New homes and factories will be built from bricks made out of the human waste of four million Londoners.
Dried sewage from millions of homes will be transformed into two million heavy-duty breeze blocks a year.
The manufacturing process is said to be more energy efficient and less damaging to the environment than traditional methods. The blocks are being made from sewage entering Europe’s largest treatment works in Beckton.
Thames Water is expecting to produce 18,000 tonnes of material every year, enough for about 2.3 million construction blocks to be used in a range of property and business developments.
The bricks have passed all necessary safety standards tests, with production having begun this week, the company said.
When effluent enters the plant, water is drained off and the leftover solids are then roasted in special machines, with the high temperatures sanitising the waste and releasing heat for producing electricity on site. The leftover ash is normally then binned.
However, the latest innovation will see the residue mixed with carbon dioxide, water, sand, and a small quantity of cement, to form aggregate.
This is then used to build individual breeze blocks — each weighing 17kg — which can be sold into the building trade. Nigel Watts, Thames Water’s head of wastewater treatment, said: “We’re transforming tonnes of waste from our sewage treatment process into a useful product, which can be used in construction in a variety of ways.
“It’s amazing to think that what’s flushed down the toilet could light up your bathroom and now help build homes, helping to support the huge growth predicted for our region.”
Bricks are usually fired in kilns at temperatures above 1,370C, releasing large quantities of CO2 into the atmosphere.
Using the dried faeces to produce synthetic aggregate traps around 800 tonnes of CO2, and will replace 18,000 tonnes of natural resources being dug out of the ground annually, Thames Water said.
The synthetic aggregate is also “carbon beneficial” as more CO2 is captured than is generated in the manufacturing process.
Mr Watts said: “We’re always looking for alternative, more sustainable ways to dispose of waste that avoids landfill and this is fantastic news for our customers, putting downward pressure on bills, and the environment, which we work hard to protect and enhance.”
As part of its business plan for 2020-25, the company has pledged to spend £2.1 billion on generating enough renewable electricity to power the equivalent of 115,000 homes.
