Chemical weapons are among the most savage weapons of war. Fired from rockets, dropped in bombs or sprayed from airplanes, they can cause an agonizing death, permanent injuries or, depending on the region, long-lasting contamination.

For many military strategists, the aim of using chemical weapons is to injure as many people and contaminate as much land as possible, thus overburdening the opponent's health system, interrupting supply lines, protecting one's own frontline against attacks and even rendering enemy weapons useless.

UN convention

Incidents with chemical weapons in World War I, particularly chlorine and mustard gas, led to an international treaty in 1925 that banned their use. But the treaty, called the Geneva Protocol, did not regulate the research, production and stockpiling of chemical weapons.

Only after the end of the Cold War was further action taken. Since 1993, a UN convention joined by 189 countries has prohibited the possession of chemical weapons.

In the 68 years between the two treaties, many countries built up huge chemical weapons arsenals. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), countries had amassed 71,196 tons of chemical warfare agents and 8.67 million pieces of chemical arms ammunition. Since the 1990s, specialized companies have been destroying these weapons and their ammunition - some, with German expertise.

In Munster in Lower Saxony, for example, the state-owned GEKA company is destroying world-war chemical munitions. Another company, Eisenmann, in Baden-Wuerttemberg, has built plants to destroy different chemical warfare agents in Russia, Albania and Japan. The company, says Eisenmann senior manager Uwe Neumann, has gained experience in handling warfare agents with chlorine and arsenic as well as organophosphorus nerve agents such as sarin or VX.

Destruction through incineration

The agents are destroyed through incineration, Neumann told DW, "in very hot furnace with a combustion temperature of about 1,200 degrees Celsius."

When the agent is swirled through the reactor and remains inside at high temperatures, it is eventually destroyed. What remains, however, is a flue gas that still contains pollutants. This gas is then cleaned through different methods, "ensuring that European Union limits are met," said Neumann.

A facility's design is determined by the materials processed. Nerve agents such as sarin and VX are organophosphorus compounds that react differently at high temperatures than, for instance, chlorine or mustard gas. "When burning organophosphorus warfare agents, we have to reckon with liquid salts," said Neumann. "These liquid salts must flow down the reactor wall so that they can be safely removed from the system."

As a result, it's possible that the first part of the system, the turbulence reactor, must be constructed differently. Plants also differ in how they clean flue gas.

Incineration is the last step in destroying warfare agents. But before that happens, the substance in the ammunition must be separated, according to chemical weapons expert Ralf Trapp. "You have to open the shells and bombs and remove the warfare agent," he told DW. "Then you have to transport this material to the destruction facility."

That step, he added, is dangerous and requires specialized, time-intensive techniques.

Decentralized facilities

Provided the chemical agents are already separated from the ammunition, says Trapp, who also works for the OPCW, there is another solution which renders chemical weapons unusable for the military.

"With various chemicals, you can do a pre-detoxification," he said. "Then you have a reaction mixture which is still toxic, but can no longer be used as a chemical warfare agent. In the end, the agent is permanently destroyed."

Neumann argues for direct destruction through incineration. It is a process, he adds, that could be completed much faster, pointing to Syria as an example. According to reports, chemical weapons there are spread across numerous storage locations, a situation, he says, that speaks against establishing a central destruction facility. "In my view, it would make more sense to consider a number of decentralized facilities," he said. "That way, you would minimize the transport routes, and thus, transportation risks."

Neumann sees opportunities for destroying chemical weapons in Syria. "If we accept 1,000 tons, then I expect we would need up to 10 years after the construction of the plant," he said. "It would probably take a year longer with smaller, decentralized plants, provided there are no problems with infrastructure and all lights are green."

Whether Syria will actually destroy its chemical weapons remains unclear. Should it come to that, the technology for destroying warfare agents is not cheap. There is a rule of thumb for calculating costs, according to Neumann.

"You have to reckon," he said, "with the cost of destroying chemical weapons being at least tens times higher than that of producing them."