Nizimuddinia zanardini macroalgae, harvested from Persian Gulf, was chem. characterized and employed for the prodn. of ethanol, seaweed ext., alginic acid, and biogas. In order to improve the products yields, the biomass was pretreated with dil. sulfuric acid and hot water. The pretreated and untreated biomasses were subjected to enzymic hydrolysis by cellulase (15 FPU/g) and β-glucosidase (30 IU/g). Hydrolysis yield of glucan was 29.8, 82.5, and 72.7 g/kg for the untreated, hot-water pretreated, and acid pretreated biomass, resp. Anaerobic fermn. of hydrolyzates by Saccharomycescerevisiae resulted in the max. ethanol yield of 34.6 g/kg of the dried biomass. A seaweed ext. contg. mannitol and a solid residue contg. alginic acid were recovered as the main byproducts of the ethanol prodn. On the other hand, the biogas yield from the biomass was increased from 170 to 200 m3 per ton of dried algae biomass by hot water pretreatment. [on SciFinder(R)]