General Information
The production of biogas, wine, rice vinegar and aginomoto has gradually realized industrialization level. In manufacturing process, a large amount of fermentation residues appear as one of the byproducts. Because of their exploitability and renewability, fermentation residues are continuously treated as a research object for new energy development and utilization experiments among which fermentation residue pelletization shows its recycling and environment friendly features. Introduction is revealed in this article including the reason, feasibility, pelletizing process, fermentation residue as well as characteristics of finished fermentation residue pellets.
1. What’s Fermentation Residue?
Fermentation refers to the process of microorganism decomposing 
organic substances, widely applied in agriculture, pharmaceuticals, brewing, food and chemistry industries. The leftovers after fermenting are called fermentation residues which can be got from the following producing process.
1.1. Animal and human manure/crop straw—biogas
1.2. Corn stalk—lactic acid and alcohol
1.3. Sweet sorghum stalks—ethyl alcohol
1.4. Dried potato or corn—wine
1.5. Sticky rice—rice wine and rice vinegar
1.6. Corn, rice, wheat and potato starch—aginomoto
From this we can see fermentation residues are most the leftovers of crops or crop straws that are frequently used to make biomass pellet fuel. As is known that, while fermenting, the chemical components of raw materials change yet many of their features remain the same. Thus, the pelletizing purpose of crop and crop straw also applies to their byproduct.
2. Why to make fermentation residue into biomass pellets?
2.1. Energy shortage
BP Energy prediction shows that, the global requirement for energy will rise by 45% up to 2030, which is equivalent to the increase of two US’s consumption. However, according to current exploiting level of fossil energy, the energy consumption in the future 20 years will not only do great harm to environment but also make its sustainability and price beyond people’s affordable scope.
The biomass power generation originated from 1970s in Denmark, and the biomass fuels such as crop straws, biogas, sawdust and rice husk are widely developed in many American and European countries since 1990. With continuous researches and development, traditional biomass resources have been gradually deep processed into various forms among which pellet fuels including fermentation residue pellets account for an essential place.
2.2. Reduce pollution and prevent fire hazard
People are used to paying much more attention to the end products than byproducts, which is why most of the fermentation residues left behind in food, brewing and other related industries are stacked up randomly by the road or in waste yard. First, this will bring our living atmosphere unnecessary pollution, leading by odor and visual damage. Second, any stacking will take up space that has higher value applied for garden or storage room building. Third, as an inflammable, the leftovers may be lighted easily by accident and cause fire hazard. However when comes to fermentation residue pelletizing, none of these is a problem.
2.3. Excellent combustion features of finished pellets
You may ask that we can use the leftovers as fuel directly, so is it necessary and wise to make them into fermentation residue pellets? Answer to this question can be learned from the following comparison.
| Item | Combustion time | Density | Application | Environmental friendly | Easy to store and deliver |
| Produced pellets | Long | High | Wide | Yes | Yes |
| Original leftovers | Short | Low | Narrow | No | No |
A. Combustion time: Because of their low moisture and ash content, fermentation residue pellets are more and more welcomed as a fuel with longer combustion time.
B. Density: The density of pelletized fermentation residues is much higher than that of original leftovers, reaching to 600-700kg/m³.
C. Application: Fermentation residue pellets can be applied both for household heating and in industrial factories, such as power station, chemistry mill and fertilizer factory, while the application scope of original leftovers is much narrower due to their inconvenience of storage and delivery.
D. Environmental friendly: Apart from the reduction of stacking pollution mentioned before, the sulfur content of pelletized fermentation residues is almost zero after processing, which prevents the appearance of acid rain.
E. Easy to store and deliver: Fermentation residue pellets weigh as high as 700kg/m³, while original leftovers only about 200-300kg. Therefore, the same space for fermentation residues can store or carry three times more pellets.
3. Is it feasible to make fermentation residue pellets?
3.1. Low cost and high profit
First, fermentation residues are easy to get. Most factories throw them away after related production is completed, so you just need pay a little or almost needn’t pay for them. Second, the wood pellet mill machine is cheap. Only several months are required to recoup this part of investment, after which all the output is profit, electricity and labor force cost plus a little routing maintenance expense. Third, since the automatic feeding and discharging devices are available, about three workers are enough for the whole producing operation.
3.2. Attribute feasibility
The following chart shows some components of fermentation residues (exemplified by wine brewing)
| Item | Water (after airing) | Lignin | Length | Ash |
| Content | 12-15% | 25%-35% | 3-5mm | 8% |
A. Water: The water content of fermentation residues after natural airing is 12-15% which is in the range of pellet mill’s requirement for raw material moisture, that is, 12%-18%.
B. Lignin: Adhesives are needed for successful molding. Lignin in leftovers can just play that role during the process of fermentation residue pelletizztion.
C. Length: The standard size to successfully do fermentation residue pellet is less than 6 mm, so no wood crusher is needed here.
D. Ash: The ash content of leftovers is only 8%, which prevents unnecessary environment pollution and avoids clogging in the process of fermentation residue pellet production.
4. How to make fermentation residue pellets?
The moisture content (after airing) and length are both within the required scope, so chipping, drying and crushing can be saved for fermentation residue pellet production. Only the following procedure is enough: pelletizing—cooling—screening—packing.
4.1. Pelletizing: As the core of fermentation residue pellets production, wood pellet mill works in virtue of high temperature and 
pressure. Leftovers are squeezed out of the die after being reshaped.
4.2. Cooling: The temperature of end fermentation residue pellets is about 90-95℃,so in order to avoid malfunction of subsequent devices, a wood cooler is required after pelletizing.
4.3. Screening: Screening is used to sieve any “fines” for further pelletized fermentation residue production.
4.4. Packing: After all the above procedures, pelletized fermentation residue should be properly packed and stored.
If you want to use the fresh leftovers without airing, just add a wood dryer before pelletizing; For a few fermentation residues whose length is beyond the required size, add a wood crusher before drying or pelletizing.
Conclusion
Want to turn waste into wealth? Want to make high profits from low investment? The above information can give you some hints about that. Making biomass into pellet fuel has become a trend, so have you kept up with it?
Related production line: 1.5 T/H Palm Waste Biomass Pellet Plant
