Ensilage and anaerobic digestion of Sargassum muticum

Many industrial sectors are likely to generate highly saline wastewater: these include the agro-food, petroleum and leather industries. The discharge of such wastewater containing at the same time high salinity and high organic content without prior treatment is known to adversely affect the aquatic life, water potability and agriculture. Thus, legislation is becoming more stringent and the treatment of saline wastewater, both for organic matter and salt removal, is nowadays compulsory in many countries. Saline effluents are conventionally treated through physico-chemical means, as biological treatment is strongly inhibited by salts (mainly NaCl). However, the costs of physico-chemical treatments being particularly high, alternative systems for the treatment of organic matter are nowadays increasingly the focus of research. Most of such systems involve anaerobic or aerobic biological treatment. Even though biological treatment of carbonaceous, nitrogenous and phosphorous pollution has proved to be feasible at high salt concentrations, the performance obtained depends on a proper adaptation of the biomass or the use of halophilic organisms. Another major limit is related to the turbidity problems inherent in saline effluents. For this reason, the major need for research in the future will be the combination of physico-chemical/biological treatment of saline industrial effluents, with regard to the global treatment chain, in order to meet the regulations.

As world energy demand continues to rise and fossil fuel resources are depleted, marine macroalgae (i.e., seaweed) is receiving increasing attention as an attractive renewable source for producing fuels and chemicals. Marine plant biomass has many advantages over terrestrial plant biomass as a feedstock. Recent breakthroughs in converting diverse carbohydrates from seaweed biomass into liquid biofuels (e.g., bioethanol) through metabolic engineering have demonstrated potential for seaweed biomass as a promising, although relatively unexplored, source for biofuels. This review focuses on up-to-date progress in fermentation of sugars from seaweed biomass using either natural or engineered microbial cells, and also provides a comprehensive overview of seaweed properties, cultivation and harvesting methods, and major steps in the bioconversion of seaweed biomass to biofuels. Copyright © 2012 Elsevier Ltd. All rights reserved.

A preliminary classification of five macroalgae from the British Isles; Fucus vesiculosus, Chorda filum, Laminaria digitata, Fucus serratus, Laminaria hyperborea, and Macrocystis pyrifera from South America, has been presented in terms of a Van Krevelen diagram. The macroalgae have been characterised for proximate and ultimate analysis, inorganic content, and calorific value. The different options for thermal conversion and behaviour under combustion and pyrolysis have been evaluated and compared to several types of terrestrial biomass including Miscanthus, short rotation Willow coppice and Oat straw. Thermal treatment of the macroalgae has been investigated using thermogravimetry (TGA) and pyrolysis-gc-ms. Combustion behaviour is investigated using TGA in an oxidising atmosphere. The suitability of macroalgae for the different thermal processing routes is discussed. Ash chemistry restricts the use of macroalgae for direct combustion and gasification. Pyrolysis produces a range of pentosans and a significant proportion of nitrogen containing compounds. High char yields are produced.