Microalgae to biodiesel: A novel green conversion method for high-quality lipids recovery and in-situ transesterification to fatty acid methyl esters.

Greenhouse gases (GHGs) emissions due to increasing energy demand have raised the need to identify effective solutions to produce clean and renewable energy. Biotechnologies are an effective platform to attain green transition objectives, especially when synergically integrated to promote health and environmental protection. In this context, microalgae-based biotechnologies are considered among the most effective tools for treating gaseous effluents and simultaneously capturing carbon sources for further biomass valorisation. The production of biodiesel is regarded as a promising avenue for harnessing value from residual algal biomass. Nonetheless, the existing techniques for extracting lipids still face certain limitations, primarily centred around the cost-effectiveness of the process.This study is dedicated to developing and optimising an innovative and cost-efficient technique for extracting lipids from algal biomass produced during gaseous emissions treatment based on algal-bacterial biotechnology. This integrated treatment technology combines a bio-scrubber for degrading gaseous contaminants and a photobioreactor for capturing the produced CO2 within valuable algal biomass. The cultivated biomass is then processed with the process newly designed to extract lipids simultaneously transesterificated in fatty acid methyl esters (FAME) via In Situ Transesterification (IST) with a Kumagawa-type extractor. The results of this study demonstrated the potential application of the optimised method to overcome the gap to green transition. Energy production was obtained from residuals produced during the necessary treatment of gaseous emissions. Using hexane-methanol (v/v = 19:1) mixture in the presence KOH in Kumagawa extractor lipids were extracted with extraction yield higher than 12% and converted in fatty acid methyl esters. The process showed the enhanced extraction of lipids converted in bio-sourced fuels with circular economy approach, broadening the applicability of biotechnologies as sustainable tools for energy source diversification.

Carbon neutrality in wastewater treatment plants: An integrated biotechnological-based solution for nutrients recovery, odour abatement and CO2 conversion in alternative energy drivers.

Wastewater treatment plants play a crucial role in water security and sanitation, ensuring ecosystems balance and avoiding significant negative effects on humans and environment. However, they determine also negative pressures, including greenhouse gas and odourous emissions, which should be minimized to mitigate climate changes besides avoiding complaints. The research has been focused on the validation of an innovative integrated biological system for the sustainable treatment of complex gaseous emissions from wastewater treatment plants. The proposed system consists of a moving bed biofilm reactor coupled with an algal photobioreactor, with the dual objective of: i) reducing the inlet concentration of the odourous contaminants (in this case, hydrogen sulphide, toluene and p-xylene); ii) capturing and converting the carbon dioxide emissions produced by the degradation process into exploitable algal biomass. The first reactor promoted the degradation of chemical compounds up to 99.57% for an inlet load (IL) of 22.97 g m-3 d-1 while the second allowed the capture of the CO2 resulting from the degradation of gaseous compounds, with biofixation rate up to 81.55%. The absorbed CO2 was converted in valuable feedstocks, with a maximum algal biomass productivity in aPBR of 0.22 g L-1 d-1. Dairy wastewater has been used as alternative nutrient source for both reactors, with a view of reusing wastewater while cultivating biomass, framing the proposed technology in a context of a biorefinery within a circular economy perspective. The biomass produced in the algal photobioreactor was indeed characterized by a high lipid content, with a maximum percentage of lipids per dry weight biomass of 35%. The biomass can therefore be exploited for the production of alternative and clean energy carrier. The proposed biotechnology represents an effective tool for shifiting the conventional plants in carbon neutral platform for implementing principles of ecological transition while achieving high levels of environmental protection.

Advanced treatment of toluene emissions with a cutting-edge algal bacterial photo-bioreactor: Performance assessment in a circular economy perspective.

