Development of microalgal biomass for biodiesel production

Ph.DDOCTOR OF PHILOSOPH

Sustainable agriculture in the Arabian/Persian Gulf region utilizing marginal water resources: Making the best of a bad situation

One way to encourage agricultural self-sufficiency in arid regions is to increase the productivity of conventional freshwater agriculture. Another way is to develop and implement novel strategies and technologies that do not deplete scarce freshwater. Here we describe several options for countries in the Gulf region to increase their agricultural production by taking advantage of a lesser used resource-marginal water. Marginal water can be treated sewage effluent, produced oilfield water, brackish groundwater or seawater. We describe how this resource can be used to grow salt-tolerant forage crops, microalgae and aquaculture crops. Policies needed to implement and/or scale-up such practices are also outlined. 2018 by the authors.Scopu

A novel electrocoagulation electrode configuration for the removal of total organic carbon from primary treated municipal wastewater

In this paper, the removal of total organic carbon (TOC) from a primary treated municipal wastewater using a new electrode configuration in electrocoagulation was evaluated. The used electrode configuration induces a dielectrophoretic (DEP) force by using an asymmetrical aluminum electrode with an alternating current power supply. The impact of applied current, electrolysis time, and interelectrode distance on the removal efficiency of TOC were evaluated. The experimental results showed that the maximum removal efficiency of TOC was obtained at 30 min electrolysis time, 600 mA applied current, and 0.5 cm interelectrode distance. Under these operating conditions, the TOC removal was 87.7% compared to 80.5% using symmetrical aluminum electrodes with no DEP effect. The energy consumption at the selected operating conditions was 3.92 kWh/m3. The experimental results were comparable with the simulation results done by COMSOL Multiphysics software. 2020, The Author(s).Open Access funding provided by the Qatar National Library. The authors would like to thank Qatar University for the provided financial support. The authors would also like to thank the central Laboratories Unit at Qatar University for TOC analysis. In addition, the authors wish to thank Qatar Foundation for the financial support provided to one of the co-authors through a graduate sponsorship research award (GSRA 6-1-0509-19021).Scopu

Potential of microalgae as a sustainable feed ingredient for aquaculture

An increase in fish consumption, combined with a decrease in wild fish harvest, is driving the aquaculture industry at rapid pace. Today, farmed seafood accounts for about half of all global seafood demand for human consumption. As the aquaculture industry continues to grow, so does the market for aquafeed. Currently, some of the feed ingredients are coming from low-value forage fishes (fish meal) and terrestrial plants. The production of fish meal can’t be increased as it would affect the sustainability and ecosystem of the ocean. Similarly, increasing the production of terrestrial plant-based feed leads to deforestation and increased freshwater use. Hence, alternative and environmentally sustainable sources of feed ingredients need to be developed. Microalgae biomasses represent potential feed source ingredients as the cell metabolites of these microorganisms contain a blend of essential amino acids, healthy triglycerides as fat, vitamins, and pigments. In addition to serving as bulk ingredient in aquafeed, their unique array of bioactive compounds can increase the survivability of farmed species, improve coloration and quality of fillet. Microalgae has the highest areal biomass productivities among photosynthetic organisms, including fodder crops, and thus has a high commercial potential. Also, microalgal production has a low water and arable-land footprint, making microalgal-based feed environmentally sustainable. This review paper will explore the potential of producing microalgae biomass as an ingredient of aquaculture feed.publishedVersio

Pretreatment of cyanobacterial Chroococcidiopsis. biomass prior to hydrothermal liquefaction for enhanced hydrocarbon yield and energy recovery

Chroococcidiopsis sp. was grown in 200 L open raceway pond. Biomass density and average biomass productivity were 0.41 g/L and 16.1 g/m2/d. Chroococcidiopsis biomass was harvested by self-settling. Self settled biomass was further subjected to centrifugation to obtain a biomass paste with 25-30% solid content. Centrifuged biomass was dried at 80 °C overnight and used as a feedstock for pretreatment step. Biomass was pretreated in water at 105 °C for 15 minutes. A slurry containing 15 wt% pretreated and untreated biomass (control) in deionized water was prepared and subjected to hydrothermal liquefaction for biocrude oil production. Hydrothermal liquefaction for both pretreated and untreated biomass was conducted at temperatures ranging from (275, 300, 325, 350 °C) in a 500 mL high pressure PARR reactor for 30-minute reaction holding time. Maximum biocrude yields for pretreated and untreated biomass was 42.4 % and 26.4 % based on ash free dry weight basis. Biocrude oil was characterized for hydrocarbons using GC-MS technique. Biocrude oil obtained from pretreated and untreated biomass contained 58.9% and 41.01% (C8-C19) hydrocarbons. Higher heating values for biomass and biocrude oil were 16.93 and 31.28 MJ/kg, with an energy recovery value of 41.1%

Determination of Optimum Iron Requirement for Production of Microalgae Biomass as Biofuel Feedstock

