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Three species of macroalgae were treated with the aim of reducing nitrogen, sulfur and ash within the biomass prior to hydrothermal processing. The treatments were the nutrient starvation of cultures and post-harvest washing of biomass in freshwater. Subsequently, hydrothermal liquefaction (HTL) of macroalgae was carried out in a batch reactor heated for 8 min with a maximum temperature of 345 °C. Nutrient starvation effectively reduced nitrogen and sulfur levels within the biomass, which led to a reduction in nitrogen by 51–59 wt.% and sulfur by 64–88 wt.% within the biocrude. The yield of biocrude was highest for Derbesia at 38.6–41.7 wt.% and Oedogonium at 35.6–38.8 wt.% when not starved, but was reduced by up to 19 wt.% when the biomass was starved. The washing of biomass consistently reduced the ash content for all species by 7–83 wt.%. The removal of ash affected neither the quality nor the quantity of biocrude produced. The two treatments demonstrate that macroalgal biomass can be effectively manipulated in the production process to modify the composition of the feedstock and, consequently, improve the quality of biocrude. Additionally, reducing the ash content of biomass minimizes its potential impact on HTL processing equipment.

This paper proposes a mapping model for seaweed aquaculture based on Interval Type-2 Fuzzy Sets (IT2FS) and Multi-Layer Perceptron (MLP) algorithm as a new framework to map potential area for seaweed cultivation to face uncertainty business environment. The main output of this research is a framework as a conceptual model for seaweed potential area mapping based on IT2FS and MLP; and visualization model from the proposed framework using google map API. We use MLP to learn historical data of variables that affect seaweed cultivation and predict future environment condition. The output of MLP used as input for IT2FS for inference process. The decision output from IT2FS is potential or not potential with specific prediction of production size for each region. We test our model for potential mapping in South Sulawesi’s seaweed aquaculture Indonesia. The test result shows our mapping model can provide potential area with total production size each area in South Sulawesi Indonesia.

Marine algae, popularly known as sea-weeds, are sources of food, fodder, ferti-lizer, medicine and chemicals1. Worldtrade in seaweed and its products was val-uedat US $50million in 1970, US $250million in 1990 and US $6.2billion in1999 (refs 1 and 2). About 20,000 marinealgae species are distributed throughoutthe world, out of which only 221 speciesare utilized commercially. These include145 species for food and 110 species forphycocolloid production1.Porphyra(Ban-giales,Rhodophyta) popularly known as‘Nori’ in Japan, ‘Kim’ in Korea and ‘Zicai’in China has an annual value of over US$1.8billion3.Porphyrais primarily usedas food, wrapped around the Japanesedelicacy ‘Sushi’ whichconsists of roas-ted blades, raw fish, rice and other ingre-dients. The alga is not only delicious butalso contains high levels of protein (25–50%), vitamins (higher vitamin C than inoranges), trace minerals and dietary fibres4.The plant contains nearly17 types offree amino acids, including taurine whichcontrols blood cholesterol levels5. Thealga is a preferred source of the red pig-mentr-phycoerythrin, which is utilizedas a fluorescent ‘tag’ in the medical diag-nostic industry6.Porphyrahas been cul-tivated for the past hundred years in Japanand today it is one of the largest aquacul-ture industries in Japan, Korea andChina6. Because of its economic impor-tance and other health benefits,Porphyracultivation is now being expanded toother countries7. Recently, it has beenfound that the plant has much more poten-tial and can be used as an experimentalsystem likeArabidopsis thalianain thehigher plants, some aspects of which arediscussed here.

Recent studies combining biochemical, molecular, and traditional morphological and ecological traits have shown that some currently recognized species of the red algal genus Porphyra are actually form species or complexes comprising several morphologically similar but genetically distinct taxa. Conflicting reports of chromosome numbers and differences in DNA sequences for Porphyra purpurea (Roth) C. Agardh have raised suspicion that more than one taxon has been confused under this name in the Northwest Atlantic. We have identified one of these cryptic taxa and describe it here as a new species, Porphyra birdiae. Like P. purpurea, it has an ovate to broadly elongate, foliose blade with reproductive areas segregated by a distinct line into male and female sectors. While reproductive specimens have historically been confused with P. purpurea, non-reproductive specimens of P. birdiae have been incorrectly identified as P. umbilicalis Kutzing. Although P. birdiae is morphologically similar to both of these species, sequences of SSU (nuclear small subunit rRNA gene) and rbcL (plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene) indicate that it is not closely related to either one. Based on rbcL sequences, P. birdiae is closely related to P. aestivalis Lindstrom et Fredericq, a proposed new species from Alaska.