I saw everything

Chapter 171 Erwinia
6 month 29 day.

It was also the second day after Jiang Miao arrived at the Mo Nan branch.

Jiang Miao borrowed a laboratory set up by United Mining near the county seat of Jiayuan County. This laboratory was previously a small breeding laboratory invested by a cattle and sheep breeding company. However, in 23, the company ran into operational problems and was taken over by United Mining in April as an experimental base for researching bio-mining technology.

The laboratory is located in the southeast of the county seat, covering an area of ​​240 acres. Although the equipment inside is not very good, it can at least meet some microbial research needs.

As for Jiang Miao's loan, Lin Yonghua originally planned to let him use it for free, but Jiang Miao refused and asked them to prepare a lease contract. After all, he didn't need that little money. United Mining was not a wholly-owned subsidiary of Hailufeng Company, so this kind of thing should be taken more seriously.

Inside a simple laboratory.

Jiang Miao obtained various bacteria and fungi stored here. After all, this laboratory is to study biological mining technology, so there must be related microbial strains.

Last night, Jiang Miao got an inspiration during his conversation with Wu Song.

Wu Song mentioned the breeding base. With the expansion of the scale of cattle and sheep breeding, the cow dung and sheep dung excreted by cattle and sheep must be treated as soon as possible.

Generally speaking, there are four ways to deal with cattle and sheep manure in farms.

One method is to pile it up directly in the open air, then use it as fuel after it is air-dried.

One is to sell it to other companies or self-employed individuals in need.

One is to ferment compost and then return the fermented soil to the field as organic fertilizer, or sell the organic fertilizer.

One method is to first use it for fermentation to produce biogas, and then process the sludge and liquid into organic fertilizer for secondary use or sale.

Currently, the Mo Nan breeding base has adopted the third option, fermenting it into organic fertilizer.

As for why the fourth option with better economic benefits is not adopted, the answer is climate reasons.

The climate in the eastern part of the southern desert is similar to that in the northeast; it’s too cold.

You should know that in biogas fermentation, the temperature with better fermentation efficiency is 30-35 degrees Celsius. There are only 30-30 days a year in the eastern part of Monan when the daytime temperature is above 40 degrees Celsius.

Even if a cellar-type fermentation site is used, which can keep warm underground, the surface temperature still needs to be higher than 20 degrees Celsius. However, the number of days when the daytime temperature in the eastern part of Monan is higher than 20 degrees Celsius is only 90 to 120 days.

If artificial heating is used to maintain the fermentation temperature, is there still any point in fermenting biogas?

After all, the purpose of fermenting biogas is to use it as energy. Using artificial heating to maintain the temperature of the fermentation tank in cold weather will greatly increase production costs. The cost-performance ratio is too low and there is no economic benefit.

In the early 2000s, small-scale household biogas fermentation systems were vigorously promoted in the Yangtze River Basin in China. However, now those biogas fermentation cellars have been basically abandoned. The reason is that when the temperature drops, the fermentation efficiency drops significantly and the gas production decreases sharply.

Currently, only some areas in Guangxi Province still have villagers using biogas. This is because the climate in Guangxi Province is relatively hot, with daily temperatures above 20 degrees Celsius for about 200 to 250 days each year. Especially in the southern coastal areas of Guangxi Province, the temperature is above 250 degrees Celsius for almost 20 days. This environment allows the biogas fermentation system to operate efficiently for a long time.

Therefore, Wu Song never thought about building a biogas fermentation system near the breeding farm in Jiayuan County. After all, such a project is a thankless task.

But Wu Song's words reminded Jiang Miao.

Cow and sheep manure is actually a very complex resource.

It can be used as a raw material for organic fertilizer, a cultivation substrate for edible fungi, directly as a fuel, or fermented to produce biogas.

This is because cattle and sheep are unable to completely digest the roughage they eat, that is, they cannot completely digest the grass, and a large portion of the cellulose and lignin in the grass will remain.

In dry cattle and sheep manure, cellulose, hemicellulose and lignin account for 70-80%, and the remaining components are humus, water and inorganic salts.

This is also the fundamental reason why cow and sheep manure can be used as fuel after drying, because it is rich in carbon sources.

Under complete combustion conditions, the calories of 1 ton of dry cattle and sheep manure from grass-fed cattle and sheep are roughly equivalent to 0.75 tons of thermal coal; if the cattle and sheep manure is higher in grain-fed content, each ton is equivalent to 0.7 tons of thermal coal.

