A Review on Anaerobic Digestion of Lignocellulosic Wastes: Pretreatments and Operational Conditions

Abstract

Anaerobic digestion (AD) has become extremely popular in the last years to treat and valorize organic wastes both at laboratory and industrial scales, for a wide range of highly produced organic wastes: municipal wastes, wastewater sludge, manure, agrowastes, food industry residuals, etc. Although the principles of AD are well known, it is very important to highlight that knowing the biochemical composition of waste is crucial in order to know its anaerobic biodegradability, which makes an AD process economically feasible. In this paper, we review the main principles of AD, moving to the specific features of lignocellulosic wastes, especially regarding the pretreatments that can enhance the biogas production of such wastes. The main point to consider is that lignocellulosic wastes are present in any organic wastes, and sometimes are the major fraction. Therefore, improving their AD could cause a boost in the development in this technology. The conclusions are that there is no unique strategy to improve the anaerobic biodegradability of lignocellulosic wastes, but pretreatments and codigestion both have an important role on this issue.

Anaerobic Digestion of Industrial Tempeh Wastewater with Sludge from Cow Manure Biogas Digester as Inoculum: Effect of F/M Ratio on the Methane Production

“…More VFAs will be produced in this condition, resulting in pH drop, and subsequently affecting the composition of ionized ammonia (NH4 + ) and free ammonia (NH3). In this case, free ammonia (NH3) is the direct inhibitor to the methanogens because of its high permeability to the cell membranes [19]. In this study, it was indicated that ammonia (NH3) did not severely affect biogas production, considering that the concentration still at an acceptable level (Fig.…”

“…The turn-back pattern designates that the acidogenesis process will be gradually completed and followed by acetogenesis or methanogenesis. This pH turn-back is important since methanogenesis is reported to have optimum performance at the pH of 6.8-7.2 [17], [19]. The pH increase's ability may be determined by the alkalinity of the substrate/inoculum involved (adjusted) and the breakdown result of protein compounds.…”

Towards the Anchovy Biorefinery: Biogas Production from Anchovy Processing Waste after Fish Oil Extraction with Biobased Limonene

“…For this reason, it is possible that co-digestion with an additional substrate that has a higher C/N would be beneficial, as already demonstrated for other N-rich substrates (e.g., manure, slaughterhouse waste) [48,49].…”

Thermophilic Solid-State Anaerobic Digestion of Corn Straw, Cattle Manure, and Vegetable Waste: Effect of Temperature, Total Solid Content, and C/N Ratio

“…TAN includes both NH 4 + and free ammonia (FAN, NH 3 ). FAN is the main cause of ammonia inhibition because it is membrane permeable [ 26 , 27 ]. So far, a FAN calculation method has rarely been applied in SS-AD, the digestate of which generally has a higher ionic strength than that in L-AD [ 23 ].…”