Sharon Velasquez

Newcastle University | NCL · School of Chemical Engineering and Advanced Materials

Wastewater represents an alternative source of nutrients in which to grow microalgae, whilst improving the quality of the wastewater, and reducing the downstream treatment required. However, commercialisation of microalgal cultures for such duties faces a number of challenges, predominantly high cost and low productivity. Suspended-solid reactors (...

Microalgae cultivation in wastewater has been widely researched under laboratory conditions as per its potential to couple treatment with biomass production. Currently, only a limited number of published articles consider outdoor and long-term microalgae-bacteria cultivations in real wastewater environmental systems. The scope of this work is to de...

This book provides comprehensive insights on existing technologies and up-to-date advances in the field of waste management and treatment using algal-based technologies via different approaches and systems. Coverage includes: Process fundamentals of algae-based wastewater treatment, including metabolic modelling, algal species for resource recovery...

Amongst the many treatments available for the removal of emerging contaminants in wastewater, microalgal cultures have been shown to be effective. However, the effectiveness of exposure of a native microalgal consortium to emerging contaminants such as bisphenol-A (BPA) and triclosan (TCS) to determine the half-maximum effective concentrations (EC5...

The use of microbes to treat a variety of wastewaters has been explored for a long time. A considerable amount of interest has been shown in yeasts' ability to remove pollutants. The use of yeast under nonsterile conditions can potentially result in higher pollutant removal rates at low production costs. The intention of this chapter is to condense...

In recent years, there has been significant interest in yeast-based wastewater treatment due to its high pollutant removal rate and ability to perform in non-sterile environments. In this work, a kinetic model was developed to predict yeast growth and substrate consumption during wastewater treatment. To determine the biological constants for use i...

In this study, organic acids were demonstrated as a promising carbon source for bisabolene production by the non-conventional yeast, Rhodosporidium toruloides, at microscale with a maximum titre of 1055 ± 7 mg/L. A 125-fold scale-up of the optimal process, enhanced bisabolene titres 2.5-fold to 2606 mg/L. Implementation of a pH controlled organic a...

In this study, organic acids were demonstrated as a promising carbon source for bisabolene production by the non-conventional yeast, Rhodosporidium toruloides , at microscale with a maximum titre of 1055 ± 7 mg/L. A 125-fold scale-up of the optimal process, enhanced bisabolene titres 2.5-fold to 2606 mg/L. Implementation of a pH controlled organic...

The ability of microalgae to adsorb heavy metals from their environment has been well documented, with numerous previous studies documenting their metal binding ability. This ability has brought interest of the water treatment industry as metal removal to ppb concentrations is an expensive undertaking using conventional methods. To date, few resear...

This paper evaluates the relation between the efficiency of harvesting microalgae biomass or biomolecules (proteins, lipids and carbohydrates) and the surface activity of the amphiphiles released during the harvesting process. Microalgae cultivated in wastewater was evaluated using a laboratory scale ozone-flotation reactor. Applying the highest bi...

This chapter focuses on new process intensification routes that can be applied to different stages within the microalgal biofuel production system: cultivation, harvesting, pretreatment, and conversion. Microalgae cultivation can be in open or closed bioreactors, at batch or continuous mode, using either fresh, sea, or wastewater as medium. Intensi...

Due to the increase in greenhouse gas emissions by combustion of fossil fuels, new alternatives for obtaining clean energy have been investigated. In this work, a wild microalgae consortium, grown in treated wastewater, was used to produce bio-oil by catalytic solvent liquefaction process. Tetralin and zeolite HZSM-5 (Si/Al = 80) were employed as a...

The use of ozone-air flotation for microalgae harvesting was investigated, in terms of its environmental feasibility and use in catalytic HTL. The environmental feasibility was determined by the Net Energy Ratio (NER) and carbon footprint metrics following a life cycle assessment (LCA). The effect of the variables in the catalytic HTL process (cata...

Either ozone or ultrasound pretreatment was applied to identify and evaluate their effect over the protein fraction of Desmodesmus sp. and Tetradesmus obliquus biomass cultivated in wastewater. Studies of SDS-PAGE, protein solubility, sulfhydryl and disulphide bond contents, and DSC were performed to evaluate the effect of each pretreatment on abun...

Ultrasound pre-treatment and protein extraction of Desmodesmus sp. and Tetradesmus obliquus biomass induced residual microalgae/polycaprolactone (PCL) biocomposites with higher viscoelastic and mechanical properties as injection mould temperature increased. This was probably associated to the promotion of microalgae proteins-PCL interactions. The P...

This study addresses the development of a non-sterile heterotrophic microalgae process, mainly using Scenedesmus sp., for the treatment of wastewater with high concentration of organic matter and biomass production. Urban and swine wastewaters were used as source of organic carbon. A C:N ratio of 3.4:1 provided a maximum biomass concentration of 1....