This is not proper bio-coal.

As to why no thermal power plant uses cow dung or sheep dung as fuel, there are many reasons.

For example, the channels for obtaining raw materials are relatively complicated, collection is difficult, and the production areas are scattered, which is not conducive to the stable production of thermal power plants; there are certain differences in the calorific value of cattle and sheep manure in various places, which increases the difficulty of heat management in the power generation process; if the cattle and sheep manure is not dried in advance, it will increase the difficulty and cost of transportation, and the smell is very unpleasant.

At the same time, the price of thermal coal used as fuel is only 500 to 800 yuan per ton.

Therefore, no thermal power plant will use cow or sheep dung as fuel.

However, some herdsmen in the southern desert, western regions and snowy regions of China dry cow and sheep dung and use it as fuel in their daily lives.

Jiang Miao didn't build a thermal power plant just for the hundreds of tons of fresh cow and sheep dung every day.

He thought of another technology that could make use of the cow and sheep manure: microbial fuel cells.

The so-called microbial fuel cell technology is a technology that utilizes the extracellular electrogenic bacteria in microorganisms to migrate electrons produced during metabolism, thereby achieving bio-power generation.

The advantage of this technology is that it is environmentally friendly.

The disadvantage is that the efficiency is too low. Each cubic meter of high-carbon source culture medium can only generate 10 to 20 kWh of electricity; while direct combustion power generation can generate about 500 kWh of electricity.

The two are not comparable.

Moreover, the so-called power generation per cubic meter of high-carbon source culture medium is also achieved under very good laboratory conditions.

For example, in a paper published on June 2024, 6, a research team led by Chinese scientists Duan Xiangfeng and Huang Yu developed a new type of microbial flow fuel cell (MFFCs), which uses artificial electron mediators to efficiently transfer bacterial metabolic electrons in the flowing medium, with a maximum power density of up to 23 mW/cm (equivalent to 17.6 watts per cubic meter).

According to the data obtained by Jiang Miao, their experimental system can only run for about 90 hours in a laboratory environment, after which its efficiency drops sharply.

According to this data, after being converted into cubic meters, during the stable peak power generation period, it can generate about 15.84 degrees of electricity. Combined with the subsequent low-power power generation, the maximum is about 20 degrees.

However, the maximum power of microbial fuel cells under non-laboratory conditions is only tens of watts per cubic meter.

Of course, under non-laboratory conditions, since bacteria do not decompose organic matter very quickly, the power generation time will be extended to several months, so the total power generation is still around 10 to 20 degrees.

如果每立方米发电功率176瓦特，可以维持1个月时间，那一个月的发电量就是126.72度、两个月就是252度、三个月则来到了378度。

Is it possible to achieve stable power generation for a long time under high power conditions?

The answer is yes.

Currently, under non-laboratory conditions, the energy conversion efficiency of extracellular electrogenic bacteria is 10-30%, while under laboratory conditions it can reach 60-70%.

And one situation needs special attention.

That is, the organic matter in the culture medium ≠ the organic matter consumed by the extracellular electrogenic bacteria.

Extracellular electrogenic bacteria can only decompose and digest a small portion of organic matter.

For example, among the extracellular electrogenic bacteria, Pseudomonas aeruginosa, its diet only includes: carbohydrates
Glucose, xylose, starch in sugars; amino acids, urea in nitrogen-containing compounds; triglycerides, phospholipids in fats; aromatic compounds.

From this we can see that many extracellular electrogenic bacteria cannot directly digest cellulose, hemicellulose and lignin in cattle and sheep manure.

If cellulose, hemicellulose and lignin can be decomposed into glucose, monosaccharides and aromatic compounds, they can be directly utilized by some extracellular electricity-producing bacteria.

In fact, a small number of extracellular electrogenic bacteria can also decompose cellulose, hemicellulose, and lignin, but the decomposition efficiency is relatively low.

What Jiang Miao has to do now is to develop extracellular electricity-producing bacteria that can efficiently decompose cellulose, hemicellulose, and lignin. In fact, the European Union has a related scientific research team that has transformed E. coli through genetic modification technology, giving it the ability to generate electricity through metabolism, while also allowing it to decompose some hemicellulose.

