LOW-TECH MAGAZINE

Urban Fish Ponds: Low-tech Sewage Treatment for Towns and Cities

In the mid 20th century, whole cities' sewage systems safely and successfully used fish to treat and purify their water. Waste-fed fish ponds are a low-tech, cheap, and sustainable alternative to deal with our own shit -- and to obtain high protein food in the process.

Recycling animal and human dung is the key to sustainable farming

Flushing the water closet is handy, but it wreaks ecological havoc, deprives agricultural soils of essential nutrients and makes food production dependent on fossil fuels. For 4,000 years, human excrements and urine were considered extremely valuable trade products in China, Korea and Japan. Human dung was transported over specially designed canal networks by boats.

Thanks to the application of human "waste" products as fertilizers to agricultural fields, the East managed to feed a large population without polluting their drinking water. Meanwhile, cities in medieval Europe turned into open sewers. The concept was modernized in late 19th century Holland, with Charles Liernur's sophisticated vacuum sewer system.

Bring back the horses

Replacing tractors with real horse power could be the revolution that agriculture needs.

Horses and other draft and pack animals revolutionized transportation, war, hunting, manufacturing and agriculture. Work horses formed the backbone of industrial society until the first decennia of the 20th century, mining coal, ploughing fields and transporting goods and people in fast growing cities.

Reintroducing horses in city traffic would be a bad idea - cars might be noisy, dangerous and polluting, but mounts are even worse. In agriculture, however, animal power would bring surprisingly large environmental profits.

Leave the algae alone

While the first generation of biofuels is wreaking havoc on the environment and the food markets, the second generation is set to make things even worse.

Since it has become clear that ethanol and biodiesel made from food crops are doing more harm than good, the hope for finding a substitute for oil has shifted to algae and cellulose. If we can believe the advocates of this ‘second generation’ of biofuels, these combustibles will deliver way more energy than it takes to make them, without threatening the world’s food and water supplies. Upon taking a closer look, however, this is very hard to believe. They might even cause bigger problems than biofuels made from food crops. Maybe this time around we could sort this out before the damage gets done?