After months of research, Batserger, a surveyor appointed by the Sewerage Commission, proposed a plan to use the tides of the River Thames to discharge sewage from the deliberately sloped sewers into the mouth of the Thames. This is a clever plan, when the tide of the Thames recedes, it will take all the sewage away, but the committee members have reason to suspect that if the time is not in place, the sewage will be poured into the Thames, which will be miserable.

As chairman of the committee, Downing decided to push the technology forward once again, proposing a wastewater treatment scheme to purify the wastewater with biofilm, which was built in the eastern suburbs of London, at the midpoint of the line in Basserger, and said that the biofilm-purified sewage could hardly be seen with the eyes of clean river water, so that the risk of sewage backfilling could be minimized. The commissioners were not convinced of such a good thing, and promised to give Downing a little time to develop his biofilm.

The biofilm method is an aerobic biological method for treating wastewater. It is characterized by microorganisms adhering to the surface of the filter media as a medium and growing into a membrane composed of microorganisms. After the sewage comes into contact with it, the dissolved organic pollutants in it are adsorbed by the biofilm, and then oxidized and decomposed, converted into H2O, CO2, NH3 and microbial cytoplasm, and the sewage can be purified. The biofilm method usually does not require aeration, and the oxygen required by the microorganisms comes directly from the atmosphere.

In general, the process is as follows: the sewage is collected through the municipal pipe network and enters the treatment plant, where the larger solids such as sediment and paper are removed by the grid filtration, and then enters the first stage sedimentation tank. The sewage stays in the pre-sedimentation tank for several hours, and after the solid pollutants in it settle, it enters the secondary biochemical treatment reaction tank. The reaction tank is an aerobic aeration tank. A large amount of air is introduced into the aeration tank to promote aerobic bacterial growth. Bacteria feed on organic pollutants in the water, which grow in large quantities to form sludge-like suspended solids. At this point, the wastewater is introduced into a secondary sedimentation tank to settle the sludge, which is dominated by bacteria and other microorganisms. The treated sewage can be similar to clean water in terms of vision and smell.

What Tang Ning has to do is to show this process with his favorite small model, this time many processes have to wear masks, alas, I didn't expect to do this kind of dirty work, the work of civil servants is not easy to do!

It's finally time to enter the world of microbiology. At the heart of this technology is the use of culture vessels to screen for the most suitable aerobic microorganisms. Downing converted a small library into a microbiology lab. At this time, the low-power wind turbine was able to illuminate his entire manor, and even the street lamps were there, and the thieves did not dare to come.

Two people on the Sewerage Board in Downing objected to the construction of the sewer line at the same time as the underground electrical cable and the heating and gas pipes, which would add considerable expenses. Downing took them to his house to see these electric lights, spoiling the future, saying: "In the future, every household will use such electric lights, and the people of London will no longer be plagued by fires, and the use of electricity will be more." ”

Opposition Party No. 1: "Isn't it the same if the cable is built on the ground?" It's a lot cheaper, and I don't know when I'll be able to use so many pipes, so I think it's better not to waste the sewer money. ”

Tang Ning: "It's like encountering a mountain when building a railway, is it better to dig a tunnel or go around it?" On the surface, it may seem like a cheaper bypass, but it slows down the railway, wastes passengers' time, and is a permanent waste. Underground cables are more durable, safer, and do not affect the city's landscape, making them more cost-effective in the long run. London is the center of the world, and we have to set an example for our little brothers. The use of electricity is going to grow very rapidly, and you see, Mr. Faraday is working full-time on R&D for the power company, and that day is not far off. ”

The two opposition parties actually had a great deal of respect for the number one philanthropist in history, and Downing had so much sincerity in inviting them to his home to see the electric light of the future, that they finally had nothing to say.

They were also the first to see a small model of the sewage treatment plant, and they were amazed by the miraculous ability of microorganisms to clean up the filthy sewage so easily, giving them confidence in the sewage treatment plant in Downing.

