PFC 70. Conba Nitrate Production Process
70. Conba Nitrate Production Process
Now that we know the scientific principles, the rest is much simpler.
In principle, ammonia will be gradually oxidized to nitric acid under the action of microorganisms. This reaction is mainly accomplished by "nitrifying bacteria".
These bacteria prefer aerobic environments and are therefore commonly found in well-aerated soil, manure, compost, and activated sludge.
The entire oxidation process is divided into two steps: the first stage is nitrosation, in which ammonia is converted into nitrous acid; the second stage is nitrification, in which nitrous acid is further oxidized into nitric acid.
The activity of nitrifying bacteria is affected by factors such as pH, moisture, and temperature.
Neutral and alkaline environments are most suitable for nitrification.
Soil moisture content and aeration directly affect the strength of the nitrification reaction.
When soil moisture is maintained at about 60% of its maximum water holding capacity, the activity of microbial communities is optimal. If the soil is too dry, nitrifying bacteria will have difficulty surviving.
The optimal temperature range for nitrification is between 4℃ and 40℃. The temperature tolerance of native nitrifying bacteria varies in different regions.
The microbial community in tropical soils can even thrive at temperatures up to 35°C.
These types of bacteria thrive in warm climates, which explains why nitrates tend to be released in the spring and summer in the Bengal and Bihar regions of India, while nitrate production drops significantly in the autumn and winter when temperatures drop.
However, there is a crucial prerequisite: the nitrate-producing area needs to be relatively dry.
If rainfall is frequent, rainwater will directly dissolve and carry away potassium nitrate in the soil, and the yield of nitrate soil will decrease sharply.
This is the case in coastal and island areas. Although the local temperature is high, the spring and summer rainy season is long. The nitrates produced by the microbial community are washed away by the rain, making it difficult to accumulate usable nitrate soil.
In his early years, Dugen did some research to win over a girl who kept ornamental koi fish at home. He learned that in addition to human and animal excrement, fish and shrimp carcasses were also excellent nutrients for cultivating nitrifying bacteria.
Fish and shrimp release large amounts of ammonia when their excrement and bodies decompose, and ammonia is the nutrient that nitrifying bacteria rely on for survival.
In a closed water body, excessive ammonia concentration can cause biological poisoning, so fish keepers pay great attention to creating nitrifying bacteria tanks.
Conversely, this characteristic can be utilized to artificially cultivate microbial communities and accumulate nitrates.
Having made up his mind, Dugan asked Megan to send someone to carve out an acre of land inland south of Calcutta.
This area is at a lower latitude and has a higher average temperature year-round, which perfectly matches the growth requirements of nitrifying bacteria.
The workers first dug a narrow ditch half a foot wide and five feet deep along the edge of the plot. They also built a shed outside, which looked similar to the sheds for parking electric bicycles in later generations.
The most important step is to implement seepage prevention measures; otherwise, all previous efforts will be in vain.
Since cement had not yet been invented, Dugan used the watertight technology of the British Royal Navy warships to solve the seepage problem.
The craftsmen first compacted the five-foot-deep pit, then created a gentle slope at the bottom to facilitate drainage of accumulated water, and also carved gentle slopes on the four sides to prevent collapse.
They then used local materials, laying thick hardwood planks to resemble a ship's hull to cover the bottom and walls of the pool. They deliberately left gaps between the planks and then used a mortar chisel and a wooden mallet to forcefully hammer hemp fibers soaked in pine resin and coal tar into the gaps.
This hemp fiber, taken from old ship cables, expands when it comes into contact with water, making it the most reliable first line of defense against water damage for ships over thousands of years.
After all the gaps between the boards were filled, the workers set up an iron pot to boil pine resin asphalt. Once the grease had melted into a boiling liquid, it was evenly applied to the surface of the wooden boards, with a thicker coating at the corners, nail holes, and joints. After cooling, it formed a dense, waterproof black hard shell.
In fields with favorable conditions, the method of covering the bottom of warships with copper plates is also adopted, with thin copper plates covering the asphalt. The plates are overlapped and densely nailed with copper nails to further enhance the seepage prevention and corrosion resistance.
A narrow ditch was dug around the perimeter of the nitrate field and filled with layers of compacted clay to completely block lateral soil seepage.
Finally, spread a layer of fine sand on the waterproof layer to prevent hard objects from scratching the impermeable layer during cultivation, and then cover it with the cultivated topsoil.
The entire method is derived from the techniques of warship construction and repair. Even if water is sprinkled every day to maintain the soil and water, the fertilizer in the pit will not leak out at all, perfectly avoiding the hidden dangers of bacterial and nutrient loss.
To ensure the yield of the nitrate fields, Dugen established strict daily management requirements: designated personnel regularly tilled and loosened the soil to ensure soil aeration; large quantities of fish and shrimp were purchased from local fishermen every day, mashed into a paste, and spread thinly and evenly on the ground; pigsties, cattle sheds, and collected human and animal excrement were transported from various places, diluted with water, and then sprinkled together; water was also sprinkled in the sheds regularly to keep the soil moisture within a suitable range.
