The utilization of lignocellulosic biomass in various applications has a promising potential as advanced technology progresses due to its renowned advantages as cheap and abundant feedstock. The main drawback in the utilization of this type of biomass is the essential requirement for the pretreatment process. The most common pretreatment process applied is chemical pretreatment. However, it is a non-eco-friendly process.
|No.||Title||Highlights of Review||Ref.|
|1.||Enzymatic pretreatment of lignocellulosic biomass for enhanced biomethane production-A review||
|2.||A review on the environment-friendly emerging techniques for pretreatment of lignocellulosic biomass: Mechanistic insight and advancement||
|3.||Recent Insights into Lignocellulosic Biomass Pyrolysis: A Critical Review on Pretreatment, Characterization, and Products Upgrading||
|4.||Recent advances in the pretreatment of lignocellulosic biomass for biofuels and value-added products||
|5.||Emerging technologies for the pretreatment of lignocellulosic biomass||
|Retting Period||0 Days||7 Days||14–20 Days||After 50 Days|
|Changes in the hemp stem’s and fibre’s ultrastructure||(i) Stem with a well-preserved layered structure
(ii) Un-collapsed, unbroken cells with their original cell geometry
(iii) Living cells with cytoplasm
(iv) Cuticle and trichomes are unharmed on the clear surface.
(v) Chloroplasts in abundance in the upper epidermis
|(i) The structure as a whole is in good condition.
(ii) Fungal growth on the outside of the stems and inside the stems
(iii) With damaged epidermis and parenchyma, cellular architecture is less stable.
|(i) Cuticle has seriously deteriorated.
(ii) Changes in cellular anatomy, as well as significant loss of live cells
(iii) Fibre bundles were isolated from each other and the epidermis.
(iv) Thick-walled cells populate seldom; parenchyma degrades completely, although chlorenchyma suffers less harm.
(v) Bast fibres with sporadic moderate attacks
(vi) Fungi colonisation and decay morphology were both affected by fibre morphology.
|(i) The structure of hemp was severely harmed and dissolved.
(ii) The epidermis and cambium were heavily invaded by dominating bacteria.
(iii) In the bast regions, the parenchyma cells have been destroyed, and the structural integrity has been lost.
(iv) All cell types, including fibre cells, have hyphae inside their lumina.
(v) BFIs are more intense inside the stem.
(vi) Anatomy and ultrastructure have been severely harmed.
(vii) Bast fibres with a thick wall and degradation properties
(viii) Effects on the ultrastructure of the fibre wall.
|The dynamics and activity of microbes||Fungi
(i) Rarely seen Bacteria
(ii) Not observed Fungi
(i) Mycelia with sparse growth
(ii) Less variety
(iii) Outside of the cortical layers, colonisation occurs largely in live cells.
(iv) Trichomes near to the surface trichomes have dense colonisation.
(v) Dependence on readily available food
(vi) Damage to cell walls is reduced.
(i) Less abundant
(i) Extensive and plentiful
(ii) Mycelia densely covering the cuticle
(iii) diverse population
(iv) a large number of spores
(v) Interactions and activities that are intense
(ii) Diverse population
iii) Over the cuticle, colonies
(iv) Associated with hyphae and fungal spores
(v) After 20 days, there are more noticeable activity
(vi) Cuticle has severely deteriorated
(i) Less abundant on the outside of the stem
(ii) Mycelia on the surface is dead, but there are active hyphae inside the stem
(iii) Mycelia, an invading bacteria’s sole source of nourishment, showed bacterial mycophagy (i.e., extracellular and endocellular biotrophic and extracellular necrotrophic activities).
(i) Highly abundant inside and outside the stems
(ii) Highly dominant and diverse role.
(iii) Visible as dense overlay representing
(b) Morphologically different
(c) Randomly scattered cells
(iv) Showed strong BFIs
(v) Using fungal highways, bacterial movement occurs over and inside the hemp stem.
(vi) Cutinolytic and cellulolytic activities were improved.
|Substrate||Conditions||Component’s Degradation (%)|
|1st Step||2nd Step||Lignin||Hemicellulose||Cellulose|
|Corn stalks||Irpex lacteus (28 °C, 15 d)||0.25 M NaOH solution
(75 °C, 2 h)
|Populus tomentosa||Trametes velutina D10149 (28 °C, 28 d)||70% (v/v) ethanol aqueous solution containing 1%(w/v) NaOH (75 °C, 3 h)||23.08||22.22||18.91|
|Willow sawdust||Leiotrametes menziesii (27 °C, 30 d)||1% (w/v) NaOH (80 °C, 24 h)||59.8||68.1||51.2|
|Abortiporus biennis (27 °C, 30 d)||54.2||51.8||29.1|
|Populus tomentosa||Trametes velutina D1014 (28 °C, 56 d)||1% sulphuric acid (140 °C, 1 h)||23.82||75.96||(+) 18.74|
|Oil palm empty fruit bunches||Pleurotus floridanus LIPIMC996 (31 °C, 28 d)||Ball milled at 29.6/s for 4 min. Phosphoric acid treatment (50 °C, 5 h)||(+) 8.29||60.63||(+) 37.52|
|Olive tree biomass||Irpex lacteus (Fr.238 617/93) (30 °C, 28 d)||2% w/v H2SO4 (130 °C, 1.5 h)||(+) 105.82||75.29||(+) 62.95|
|Corn Straw||Echinodontium taxodii (25 °C, 15 d)||0.0016% NaOH and 3% H2O2 (25 °C, 16 h)||52.00||23.64||(+) 45.45|
|Hemp chips||Pleurotus eryngii (28 °C, 21 d)||3% NaOH and 3% (v/v) H2O2 (40 °C, 24 h)||55.7||23.2||25.1|
|Sugarcane straw||Ceriporiopsis subvermispora (27 °C, 15 d)||Acetosolv pulping (Acetic acid with 0.3% w/w HCl) (120 °C, 5 h||86.8||93.8||32.1|
|Pinus radiata||Gloeophyllum trabeum (27 °C, 28 d)||60% ethanol in water solvent (200 °C, 1 h)||74.26||80.74||-|
|Biological—liquid hot water (LHW) pretreatment|
|Soybean||Liquid Hot water (170 °C, 3 min, 400 rpm, 110 psi, solid to liquid ratio of 1:10)||Ceriporiopsis subvermispora (28 °C, 18 d)||36.69||41.34||0.84|
|Wheat straw||Hot water extraction (HWE) (85 °C, 10 min, solid to liquid ratio of 1:20)||Ceriporiopsis subvermispora (28 °C, 18 d)||24.87||13.19||1.86|
|Biological—steam explosion pretreatment|
|Beech woodmeal||Phanerochaete chrysosporium (37 °C, 28 d)||Steam explosion (215 °C, 6.5 min)||42.00||-||-|
|Sawtooth oak, corn and bran||Lentinula edodes (120 d)||Steam explosion (214 °C, 5 min, 20 atm)||17.1||80.43||(+) 5.19|