Underground in places nobody like to look , bacterium are doing terrible things to our sewage pipes . The concrete pipe that conduct our waste material are literally dissolving off , forcing technologist into a messy , expensive battle against tiny microbes .
“ The veins of our metropolis are in serious worry , and they ’re in serious bother because of corrosion , and this erosion has been out of the blue and it ’s quicken , ” enjoin Mark Hernandez at asymposium on the microbiology of the built environmentin Washington DC yesterday . Hernandez is a civil railroad engineer , but he ’s meeting with microbiologists because this problem is bacterial . fundamentally , it ’s an contagion of the nation ’s sewage organization .
The sewer as a microbial ecosystem
Here ’s what ’s going on . One set of microbes pass off hydrogen sulfide , the gas that is also responsible for raw sewerage ’s unpleasant smell . This gas meet the empty outer space between the top of the pipe and the water menstruum . Another circle of microbes know in this headspace turns atomic number 1 sulfide to sulfuric acid , which eats away at concrete , leaving behind gypsum , the powdery clobber you find in drywall .
“ fundamentally what we ’re ending up with is wet drywall , ” said Hernandez . This is one reason the American Society of Civil Engineers hasgave our sewer water infrastructurea D grade .
The current solution is to put plastic liners into the concrete pipes , a operation that is almost as expensive as dig them up entirely . But if the job is microbial , perhaps the solution is , too ?
Photo of concrete cubes placed in sewerage pipes via Mark Hernandez
When Hernandez and his team sequenced bacteria populate in the headspace of unlike pipes , they found only three or four species — an extremely remarkable want of diversity . With so few existent problematic microbes , there could be a way justto direct them specifically with some eccentric of antibiotic or evenbacteria - infecting virus .
The solution they settled on was shotcrete — a type of concrete that can be spray onto the inside of pipes — embed with small amounts of charcoal and bacteria - kill metals like chrome . As the dose corrode through this concrete , metal would be released . Based on Hernandez ’s tests , this concrete did restrain up better against sewerage microbes — indicate a promising result to erosion .
Designing water pipes for—rather than against—bacteria
But gatherings of microbiologists can be funny things these days . With the technological ability to sequence bacterial samples from every table top , belly clitoris , and shoe , we ’ve do to understand that everything is breed in millions of bacterium — mostly unknown , mostly benign , some even beneficial . Instead of just examine to kill the few harmful single , perhaps we can build environments that encourage the growth of others , which then keep out the bad I — an ecological and architecture version ofprebiotics .
That was the premise of a talk at the same symposium by Amy Pruden , a professor of civili engineering at Virginia Tech . If sewers are the vein of our city , than drinking urine pipes are the artery . Pruden talk about how the very design of our drinking water system could be prebiotic to encourage the growth of undecomposed bug and discourage the ones that cause disease . There are , after all , an estimated10 to 100 million free - floating organismsin every dry quart of drunkenness water . “ We ca n’t continue to fool ourselves that drink water is sterile , ” she say .
Like all research into how prebiotics , peculiarly in a linguistic context outside of the man gut , it ’s still very conceptual . But there are so many factors that can be design or engineer to manage the microbiome of the water system : chlorine or chloramine-T as antimicrobial , plumb configuration , tube material , temperature of the urine heater , and on and on .
It helps to think of the whole body of water system — from drinking water supply to waste water — as one interconnect microbic ecosystem . The chemicals that we sum in every stage feign the ecosystem , whether it ’s the chlorine to disinfect drinking water , the antibiotic flushed down the toilet , or the metals that might protect our concrete pipes . And it ’s important because we thenrely on those microbes to treat out sewage . sewerage treatment plants ? They ’re essentially a series of tanks that get bacterium do the body of work of breaking down our waste . In laying down miles of pee tobacco pipe , we ’ve create an entire microbial ecosystem under our feet .
https://gizmodo.com/an-inside-tour-of-san-franciscos-sewage-treatment-plan-1546975727
Top image : AP Photo / Mary Altaffer
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