Oil from Sewage

‘‘Sludge is a major problem in the world. Cities pay $50 a tonne or more to get rid of it,’’ Amor recently told CNet. ‘‘And it’s good-quality light oil.’’ A tonne of high-quality sludge can produce about 30 kg of such oil, he said.

Although Israel has found a fairly sizable natural-gas field off its coast in 1999, the country relies on exports of oil and coal to keep the lights on. Getting energy out of sludge potentially could help alleviate the problem. The energy could be sold or, on a more practical level, used to keep things running in the cities where it is harvested, CNet said.

BioPetrol has a special technology that precludes the use of microbes to break down the organic matter. Measures to be implemented to resolve the problem of sewage sludge that contain a high degree of organic matter could primarily aim at recycling it through a thermo chemical pyrolysis process in order to recover hydrocarbons that make up the structure of sewage sludge. Pyrolysis of sewage sludge produces oil, gas and char products. The pyrolysis oils have also been shown to contain valuable chemicals in significant concentrations and hence may have the potential to be used as chemical feedstock. The production of a liquid product increases the ease of handling, storage and transport.

The technology (patent pending) is capable of processing carbon wastes, other than sewage sludge, including agri-wastes, bagasse, pulp and paper residues, tannery sludge and other end-of-life products such as plastics, automobiles tyres and the organics in municipal solid waste.

The process of low temperature thermochemical conversion of municipal sewage sludge to oil is a new technology in developed countries. The amount of investment is still less than the amount invested in the sewage sludge incineration process, and the operational economy of the process is obviously superior to incineration.

‘‘The end result is the on-site reduction of dry sludge volume from 100 per cent to 5 per cent,’’ according to an information sheet hosted by the Israeli Industry Center for R&D.

The idea first came from Ari Sofer, an expert in sewage who operated facilities in the United States and Israel. Typically, people try to chemically convert sludge into fertiliser. “That gave him the idea,” Mor says. BioPetrol is currently trying to raise $1 million to build a prototype facility.