Make Money from Human Excreta or Human Waste
Biogas can be extracted from human and animal waste as well as from many decomposing materials. There are many communities for example in Africa where the villagers build together with experts in biogas construction centralised septic tanks with biogas extraction capabilities.
Biogas from Waste
Electricity is being powered by mostly expensive sources such as oil, gas and coal and supplied by big electricity suppliers concentrated in developed urban areas. Renewable energy is fast being adopted by consumers such as solar, wind sources and biogas sources. The biogas industry is valued as of 2019 to be $55.1 billion with expected growth of CAGR 4.48% .
One can setup a business creating home biogas generation units and sell them to consumers located in areas with unreliable or expensive electricity sources. Since biogas generation can be complicated thing especially for home amateurs one can be an educator or even a maintenance person for those with home biogas generation units.
Human waste can also be made into compost once it is properly treated and becomes safe to be mixed with crops grown for human consumption. There is however stigma associated with using human and even animal waste as compost and human and animal waste are plentiful and easily created. Those who use it can easily supply themselves with it at very low costs.
Building Materials from Waste
Houses and other structures can also be made out of human waste. Incinerated sewage sludge ash is mixed with vegetable oil to make bricks. These bricks have the advantage of being lighter and stronger than common bricks. There are many companies now from Europe to Africa developing these kinds of bricks for construction use.
Sewage Treatment Plants have a Commercial Advantage
Although sewage processing facilities like Thames Water in the UK have the advantage in this kind of business because they have steady access to sewage as well as financial resources smaller companies can still compete if they find a profitable way of collecting human waste. This is especially to those who are located in areas where centralised sewage facilities do not exist.
Biomass
Human and animal waste dried in the sun can also be used as a fuel. It is called Biomass. In many developing countries such as those in Africa a majority of households cook food using biomass. This is used in place of common charcoal whose supply is diminishing already because of forest degradation.
Biomass also has the advantage of burning 2 times longer than charcoal and emits less carbon monoxide in the air. It is also cheaper compared to charcoal.
Creating biomass is not as simple as drying up poop in the sun although there are many rural tribes that directly use sun dried poop as cooking fuel for example in the steppes of Mongolia where vast tracts of pasture grasslands exists with no trees.
Safe biomass is produced by the treatment of fecal waste by cooking it in containers to kill any harmful pathogens. The resulting product is then sun dried for hours in high temperatures. As it dries up it solidifies into briquettes due to its high fiber content.
There is big potential to make money and save the environment as well. Many European countries for example buy their charcoal from Africa where the people there burn wood from the forest to produce it. Enterprising persons can convince European buyers who use charcoal for cooking and burning to use biomass instead.
Mining Waste
Human waste can also be mined for precious materials although one would need industrial sized capabilities to collect and treat human waste sewage.
An article from RT or Russia Today titled Feces to fortune: US sewage may contain billions in precious metals reported that according to a study done by the US Geological Survey (USGS) sewage sludge generated by 1 million people contained 13 million dollars worth of precious metals.
They further reported that a Japanese sewage treatment facility already extracts precious metals from sewage. This sewage treatment facility in Japan has been mining gold from human waste sludge since 2009.
The sewage treatment facility located in Nagano prefecture, northwest of Tokyo once recorded being able to mine from every ton of incinerated sludge ash 1,890 grams of gold. We also have to consider the possibility of being able to mine other precious metals from sewage.
Conclusion
As can be seen there is money in human waste. People will gladly pay other people to remove their human waste from their homes. Once collected they can be turned into building blocks and turned into various fuel sources which the seller can earn money from.
If you can handle the stigma associated with handling human or animal waste then you stand to make good money from it. Most of your potential competitors would be turned off by the difficulty of handling it due to its smell and composition. Most people are even ashamed of being associated with human waste.