Olive mill wastewater transformed: From pollutant to bio-fertilizer, biofuel.

Olive mill wastewater transformed: From pollutant to bio-fertilizer, biofuel. Olive oil has long been a popular kitchen staple. Yet producing the oil creates a vast stream of wastewater that can foul waterways, reduce soil fertility and trigger extensive damage to nearby ecosystems. Now scientists report on the development of an environmentally friendly process that could transform this pollutant into 'green' biofuel, bio-fertilizer and safe water for use in agricultural irrigation. During processing, olives are crushed and mixed with water in mills. The oil is separated out of this mixture, and the dirty water and solid residue are discarded. In Mediterranean countries, where 97 percent of the world's olive oil is produced, olive mills generate almost 8 billion gallons of this wastewater annually. Disposing of it has become problematic. Dumping it into rivers and streams can potentially contaminate drinking water and harm aquatic life. Pumping it onto farm land damages the soil and reduces crop yields. Some researchers have tried burning the wastewater with mixtures of solid waste from the mills or waste wood. But these approaches have either been too costly or have produced excessive air pollution. Mejdi Jeguirim and colleagues took a different approach. They wanted to see if they could convert olive mill wastewater (OMW) from a pollutant into sustainable products for practical use.