A massive flood of toxic red sludge in Hungary reached the Danube River on Thursday. Hundreds of millions of gallons of red sludge was released Monday when a collection reservoir broke at an aluminum plant in western Hungary. Emergency workers fought to dilute the toxicity of the red sludge, and officials said the ecosystem of the Danube River did not face a serious threat.
Blue Danube tainted by red sludge
Fears that the Danube River, Europe’s second longest waterway, would be poisoned by toxic sludge were voiced soon after the reservoir was breached at the Ajkai Timfoldgyar Zrt alumina plant 100 miles west of Budapest near the town of Ajka. CNN reports that the ecological catastrophe killed two children, an elderly woman and a 35-year-old man trapped in a vehicle overwhelmed by the flash flood of toxic sludge. Three people are missing. About 250 people were evacuated. The breached reservoir has been repaired, and the toxic flow has stopped but not soon enough to prevent the red sludge from draining into the Danube River.
Danube tributaries dilute toxic flood
The Danube River may have been spared by its tributaries that diluted the sludge. Hungarian disaster response spokesman Tibor Dobson told Reuters that all the fish were killed in the Marcal River, which bore the brunt of the toxic spill. Some fish survived by the time the sludge reached the Monsoni-Danube rivers. Emergency crews tried to dilute the sludge to reduce its alkalinity, which registered at a highly caustic pH of 13 when the toxic flood was unleashed. Environmental groups had hoped the spill’s alkalinity would fall significantly once it reached the Raba, but it registered a pH of 9 to 10.
Cause of toxic sludge’s high alkalinity
The toxic sludge is waste from aluminum production that contains heavy metals and processing chemicals. Paul Younger, professor at Newcastle University, told the BBC that high alkalinity is the major problem. A pH of 0 to 5 is acidic. A pH of 6 to 8 is neutral. Hot tubs and swimming pools should have a pH of 7, which is considered safe. At a pH of 9, the toxic sludge can damage lungs and the digestive system. Younger compared the toxic sludge that hit the Danube River with kitchen cleaning products that could dissolve a top layer of skin with extended contact.