An economic and ecological perspective of ethanol production from renewable agro waste: a review

Abstract

Agro-industrial wastes are generated during the industrial processing of agricultural products. These wastes are generated in large amounts throughout the year, and are the most abundant renewable resources on earth. Due to the large availability and composition rich in compounds that could be used in other processes, there is a great interest on the reuse of these wastes, both from economical and environmental view points. The economic aspect is based on the fact that such wastes may be used as low-cost raw materials for the production of other value-added compounds, with the expectancy of reducing the production costs. The environmental concern is because most of the agro-industrial wastes contain phenolic compounds and/or other compounds of toxic potential; which may cause deterioration of the environment when the waste is discharged to the nature. Although the production of bioethanol offers many benefits, more research is needed in the aspects like feedstock preparation, fermentation technology modification, etc., to make bioethanol more economically viable.

Bioethanol Production from Renewable Raw Materials and its Separation and Purification: a Review

“…Despite huge interest and adequate progress in the lignocellulosic bioethanol research and development, many challenges still need to be solved ( 26 , 86 , 104 - 107 ). …”

Rapid and Effective Oxidative Pretreatment of Woody Biomass at Mild Reaction Conditions and Low Oxidant Loadings

“…Microplate (96-well; Sarstedt, Germany) layout for three-tier screening. Fusarium oxysporum wild-type strain 11C (WT) and putative transformants were inoculated into columns (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) and screened across five treatments: T1; no ethanol, T2; hygryomcinB (60 μg ml -1 ; Sigma, UK), T3; 0.5% (vv -1 ) ethanol (ethyl alcohol; Sigma, UK), T4; 6% (vv -1 ) ethanol T5; 10% (vv -1 ) ethanol with treatments positioned in rows (A-F) (Primary-tier) (A) or into rows (A-H) and then transferred and Generating and screening Fusarium oxysporum strain 11C transformants. Inoculation of Fusarium oxysporum strain 11C into Mung bean broth [32] for 5 days at 25°C and collection of conidia by filtration through sterile cheesecloth, washing twice with sterile distilled water and adjusting spore concentration to 10 4 conidia per ml (A) Inoculation of Agrobacterium tumefaciens strain AGL-1 to minimal medium (MM) [34] supplemented with Kanamycin (50 μg ml -1 ) for 2 days at 28°C (OD 600nm 0.4-0.6) followed by dilution to OD 600nm of 0.15 in induction medium (IM) [34] supplemented with 200 μM acetosyringone (AS) and incubation for 6 hours at 28°C (B) Co-cultivation of an equal volume of bacterial and fungal cells for 30 minutes at 28°C in liquid co-cultivation medium [34] followed by spreading 100 μl mix onto a UVsterilised cellulose filter membrane placed on solid cocultivation medium on large Petri plates (150x20mm) for 2 days at 25°C where if transformation is successful, T-DNA is transferred from AGL-1 to F. oxysporum strain 11C and randomly integration into the fungal genome results (C) Transfer of cellulose filter membrane to modified selection medium (SM) on large Petri plates (150x20mm) supplemented with 60 hygromycinB for 7-9 days at 25°C followed by isolation of hygromycinB (60 μg ml -1 ) resistant putatively transformed colonies into microtiter (96-well) plates with minimal medium [37] supplemented with hygromycinB (60 μg ml -1 ) for 3 days at 25°C (D) Transfer of putative transformants to microtiter (96-well) plate with minimal medium supplemented with ethanol and butanol selection for primary alcohol tolerance screening followed by purification and PCR prior to two additional rounds of screening (2° and 3°) and selection of candidates for future analysis (E).…”

“…Inoculum was harvested by centrifugation and washed twice with sterile distilled water and resuspended in minimal medium [37] to a concentration of 10 6 ml -1 conidia. Microtiter (96-well) plates were prepared with wells containing 100 μl minimal medium supplemented with either no alcohol, ethanol [2,4,6,8 Figure S1C for plate layout). Each plate was inoculated with 100 μl fungal conidia (10 6 ml -1 ) (eight wells per treatment per wild type/ transformant strain).…”

Combined sodium hydroxide and ammonium hydroxide pretreatment of post-biogas digestion dairy manure fiber for cost effective cellulosic bioethanol production

“…The effects anaerobic bacterial digestion lead to smaller particle sizes [20]. In general, particle size plays a significant role in the effectiveness of the pretreatment and fermentation steps [51,52], with smaller fiber size being advantageous for bioconversion. The PBD manure fiber contained 41.1% carbohydrate by weight, of which 23.6% was glucose and 17.5% other sugars (xylose, galactose, arabinose and mannose) ( Table 1).…”