Cristiano Varrone

Aalborg University · Department of Chemistry and Bioscience

Nowadays, fermentation of organic wastes for the production of carboxylic acids as precursors of higher-value products has attracted significant attention. In this paper, sewage sludge and food waste were co-fermented to produce carboxylic acids and study the subsequent chain elongation process. The Copenhagen waste stream scenario was taken as a c...

Acetate (HAc) production via acetogenesis is a promising biorefinery approach for waste activated sludge (WAS); however, it is hampered by the thermodynamic constraints of the bioconversion of 3-5 carbon atom short-chain fatty acids (SCFAs). Sulfate radical (SO4∙‾)-based advanced oxidation is regarded as an appropriate candidate for accelerating WA...

Plastic and plastic recycling/degradation has been in the spotlight during last decade, due to its increasing waste accumulation in all world’s ecosystems and the huge challenge deriving from micro-plastic pollution. Therefore, different strategies are under investigation, trying to cope with this problem. Although depolymerisation of plastics by c...

Crude glycerol is an important by-product of the biodiesel industry, which can be converted into volatile fatty acids (VFA) and/or 1,3-propanediol (1,3-PDO) by fermentation. In this study, a selective conversion of VFA to polyhydroxyalkanoates (PHA) was attained while leaving 1,3-PDO in the supernatant by means of mixed microbial consortia selectio...

This study investigated the possibility to perform statistical optimization of an enriched mixed microbial consortium, MMC, fed in continuous with a highly inhibiting 2G glycerol, for the joint production of 1,3 propanediol (1,3 PDO) and butyric acid (BuA). Key variables taken into consideration were HRT, pH and feed concentration. The optimized pr...

Pesticides are biologically active compounds, which refer to "any substance or mixture of substances intended for preventing, destroying, repelling or mitigating pests". This includes not only insecticides, but also herbicides, fungicides, and various other substances used to control pests, as well as plant regulators, defoliants and desiccants. Th...

Sulfadiazine (SDZ) is one of the most representative sulfonamides antibiotics, and its biodegradation has become a research hotspot in recent years. The present study innovatively adopted a microbial fuel cells with a Nickel (Ⅱ) and Manganese (Ⅱ)-decorated graphite felt bioanode (Ni(Ⅱ)/Mn (Ⅱ)-MFCs) to remove SDZ. The results demonstrated that the N...

Large-scale worldwide production of plastics requires the use of large quantities of fossil fuels, leading to a negative impact on the environment. If the production of plastic continues to increase at the current rate, the industry will account for one fifth of global oil use by 2050. Bioplas-tics currently represent less than one percent of total...

An economically viable production of second-generation bioethanol by recombinant xylose-fermenting Saccharomyces cerevisiae requires higher xylose fermentation rates and improved glucose–xylose co-consumption. Moreover, xylose-fermenting S. cerevisiae recognises xylose as a non-fermentable rather than a fermentable carbon source, which might partly...

It is widely accepted that plastic waste is one of the most urgent environmental concerns the world is currently facing. The emergence of bio-based plastics provides an opportunity to reduce dependency on fossil fuels and transition to a more circular plastics economy. For polyethylene terephthalate (PET), one of the most prevalent plastics in pack...

Polyethylene terephthalate (PET) is the most widely used polyester plastic, with applications in the textile and packaging industry. Currently, re-moulding is the main path for PET recycling, but this eventually leads to an unsustainable loss of quality; thus, other means of recycling are required. Enzymatic hydrolysis offers the possibility of mon...

It is widely accepted that plastic waste is one of our most urgent environmental concerns the world is currently facing. Plastic has contributed greatly to innovation in all fields, but the raw material for its production (fossil fuels), as well as the linear economy in which it is currently produced and used, makes the material problematic from a...

The aim of this study was to compare the techno-economic feasibility of five different scenarios to valorize sewage sludge in co-digestion with another organic waste. The first three scenarios were based on real full-scale processes in Scandinavia, furthermore two original biorefinery scenarios for carboxylates and biogas production were proposed....

