Food waste bioethanol

Geobacillus stearothermophillus, for example is one of the most commonly used thermophilic bioethanol producing strains. It is a rod-shaped. Grampositive bacterium with a living temperature of 30-75 °C. It was first isolated from food waste materials. Wild G. stearothermophillus strain produces lactic acid as the main product with trace amounts of ethanol, acetic acid and formic acid as by-products. The genetic modification on G. stearothermophillus has been investigated to block the pathway from pyruvate to... 

Alamanou, D.G., Malamis, D., Mamma, D., Kekos, D., 2015. Bioethanol from dried household food waste applying non-isothermal simultaneous saccharification and fermentation at high substrate concentration. Waste and Biomass Valorization 6 (3), 353—361. 

Table 20.4 Bioethanol production from food waste... 

Both in the USA and the EU, the introduction of renewable fuels standards is likely to increase considerably the consumption of bioethanol. Lignocelluloses from agricultural and forest industry residues and/or the carbohydrate fraction of municipal solid waste (MSW) will be the future source of biomass, but starch-rich sources such as corn grain (the major raw material for ethanol in USA) and sugar cane (in Brazil) are currently used. Although land devoted to fuel could reduce land available for food production, this is at present not a serious problem, but could become progressively more important with increasing use of bioethanol. For this reason, it is important to utilize other crops that could be cultivated in unused land (an important social factor to preserve rural populations) and, especially, start to use cellulose-based feedstocks and waste materials as raw material. 

All considerations for the use of lignocelluloses for the production of bioethanol or other platform chemicals should include the overall mass and energy balance as well as the availability through the year and the transportation needed. Regarding a study of IEA/OECD 2010 [9], there is no additional land available in the short term and only 10% of global forestry and agricultural residues are assumed to be available for biofuel or platform chemical production. Therefore, there will always be a direct competition of bioethanol or other platform chemicals production with food production even if so-called plant waste material is used as the real limitation is the arable land available. 

While those processes involving enzymes tend to progress at rather leisurely paces, some fermentation processes may be limited by oxygen availability and therefore susceptible to mass transfer intensification. The ability to intensify such reactions remains attractive in food production, some pharmaceutics production and waste disposal - in fact reactors such as those based upon oscillatory baffle movement are becoming increasingly a commercial reality - typified by the work of co-author Dr Adam Harvey at Newcastle University on his portable bioethanol plant. (As an aside, a literature search of process intensification inevitably encompasses intensive agriculture - PI on a grander scale )... 

Because of the high demand of biofuels in the present situation, several biorefineries have been established based on the availability of agriculture and forest products and also in efforts to utilize wastes obtainable from the paper and pulp industry, sugar mills, etc. (Cherubini et al., 2009). This system yields transportation fuels such as biodiesel and bioethanol, platform chemicals, and some chemical intermediates for cosmetics and pharmaceuticals. Since the Phase III biorefineries are the ones that may be expected to serve as an all-in-one source of food, feed, and platform chemicals, the various known forms of Phase 111 biorefineries are discussed in some detail below. 

Bioethanol (mainly from sucrose and starchy crops) and biodiesel production (via transesterihcation of triglycerides) are the main first-generation biofuels that are currently produced on industrial scale. Biodiesel is produced by transesterihcation of triacylglycerols with short-chain alcohols (mainly methanol or ethanol) to produce monoalkyl esters, namely fatty acid methyl esters (FAMEs) and fatty acid ethyl esters (FAEEs). The worldwide production of biodiesel is mainly dependent on the utilization of waste oils, animal fats, and oilseeds such as rapeseed, sunflower, and soybeans. The recent food crisis has shown that research should focus on the development of second-generation biofuels generated from lignocellulosic raw materials and industrial waste streams (eg, food industry wastes). 

Bioethanol is currently the most common biofuel worldwide (Ullah et al., 2014). It has many desirable features as an alternative to petroleum (Akhlaghi et al., 2015) and could help make a smoother transition from petroleum to bio-based industries (Chundawat et al., 2007). Unlike other bioalcohols which are still under investigation, bioethanol has emerged as a potential transportation fuel and has been used as oxygenate to replace MTBE (methyl tertiary butyl ether). Currently, the majority of bioethanol has been generated from food crops (Singh et al., 2014) and it is expected that new-generation biorefinery, which aims to use waste-derived feedstock, can reduce the need for food-crop-based bioethanol in the near future. 

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