Microalgae biomass is considered as one of the promising alternative feedstock for biofuel production. The biomass productivity of some of the microalgae can exceed an order of magnitude compared to any other terrestrial plant. Apart from nitrogen and phosphorus, iron is one of the major elements that must be provided to microalgae culture for high density biomass production. The amount of iron that is required per cell or per unit of microalgae biomass will vary among microalgae strains. Depending on the concentration of iron in the cultivation media, the microalgae will accumulate different amount of iron and this process may alter the compositions of other major metabolites. In order to be competitive the cost of microalgae biomass production should be lower and the desired metabolites should be present in higher percentages; therefore, the appropriate concentration of iron should be determined. On the contrary, there are very limited study on the microalgal iron requirement. The first objective of this study is to determine the minimum concentration of iron requirement by some of the locally isolated potential microalgae. The second objective of this study is to characterize the lipid accumulation under different iron concentrations. Gillard f/2 and BG-11 are the two common nutrients composition used to culture marine and freshwater microalgae respectively. In these two nutrients media, the concentrations of iron are 0.65 mg/l and 1.24 mg/l for Guillard F/2 and BG-11 media respectively. Due to some limitations, in most of the cases the concentrations of phototrophic microalgae in large scale biomass production doesn't exceed 0.5 g/L. If these two media are to be used in large scale, iron requirement can be calculated as 1.3 kg (6.3 kg as FeCl3.6H2O) and 2.4 kg (12 kg as FeCl3.6H2O) respectively for each ton of biomass production. Therefore, the cost of the iron fertilizer can be significant for low cost feedstock; furthermore, if there is residual iron in the discharge water it will require additional treatment steps. Three local marine microalgae (Nannochloris sp., Tetraselmis sp., Chlorocystis sp.) and three local freshwater microalgae (Scenedesmous sp., Chlorella sp., Neochloris sp.) were selected to study their iron requirement. Apart from iron, all the nutrients were added as per f/2 or BG-11 media concentrations. However, for the marine microalgae, the range of iron concentration was 0 to 1 mg/L while for the freshwater microalgae it was 0 to 3 mg/L. All the experiments were conducted in triplicates. 10 ml of culture was inoculated in 90 ml containing any culture media in a 250 ml flask; the flasks were kept in an orbital shaker which was maintained at 120 rpm speed, 25°C, 12 hours photoperiod. The growth period for any strain was kept fixed at 7 days. It was found that marine Naanochloris sp. didn't require the addition of iron; the available iron in the seawater is sufficient to produce 0.5 g/L biomass density. The other two strains had also smaller iron requirement compared to f/2 media. For the three freshwater microalgae, there was also minor requirement for iron (1 mg/L) which was much lesser than iron concentration in BG-11 media. Iron deficiency, during the cultivation process, resulted in bleaching and changes in metabolites (especially in pigments). Nannochloris sp. and Scenedesmous sp. will be later grown in outdoor small raceway tanks (1000 liter) to verify the indoor small scale results.qscienc

The epidemiology of melioidosis and its association with diabetes mellitus : a systematic review and meta-analysis

Melioidosis is an under-recognized fatal disease in humans, caused by the Gram-negative bacterium Burkholderia pseudomallei. Globally, more than 35,000 human melioidosis cases have been reported since 1911. Soil acts as the natural reservoir of B. pseudomallei. Humans may become infected by this pathogen through direct contact with contaminated soil and/or water. Melioidosis commonly occurs in patients with diabetes mellitus, who increase the occurrence of melioidosis in a population. We carried out a systematic review and meta-analysis to investigate to what extent diabetes mellitus affects the patient in getting melioidosis. We selected 39 articles for meta-analysis. This extensive review also provided the latest updates on the global distribution, clinical manifestation, preexisting underlying diseases, and risk factors of melioidosis. Diabetes mellitus was identified as the predominant predisposing factor for melioidosis in humans. The overall proportion of melioidosis cases having diabetes was 45.68% (95% CI: 44.8–46.57, p < 0.001). Patients with diabetes mellitus were three times more likely to develop melioidosis than patients with no diabetes (RR 3.40, 95% CI: 2.92–3.87, p < 0.001). The other potential risk factors included old age, exposure to soil and water, preexisting underlying diseases (chronic kidney disease, lung disease, heart disease, and thalassemia), and agricultural activities. Evidence-based clinical practice guidelines for melioidosis in patients with diabetes mellitus may be developed and shared with healthcare professionals of melioidosis endemic countries to reduce morbidity. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Energy recovery and nutrients recycling from municipal sewage sludge

Hydrothermal Liquefaction (HTL) could be a promising and better alternative to other techniques for energy recovery from municipal sewage sludge (MSS). However, the nutrients (i.e., N, and P) recovery potential from the byproducts, generated in the HTL of MSS, needs to be studied so that a comprehensive sludge management practice could be adopted. In this study, HTL process temperature (275–400 °C), and reaction time (30–120 min) were first investigated for biocrude yield and release of the nutrients to the aqueous phase liquid (APL) and biochar. The maximum energy recovery (i.e., 59%) and maximum energy return on investment (i.e., 3.5) were obtained at 350 °C and 60 min of holding time. With the increase in HTL reaction time, the concentration of nitrogen in the APL increased (5.1 to 6.8 mg/L) while the concentration of phosphorus decreased (0.89 to 0.22 mg/L); the opposite was observed for the biochar. The nutrient recycling efficiency from the APL using microalgae was found to be strain-specific; nitrogen recycling efficiency by Picochlorum sp. and Chlorella sp. were 95.4 and 58.6%, respectively. The APL, derived from 1 kg MSS, could potentially produce 0.49 kg microalgal biomass. Since the concentrations of various metals in the biochar samples were substantially lower compared to their concentrations in raw MSS, the application of biochar as a soil conditioner could be very promising. Overall, net positive energy could be recovered from MSS using the HTL process, while the nutrients in the APL could be used to cultivate specific microalgae, and biochar could be applied to enhance the soil quality.The authors would like to acknowledge the support of Qatar National Research Fund (QNRF, a member of Qatar Foundation) for providing the funding (under grants UREP21-101-2-045, and NPRP8-646-2-272) for this study. The authors thank Ms. Noora from Environmental Science Center (ESC), QU, for the GC–MS analysis of the biocrude samples. The authors would also like to acknowledge the support of Mr. Solaiman from Central laboratory Unit (CLU) of Qatar University for the ICP-OES analyses of the samples