Background Wild-type yeasts have been successfully used to obtain food products, yet their full potential as fermenting microorganisms for large-scale ethanol fuel production has to be determined. In this study, wild-type ethanologenic yeasts isolated from a secondary effluent were assessed for their capability to ferment saccharified microalgae su...

Microbial electrosynthesis (MES) uses microbes and electricity to convert CO2 to high-grade chemicals alleviating greenhouse gas (GHG) emissions. Little is known on the environmental loads associated with the scale-up of the technology. Initially, the MES environmental impacts of synthesizing acetic, formic, or propionic acids, methanol, or ethanol...

Background: Wild type yeasts have been successfully used to obtain food products, yet their full potential as fermenting microorganisms for large-scale ethanol fuel production has to be determined. In this study, wild type ethanologenic yeasts isolated from a secondary effluent were assessed for their capability to ferment saccharified microalgae s...

This study focused on the simultaneous recovery of carbohydrates (CHO) and phosphorus (P) from Desmodesmus sp. biomass cultivated in municipal wastewater through a sequential pretreatment. The pretreatment consisted first of ultrasound to trigger cell disruption followed by ozonation to recover CHO and P. For ozone pretreatment, three different par...

This study applies individual and combined application of ultrasound and ozone pretreatments for the tandem recovery of microalgae biocompounds (lipids, proteins, and, carbohydrates) and phosphorus from Scenedesmus obliquus cultivated in wastewater. Results of individual application showed that ultrasound released protein to the aqueous phase (99 ±...

The objective of this research was to study a novel ozone-air flotation microalgae harvesting method and evaluate its effect on the recovery of biomass and biocomponents (lipids, carbohydrates, proteins). Best processing conditions were established using a response surface methodology (RSM). Microalgae separation and biocomponent recovery were eval...

This study evaluates the effect of ultrasound and ozone pretreatments for the subsequent recovery of Desmodesmus sp. biocomponents-lipids, proteins, and carbohydrates-using a response surface methodology. Both pretreatments impact on the recovered lipids quality, solvent waste production and extraction time is analysed for process intensification p...

Currently over 80% of wastewater generated globally, is discharged into surface waters without adequate treatment. Major environmental and public health risks associated with such releases are particularly prevalent in developing countries where the infrastructure and financing for effective treatment is lacking. Novel low cost integrated wastewate...

This work explored bio-crude oil production and the hydrocarbon distribution resulting from a catalytic HTL process with a feedstock composed by native consortium of microalgae (mostly cyanobacteria) with low lipid and high protein content. Two harvesting methods ozone-flotation and centrifugation were compared. Also, the effect of the catalysts, H...

A scalable, solar energy driven microbial spinning disc gas absorber-converter technology has been developed by a novel combination of advanced photoreactive biocomposite materials with a continuous thin film flow spinning disc bioreactor (SDBR). Chlorella vulgaris microalgae were incorporated into a porous paper biocomposite for the first time wit...

An alternate approach to urban and regional planning is presented that considers the wastewater infrastructure from an energy consumption and carbon production perspective. The existing wastewater infrastructure from four counties in North East England region is investigated, which includes energy and carbon dioxide (CO2) data from 87 wastewater tr...

A simple and robust microalgae kinetic model has been developed for application in the prediction and control of algae cultivations in wastewater. The microalgae kinetic model was calibrated using experimental cultivation data from Desmodesmus sp. to determine specific microalgae growth rates (μ max and μ maxNO3), microalgae death rates (μ d), and...

The use of ozone has been investigated as a harvesting technique (ozone-flotation) for microalgae recovery from wastewater. This document summarizes the most outstanding results achieved to date by our working group, including the ozone effect on the lipid and fatty acid methyl ester (FAME) content. Additionally, the effect of the initial concentra...

Online monitoring of groundwater quality in shallow wells to detect faecal or organic pollution could dramatically improve understanding of health risks in unplanned peri-urban settlements. Microbial fuel cells (MFC) are devices able to generate electricity from the organic matter content in faecal pollution making them suitable as biosensors. In t...

This study examines the latest advancements in the field of Microbial ElectroSynthesis (MES) and reports a unique sustainability and economic assessment for the production of five alternative compounds (formic, acetic, propionic acids; methanol and ethanol). Different chemical production conditions were compared by modelling a 1000 t per year produ...

In this paper, a mixed microalgal consortium (including cyanobacteria) was separated from treated wastewater by ozoflotation to evaluate the method's effect on protein excretion, lipids extraction, and cell recovery. Microalgae suspensions obtained from an artificial lake, Lake Nabor Carrillo, were subjected to different ozoflotation conditions (0....

Microalgae has large scale cultivation history particularly in aquaculture, pigments and nutraceutical production. Despite the advantages of microalgal oil as feedstock for biodiesel production, algal biodiesel is still at laboratory scale due to technical challenges required to be overcome to make it economical and sustainable. Indeed, complete dr...

Microbial electrosynthesis (MES) and anaerobic fermentation (AF) are two biological processes capable of reducing CO2, CO and water into acetic acid, an essential industrial reagent. In this study, we evaluated investment and production costs of acetic acid via MES and AF, and compared them to industrial chemical processes: methanol carbonylation a...

