Hungary toxic sludge spill reaches Danube

Geza Molnar

October 7, 2010

Hungary's toxic sludge spill, which has killed four people, reached the Danube river Thursday, threatening to contaminate the waterway's entire ecosystem, officials told AFP.

"The red mud pollution has reached the Danube -- its so-called Mosoni Branch, about 10 kilometres (six miles) from the main branch of the river -- this morning," said Tibor Dobson, the local head of the disaster relief services.

"At 09:27 am (0727 GMT), the pH level stood at 9.3. The experts are still measuring the pollution levels and the pH levels are descending."

Water authority official Jozsef Toth told AFP earlier that samples taken at the confluence of the Raba river and the Danube showed "alkalinity slightly above normal, with a pH value of 8.96-9.07," against a normal tally of 8.0.

On a scale of 1-14, pH values of 1-6 are acid, between 6 and 8 are neutral, and readings of 8-14 are alkaline.

A wave of toxic mud was unleashed Monday from the reservoir of an alumina plant at Ajka, 160 kilometres (100 miles) west of Budapest.

The red mud travelled down the Raba river and reached the Danube waters at around 0630 GMT at Gyor.

The industrial accident triggered by the collapse of walls at the factory reservoir on Monday has been described as an ecological disaster and is now threatening the entire ecosystem of the Danube, Europe's second longest river which runs from Hungary through Croatia, Serbia, Bulgaria, Romania and Ukraine before flowing into the Black Sea.

Three adults and a child died when the tidal wave of mud smashed into surrounding villages on Monday. More than 120 people were injured, suffering from burns, and three people are still missing.

At two of the hardest hit villages, Devecser and Kolontar, water samples from the river Torna, which flows into the Raba, showed pH levels of around 10 on Thursday, but these were falling, Dobson said.

On Monday, after the accident happened, the reading was pH 13.5.

Dobson said neutralising efforts, using acid and gypsum, were helping to bring the pH levels down.

Groundwater in the wells in the region showed neutral readings of pH 7.5.

Earlier, Prime Minister Viktor Orban visited Kolontar -- where all four victims died -- to see the extent of the destruction.

The mud -- a residue from aluminium production which is highly corrosive and contains toxic heavy metals such as lead, cadmium, arsenic and chromium -- destroyed all vegetation other than trees and seeped into hundreds of houses in villages.

Witnesses say the force of the wave was so strong that cars were sucked out from their garages and it tore out windows and doors, covering everything.

A bridge in Kolontar was swept away and the army had to build a temporary one to replace it.

Orban suggested reconstruction could be very problematic.

"Unfortunately, my impression is that any reconstruction, beyond the bridge, would be useless.

"It'll probably be necessary to clear a new area for the villages and pull down the destroyed part for good. It'll be impossible for people to live here," Orban said.

Chapter 7. Environmental Management in the Bauxite, Alumina, and Aluminum Industry in Brazil

[...]

Nature and extent of environmental degradation

The three phases of this industry — bauxite mining and exploration, refining, and smelting — can each have many effects that are potentially hazardous to the environment. But before addressing these concerns, I will briefly consider the production process, as described by Warhurst (1991a, p. 23):

    Bauxite is the raw material from which alumina is extracted. Bauxite occurs in a small number of high-grade deposits mainly within a tropical zone extending up to 20 degrees north and south of the equator. The technology of alumina production varies with type of bauxite ores which fall into three groups: Monohydrate bauxite is generally found in boehmite in Europe and northern Asia and is processed using a European version of the American Bayer process (described below); Trihydrate bauxite is found as gibbsite in Surinam, Guyana, Guinea, Ghana and Australia and is processed by the American Bayer process. The Jamaican type of bauxite is characterized by a mixture of gibbsite and boehmite and is found in Jamaica, Haiti and the Dominican Republic. It is processed using a method which combines elements of the European and American Bayer process.

    The basic Bayer process involves the following operations… . Dried, ground bauxite is mixed in a large digester vessel with caustic soda which dissolves the aluminum oxide under strong pressure. Impurities, such as iron oxide and silica, are filtrated out in their solid state. Then the sodium aluminate liquor is seeded with hydrated alumina crystals and part of the solution combines with the "seeds" to form alumina hydrate crystals. These are then calcinated in long rotary kilns under high temperatures. This leaves calcinated aluminum as a white powder which is then ready for transformation into aluminum metal. On average, 2.25 tonnes of bauxite generates one tonne of powder.

    Finally, aluminum is separated from its oxide by the highly energy-intensive Hall–Heroult process. The process takes place in carbon-lined reduction cells. First, alumina is dissolved in a molten salt called cryolite to which aluminum fluoride is added continuously to maintain the required density, conductibility and viscosity. Second, a carbon anode is lowered into the solution causing a continuous electric current to pass through the mixture to the carbon cell lining, which acts as the cathode. This causes the dissolved alumina to separate out into aluminum metal and oxygen, and since the former is heavy it is attracted by the cathode to the bottom of the pot, while the oxygen settles on the carbon anode to form carbon dioxide. The molten aluminum in the pot is syphoned into crucibles and transferred to alloying furnaces to make alloys. Finally, the metal is cast in an ingot mould.

The potential hazardous impacts of these processes can be divided into those strictly affecting the physical and natural environment and those of a socioeconomic nature (UNEP 1984).

Mining

In ore mining, the environmental effects are highly site specific, but, on the whole, the main impact comes from clearing the vegetation in bauxite mining, exploration, and mine development. A secondary effect is that brought about by the dumping of wastes or the inadequate management of tailings. This can degrade the habitat of local flora and fauna and make future land use difficult for reforestation, agriculture, or cattle breeding.

Mining can also affect local water and air quality. For example, with the removal of overburden, runoff can become contaminated, more acidic, and more turbid. Erosion within the mined areas can be rapid if the soil is not recovered and reforested. The removal of vegetation can then bring about loss of flora and fauna, destruction of wildlife habitats, a possible spread of plant disease, increased soil erosion, changes in weather conditions, dust, and a possible need for runoff water treatment. In open-cast or surface mining, the areas cleared of vegetation may disrupt the landscape and produce a negative visual impact.

Beyond this, fugitive dust and noise from heavy machinery and explosives may be a source of disruption in the external environment for nearby communities and a health hazard in the working environment.

Adverse socioeconomic impacts depend largely on the proximity of the mines to established communities. Impacts can include breakup of cultural traditions, lifestyles, and kinship groups; substantive changes in agricultural crops, techniques, and marketing resulting from weather and soil disruptions; and lack of infrastructure, other employment opportunities, housing, and educational and recreational facilities for the personnel.

Equitist wrote on Oct 10^th, 2010 at 9:56am:



Yeah, there is no caustic soda involved with Bauxite mining, so it's not the same deal as Hungary. Bauxite from Weipa and any new bauxite mines would be shipped to Alumina refineries like the two in Gladstone, Queensland.  

I conducted an environmental audit of an Alumina refinery back in the 90's.

Any residual hydroxide is effectively converted to carbonates - magnesium and calcium.

Another refinery is planned as part of the Chalco development at Abbot Point near Bowen in North Queensland, alongside the coal-loading jetty. Again, this would be right on the edge of the sea, with no possibility of stopping a flood of toxic mud.

During very wet periods parts of these flats may become temporarily inundated with brackish water and support emergent or aquatic beds.