"Let's start digging the sewers around the Thames and improve the open sewers as quickly as possible," Downing said. Now that the air is not well ventilated in winter, you can smell the Thames in the Houses of Parliament. ”

A few days later, with the approval of the full committee members, the sewer project with a budget of up to £3 million was launched!

At this time, another plan to clean up the environment gradually took shape in Downing's mind - transportation. At that time, the best means of private transportation was the horse-drawn carriage, which was not only expensive and difficult to maintain, but also had to hire a coachman, and polluted the environment because of horse manure. Downing hates industrial products that pollute the environment the most, and he is not prepared to invent the internal combustion engine according to the laws of scientific and technological development, which is a backward technology, its exhaust smell is bad and toxic, and even more incurable is the noise caused by the four-stroke. Downing is ready to directly invent the fuel cell engine in the era of green energy.

Fuel cells use hydrogen or hydrocarbon fuels (mainly natural gas, mainly methane) to react with oxygen in the air to produce electricity, so fuel cells are more like small power plants and have the same energy limit as an internal combustion engine – the size of a fuel tank.

The principle of the internal combustion engine is to convert the chemical energy contained in gasoline and diesel into thermal energy, and then convert it into mechanical energy through the classic four-stroke, because a large amount of energy is wasted in the form of thermal energy in the process, so the energy conversion efficiency is not high, 10-50%. The fuel cell is converted from hydrogen or natural gas and coal gas into electrical energy, and then from electrical energy to mechanical energy, in which the conversion efficiency of electrical energy to machinery is very high, as long as the motor conversion efficiency of more than 200 watts can easily reach 99%, so that the conversion efficiency of fuel cells can be as high as 85%.

Fuel cell technology is better than the battery in that its energy density is higher, battery cars will be plagued by this problem for a long time, the same weight of fuel cell can run 600 kilometers, the battery can only run 60 kilometers, the gap is huge. With the increase of power, the battery is even more inadequate.

The problem of fuel cells is that they are not intuitive, costly, and difficult to maintain, but in the era when the internal combustion engine was not popular, the emergence of the new force under the control of Downing may partially solve these two problems. In the history of scientific and technological development, as early as the 1830s, someone has put forward the theory of hydrogen and oxygen fuel cells, and the use of platinum powder as an anode reaction catalyst is the reason why this technology has not been applied on a large scale for a long time, because platinum is also called platinum, which is a precious metal. An important part of Downing's approach is to reduce the cost of precious metals by using almost 100% recycling.

The use of carbon-containing fuels is prone to carbon accumulation and is more expensive to maintain, but the use of a liquid such as methanol will be very convenient for transport and storage. Hydrogen is the lightest element in the universe, even the most airtight container, it will escape after a long time, it has the advantage of being the cleanest, and the equipment is not prone to chemical attack.

Downing is ready to take the best of both worlds, using methanol as the carrier for transportation and storage, and the main products of the refinery in the future will no longer be gasoline and diesel, but methanol. Methanol is converted into hydrogen at a hydrogen refueling station using fuel recombination. The more complex the hydrocarbon cracks, the higher the temperature required, 300 degrees Celsius for methanol reconstitution and up to 800 degrees for gasoline. High temperatures mean that a cooling fan is added, and noise will appear, so Downing doesn't want every car to have its own fuel reconstitution equipment, at most long-distance buses and trucks, long-term electric trains and ships, and city cars are not necessary.

Fuel cells are a complex technology, and the real practical application was not applied until the Apollo moon landing to solve the problem of electricity and water, and German submarines were also used to control noise and avoid sonar during World War II. It involves chemical thermodynamics, electrochemistry, electrocatalysis, materials science, power systems and automatic control and other disciplines, which is quite conducive to Downing's long-term monopoly of the market, when he no longer monopolies, I am afraid that the world is already the world of fuel cell engines, and the earth of smoky miasma and roaring engines of internal combustion engine cars may never reappear, which is a great and bold contribution made by Downing to build a beautiful human homeland.

This is probably three or five years later, and Downing will first complete the accumulation of technology in private transportation, starting with the invention of the bicycle.