The industrial revolution in the 19th century led to a rapid rise of town sewage that needed to be collected and disposed of. City administrators, engineers, and scientists had to look for solutions that were both safe and economical. John Bennett Lawes and Henry Gilbert, the founders of the Rothamsted Experimental Station in England, summarize their research on this subject in this paper.
They stated: “It is no less true than strange that, after so many centuries of advance in regard to almost every other requirement of civilized life, the lesson should not have been learned of how to dispose of the excretal matters of large populations, in such a manner as to secure both their collection and removal without nuisance and injury to health and their economical utilization for the reproduction of food.” In their paper, they review how others have tried to deal with these problems and follow with detailed discussions of the composition and value of town sewage and its applications to agricultural land.
Using the town Rugby as an example, they calculated that every individual contributes to about 60 tons of sewage per year, containing 12.5 pounds of ammonia from urine and feces. They also realized that the usage of water per head was increasing, resulting in more liquid sewage of low nutrient value to crops. Their main conclusions were: (i) removing the waste of large populations requires liberal amounts of water; (ii) discharging town sewage into rivers renders them unfit as water supply for other towns, destroys fish, causes diseases, and is a great waste of nutrients; (iii) the proper mode of both utilizing and purifying sewage is to apply it to land; and (iv) diluted town sewage is best fitted for application to grassland, which can receive it throughout the year, thus increasing the production of milk, butter, and cheese, as well as manure.
We have come a long way in our understanding of sewage, engineering better collection and processing systems in towns, and regulating the use of sewage in agriculture. Sewage has also changed over time and nowadays also contains pollutants that were not known at that time. Nevertheless, this paper is early circular economy thinking in action and is as relevant today as it was 150 years ago.
