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In the present work, Ulva lactuca, a marine macroalgae was used for the production of biodiesel. The ultrasound assisted extraction of oil from autoclaved algal biomass was found effective with maximum yield. The maximum oil was extracted at optimal conditions of 5% moisture content of algal biomass, 0.15 mm size of biomass, 6:1 solvent: solid ratio, at 55 °C in 140 min. The n-hexane with co-solvent methyl tertbutyl ether has shown higher oil when compared to other co-solvents. The extracted oil was transesterified into biodiesel using silica doped with zinc oxide as novel heterogeneous nanocatalyst. The maximum biodiesel yield of 97.43% was obtained at optimized conditions of 800 °C calcination temperature, 8% catalyst concentration, 9:1 methanol to oil ratio, 55 °C reaction temperature and 50 min reaction time. The kinetics of the transesterification reaction was also studied. The Ulva lactuca was found as a potential source for biodiesel production.

Catalytic pyrolysis of ulva lactuca (UL) macroalgae was studied over a series of ZrO2 supported metal such as Co, Ni and Co-Ni metal catalysts at temperature range of 300-500 °C. Highest bio-oil yield (47.8 wt%) was found with Co-Ni/ZrO2 (10 wt%) catalyst while non-catalytic yielded 42.5 wt% bio-oil. Moreover with increases the metal amount to 15 wt%, the bio-oil yield slightly increased (49.2 wt%). The bio-oil quality significantly improved with using the catalysts compared to the non-catalytic pyrolysis. Catalytic pyrolysis also revealed that introducing Co-Ni into the ZrO2 could result in higher surface area and which increased active sites. Catalytic bio-oils were consisted of mainly long chain hydrocarbon in the range of C6-C16. Moreover, the catalytic bio-oils were showed the higher 'high heating value' (HHV) 38.1 MJ/kg as compare to non-catalytic bio-oils (29.4 MJ/kg). Catalysts have been showed excellent recyclability on bio-oil yield and compounds selectivity.

Exploiting solar energy for growing algal biomass in waters enriched with farm manures is a holistic method of waste management. The proposed cultivation strategy termed SAR'CENA ('Synergistic Algal Refinery for Circular Economy using Nutrient Analogues), involves integrated cultivation of microalga, Scenedesmus obliquus and marine macroalga, Ulva lactuca in litter to harness biorefinery products. From various litters tested, poultry litter manure (PLM) was most amenable for growth. The microalga yielded 410 ± 6.2 g·DW· m−2· d−1 of biomass with total nitrogen (TN) concentration of 70 mg·L−1 in the media, while the macroalgae yielded 334 ± 9.9 g DW m−2 d−1 of biomass with TN concentration of 17.5 mg·L−1. The nutrient uptake efficiency was observed to be >60% with uncompromised biomass composition. Thus, SAR'CENA is projected as an ideal farming solution incorporating efficient waste management and feedstock generation thereby establishing a circular economy towards clean energy.

Conventional open-sea cultivation constrained by environmental factors is singly incompetent to sustain the rising seaweed demand. This necessitates a complementary strategy to reinforce the existing cultivation system and expand the global seaweed industry. Present study proposes cultivation of Ulva lactuca in temperature controlled flat panel photobioreactors under natural illumination. Adaptability of U. lactuca to the flat panel system is apparent through growth studies and photosynthetic performance (Fv/Fm) across individual panels. Evident effect of annual variation in irradiance on daily growth rates, biomass productivity and composition is portrayed. Significance of initial stocking density and harvesting frequency is highlighted. Poultry litter extract was used as an alternative N-source for sustainable cultivation. The maximum achievable productivity was 303gm-2d-1 (fresh weight) expanding to 910tonsha-1yr-1 including biomass composition consistent with the control media. The present pilot scale study delivers valuable information for commercial scale photobioreactors for seaweed cultivation.

The present study describes an advanced biorefinery model for marine macroalgae that assumes significant importance in the context of marine bio-economy. The method investigated in this study integrates the extraction of crude proteins with recovery of minerals rich sap, lipids, ulvan and cellulose from fresh biomass of Ulva lactuca. The protein content extracted was 11±2.12% on dry weight basis with recovery efficiency of 68.75±4.01%. The amino acid composition of crude protein fraction showed iso-leucine as the most abundant amino acid with 16.51±0.03% followed by histidine, arginine, tyrosine, serine, aspartic acid, threonine, phenyl alanine, leucine, alanine, lysine, glycine and glutamic acid (0.22±0.24%). The digestibility of protein was as high as 85.86±5.92% indicating its suitability for use in food supplements. The protein production with co-recovery of other products would not only result in effective utilisation marine macroalgal resources but also forms the basis for marine bio-economy.

