The Beautiful Red Danube

The Beautiful Red Danube

This is the kind of pollution we ought to be focusing on instead of CO2: water pollution. A horrific toxic spill about 100 miles southwest of Budapest has killed an unknown number of people, destroyed a village, and killed every fish in some smaller waterways before pouring into the Danube.

The spill is 185 million gallons of "red sludge" from an aluminum plant, with a pH of 13, which is to say "Drano." The pH scale only goes to 14 on the alkaline side. The equivalent on the acidic side is battery acid. Per the BBC: The muddy red sludge is waste from the early stages of aluminium production. Aluminium-containing ore, bauxite, is washed at high temperatures in sodium hydroxide (lye). This dissolves the aluminium, which can then be processed further, but the red sludge is left behind as a waste product containing a mixture of oxides of iron (rust), aluminum silicon, calcium, titanium, sodium, and trace amounts of other nasties like mercury and lead. Officials are reported to be using calcium nitrate (saltpeter), calcium sulfate dihydrate (gypsum), and even huge quantities of acetic acid (vinegar) to try to counter the spill's highly caustic alkaline effects. The spill is now measured at between 8.5 and 9.3 pH at the confluence with the Danube. A pH of 8.5 is at the high end of normal alkalinity for surface water. A kitchen cleanser might have a pH of 9.3.

The world's dozen largest aluminum plants are in Australia, Brazil, and China. The United States ranks 35th in worldwide production with a million tons of aluminum a year. The three U.S. plants are in Louisiana and Texas. The Louisiana plant is on the Mississippi River, while the two Texas plants are both within 50 miles of my home in opposite directions on the coast. American plants differ from the Hungarian operation in that they store the metal-oxide product in a dry form. Although this "dry-stacking" is not legally required, manufacturers consider it safer and less toxic. The hot weather and flat terrain of the Texas and Louisiana Gulf Coast permit sludge ponds to dry quickly with what we all hope is a minimal risk of a levee breach. The trick is to keep the sludge damp enough to avoid blowing dust, but dry enough that heavy equipment can drive over it. American manufacturers then remove and recycle the caustic lye, which leaves a sludge waste with a more neutral pH that can be covered over and landscaped with plants that finalize the pH-normalization process. The material is still loaded with metals and remains contained by a levee. The main danger is flooding from massive tropical storms; so far, the designs have proved adequate.