New Technology Turns Poo Sewage Sludge to Petroleum-Like Biocrude Oil

A team of scientists from the Pacific Northwest National Laboratory (PNNL) at the US Department of Energy has found a way to reuse sewage sludge into biocrude oil, turning human waste into reusable fuel.

According to the study published by the PNNL, the researchers has devised a simple technology called hydrothermal processing (HTP). During HTP, sewage sludge is pressurized to about 3,000 pounds per square inch and then put into a reactor (a pressurized tube that's extremely hot at 660 degrees Fahrenheit). The heat in the reactor enables the cells in the sludge to break down, forming tow bydproducts: biocrude oil and "an aqueous liquid phase" that can be transformed into other kinds of chemical products.

"HTP converts organic material into biocrude oil, natural gas, or both, with potentially more than 99% conversion of organics. HTP uses the same processes which form fossil fuels, (heat, pressure, time, and water), but amplifies these conditions so the conversion occurs in a much shorter timeframe. This technology is specifically designed for wet feed stocks. The byproduct is clear, sterile water," the Water Environment & Reuse Foundation (WERF) told Treehugger.

WERF tagged the HTP as a "highly disruptive" technology as initial tests showed that apart from the 60 percent of carbon in the sewage sludge that was converted into biocrude oil, the process also produced methane-rich gas and water.

"There is plenty of carbon in municipal waste water sludge and interestingly, there are also fats. The fats or lipids appear to facilitate the conversion of other materials in the wastewater such as toilet paper, keep the sludge moving through the reactor, and produce a very high quality biocrude that, when refined, yields fuels such as gasoline, diesel and jet fuels," said Corinne Drennan, who is responsible for bioenergy technologies research at PNNL, in a press release.

The new technology could open the possibility of reusing wastewater treatment plants into renewable energy. If this could happen in the future, this means that processing, transport and disposal of waste from sewage treatments could be eliminated, cutting extra costs.

HTP could also lead to the production of clean fuels from agricultural wastes which is previously thought to be too expensive to turn into biofuels because of its wet consistency. The current technology is licensed to Utah-based company Genifuel Corporation, which is working with Metro Vancouver to make the technology possible.

"If this emerging technology is a success, a future production facility could lead the way for Metro Vancouver's wastewater operation to meet its sustainability objectives of zero net energy, zero odours and zero residuals," said Darrell Mussatto, chair of Metro Vancouver's Utilities Committee.