It was not difficult for Jiang Miao to conduct this kind of directional research.

Screening and cultivating efficient specialized extracellular electricity-producing bacteria is Jiang Miao's forte.

He doesn't even need to use genetic modification technology. He can directly force the extracellular electricity-producing bacteria to mutate through various artificial environmental pressures. Bacteria reproduce very quickly and mutate very quickly, which is very beneficial for the specialized cultivation of bacterial species.

Using electric current, pH, chemicals, freezing, high temperature, ultraviolet rays and other means, as well as various simulated cultivation environments, it only took Jiang Miao three days to obtain a specialized extracellular electricity-producing bacteria.

The parent strain of this extracellular electrogenic bacteria is the Erwinia billingiae QL-Z3 strain of the genus Erwinia. According to its original characteristics, if lignin is used as the only carbon source, its lignin degradation rate can reach 25.24%.

After multiple mutations and screening and cultivation, the bacteria can not only degrade lignin, but also cellulose and hemicellulose, with the highest degradation rate reaching about 97%.

Of course, this optimal degradation rate is definitely not so easy to achieve.

To be precise, this new bacterium named "Owen Electric Bacteria" by Jiang Miao needs to meet very stringent conditions to achieve the best degradation rate. There are four conditions:
First, the temperature of the living environment must reach 20 to 28 degrees Celsius.

Secondly, it needs to coexist with a special Gram-negative bacterium, which secretes a substance called quorum sensing signal molecule during its growth. When the bacterial density reaches a certain threshold, these signal molecules will activate a series of gene expressions to promote the reproduction of itself and the Erwinia bacteria. The metabolites of the two can promote each other.

Third, a specific dose of soy genistein (a type of estrogen) needs to be added to stimulate the further reproduction of Owen's electric bacteria and the degradation of lignin, cellulose, and hemicellulose.

Fourth, the oxygen concentration in the environment needs to reach 32%.

In fact, during the experiment, Jiang Miao did find other mutant bacteria with fewer degradation conditions, but it was precisely because of the fewer conditions that Jiang Miao did not dare to use them.

Because the fewer restrictions on reproduction conditions, the greater the ability to spread widely in nature.

Erwinia is a plant saprophytic bacterium. If its ability to degrade lignin, cellulose and hemicellulose is so strong, and there are no restrictions on its reproduction, it will destroy all the flowers, plants and trees in the world in just a few years.

If one of the above conditions is not met, the degradation efficiency of the Owen electric bacteria will drop sharply.

Moreover, the bacteria have no resistance to Bacillus that are widely present in the soil, especially the metabolites of Bacillus subtilis, which can directly cause the Irvingian bacteria to be unable to reproduce, resulting in large-scale death.

It is precisely this harsh living condition that allowed Jiang Miao to select it from billions of mutated bacteria.

When conditions are optimal, it is estimated that it will only take 143 hours for Irving's electric bacteria to degrade 80% of the cellulose, hemicellulose and lignin in cattle and sheep manure with a moisture content of about 97%. Its maximum power generation capacity is 473 watts per cubic meter, so it can generate 67 degrees of electricity.

However, this optimal degradation condition is not the optimal power generation condition.

At 23 degrees Celsius, with a specific dose of soy genistein and 26.4% oxygen in the air, the power generation capacity of Irving's electric bacteria will drop to 320 watts per cubic meter, but its stable power generation time reaches 360 hours, and the power generation can reach about 115 degrees.

However, in this case, the degradation of lignin, cellulose and hemicellulose will be incomplete, and about 20-30% will remain.

In front of Jiang Miao is a simple cow dung solution battery.

In order to ensure that electrons in the battery solution were efficiently transferred, he tried various anode and cathode materials over the next few days, trying to find one that was cheap and easy to use.

After some attempts, he found that the material with the best transfer efficiency was the gold plate negative electrode and the stainless steel anode, and the electron transfer efficiency could reach about 98%.

However, stainless steel has a fatal problem as the anode of the microbial fuel cell. That is, during use, stainless steel will be corroded little by little. As the operating time goes by, the electron transfer efficiency of the stainless steel anode will become lower and lower. It is estimated that it can only be used for 500 to 600 hours before the stainless steel plate needs to be replaced.

Therefore, Jiang Miao chose non-consumable graphite plates as the anode material, which has an electron transfer efficiency of 92%.

