Using sludge to make sewage pipes self-healing

By preventing sludge from entering landfill, this innovative repair method also reduces CO2 emissions

Spotted: Sewage pipe maintenance is costly and time-consuming, with most repairs failing after 10 years. Mainland Australia’s 400 drinking water treatment plants each spend millions of dollars disposing of sludge in landfill every year. And, for every tonne of that sludge that is delivered to a dump site, more than 29 tonnes of carbon dioxide are released into the atmosphere, presenting a potential hazard to the health of waterways if chemicals leach into the ground. 

Finding ways to turn waste products into something useful, in ways that do no further damage to the environment, is becoming increasingly common as innovators and scientists get creative with the many leftovers created by global production processes. One such scientist, Professor Yan Zhuge, a Professor in Structural Engineering at the University of South Australia, has developed a way to put water treatment sludge to use and prevent it from entering landfill. 

Combining sludge from wastewater treatment plants with calcium hydroxide powder and encapsulating it all in a pH-sensitive shell creates a material that is highly resistant to microbially induced corrosion and also acts as a healing agent, repairing cracks. Bacteria found in most wastewater produces corrosive acids that eat away at the pipes, but by embedding these microcapsules in concrete sewer pipes, repairs and new piping should remain far stronger and more effective for a longer period. The new material will also prevent many tonnes of sludge from entering landfill, thus reducing the volume of polluting emissions released by the water treatment industry.  

Self-repair in areas that get significant amounts of use, such as roads and walkways, could be key to reducing carbon emissions from construction and maintenance. Springwise has previously spotted a recycled rubber pavement that repairs itself when it rains, and a self-repairing concrete that sequesters carbon to fill cracks.

Written By: Keely Khoury