In addition, Dugan also required Megan to send people to burn the remains of plants such as rice straw, reeds, wild grass, corn stalks, sugarcane leaves, and cotton stalks into ashes every day and scatter them all into the saltpeter field.
Wood ash is rich in elements such as potassium, calcium, and magnesium. It can provide raw materials for the conversion of nitrates into potassium nitrates. Its alkaline nature can also neutralize the weak acidity brought by manure and urine, stabilize the acid-base environment of the soil, and protect the living environment of nitrifying bacteria.
There is another crucial aspect to the entire process: suppressing denitrifying bacteria*.
These anaerobic bacteria will decompose nitrates back into nitrogen gas, directly reducing the output.
The method to suppress it is very simple: provide a continuous supply of oxygen.
On the one hand, the site is kept well ventilated throughout the process, and on the other hand, windmills are set up around the field to drive rows of small wind turbines to continuously deliver air.
Sufficient oxygen can suppress anaerobic bacteria, promote aerobic nitrifying bacteria, and also dispel the pungent odor produced by nitrification fields.
Megan asked, "What if there's no wind?"
Dugan rolled his eyes at Megan. "If you really want to beat Garfield, you'll definitely find a way."
Megan then ordered that the windmills be driven by oxen pulling a millstone when there was no wind, and by human power when there were not enough oxen.
If the wind wasn't strong enough, they'd use animal power; if animal power wasn't strong enough, they'd use manpower. In short, Megan was determined to win.
In any case, it's the Indians who are working themselves to the bone.
The results of this artificial breeding program are astonishing.
After a full month of cultivation, several experienced Indian nitrifiers sent by Megan arrived with their apprentices to harvest the nitrates. They stared in disbelief at the white layer of crystals covering the ground.
This plot of land yielded over 7,000 jin of high-quality saltpeter, equivalent to approximately 4.2 tons.
After five days of refining and purifying, they finally obtained 2.1 tons of high-quality potassium nitrate.
Tests revealed that this batch of nitrate clay contained a nitrate content of up to 50%.
Dugan was quite satisfied with the result.
Megan was also pleased and ordered extra meals for all the Indian workers, so they could work day and night.
Relying on the division and proliferation of microorganisms to produce nitrate on a large scale has indeed doubled the efficiency.
Dugan felt gratified seeing Megan so happy, like a child.
My older brother used to always clean up my messes, but now I'm finally able to help him solve his problems too.
"Dugan, you're a genius!" Megan exclaimed, beaming as she looked at the white, tar-covered soil.
Dugan explained, "The microbial community has now completed its first generation of reproduction. This is just the first harvest. From now on, we won't need to wait a whole month. We can harvest a batch of nitrate soil approximately every fifteen days. We just need to backfill with new soil after each harvest to prevent the soil layer from sinking."
However, Dugen was not complacent. This acre of land was just an experimental field, and he was particularly worried that the spread of bacteria would cause water and soil pollution.
But Megan was unconvinced. "Pollution? What is pollution?"
Dugan thought about it and realized that it made sense. This was India, not his own home. What did it matter to him whether it was polluted or not?
However, Dugan still persuaded Megan to begin constructing a formal, mass-production nitrate field upstream of the river.
The new site was dug five feet deep, with bricks laid at the bottom first, followed by a waterproof layer. High cement walls were then built around the site, transforming the entire area into an independent pool that completely isolates the soil from the outside world and prevents the leakage of microorganisms.
The temporary straw structure for the roof was abandoned in favor of brick and stone pillars and wooden planks to build a permanent rain shelter.
If possible, we can replace the wooden roof with glass to further increase the temperature inside the field by allowing sunlight to reach it, which would make the yield more stable.
The water supply system has also been fully upgraded: relying on windmills to pump water from the river, send it into a series of water towers, and then connect it to the roof through a network of terracotta pipes for top spraying.
With this system, the frequency and amount of watering can be controlled uniformly, eliminating the need for manual spraying.
To reduce costs, the fish and shrimp slurry originally used to cultivate the first generation of nitrifying bacteria was replaced by human and animal excrement.
However, later on, because human excrement became more readily available, it all became human excrement.
As a result, a strange phenomenon occurred in the nitrate field managed by Megan: the foreman forced the workers to eat and defecate more, and anyone who was lazy and ate or defecated less would be whipped.
Later, as production capacity expanded further, the excrement from the saltpeter field workers alone was no longer sufficient.
As a result, a large number of civilians gathered near the salt fields and spontaneously formed villages, specializing in selling their excrement to the East India Company.
But these commoners were already poor, and they couldn't even afford three meals a day.
Thus, the East India Company formed an employment relationship with them, with the company providing food and the company providing the food and the company providing the food and the food and the food.