Biorefinery Safety: A Case Study Focused on Bioethanol Production

With reference to the framework for energy and climate, the European Union (EU) has stated that at least a 32% share of renewable energy consumption has to be achieved within 2030. This context generates attention to the potential hazards, which are associated with flammable biofuels, such as the bioethanol. One of the main hazards, referred to such biofuel, is the formation of potentially explosive atmospheres due to its evaporation from pools in case of accidental releases. In fact, in a bioethanol production plant (biorefinery), there are several components (flanges, valves, pumps, etc.), which can become potential emission sources in case of failure. Bioethanol is a high-boiling liquid, because its boiling temperature (Tboiling = 78°C) is higher than ambient temperature. Therefore, in case of release and spreading on a certain medium, evaporation occurs because of vapor diffusion. The chapter is focused on a case study. In particular, the chapter illustrates a comparison between two predictive models aimed at estimating the bioethanol evaporation rate, which is a fundamental parameter for determining the dilution degree and classifying the workplaces, where potentially explosive atmospheres could occur. The study investigates the influence of bioethanol release temperature and therefore of its vapor pressure on evaporation rate

Biogas Production Plants: A Methodological Approach for Occupational Health and Safety Improvement

Existing lessons on public safety, referred to as new biotech plants, suggest that the development of effective, responsive and responsible safety standard can improve the trust of the public in the new generation plants such as biorefineries. This implies the need for specific risk assessment aimed at defining the mitigation measures, which can minimize the impact of hazards on workers’ health. The main hazards, referred to biogas production process, are biohazard, fires and potentially explosive atmospheres. In particular, the last two hazards strictly depend on the presence of methane in the biofuel. This chapter presents the results of a work aimed at providing the biogas industry with a practical tool, which can be used to carry out the analysis of hazards of biogas plants. The adopted method for developing the tool is based on the well-known checklist approach. The checklist is a valuable support for the plant operator to evaluate periodically the actual effectiveness of the overall safety measures and ensure a safer management of the biogas plant. The checklist can meet these requirements. This chapter reports the main preventive, protective and managerial measures, which can be adopted to decrease the hazardous outcomes on workers’ health and safety

Occupational Health Issue in a 2G Bioethanol Production Plant

The interest of scientists and health authorities in occupational risk related to biofuels production has recently increased due to the development of agro-industrial waste recycling processes in the framework of the European circular economy strategy and energy production from renewable sources. A common biofuel is the bioethanol, which is a leading candidate to substitute the gasoline as a transport fuel and it can be produced via biomass fermentation process. In biofuels production plants, some work activities in processing of biomass, are sources of airborne dust and the employers should demonstrate that adequate control measures have been implemented in order to prevent workers exposure. In the chapter, the production process of a 2G bioethanol plant has been analyzed in order to specify the process phases, which could generate occupational health issue related to airborne dust, and to provide technical recommendations

From soil remediation to biofuel. Process simulation of bioethanol production from Arundo donax

A range of energy crops can be grown on marginal land (i.e. land that is not suitable for food crop production or contaminated site) to provide feedstocks for bioenergy, non-food products and biofuels. The food versus fuel debate had a significant negative impact in Europe on first generation biofuels production from food crops (i.e. wheat, rapeseed, etc). A new approach involving the use of marginal land for the production of lignocellulosic species for the production of bioethanol is now pursued in Italy and in many other countries, where the demand for high quality water resources, arable land, food and fossil fuels is rapidly growing. With an emerging “feed versus fuel debate” there is a pressing need to find options for the use of marginal lands and wastewaters or saline ground waters to produce second generation biofuel or bio paper crops. Arundo donax was selected as a potential crop for use in these areas, since it produces more cellulosic biomass and sequesters more contaminants, using less land and pesticides than any other alternative crops reported in the literature. The objective of this paper is to evaluate economically a simplified process for the production of second generation bioethanol from A. donax. Process calculations and economic analyses are performed using the software SuperPro Designer®

The interplay of StyR and IHF regulates substrate-dependent induction and carbon catabolite repression of styrene catabolism genes in Pseudomonas fluorescens ST

<p>Abstract</p> <p>Background</p> <p>In <it>Pseudomonas fluorescens </it>ST, the promoter of the styrene catabolic operon, P<it>styA</it>, is induced by styrene and is subject to catabolite repression. P<it>styA </it>regulation relies on the StyS/StyR two-component system and on the IHF global regulator. The phosphorylated response regulator StyR (StyR-P) activates P<it>styA </it>in inducing conditions when it binds to the high-affinity site STY2, located about -40 bp from the transcription start point. A <it>cis</it>-acting element upstream of STY2, named URE, contains a low-affinity StyR-P binding site (STY1), overlapping the IHF binding site. Deletion of the URE led to a decrease of promoter activity in inducing conditions and to a partial release of catabolite repression. This study was undertaken to assess the relative role played by IHF and StyR-P on the URE, and to clarify if P<it>styA </it>catabolite repression could rely on the interplay of these regulators.</p> <p>Results</p> <p>StyR-P and IHF compete for binding to the URE region. P<it>styA </it>full activity in inducing conditions is achieved when StyR-P and IHF bind to site STY2 and to the URE, respectively. Under catabolite repression conditions, StyR-P binds the STY1 site, replacing IHF at the URE region. StyR-P bound to both STY1 and STY2 sites oligomerizes, likely promoting the formation of a DNA loop that closes the promoter in a repressed conformation. We found that StyR and IHF protein levels did not change in catabolite repression conditions, implying that P<it>styA </it>repression is achieved through an increase in the StyR-P/StyR ratio.</p> <p>Conclusion</p> <p>We propose a model according to which the activity of the P<it>styA </it>promoter is determined by conformational changes. An open conformation is operative in inducing conditions when StyR-P is bound to STY2 site and IHF to the URE. Under catabolite repression conditions StyR-P cellular levels would increase, displacing IHF from the URE and closing the promoter in a repressed conformation. The balance between the open and the closed promoter conformation would determine a fine modulation of the promoter activity. Since StyR and IHF protein levels do not vary in the different conditions, the key-factor regulating P<it>styA </it>catabolite repression is likely the kinase activity of the StyR-cognate sensor protein StyS.</p