A novel approach for the treatment of VOCs (by using toluene used as a model compound) and the simultaneous conversion of carbon dioxide into valuable biomass has been investigated by using a combination of an activated sludge moving bed bioreactor (MBBR) and an algal photo-bioreactor (PBR). The first unit (MBBR, R1) promoted toluene removal up to 99.9 % for inlet load (IL) of 119.91 g m-3 d-1. The CO2 resulting from the degradation of toluene was then fixed in PBR (R2), with a fixation rate up to 95.8 %. The CO2 uptake was promoted by algae, with average production of algal biomass in Stage VI of 1.3 g L-1 d-1. In the contest of the circular economy, alternative sources of nutrients have been assessed, using synthetic urban wastewater (UWW) and dairy wastewater (DWW) for liquid renewal. The produced biomass with DWW showed a high lipid content, with a maximum productivity of 450.25 mg of lipids L-1 d-1. The solution proposed may be thus regarded as a sustainable and profitable strategy for VOCs treatment in a circular economy perspective.

Smart instrumental Odour Monitoring Station for the efficient odour emission management and control in wastewater treatment plants.

Odour emission assessment in wastewater treatment plants (WWTP) is a key aspect that needs to be improved in the plant management to avoid complaints and guarantee a sustainable environment. The research presents a smart instrumental odour monitoring station (SiOMS) composed of an advanced instrumental odour monitoring system (IOMS) integrated with other measurement units, for the continuous characterization and measurement of the odour emissions, with the aim of managing the potential odour annoyance causes in real time, in order to avoid negative effects. The application and on-site validation procedure of the trained IOMS is discussed. Experimental studies have been conducted at a large-scale WWTP. Fingerprint analysis has been applied to analyze and identify the principal gaseous compounds responsible for the odour annoyance. The artificial neural network has been adopted to elaborate and dynamically update the odour monitoring classification and quantification models (OMMs) of the IOMS. The results highlight the usefulness of a real-time measurement and control system to provide continuous and different information to the plant operators, thus allowing the identification of the odour sources and the most appropriate mitigation actions to be implemented. The paper provides important information for WWTP operators, as well as for the regulating bodies, authorities, manufacturers and end-users of odour monitoring systems involved in environmental odour impact management.

Large Meckel's Diverticulum Enterolith. A case of small bowel obstruction.

The Meckel's diverticulum is usually asymptomatic but in sometimes it presents severe complications, such as bleeding or perforation. The presence of enterolith inside a Meckel diverticulum is rare. In this report, we present a case of a 56- years- old man, with an abdominal pain and small bowel obstruction for a enterolith. Preoperative radiologic studies in Emergency Room (ER) didn't reveal this stone, but realeved a small bowel obstruction. Initially, we tried a conservative management, however after about 48 hours, due to worsening symptoms, the patient undergoes an exploratory laparotomy and a intestinal resection. Key words: Enteriith, Meckel's diverticulum, Small bowel obstruction.

Advances in technological control of greenhouse gas emissions from wastewater in the context of circular economy.

This review paper aims to identify the main sources of carbon dioxide (CO2) emissions from wastewater treatment plants (WWTPs) and highlights the technologies developed for CO2 capture in this milieu. CO2 is emitted in all the operational units of conventional WWTPs and even after the disposal of treated effluents and sludges. CO2 emissions from wastewater can be captured or mitigated by several technologies such as the production of biochar from sludge, the application of constructed wetlands (CWs), the treatment of wastewater in microbial electrochemical processes (microbial electrosynthesis, MES; microbial electrolytic carbon capture, MECC; in microbial carbon capture, MCC), and via microalgal cultivation. Sludge-to-biochar and CW systems showed a high cost-effectiveness in the capture of CO2, while MES, MECC, MCC technologies, and microalgal cultivation offered efficient capture of CO2 with associate production of value-added by-products. At the state-of-the-art, these technologies, utilized for carbon capture and utilization from wastewater, require more research for further configuration, development and cost-effectiveness. Moreover, the integration of these technologies has a potential internal rate of return (IRR) that could equate the operation or provide additional revenue to wastewater management. In the context of circular economy, these carbon capture technologies will pave the way for new sustainable concepts of WWTPs, as an essential element for the mitigation of climate change fostering the transition to a decarbonised economy.

Wastewater treatment and fouling control in an electro algae-activated sludge membrane bioreactor.

