Research: Cement-Free Concrete Beats Corrosion
This week, engineers from RMIT University (Melbourne, Australia) announced that they have developed an eco-friendly, zero-cement concrete that can withstand corrosive acidic environments, commonly observed in sewage pipes and other types of wastewater infrastructure.
A paper on the study, "Development of zero cement composite for the protection of concrete sewage pipes from corrosion and fatbergs" has since been published in Resources, Conservation & Recycling.
In an attempt to combat build-ups of fat, oil and grease—often referred to as “fatbergs”—in sewers and pipelines, lead RMIT researcher Rajeev Roychand and his team developed a concrete that eliminates the chemical compound that promotes corrosion and fatbergs, free lime.
“The world’s concrete sewage pipes have suffered durability issues for too long,” Roychand said. “Until now, there was a large research gap in developing eco-friendly material to protect sewers from corrosion and fatbergs. “But we’ve created concrete that’s protective, strong and environmental—the perfect trio.”
According to RMIT, the material consists of manufacturing by-products including a zero-cement composite of nano-silica, fly-ash, slag and hydrated lime. In using the industrial by-products, the end result is reported to surpass sewage strength standards set by ASTM International and is more durable than ordinary Portland cement.
“Though ordinary Portland cement is widely used in the fast-paced construction industry, it poses long term durability issues in some of its applications,” Roychand reported. “We found making concrete out of this composite blend—rather than cement—significantly improved longevity.”
Additionally, the final product is also environmentally friendly, reduces concrete corrosion by 96% and totally eliminates residual lime that is instrumental in the formation of fatbergs.
While RMIT says replacing underground concrete pipes is a tedious task, the study has proven certain by-products could help to reduce the annual costs of maintaining sewage networks and greenhouse gas emissions. Roychand and his team are looking to collaborate with manufacturers and government to develop more applications for their zero-cement concrete.
Amidst the ongoing COVID-19 pandemic, the wastewater industry has been recognized for its essential critical infrastructure workers and treatment facility reports. Initially, during the early weeks of the pandemic’s outbreak, multiple reports across the U.S. reported that wastewater treatment officials had to remind their local residents not to flush sanitary wipes down the toilet. Many of the affected areas’ plumbers and public officials were reportedly experiencing a surge in backed-up sewer lines and even overflowing toilets, among other issues.
However, the cause wasn’t just common wipes and paper products we saw a shortage of that were the issue, but what the materials were absorbing. Medium reported at the time that wipes can bind with fats, oils and grease—another thing you shouldn’t put down your drain—creating a more solid verses soluble issue.
As aforementioned, the waste cluster forms a fatberg, which can sometimes reach the consistency of concrete. The state of New York reports that it spends roughly $18.8 million every year just to degrease, unclog and repair sewers and plant equipment affected by fatbergs.
Roughly a month after the surge in reports, researchers from the Center for Environmental Health Engineering at Arizona State University's Biodesign Institute reported that they had begun monitoring regional levels of SARS-CoV-2—the virus that causes COVID-19—in wastewater.
The research was conducted through a partnership between the university and the City of Tempe, Arizona.
In their redefined method, known as wastewater-based epidemiology, the researchers collected sewage samples so that clues could be analyzed over human health, and that levels of coronavirus infection at both a local and global scale could be detected. The high sensitivity of the type of study is also reported to have the potential to detect the signature of a single infected individual among 100 to 2 million persons.
According to ASU, the research method could lead to real-time monitoring of disease outbreaks, resistant microbes, levels of drug use or health indicators of diabetes, obesity and other maladies.
By June, the United States Environmental Protection Agency announced that its researchers would be engaging in research practices to help states, tribes, local, territorial governments, and public health agencies in reducing the risk of exposure to SARS-CoV-2.
One of the practices involved developing and applying methods for measuring SARS-CoV-2 levels in wastewater after conducting preliminary research that indicated that monitoring wastewater for the presence of SARS-CoV-2 may be useful as a sensitive early indicator of an of an infected community.
The wastewater monitoring would also be able to provide indications if a community was experiencing a decrease in infection levels as well and hoped to better understand potential risks from exposure to untreated sewage.
Since the report, the EPA has issued a draft report from the Scientific Advisory Board entitled “EPA’s Identification of Research Needs to Address the Environmental and Human Health Impacts of COVID-19.”
According to the report, researchers will be using a combination of molecular and culture-based methods to characterize SARS-CoV-2 in wastewater over a six-month pilot project. The research is slated to be conducted the city of Cincinnati, where its has combined and non-combined sewer systems.
Through testing and evaluating the wastewater, Garland says researchers will know how long the virus lives in waste, how to test sewage consistently for the virus, and how to consider wastewater systems where sewage is diluted by industrial waste or stormwater before reaching a treatment plant.