As for the gold plate, it will not be consumed. Although using gold as the battery cathode is a bit extravagant, it is not a consumable. At most, over time, a small amount of gold elements will migrate to the layer of the gold plate that contacts the battery fluid. However, the amount of migration is very small. According to the data Jiang Miao observed from the identification panel, it is estimated that it will take hundreds of years for one tenth of the gold elements to migrate out.

Since the optimal power generation reaction conditions of Irvine electric bacteria are relatively harsh, and it requires an expensive gold plate cathode, it certainly cannot be used as a mobile power source.

But as a fixed power generation equipment, there is no big problem.

The five constraints are relatively easy to solve in a fixed environment.

The temperature can be controlled by equipment such as central air conditioning.

The oxygen content in the air can be measured by an oxygen sensor and an air separator to produce pure oxygen, which is then quantitatively injected into the battery room.

If it cannot come into contact with Bacillus, the raw materials must be sterilized at high temperature.

Certain Gram-negative bacteria can be grown on a large scale.

Soy genistein can be extracted from soybean meal, and since the amount used is not large, it does not increase the cost much, but it is a consumable.

Gram-negative bacteria and soy genistein are also key raw materials for the entire system, because these two things can affect the degradation efficiency of Irvingia bacteria, thereby affecting the power generation capacity, which makes the power output power of this microbial fuel cell highly controllable.

Jiang Miao estimated that the current breeding farms of the Mo'nan branch produce about 300 tons of fresh cattle and sheep manure (with a water content of 60-85%) every day. After disinfection, they can be directly inoculated with Owen electric bacteria and special Gram-negative bacteria, and then a certain amount of soy genistein can be added to produce 300 cubic meters of microbial fuel cells.

300 cubic meters of microbial fuel cells can produce approximately 3.17 kilowatt-hours of electricity.

As long as the cycle is established, 3.17 kWh of electricity can be produced every day, and 1141 million kWh of electricity can be produced per year.

Of course, to achieve circulation, it is necessary to prepare batteries with a capacity of at least 4500 cubic meters. Taking into account the outer shell and other supporting facilities, the volume inside the power generation room must be at least 3 cubic meters, which is a factory building with an area of ​​5000 square meters and a height of about 6 meters.

Less than 8 acres of industrial land is not a problem.

But what really troubled Jiang Miao was the gold plate that served as the battery's cathode.

He adjusted it several times, and even if he reduced the usage to the minimum, he still needed 0.4 kilograms of gold per cubic meter of battery.

4500 cubic meters would require 1800 kilograms of gold.

Of course, instead of gold, platinum can also be used. Platinum is cheaper, about 2.27 million yuan per ton. With gritted teeth, Hailufeng Company can still afford it.

After much consideration, Jiang Miao decided to abandon the use of gold and platinum as cathodes and instead use high-purity manganese monoxide plates with lower efficiency, which reduced the electron transfer efficiency to 86%.

After completing these experiments, Jiang Miao has been in Mo Nan for nearly a month.

He destroyed all the experimental records and the makeshift power generation devices, leaving only 10 strains of Irving's electric bacteria.

He stored four of them in the chairman's special safe at the Tamin Chagan base.

He instructed the company's logistics drivers to transport the remaining 6 portions back to Shanmei in three routes. In order to be on the safe side, he set up a simple device in the culture storage container. Without the help of his identification panel, if others forced it open, the hydrochloric acid and nitric acid stored inside would be mixed into aqua regia, and the Owen electric bacteria stored inside would be destroyed.

The four strain storage containers stored at the Taminchagan base have the same settings.

Of course, even if you happen to be able to open the storage container safely, the bacteria inside will need special conditions to ferment, otherwise you will only get a small bottle of useless bacteria powder.

All the technologies of this microbial fuel cell system have been memorized in Jiang Miao's mind.

However, he knew that this kind of microbial technology would most likely have to be handed over to Shuya, including the previous biological mining technology.

This technology actually has room for further development.

For example, improving the materials of the anode and negative electrodes can improve the efficiency of electron migration.

Or continue to improve the power generation capacity of bacteria. According to Jiang Miao's current progress, the energy generated by Owen electric bacteria in the process of decomposing organic matter is about 300 degrees per cubic meter. However, only 115 degrees of energy are converted into electrical energy, and the efficiency is about 38%.

(End of this chapter)