Fate of antibiotic resistant E. coli and antibiotic resistance genes during full scale conventional and advanced anaerobic digestion of sewage sludge.

Antibiotic resistant bacteria (ARB) and their genes (ARGs) have become recognised as significant emerging environmental pollutants. ARB and ARGs in sewage sludge can be transmitted back to humans via the food chain when sludge is recycled to agricultural land, making sludge treatment key to control the release of ARB and ARGs to the environment. This study investigated the fate of antibiotic resistant Escherichia coli and a large set of antibiotic resistance genes (ARGs) during full scale anaerobic digestion (AD) of sewage sludge at two U.

How to make methodological decisions when inferring social networks.

Social network analyses allow studying the processes underlying the associations between individuals and the consequences of those associations. Constructing and analyzing social networks can be challenging, especially when designing new studies as researchers are confronted with decisions about how to collect data and construct networks, and the answers are not always straightforward. The current lack of guidance on building a social network for a new study system might lead researchers to try several different methods and risk generating false results arising from multiple hypotheses testing.

Using microalgae in the circular economy to valorise anaerobic digestate: challenges and opportunities.

Managing organic waste streams is a major challenge for the agricultural industry. Anaerobic digestion (AD) of organicwastes is a preferred option in the waste management hierarchy, as this processcangenerate renewableenergy, reduce emissions from wastestorage, andproduce fertiliser material.However, Nitrate Vulnerable Zone legislation and seasonal restrictions can limit the use of digestate on agricultural land.

Methanogenic capacity and robustness of hydrogenotrophic cultures based on closed nutrient recycling via microbial catabolism: Impact of temperature and microbial attachment.

A biological methanation system based on nutrient recycling via mixed culture microbial catabolism was investigated at mesophilic (37 °C) and thermophilic (55 °C) temperatures. At mesophilic temperatures, the formation of biofilms on two different types of material was assessed. Results showed that with intense mixing the biofilm reactors presented methanogenic capacities (per working volume) 50% higher than the ones operated with suspended cultures.

Integration of Power to Methane in a waste water treatment plant - A feasibility study.

The integration of a biomethanation system within a wastewater treatment plant for conversion of CO and H to CH has been studied. Results indicate that the CO could be utilised to produce an additional 13,420m/day of CH, equivalent to approximately 133,826kWh of energy. The whole conversion process including electrolysis was found to have an energetic efficiency of 66.

Biomineralization potential and cellular response of PHB and PHBV blends with natural anionic polysaccharides.

In this paper, the biomineralization potential and cellular response of novel blend films of the anionic sulfated polysaccharides kappa-carrageenan (KCG) and fucoidan (FUC) derived from seaweeds with semi-crystalline polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV), respectively, were analyzed. The incorporation of KCG and FUC into PHB and PHBV, which has been studied here for the first time, led to an overall decrease in crystallinity, enhanced surface hydrophilicity, reduced brittleness and faster degradation of the polymer blend films. All PHB/KCG, PHBV/KCG and PHBV/FUC films exhibited a two-stage mass loss profiles with pH stabilization.

Enhancement of microbial density and methane production in advanced anaerobic digestion of secondary sewage sludge by continuous removal of ammonia.

Ammonia inhibition mitigation in anaerobic digestion of high solids content of thermally hydrolysed secondary sewage sludge by the NH affinitive clinoptilolite and a strong acid type ion-exchange resin S957 was investigated. Continuous NH-N removal was achieved through ion-exchanging at both temperatures with average removals of 50 and 70% for the clinoptilolite and resin dosed reactors, respectively. Approximate 0.

Closed nutrient recycling via microbial catabolism in an eco-engineered self regenerating mixed anaerobic microbiome for hydrogenotrophic methanogenesis.

A novel eco-engineered mixed anaerobic culture was successfully demonstrated for the first time to be capable of continuous regeneration in nutrient limiting conditions. Microbial catabolism has been found to support a closed system of nutrients able to enrich a culture of lithotrophic methanogens and provide microbial cell recycling. After enrichment, the hydrogenotrophic species was the dominating methanogens while a bacterial substratum was responsible for the redistribution of nutrients.