The kinetics of alkali-catalysed reactive extraction (“in situ transesterification”) of Chlorella vulgaris with methanol to produce biodiesel were investigated. Both the experiment and the model showed that a maximum 96% biodiesel yield can be obtained in 10 min before saponification FAME losses become significant. This high FAME yield was achieved...

A process evaluation of AuCl4− (<300 mg/L, <pH 3, H2 e-donor) sorption kinetics and mass transfer analysis by initially viable Shewanella putrefaciens is presented here. Following on from previous reports of a thermodynamically spontaneous reaction, high sorption capacity of 1346 mg/g and significant evidence of zero valent gold nanoparticles (AuNP...

This article reports an in situ transesterification/reactive extraction of Nannochloropsis occulata for fatty acid methyl ester (FAME) production using H2SO4, sodium dodecyl sulphate (SDS) plus H2SO4 and zirconium dodecyl sulphate (ZDS). A maximum 67 % FAME yield was produced by ZDS. Effect of inclusion of sodium dodecyl sulphate (SDS) in H2SO4 for...

This article reports a high yielding technique of synthesizing zirconium dodecyl sulphate (“ZDS”) for in situ transesterification of Nannochloropsis occulata and Chlorella vulgaris for fatty acid methyl ester (FAME) production. ZDS produced a significantly higher FAME yield in N. occulata than in C. vulgaris (p = 0.008). The varying performance of...

The microbiological influence of gram negative dissimilative bacteria on the electrodeposition of gold [AuCl4]− ion is analysed. Previous investigations have shown positive shifts in revisable potentials of gold in the presence of initially live gram negative bacterial cells, Shewanella putrefaciens in the electrolyte bath. This manuscript gives fu...

We report influences of the gamma proteobacteria Shewanella putrefaciens CN32 on electronation and electrodeposition phenomena of gold, cobalt and iron ionic species dissolved in aqueous effluents of low pH as novel strategies for the recovery and remediation of these metals. Linear sweep and cyclic voltammetry was used and analysed for the evaluat...

ALGAL FAME PRODUCTION WITH A NOVEL SURFACTANT BASED CATALYST IN A REACTIVE EXTRACTION *Kamoru A. Salam, **Sharon B. Velasquez-Orta, ***Adam P. Harvey *Kamoru.salam@ncl.ac.uk, **Sharon.velasquez-orta@ncl.ac.uk, ***adam.harvey@ncl.ac.uk School of Chemical Engineering and Advanced Materials (CEAM), Newcastle University, NE1 7RU, United Kingdom...

In situ transesterification of lipids in algal biomass reduces the number of unit operations by producing alkyl esters (biodiesel) directly from the lipid phase. The production of alkyl esters by in situ transesterification from marine microalgae Nannochloropsis oculata and freshwater microalgae Chlorella sp. was evaluated using different catalysts...

Using technologies such as anaerobic digestion for energy generation from wastewater demands a change in infrastructure that several treatment works are not prepared to immediately implement. This works explores the use of energy production technologies to increase the sustainability of conventional aerobic wastewater treatment plants. The first op...

In situ transesterification, or “reactive extraction”, of lipids in algal biomass has the potential to greatly simplify and reduce costs of the production of algal biodiesel, as it reduces the number of unit operations by contacting the biomass directly with the alcohol and catalyst required to convert lipids to their alkyl esters (biodiesel). A de...

This study determined the influence of substrate degradation on power generation in microbial fuel cells (MFCs) and microbial community selection on the anode. Air cathode MFCs were fed synthetic medium containing different substrates (acetate, glucose and starch) using primary clarifier sewage as source of electroactive bacteria. The complexity of...

In situ transesterification, or "reactive extraction", of lipids in algal biomass reduces the number of unit operations by contacting biomass directly with the alcohol and catalyst required to convert lipids to their alkyl esters (biodiesel). A series of experiments were conducted to evaluate biodiesel production from marine microalgae Nannochlorop...

This study reports an investigation of the effect of the anode surface area on the performance of a single chamber microbial fuel cell (SCMFC) based biosensor for measuring the organic content of wastewater. A packed bed of graphite granules was used as the anode. The surface area of the anode was changed by altering the granule bed thickness (0.3...

The effect of electron shuttles on electron transfer to microbial fuel cell (MFC) anodes was studied in systems where direct contact with the anode was precluded. MFCs were inoculated with Shewanella cells, and flavins used as the electron shuttling compound. In MFCs with no added electron shuttles, flavin concentrations monitored in the MFCs' bulk...

Bioelectricity production from a phytoplankton, Chlorella vulgaris, and a macrophyte, Ulva lactuca was examined in single chamber microbial fuel cells (MFCs). MFCs were fed with the two algae (as powders), obtaining differences in energy recovery, degradation efficiency, and power densities. C. vulgaris produced more energy generation per substrate...