Technology▼Solutions Removing methyl bromide from shipping operations
ALBERT E. THEBERGE, NOA A CORPS ( RE T. )
bleach, and it can go into a sanitary waste stream.” Miller’s calculations show that removing MeBr from the fumigation The deadline for the 1987 Montreal “Here we have an ideal system,” exhaust of a standard shipping conProtocol’s phaseout by developed Miller says. The bacteria “are gobtainer in half an hour would require countries of methyl bromide (MeBr), bling up and thriving on this thing a 10,000-L bioreactor, which he envia pesticide that depletes stratothat you want to get rid of.” sions as a stainless-steel vat 12 ft tall spheric ozone, came and went in The global background levels of and ~4 ft in diam. 2005. Although some countries have MeBr hover near 10 ppt, much lowKelly Goodwin, a U.S. National achieved a 100% phaseout, others, er than the hundreds of parts per Oceanographic and Atmospherincluding the U.S., received exempmillion pumped into shipping conic Administration researcher who tions for certain applications for tainers for fumigation, according has studied the biogeochemistry of which they claimed that no efMeBr, points out that Miller’s fective or affordable replacesystem offers advantages over ment existed for the pesticide. activated charcoal adsorption. The focus of most of the acThe pesticide can be adsorbed tions taken so far has been on on the charcoal and recovered, the protocol’s targeted applicabut the technique still creates tion of MeBr as a soil fumigant emissions. Moreover, recycled to kill insects and pathogens in MeBr does not have a market in agricultural fields. But the protothe U.S., because it is not regiscol does not cover the pesticide’s tered as a fumigant. uses for sterilizing structures Despite these advantages, and disinfecting goods before Miller says that commercial inshipping. Such quarantine and terest in building a pilot system No regulations govern the use of methyl bromide for pre-shipment applications achas been scant because of the disinfecting goods in shipping containers. count for ~25% of the >45,000 t of lack of regulations for shipping MeBr consumed globally in 2000, acto Miller. After ~36 h, the operators and quarantining uses of MeBr. cording to the UN Environment Proopen a vent, start a fan, and blow the That will change, according to an gramme’s Methyl Bromide Technical gas out into the atmosphere. Miller’s official of the European CommisOptions Committee. system calls for this gas to be passed sion’s Ozone Layer Protection Team. “There’s no limit as far as what through the bioreactor instead. Just He explains that the parties to the can be emitted” by these shipping one pass is required, he says. Montreal Protocol focused on conand quarantining operations, says The bioreactor is a tower containtrolling emissions from soil fumigaLaurence Miller, an oceanographer ing a liquid phosphate medium with tion, which they deemed a critical and chemist at the U.S. Geological cells of a bacterial strain called IMBuse of MeBr, for two reasons. It was Survey. Miller and his colleagues ad1, which Miller and his colleagues the biggest application area, forming dressed this problem by developing discovered in agricultural soils dur~75% of the pesticide’s consumption, a bioreactor to target these emising past research. The temperaand was easier to tackle, because sions, and they received a U.S. patture is kept at 28 °C, and the waste countries with shipping fumigation ent on their design this spring. stream is diluted with air to keep operations would need to agree on They first described the bioreacMeBr levels at