Third generation poly(hydroxyacid) composite scaffolds for tissue engineering.

Bone tissue engineering based on scaffolds is quite a complex process as a whole gamut of criteria needs to be satisfied to promote cellular attachment, proliferation and differentiation: biocompatibility, right surface properties, adequate mechanical performance, controlled bioresorbability, osteoconductivity, angiogenic cues, and vascularization. Third generation scaffolds are more of composite types to maximize biological-mechanical-chemical properties. In the present review, our focus is on the performance of micro-organism-derived polyhydroxyalkanoates (PHAs)-polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV)-composite scaffolds with ceramics and natural polymers for tissue engineering applications with emphasis on bone tissue.

The use of NaCl addition for the improvement of polyhydroxyalkanoate production by Cupriavidus necator.

External stress factors in the form of ionic species or temperature increases have been shown to produce a stress response leading to enhanced PHA production. The effect of five different NaCl concentrations, namely 3.5, 6.

Increasing polyhydroxyalkanoate (PHA) yields from Cupriavidus necator by using filtered digestate liquors.

The production of polyhydroxyalkanoates (PHAs) using digestate liquor as culture media is a novel application to extend the existing uses of digestates. In this study, two micro-filtered digestates (0.22 μm) were evaluated as a source of complex culture media for the production of PHA by Cupriavidus necator as compared to a conventional media.

Monitoring methanogenic population dynamics in a full-scale anaerobic digester to facilitate operational management.

Microbial populations in a full-scale anaerobic digester fed on food waste were monitored over an 18-month period using qPCR. The digester exhibited a highly dynamic environment in which methanogenic populations changed constantly in response to availability of substrates and inhibitors. The methanogenic population in the digester was dominated by Methanosaetaceae, suggesting that aceticlastic methanogenesis was the main route for the production of methane.

Addressing the challenge of optimum polyhydroxyalkanoate harvesting: monitoring real time process kinetics and biopolymer accumulation using dielectric spectroscopy.

In this study, dielectric spectroscopy was utilised to evaluate and define the optimum harvesting time for polyhydroxyalkanoates (PHA) production. It is essential to harvest PHA at the optimum time during fermentation for maximum yield, otherwise cells start degrading. Two carbon sources (acetic and butyric acids) were used in laboratory based experiments and a number of samples were measured ex situ for PHA production.

Integration of NIRS and PCA techniques for the process monitoring of a sewage sludge anaerobic digester.

This study investigates the use of Hotelling's T(2) control charts as the basis of a process monitor for sewage sludge anaerobic digestion. Fourier transform near infrared spectroscopy was used to produce partial least squares regression models of volatile fatty acids, bicarbonate alkalinity and volatile solids. These were utilised in a series of principle component analysis models along with spectral data from digestate and feedstock samples to produce a pseudo steady state model, which was then used with an independent test set to evaluate the system.

Life cycle assessment of biohydrogen and biomethane production and utilisation as a vehicle fuel.

Environmental burdens for the production and utilisation of biomethane vehicle fuel or a biohydrogen/biomethane blend produced from food waste or wheat feed, based on data from two different laboratory experiments, have been compared. For food waste treated by batch processes the two stage system gave high hydrogen yields (84.2l H2kg(-1) VS added) but a lower overall energy output than the single stage system.

Life cycle assessment of biogas infrastructure options on a regional scale.

A life cycle assessment has been completed of potential biogas infrastructures on a regional scale. Centralised and distributed infrastructures were considered along with biogas end uses of Combined Heat and Power (CHP) and injection to the gas grid for either transport fuel or domestic heating end uses. Damage orientated (endpoint) life cycle impact assessment method identified that CHP with 80% heat utilisation had the least environmental impact, followed by transport fuel use.

ADM1 can be applied to continuous bio-hydrogen production using a variable stoichiometry approach.

The IWA Anaerobic Digestion Model No.1 (ADM1) has been extensively used in recent years. However, its application to non-methanogenic systems is limited by the use of constant-stoichiometry to describe product formation from carbohydrate fermentation.