Electro-fermentation (EF) is an attractive way to implement the chain elongation (CE) process, by controlling the fermentation environment and reducing the dosage of external electron donors (EDs). However, besides the coexistence performance of external EDs and electrode, applications of EF technology on the fermentation broth containing both EDs...

Wastewater and sewage sludge contain organic matter that can be valorized through conversion into energy and/or green chemicals. Moreover, resource recovery from these wastes has become the new focus of wastewater management, to develop more sustainable processes in a circular economy approach. The aim of this review was to analyze current sewage s...

Bioelectrochemical systems (BESs) are emerging technologies that are based on catalyzing (bio-)anode and (bio-)cathode reactions from waste biomass by exoelectrogenic microorganisms. Microbial electrolysis cell (MEC), which is one of the BESs’ technologies, is typically used to degrade organic wastes or wastewater for bioenergy recovery and biosynt...

C1-C7 carboxylates were successfully recovered from fermented organic waste. • Strong anion exchange resin preferentially adsorbed hexanoate and heptanoate. • Longer carboxylates were also easier desorbed, allowing their enrichment. • Hexanoate and heptanoate were concentrated up to 0.29 mol/kg and 0.18 mol/kg, respectively. A R T I C L E I N F O K...

The aim of this study was to find microorganisms that are capable of a dual function: degrading the pesticide Dicamba and at the same time act as biological control agent against the fungal plant pathogen Fusarium culmorum. Link: http://remtechexpo.com/images/2020/Pubblicazioni/ABSTRACT-REMTECH-DIGITAL2020.def.pdf

Aimed at the low ratio of carbon and nitrogen (C/N, approximately 7/1) of waste activated sludge (WAS), which would inhibit the acetogenesis process during anaerobic fermentation, this study introduced three brewing wastes, including vinegar (VR), stillage (SR) and soy sauce (SSR) residues, to promote acetogenesis by co-fermenting with WAS. Results...

The increasingly rapid growth of both, population- and food demands has driven a research race in food production efficiency through the last century, which has made the pesticide use seemingly unavoidable. However, many pesticides are very persistent and tend to accumulate in the ecosystem, often threatening biodiversity and public health. Althoug...

This study started as a collaboration with the chemical company FMC, who asked us to find new microbial strains or consortia able to degrade some of their pesticides and herbicides. After enriching and isolating strains, able to grow on the pesticides as the only carbon source for several months, we are now proceeding with the screening of the degr...

We coupled a CSTR used for the glycerol fermentation (inoculated with an enriched mixed microbial consortium) with an SBR where the effluent of the first reactor was converted into PHA (using another enriched consortium).

We coupled a CSTR used for the glycerol fermentation (with an enriched mixed microbial consortium) with an SBR where the effluent of the first reactor was converted into PHA (using another enriched consortium).

A representative organic waste from both Denmark and Norway was studied for revalorization of sewage sludge by co-digestion. Chemical composition of the samples, which may vary depending on region and time of collection, was studied since it can affect the co-digestion process and its outcome. Experiments to produce VFAs from sewage sludge and OFMS...

CHARACTERISING PET DEGRADING IDEONELLA SAKAIENSIS & ENGINEERING OF PETase THROUGH MUTAGENESIS

Carboxylic acids, especially the short chain (C2 and C3) fatty acids, is the preferable carbon source for many bioprocesses. The production efficiency of volatile fatty acids (VFAs) recovery from waste activated sludge (WAS) is limited by an unbalanced nutrient component. In this study, a low-cost alternative approach (i.e., co-digesting with vineg...

Crude glycerol, a by-product from the biodiesel industry, can be converted by mixed microbial consortia into 1,3-propanediol (1,3-PDO) and volatile fatty acids. In this study, further conversion of these main products into polyhydroxyalkanoates (PHA) was investigated with the focus on 1,3-PDO. Two different approaches for the enrichment of PHA accu...

