Amsterdam might house some of the world's most beautiful canals but you probably wouldn't want to take a dip in one. Rusty bikes, plastic and raw sewage pollute the waterways. But just a short ferry ride from the city center, a green haven has bloomed in a canal once thought to be beyond repair.

For 80 years, the Van Hasselt Canal in North Amsterdam was part of a commercial shipyard. Decades of industrial use poisoned the water and land with heavy metals and chemicals. When the shipyard closed in 2000, it remained deserted for over a decade. That was until 2013 when a group of volunteers - tapping into the city's creative spirit - decided to transform the polluted area.

The result is De Ceuvel - a creative and autonomous co-working space with a focus on green technology. Now just a year after opening, the 15 office spaces and studios built into refurbished houseboats have attracted a mix of hipsters, artists, hippies and startup founders. And De Ceuvel has become a hotspot for sustainable enterprise. But how did they do it?

What was an old, polluted shipyard is now a creative co-working space with offices inside refurbished houseboats

Getting creative

As it turns out, it's not easy to build offices on contaminated soil. This called for some innovative thinking, says Guus van der Ven from Metabolic, the consulting firm behind developing and executing the site's overall sustainability plan.

"Because of the pollution of the soil, we couldn't dig deeper than 50 centimeters, so you cannot lay a foundation, you cannot make a sewer connection or a gas connection, so we had to get creative," van der Ven told DW.

To get around these problems, environmental scientists and architects used an array of clean technologies, including solar-powered air-conditioning and heating systems, compost toilets and some other surprising low-tech sustainable solutions.

Green and low-tech: Plant sewage systems

Instead of building a conventional sewage system, De Ceuvel's sustainable architects opted to harness the biofiltration powers of plants such as willow, hemp and bamboo to filter all of the community's waste water. The plants' roots create bacteria that clean up the water.

Fast growing plants, like elephant grass (pictured), replace standard sewer connections and are used to filters grey water from the offices

"It's an easy, cheap, natural alternative to a sewage system," says van der Ven. No pumps or sewer connections are necessary, all the tenants have to do is use biodegradable soap. And there's another bonus: De Ceuvel uses 75 percent less water than conventional offices.

The community uses a similarly ingenious system to scrub the polluted land. The houseboat offices are moored along a winding bamboo walkway, lined with soil-cleaning plants. They are called hyperaccumulators and absorb high concentrations of metals, while plants called excluders stabilize the earth. When the plants are harvested each year, the soil pollutants go with them.

"In the end, instead of having a hundred truck loads of polluted soil, you get a few cubic meters of concentrated pollution," says van der Ven. De Ceuvel's ground is now a lot cleaner, but van der Ven explains they're still not sure what to do with the polluted plants once they've been harvested.

Growing food with human waste

At De Ceuvel, human feces are collected in compost toilets and then used to fertilize food

Literally nothing goes to waste at De Ceuvel - not even poop, thanks to the on-site compost toilets. Fertilizer created using the composting facilities is put to work growing food in the De Ceuvel greenhouse. But that's after it's been tested in the community's lab for pathogens.

"Then we eat the food that was fertilized with our own feces, we go to the toilet again, use the feces to grow more food and we close the circle," says van der Ven. "We want to show that closing a nutrient cycle in an urban setting is possible."

The community also recovers phosphorus from pure urine collected from the waterless urinal at Café de Ceuvel, where entrepreneurs, families and tourists hang out by the waterfront. Phosphorus is an essential nutrient for plant growth and is widely used as a fertilizer. But it will run out one day as phosphate rock minerals - the only significant global resource of the nutrient - continue to be mined heavily.

"Given how quickly we are depleting the world's phosphate stocks - why wouldn't we make use of our human waste, which contain important nutrients that can be used to grow food?” asks van der Ven.

At Cafe de Ceuvel, entrepreneurs and visitors can hang out while helping to close the nutrient cycle: the pee from the urinals is used to fertilize food grown in the greenhouse

Making sustainability social

For van der Ven, it's not just about transforming technical systems but also social systems using the green solutions they've developed at De Ceuvel.

"We think technical development is important," he says. "But we believe it's very important to also involve the people to create awareness and a conscience for sustainability."

That's why van der Ven and his team invited all of the De Ceuvel tenants to build the water filtration systems themselves before moving in. This helped create a sustainable community mindset before the co-working space had even opened.

"That way, they won't just use non-biodegradable soap in their offices and destroy the natural filters because they know how much work it is to build one," van der Ven adds, laughing.

All technologies on-site are decentralized, so every boat has its own compost toilet, its own solar panels and its own heat pump. Because they were involved in the building process, the tenants can take care of the systems themselves.

"De Ceuvel is the proof that you don't need big companies to build an elaborate and expensive sewage and heating system and monitor them from somewhere in China. It works locally and naturally if you build a sustainable and environmentally-aware community," says van der Ven.

"This is a tech playground where we are trying out different, new types of clean technologies," says Guus van der Ven

Still, there's plenty more to do at De Ceuvel - like figuring out how to deal with the contaminated plants post harvesting.

"But that's why this is a tech playground," he says. "We are trying out different, new types of clean technologies. We purposefully chose technologies that aren't established yet to test them and to see whether they can provide a solution in the future."