The role of different methanogen groups evaluated by Real-Time qPCR as high-efficiency bioindicators of wet anaerobic co-digestion of organic waste

Methanogen populations and their domains are poorly understood; however, in recent years, research on this topic has emerged. The relevance of this field has also been enhanced by the growing economic interest in methanogen skills, particularly the production of methane from organic substrates. Management attention turned to anaerobic wastes digestion because the volume and environmental impact reductions. Methanogenesis is the biochemically limiting step of the process and the industrially interesting phase because it connects to the amount of biogas production. For this reason, several studies have evaluated the structure of methanogen communities during this process. Currently, it is clear that the methanogen load and diversity depend on the feeding characteristics and the process conditions, but not much data is available. In this study, we apply a Real-Time Polymerase Chain Reaction (RT-PCR) method based on mcrA target to evaluate, by specific probes, some subgroups of methanogens during the mesophilic anaerobic digestion process fed wastewater sludge and organic fraction of the municipal solid waste with two different pre-treatments. The obtained data showed the prevalence of Methanomicrobiales and significantly positive correlation between Methanosarcina and Methanosaetae and the biogas production rate (0.744 p < 0.01 and 0.641 p < 0.05). Methanosarcina detected levels are different during the process after the two pre-treatment of the input materials (T-test p < 0.05). Moreover, a role as diagnostic tool could be suggested in digestion optimisation

Containment of a genetically modified microorganism by an activated sludge system

Abstract The effectiveness of physical, chemical and biological barriers to the diffusion of genetically modified microorganisms (GMMs) to prevent their release into the environment is currently under scrutiny worldwide because of the associated potential ecological impacts. An industrial discharge of a non-sterilized fermentation broth containing GMM biomass into a conventional municipal wastewater treatment plant would deliver the GMMs into the activated sludge system process (ASSP). The present work aimed to model and evaluate the containment capability of a small ASSP (part of a 20,000 people equivalent municipal plant) in the event of receiving GMM biomass from a medium-small biotechnological plant dedicated to the production of polyhydroxyalkanoates (3000 t/year of biopolymer). An actual GMM (Pseudomonas putida KTOY06) was injected into a bench-scale ASSP (ASSPLab) in a quantity proportional to the relative dimensions of the plants mentioned. The experimental and model results indicated that the ASSP of the target municipal treatment plant would not be capable of holding back such a sudden input of GMM; 6 h after the discharge, 11–15 % of injected GMM cells were released through the clarified stream of the ASSPLab, with the rest being gradually released over time. Since the GMM employed did not exhibit any growth in the ASSPLab, its concentration in the clarified water stream would not represent a substantial risk of release into the environment if appropriate tertiary treatments were integrated. This study confirmed the necessity of a thorough risk assessment of biotechnological processes prior to their implementation

Recirculation factor as a key parameter in continuous-flow biomass selection for polyhydroxyalkanoates production

The effectiveness of polyhydroxyalkanoates (PHA) production with mixed microbial cultures (MMC) largely depends on the selection of PHA-storing microorganisms, conventionally performed in sequencing batch reactors (SBR). These, although easily allow the establishment of the required feast and famine (FF) regime, can represent a factor of cost increase when the process is scaled up. Here, a novel continuous-flow process for MMC selection under FF conditions has been developed by using two sequentially operated reactors. The feast reactor, having a tubular configuration, was continuously fed with a synthetic mixture of acetic and propionic acids (at an organic loading rate of 2.12 gCOD/L d) and the effluent of this reactor was in part sent to the CSTR famine reactor. The recirculation factor (RC), that is the ratio between the recirculation flow rate and the feeding flow rate to the feast reactor, was the main parameter investigated. Four different runs were performed with the RC varying from 1 to 8 and the increase in its value caused a decrease of the biomass residence time in each reactor. The intracellular PHA content in the feast reactor almost linearly increased up to RC 4 (with a value of 34 ± 2 %, wt/wt) and dropped at the RC 8 condition that, however, showed the maximum PHA content (58 ± 5 %, wt/wt) during the accumulation tests. Indeed, the relative abundance of sequences affiliated with putative PHA-storing bacteria increased up to 90.5 % at RC 8 and were dominated by members of the Alphaproteobacteria class mostly represented by the genus Meganema (74 %)

Environmental effects of using chelating agents in polluted sediment remediation

The results of laboratory scale experimental tests of contaminant extraction from marine sediment slurries are presented and discussed. The objective of this study was to compare the effectiveness of EDTA and rhamnolipid in copper removal from an artificially contaminated sediment. The comparison was made in terms of metal extraction yield, and in the evaluation of its mobilization towards the more exchangeable fractions in the sediment. Results show that, under acidic conditions established during washing, EDTA ensured higher extractions efficiencies of Cu (up to 95 %) than rhamnolipid, although there was less mobilization into bioavailable forms with the use of rhamnolipid. In addition, in the view of a biological treatment of the spent solution, the use of rhamnolipid resulted in a lower decrease of the specific oxygen uptake rate with respect to EDTA. In fact, the low surfactants concentration required, partially compensated the toxic effect of Cu towards biomass