling via biological processes, pursuing the recovery of material and/or the generation of energy. At the European level, most of the industrial plants treating the organic fraction of municipal solid waste (OFMSW) rely on composting, which is a well-established and reliable process that is easy to operate in different socio-economic contexts. Nevertheless, when regarded in a life cycle perspective as well as in the view of the principles of circular economy underlying waste management, several issues (e.

Recent progress and challenges in biotechnological valorization of lignocellulosic materials: Towards sustainable biofuels and platform chemicals synthesis.

Lignocellulosic materials (LCM) have garnered attention as feedstocks for second-generation biofuels and platform chemicals. With an estimated annual production of nearly 200 billion tons, LCM represent an abundant source of clean, renewable, and sustainable carbon that can be funneled to numerous biofuels and platform chemicals by sustainable microbial bioprocessing. However, the low bioavailability of LCM due to the recalcitrant nature of plant cell components, the complexity and compositional heterogeneity of LCM monomers, and the limited metabolic flexibility of wild-type product-forming microorganisms to simultaneously utilize various LCM monomers are major roadblocks.

Microplastics in sewage sludge destined to anaerobic digestion: The potential role of thermal pretreatment.

Microplastics (MPs) are plastic particles with size smaller than 5 mm: their removal in municipal wastewater treatment plants mostly results in the accumulation of the coarser fraction into the sludge. The common application of the treated sludge as soil amendment raises the issue of the uncontrolled release of MPs into the environment, which depicts the need to identify suitable counteraction strategies. This work briefly reviews the most recent studies that focus on the fate of MPs during conventional sludge treatments, and, based on the results of this analysis, proposes the thermal pretreatment (120 °C, 30 min) of waste activated sludge (WAS) containing different kinds of MPs, in order to investigate its effect on the anaerobic biodegradability as well as on the abundance and physical features of MPs.

The valorization of the anaerobic digestate from the organic fractions of municipal solid waste: Challenges and perspectives.

The anaerobic digestion is a well-established process for the treatment of organic solid waste, pursuing its conversion into a methane rich gas destined to energy generation. Research has largely dealt with the enhancement of the overall bioconversion yields, providing several strategies to maximize the production of bio-methane from the anaerobic processing of a wide variety of substrates. Nevertheless, the valorization of the process effluents should be pursued as well, especially if the anaerobic digestion is regarded in the light of the circular economy principles.

The valorisation of residual waste bales by urban mining.

In the last decade, the approach to waste management has undergone severe changes. The urgent need to face the sustainable demand for energy and materials while limiting the burdens associated to traditional waste handling practices have figured out the concept of waste as a resource. New strategies boosting the extensive recovery and diverting waste from disposal activities have been promoted and framed in the wider context of the urban mining, promoting the full exploitation of waste as resource for either new materials or energy production.

Recovery opportunities of valuable and critical elements from WEEE treatment residues by hydrometallurgical processes.

Due to the increasing demand of metals by industry and the limited availability of natural resources, the secondary supply of these elements from discarded products, such as waste electrical and electronic equipment (WEEE), is an important strategy for pursuing a sustainable development. Nevertheless, the complex and heterogeneous composition of this waste stream stands as one of the main drawbacks in the definition of innovative recovery processes. This study investigated the recovery potential of a multi-step leaching process to extract the strategic metals, namely precious metals and rare earth elements (REEs), from the dust produced during the industrial shredding treatment of WEEE.

WEEE Treatment in Developing Countries: Environmental Pollution and Health Consequences-An Overview.

In the last few decades, the rapid technological evolution has led to a growing generation of waste electrical and electronic equipment (WEEE). Not rarely, it has been exported from industrialized to developing countries, where it represents a secondary source of valuable materials such as gold, copper, and silver. The recycling of WEEE is often carried out without any environmental and health protection.

A relative risk assessment of the open burning of WEEE.

Waste electric and electronic equipment (WEEE) represents a potential secondary source of valuable materials, whose recovery is a growing business activity worldwide. In low-income countries, recycling is carried out under poorly controlled conditions resulting in severe environmental pollution. High concentrations of both metallic and organic pollutants have been confirmed in air, soil, water, and sediments in countries with informal recycling areas.

The evolution of compost stability and maturity during the full-scale treatment of the organic fraction of municipal solid waste.

Composting is the method most commonly applied worldwide for the recovery of the source sorted organic waste. The process aims at stabilizing the organic matter, so as to produce a material with soil improver properties, referred to as compost. The effective recovery of the organic waste fraction via composting implies compost safe use on soil.

Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) - A review.

Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern.

Bioleaching of metals from WEEE shredding dust.

A bioleaching process developed in two separate steps was investigated for the recovery of base metals, precious metals and rare earth elements from dusts generated by Waste Electrical and Electronic Equipment (WEEE) shredding. In the first step, base metals were almost completely leached from the dust in 8 days by Acidithiobacillus thiooxidans (DSM 9463) that lowered the pH of the leaching solution from 3.5 to 1.

A device-specific prioritization strategy based on the potential for harm to human health in informal WEEE recycling.

In developing countries, the recovery of valuable materials from Waste Electrical and Electronic Equipment (WEEE) is carried out via uncontrolled practices, posing potentially severe risks both to human health and the environment. The assessment of the risk, which depends on both the kind and hazardous properties of the substances contained in WEEE, is currently limited as the exposure scenario for the single informal practice cannot be fully characterized for this purpose. In this context, this work proposes and evaluates a strategy to identify the relative potential harm of different kinds of WEEE by their content in metals, selected as the target substances of concern.

Organic fraction of municipal solid waste from mechanical selection: biological stabilization and recovery options.

Although current trends address towards prevention strategies, the organic fraction of municipal solid waste is greatly produced, especially in high-income contexts. Its recovery-oriented collection is a common practice, but a relevant portion of the biodegradable waste is not source selected. Mechanical and biological treatments (MBT) are the most common option to sort and stabilize the biodegradable matter ending in residual waste stream.

Enhanced ozonation of selected pharmaceutical compounds by sonolysis.

In search of new options to achieve removal of pharmaceuticals in the environment, combined ultrasound and ozonation has become a focus of intense investigation for wastewater treatment. In this study, three pharmaceuticals were selected as model compounds for degradation experiments: diclofenac (DCF), sulfamethoxazole (SMX) and carbamazepine (CBZ). Comparison of the degradation rates for both ozonation and combined ultrasound/ozonation treatments was performed on single synthetic solutions as well as on a mixture of the selected pharmaceuticals, under different experimental conditions.

Effects of metabolic pathway precursors and polydimethylsiloxane (PDMS) on poly-(gamma)-glutamic acid production by Bacillus subtilis BL53.

The aims of this study were to evaluate the effects of the addition of metabolic precursors and polydimethylsiloxane (PDMS) as an oxygen carrier to cultures of Bacillus subtilis BL53 during the production of γ-PGA. Kinetics analyses of cultivations of different media showed that B. subtilis BL53 is an exogenous glutamic acid-dependent strain.

Sonolysis and ozonation as pretreatment for anaerobic digestion of solid organic waste.

This study aims to compare the efficiency of sonolysis and ozonation in improving anaerobic biodegradability of source sorted organic fraction of municipal solid waste, for the enhancing of biogas production and energy recovery as well. The methane yield of solid organic material anaerobic digestion is significantly affected by substrate availability, which can be favoured by pretreatments. In this investigation, both sonolysis and ozonation effects on substrate solubilisation and anaerobic biodegradability were evaluated under different treatment conditions.