(FREE ACCESS to the article. Anyone clicking on this link before November 25, 2017 https://authors.elsevier.com/c/1VrDy,V9BZ6ufx) This study investigated the performance of different mixed microbial cultures (MMC) able to ferment crude glycerol generated from animal fat-based biodiesel to produce 1,3 propanediol (1,3 PDO) and butyric acid, under no...

Sustainable biofuels, biomaterials, and fine chemicals production is a critical matter that research teams around the globe are focusing on nowadays. Polyhydroxyalkanoates represent one of the biomaterials of the future due to their physicochemical properties, biodegradability, and biocompatibility. Designing efficient and economic bioprocesses, co...

Current studies have employed various chemicals for disintegrating and hydrolyzing microbial cells in waste activated sludge (WAS). However, a comprehensive process assessment over the whole anaerobic digestion process has seldom been proposed. Besides, the characterization of microbial community responses to these chemicals is not well understood....

Background Bioelectrochemical systems have been considered a promising novel technology that shows an enhanced energy recovery, as well as generation of value-added products. A number of recent studies suggested that an enhancement of carbon conversion and biogas production can be achieved in an integrated system of microbial electrolysis cell (MEC...

Methane production rate (MPR) in waste activated sludge (WAS) digestion processes is typically limited by the initial steps of complex organic matter degradation, leading to a limited MPR due to sludge fermentation speed of solid particles. In this study, a novel microbial electrolysis AD reactor (ME-AD) was used to accelerate methane production fo...

http://orbit.dtu.dk/admin/files/119758498/R4_DTU_Sustain_2015.pdf

Objective of this study was the selection and adaptation of mixed microbial cultures (MMCs), able to ferment crude glycerol generated from animal fat-based biodiesel and produce building-blocks and green chemicals. Various adaptation strategies have been investigated for the enrichment of suitable and stable MMC, trying to overcome inhibition probl...

Graphical representation of the change in composition of mixed microbial cultures, at the major levels of taxonomic classification (species, genus, family, order, class, and phylum). Results from batch transfer during the enrichment of activated sludge, and for the anaerobic sludge enriched on hexane-pretreated crude glycerol in batch tests and wit...

To improve anaerobic digestibility of waste activated sludge (WAS), a novel treatment was explored by a plant-derived biosurfactant (saponin biosurfactant (SB)). SB showed positive effects on WAS hydrolysis and acidogenesis with increasing concentration, but was insignificant at dosage > 0.20 g SB/g total suspended solids (TSS). Soluble protein and...

Biohydrogen production from buffalo slurry (BS) co-fermented with cheese whey (CW) and crude glycerol (CG) was investigated using a suitable microbial community (F210) as inoculum. Mixture Design was used to find the optimal composition (%) of the three substrate components and to investigate the effect of the mixing ratio on Bio-H2 yields. Maximum...

The main objective of the research was to verify the effectiveness of a MFC (Microbial Fuel Cell) based reactor for the removal of nitrogen from digested sludge (from anaerobic treatment of livestock manure and agricultural wastes). Preliminary tests were performed to study the development of biofilm at the electrodes, by running small H- type MFC...

Self-fermentation of cellulosic substrates to produce biohydrogen without inoculum addition nor pretreatments was investigated. Dark fermentation of two different substrates made of leaf-shaped vegetable refuses (V) and leaf-shaped vegetable refuses plus potato peels (VP), was taken in consideration. Batch experiments were carried out, under two me...

Biohydrogen production from buffalo slurry (BS) co-fermented with cheese whey (CW) and crude glycerol (CG) was investigated using a suitable microbial community (F210) as inoculum. Mixture Design was used to individuate the optimal composition (%) of the three substrate components and to investigate the effect of the mixing ratio on Bio-H 2 yields....