The effect of addition of algae to activated sludge as active biomass in membrane bioreactors (MBRs) and electro-MBRs (e-MBRs) for wastewater remediation was examined in this study. The performances of Algae-Activated Sludge Membrane Bioreactor (AAS-MBR) and electro Algae-Activated Sludge Membrane Bioreactor (e-AAS-MBR) were compared to those observed in conventional MBR and e-MBR, which were previously reported and utilized activated sludge as biomass. The effect of application of electric field was also examined by the comparison of performances of e-AAS-MBR and AAS-MBR. Similar chemical oxygen demand (COD) reduction efficiencies of AAS-MBR, e-AAS-MBR, MBR, and e-MBR (98.35 ± 0.35%, 99.12 ± 0.08%, 97.70 ± 1.10%, and 98.10 ± 1.70%, respectively) were observed. The effect of the algae-activated sludge system was significantly higher in the nutrient removals. Ammoniacal nitrogen (NH3-N) removal efficiencies of AAS-MBR and e-AAS-MBR were higher by 43.89% and 26.61% than in the conventional MBR and e-MBR, respectively. Phosphate phosphorous (PO43--P) removals were also higher in AAS-MBR and e-AAS-MBR by 6.43% and 2.66% than those in conventional MBR and e-MBR. Membrane fouling rates in AAS-MBR and e-AAS-MBR were lower by 57.30% and 61.95% than in MBR and e-MBR, respectively. Lower concentrations of fouling substances were also observed in the reactors containing algae-activated sludge biomass. Results revealed that addition of algae improved nutrient removal and membrane fouling mitigation. The study also highlighted that the application of electric field in the e-AAS-MBR enhanced organic contaminants and nutrients removal, and fouling rate reduction.

Innovative membrane photobioreactor for sustainable CO2 capture and utilization.

The rising of greenhouse-gas emissions (GHG), during the last 200 years, is associated to the well known global warming phenomena. One of the main sources of CO2-equivalent GHGs emissions are the environmental protection plants accounting for 1.57% of the global emissions and thus sustainable and effective technologies for their mitigation are strongly needed. The current paper presents and discusses the assessment of an innovative membrane photo-bioreactor (MPBR) whose aim was the promotion of CO2 capture from conveyed flows, such as those from wastewater treatment plants (WWTPs), landfill and composting plants, for production and energy valorisation of algal biomass. Chlorella vulgaris microalgae strain was selected as photosynthetic platform for the abovementioned purposes. The influence of various operating parameters has been explored, including the photosynthetic photon flux densities (PPFD) (60 and 120 µmol m-2 s-1), liquid/gas ratio (L/G = 5, 10 or 15) and CO2 concentration (5, 10 and 15%) in order to investigated their effects on carbon capture effectiveness and biomass production. The results demonstrated that the increasing of PPFD significantly enhanced the biomass production in terms of biomass productivity (P) and total dry weight (DW). The highest biomass concentration of 1.01 g L-1 was achieved at PPFD of 120 µmol m-2 s-1 with a L/G of 15. Under the aforementioned conditions, carbon dioxide removal efficiency (RE) reached values up to 80%. In addition, the novel MPBR equipped with an innovative self-forming dynamic membrane (SFDM) showed a simultaneous biomass harvesting rate of 41 g m-2 h-1.

Comparative evaluation of a biotrickling filter and a tubular photobioreactor for the continuous abatement of toluene.

The negative effects of volatile organic compounds (VOCs) on humans' health and the environment have boosted the enforcement of regulations, resulting in the need of effective and environmentally friendly off-gas treatment technologies. In this work, the synergism between microalgae and bacteria was investigated as a sustainable platform to enhance the biological degradation of toluene, herein selected as a model VOC. An innovative algal-bacterial tubular photobioreactor (TPBR) was systematically compared with a conventional biotrickling filter (BTF). The BTF supported average removal efficiencies close to those obtained in the TPBR (86 ±â€¯9% and 88 ±â€¯4%, respectively) at the highest inlet load (∼23 g m3  h-1) and lowest gas residence time (0.75 min). However, the BTF was more sensitive towards the accumulation of secondary metabolites. In this regard, photosynthetic O2 supplementation (resulting in dissolved oxygen concentrations of ∼7.3 mg O2 L-1) and CO2 consumption by microalgae (which reduced the impact of acidification) enhanced toluene abatement performance and process stability.