A Vinegar-Based Effort to Save the Danube

By Amy Cowen on October 14, 2010 11:11 AM

Red Sludge: What is It?

According to The Associated Press coverage of the Hungarian spill, "red sludge is a byproduct of the refining of bauxite into alumina, the basic material for manufacturing aluminum. Treated sludge is often stored in ponds where the water eventually evaporates, leaving behind a dried red clay-like soil."

When a reservoir collapsed last week in Hungary, an estimated at 35 million cubic feet of toxic waste rushed into neighboring waterways and headed for the Danube, the second-longest river in Europe. The red sludge, a waste product from a factory that produces aluminum, destroyed many homes in Kolontar, a small nearby village, and wiped out aquatic life in local rivers and streams. As the sludge headed south for the Danube, turning waterways red as it passed through, officials were watching for dead fish.

Emergency Chemistry
In a race against the flow of sludge, scientists turned to chemistry fundamentals—acids and bases. To minimize the impact of the sludge on fish in the waters, scientists needed to lower the pH levels of the sludge (and of the Danube overall once the sludge reached it). In an attempt to counteract and neutralize the highly alkaline waste, emergency teams dumped quantities of plaster and vinegar (acetic acid) into the water.

With the sheer volume of the Danube working in its favor to help disperse the concentration of the sludge, the plaster and vinegar successfully helped lower the pH levels, diminishing the risk of further immediate environmental damage and neutralizing the sludge's impact on the Danube.

Staying Neutral
For students interested in exploring pH testing (and acidity), the following project ideas offer an inside look:

Make Your Own pH Paper (Difficulty: 4-6)

Cabbage Chemistry (Difficulty: 2)

Measuring the Amount of Acid in Vinegar by Titration with an Indicator Solution (Difficulty: 7-8)

To experiment with the science involved in water quality control and testing, explore these project ideas:

Conductance as a Water Quality Measurement (Difficulty: 5)

Using Daphnia to Monitor Water Toxicity (Difficulty: 7)

Harmful Algal Blooms in the Chesapeake Bay (Difficulty: 8)

Can Water Plants Be Used to Determine Water Quality?* (Difficulty: 4-6)

It's Raining, It's Pouring: Chemical Analysis of Rainwater (Difficulty: 5)

To find out more about the kinds of science- and engineering-based careers that deal with an emergency situation of this kind, check these career profiles:

Soil and Water Conservationist

Environmental Engineer

Environmental Compliance Inspector

[Editor's Note: This post was edited after its initial posting due to an error discovered by a reader. We erroneously referred to the sludge as "acidic" rather than "alkaline" -- which doesn't make pH sense given that vinegar was used as a counter-balance to lower the pH of the sludge. We apologize for any confusion our oversight caused.]