The project: the overall aim of this project is the valorisation of glycerol streams generated during the biodiesel production process, using microbial mixed culture (MMC) technology. The use of bioconversion into high-value products represents a promising route to achieve economic viability in the biofuel industry. Until now there have been severa...

The study of natural environments, together with the knowledge of applied microbial ecology, can drive innovation in bioenergetic applications. Hypertrophic lagoons are characterised by rapid and huge biomass blooms and decomposition. In these salty shallow-water ecosystems the microbial degradation is supported by a chain of electron acceptors, in...

Microbial electrolysis cells (MECs) use exoelectrogenic microorganisms to convert organic matter into H2, although yields can vary significantly with environmental conditions, likely due to variations in microbial communities. This study was undertaken to better understand how microbial communities affect reactor function. Using wastewater as inocu...

The study of natural environments, together with the knowledge of applied microbial ecology, can drive innovation in bioenergetic applications. Hypertrophic lagoons are characterised by rapid and huge biomass blooms and decomposition. In these salty shallow-water ecosystems the microbial degradation is supported by a chain of electron acceptors, in...

In this study, we evaluated the effectiveness of lake sediment as inoculum for hydrogen production through dark fermentation in a repeated batch process. In addition, we investigated the effect of heat treatment, applied to enrich hydrogen-producing bacteria, on the bacterial composition and metabolism. Denaturing gradient gel electrophoresis and m...

Background Sustainable biohydrogen production can be achieved by dark fermentation of organic wastes, and studies were carried out using a range of substrates and inocula. The bacterial populations involved were mainly identified as facultative anaerobes (Enterobacteriaceae) and strictly anaerobes (Clostridiales), and their dynamics in relation to...

Lignocellulosic biomass can be an ideal feedstock for fermentative hydrogen production if properly pretreated and hydrolyzed. In this research, to enhance hydrogen production from cornstalk, acid and alkali pretreatments were performed. Alkali pretreatment was conducted at 80°C for 60 min and room temperature for 7 days with the addition of 4% NaOH...

The worldwide energy demand has been continuously increasing, thus requesting more sustainable alternatives to the rapidly depleting fossil fuels. Therefore, biofuels such as hydrogen, bioethanol and biodiesel are gaining more importance as a renewable and pollution-free solution, which might give a significant contribution to the future energy mix...

Most on-farm biogas plants in Europe use animal waste and co-substrates for biogas production (CH4 and CO2 mixture). However combined hydrogen and methane production in a twostage process is a concept which has been developed in recent years and it is more promising from an energy perspective. The aim of this research was to explore hydrogen produc...

Enriched activated sludge that can effectively convert crude glycerol into bio-hydrogen was selected by an eco-biotechnological approach, in very strict conditions, using biodieselderived glycerol as the only carbon source. The thus obtained functional consortium was characterized by the genera Klebsiella, Escherichia/Shigella and Cupriavidus. Duri...

The effects of environmental factors on bacterioplankton distribution along the water column of Lake Averno (Naples, Italy) have been investigated by means of denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments and multivariate analysis applied to molecular data and physico-chemical pa...

This work adopted an innovative approach for fermentative H2 production from common domestic organic waste, at 28 !C, in the absence of pretreatment: the self-fermentation of non-sterile vegetable waste and the bioaugmentation of microbial indigenous fermenting communities. For this purpose, three new H2-producing strains, Buttiauxella sp. 4, Rahne...

Design of Experiments (DoE) was applied to improve the ability of enriched activity sludge to efficiently convert crude glycerol from biodiesel industry into hydrogen and ethanol, using a very simple synthetic medium. Based on PlacketteBurman screening design, glycerol concentration, temperature and initial pH were identified as significant variabl...

Enrichment of activity sludge allowed to select a suitable microbial mixed culture able to grow on crude glycerol as the only carbon source, using a very simple synthetic medium without any extra nutrient supplements. Following to statistical optimisation, the selected pool was able to effectively convert crude glycerol into H2 and ethanol, both at...

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