Three species of macroalgae ( Ulva lactuca , Laminaria japonica and Gelidium amansii ) were converted into liquid oils via deoxy-liquefaction. The elemental analysis, FTIR and GC–MS results showed that the three liquid oils were all mainly composed of aromatics, phenols, alkanes and alkenes, other oxygen-containing compounds, and some nitrogen-containing compounds though there were some differences in terms of their types or contents due to the different constituents in the macroalgae feedstocks. The oxygen content was only 5.15–7.30% and the H/C molar ratio was up to 1.57–1.73. Accordingly, the HHV of the three oils were 42.50, 41.76 and 40.00 MJ/kg, respectively. The results suggested that U. lactuca , L. japonica and G. amansii have potential as biomass feedstock for fuel and chemicals and that deoxy-liquefaction technique may be an effective way to convert macroalgae into high-quality liquid oil.

Green seaweed Ulva lactuca harvested from the North Sea near Zeeland (The Netherlands) was characterized as feedstock for acetone, ethanol and ethanol fermentation. Solubilization of over 90% of sugars was achieved by hot-water treatment followed by hydrolysis using commercial cellulases. A hydrolysate was used for the production of acetone, butanol and ethanol (ABE) by Clostridium acetobutylicum and Clostridium beijerinckii. Hydrolysate-based media were fermentable without nutrient supplementation. C. beijerinckii utilized all sugars in the hydrolysate and produced ABE at high yields (0.35 g ABE/g sugar consumed), while C. acetobutylicum produced mostly organic acids (acetic and butyric acids). These results demonstrate the great potential of U. lactuca as feedstock for fermentation. Interestingly, in control cultures of C. beijerinckii on rhamnose and glucose, 1,2 propanediol was the main fermentation product (9.7 g/L).

Algae biomass is a potential raw material for the production of biofuels and other chemicals. In this study, biomass of the marine algae, Ulva lactuca, Gelidium amansii,Laminaria japonica, and Sargassum fulvellum, was treated with acid and commercially available hydrolytic enzymes. The hydrolysates contained glucose, mannose, galactose, and mannitol, among other sugars, at different ratios. The Laminaria japonica hydrolysate contained up to 30.5% mannitol and 6.98% glucose in the hydrolysate solids. Ethanogenic recombinant Escherichia coli KO11 was able to utilize both mannitol and glucose and produced 0.4g ethanol per g of carbohydrate when cultured in L. japonica hydrolysate supplemented with Luria-Bertani medium and hydrolytic enzymes. The strategy of acid hydrolysis followed by simultaneous enzyme treatment and inoculation with E. coli KO11 could be a viable strategy to produce ethanol from marine alga biomass.

After extensive analysis, Ulva lactuca dried algae, collected from the Monastir coastal zone, was proven to be successful as an adsorbent for the removal of certain inorganic pollutants. The main objective of this study was the nonlinear modeling of heavy metal removal from an aqueous solution, using a freely available and well analyzed biomaterial, as well as the evaluation of its efficacy on various metal ion sorptions. Although relatively low specific surface area, compared to more conventional adsorbents, the selected biomaterial displays very interesting retention capacities when used with aqueous inorganic pollutants. The pseudo, first and second-order kinetic models were used to investigate the kinetic retention mechanism. Assuming the nonlinear form, the results indicate that the retention mechanism is diffusion controlled. Concerning the heavy metal uptake capacity, it was found that the selected biomaterial has a retention capacity of 67 mg g−1 of Ni(II), 112 mg g−1 of Cu(II), 127 mg g−1of Cd(II) and 230 mg g−1 of Pb(II).

Ulva lactuca , a green seaweed, accumulates on beaches and shallow estuaries subject to eutrophication. As a residue, and a macro-algae, it is a source of sustainable third generation biofuel. Production of biomethane from mono-digestion of U. lactuca , however is problematic due to high levels of sulphur and low ratios of carbon to nitrogen. Fresh and dried U. lactuca were continuously co-digested with dairy slurry at ratios of 25%, 50% and 75% (by volatile solid content) in 6 number 5 L reactors for 9 months. The reactors digesting a mix with 75% U. lactuca struggled to reach stable conditions. Volatile fatty acid levels of 14,000 mg l −1 were experienced. The levels of ammonia increased with percentage U. lactuca in the mix. Optimum conditions were observed with a mix of 25% fresh U. lactuca and 75% slurry. A yield of 170 L CH 4 kg −1 VS was achieved at an organic loading rate of 2.5 kg VS m −3 d −1 .

The mercury biosorption onto non-living protonated biomass of Ulva lactuca, as an alternative method for mercury removal from aqueous solutions, was investigated. Batch equilibrium tests showed that at pH 3.5, 5.5 and 7 the maxima of mercury uptake values, according to Langmuir adsorption isotherm, were 27.24, 84.74 and 149.25 mg/g, respectively. The ability of Ulva lactuca biomass to adsorb mercury in fixed-bed column, was investigated as well. The influence of column bed height, flow rate and effluent initial concentration of metal was studied. The adsorbed metal ions were easily desorbed from the algal biomass with 0.3 N H(2)SO(4) solution. After acid desorption and regeneration with distilled water, the biomass could be reused for other biosorption assays with similar performances.