Potential threats to water quality are increasing. Extreme weather events can wash pollution into water systems, or leave systems without sufficient dilution. Industrial upsets can always cause issues. Increasing disposal of medicines -- and pass-through of drugs that are overused -- can be detected by ever more sensitive testing methods, leaving water treatment officials with the delicate question of how much is too much? And worst of all, authorities increasingly need to be sensitive to the risk of a terrorist threat against key infrastructures -- to which water certainly belongs.
The most recent poster child for water quality deterioration -- Flint, Michigan -- could be declared an "emergency and major disaster" if President Obama grants the governor of Michigan's request. For those who have not been following the story, citizens of Flint have suffered ever since the city changed their source to river water corrosive enough to deliver iron and lead leached from the metal delivery pipes with every twist of the tap.
As threats to the quality of our water increase, scientists have sought to develop a better safety net for ensuring water quality.
Holy grail of water quality testingThe holy grail of water testing would be online, continuous monitoring that could immediately alert authorities to shut off the taps in case of trouble and preserve clean water by segregating the problem. But measuring all the possible things that could make water hazardous poses serious challenges. Most sensors can detect certain contaminants but not others, limiting their utility. To be useful, a monitoring system must also be immediately sensitive to an emerging threat, yet not send out constant false alarms. Scientists at the Fraunhofer Institute have made a clever breakthrough with the AquaBioTox project by employing biological sensors. The AquaBioTox system diverts a sidestream of the normal water flowing in the distribution pipes to bathe a combination of bacteria, mammalian cells, and tiny water shrimp (daphnia magnia).
The bacteria and mammalian cells are engineered to produce a fluorescent protein. Because they are living systems, they react if exposed to a wide range of toxins. Daphnia magnia has long served as the mine-shaft canary in the world of water testing, as it shows a drop-off in mobility when challenged by toxins. Cameras detect a change in activity of the bio-based sensors as evidence that the cells or organisms suffer in the face of a new contaminant or a loss of water quality. The system is also self-learning. It becomes accustomed to normal variations in the water so it will not over-react and it learns to merge data from various sensors to make an overall conclusion about the water quality.
Ready for implementationThe project to develop and test the system has been ongoing since the breakthrough sensors were first announced in 2010. In 2012, a French-German cooperative project began to imagine using AquaBioTox sensors throughout a water distribution network in the SMaRT-OnlineWDN project (Security management and Reliability Toolkit for Water Distribution Networks). Last year (2015), industry insiders joined a demonstration of SMaRT-OnlineWDN in the first steps to promote implementation.
The idea behind SMaRT-online is simple: detect contamination in real time, and use computer modeling to predict the source of the problem based on the location(s) of the detectors indicating alarms as well as to manage the reaction regarding which parts of the distribution network to block to prevent further spread of the problem.
The concept intentionally addresses terrorist threats. But could it also help in cases like Flint, Michigan, or even more mundane situations? Part of the problem in Flint arises from the testing of water at the source. Contamination picked up during the water's progress through the network pipes was overlooked for far too long -- until elevated levels of lead in children's blood raised the alarm! It is not certain that the biosensors in the AquaBioTox would be detectably affected by longer-working toxins such as lead, but certainly any water with enough iron in it to appear dirty upon arrival at the bathtub tap would be picked up.
The idea of having a biological safety net detecting toxins in water before humans suffer the effects will be a dream come true for water engineers responsible for public safety. The question is whether politicians and budget managers would be willing to commit to establishing the infrastructure. Perhaps when the true costs of Flint's cost-saving measures become apparent, there will be those willing to listen to new ideas.