They’re going to have to find another name for wastewater pretty soon. This much maligned byproduct of household and industry has been quietly making a name for itself as a recoverable resource. One of the latest examples comes from South Africa, where gas and oil company, Sasol, has partnered with GE Power & Water to develop a new system for providing a high level of treatment for industrial wastewater that also recovers biogas for power generation.
The new system, called Anaerobic Membrane Bioreactor Technology (AnMBR), is transferrable to other industries, so let’s take a look and see how it works.
Recovering biogas from wastewater
Sasol has been working on the process for some time and is currently designing a second-generation version. The basic idea is to corral the organic material in industrial effluent from fossil fuel processes, and convert it directly into a methane-rich biogas.
The conversion process is carried out by the natural process of digestion, as anaerobic microorganisms feast on the organic material in the effluent (anaerobic refers to organisms that thrive without oxygen).
That’s a step above conventional treatment processes for the industry, which typically involve converting organic material to carbon dioxide.
In addition to producing a high value byproduct, the AnMBR system also results in an 80 percent drop in the amount of waste biosolids to be disposed of.
ZeeWeed is part of GE’s Ecomagination portfolio of advanced technologies. It filters out suspended solids and microorganisms with a high degree of efficiency, one result of which is a nutrient-dense waste stream that makes Sasol’s wastewater-to-gas process more cost effective.
About that fossil fuel thing…
The new process is a means to an end for Sasol, which is ultimately interested in boosting the profitability and marketability of fossil fuel conversion processes.
We’re not particularly enthused about that angle (to say the least). Strictly speaking, the biogas resulting from the Sasol process is not renewable, but since the technology is transferable, it does illustrate how continued investment in fossil fuel R&D can yield an overall payoff for improving the sustainability of industrial processes in other sectors.
That’s something to keep in mind, moving forward. Regardless of how fast or how thorough the global transition to renewable energy is, fossil fuels will continue to be part of the picture indefinitely. Just look at the history of our most primitive fuel, firewood, which has been around for more than a few millennia and continues to be a significant feature despite competition from other, newer fuels.
Putting wastewater to work
The idea of recovering methane from industrial wastewater is relatively new, but a similar methane recovery process for household wastewater has been in use at municipal treatment plants for decades.
Municipal biogas has been primarily used to power equipment on site, and that continues to be an important function. Ameresco, for example, is building a wastewater-to-biogas facility for Philadelphia that is expected to slash electricity costs for the facility.
More recently, the train has left the station, so to speak, as treatment facilities find off site markets for their biogas. Ameresco provides another example in San Antonio, which recently became the first municipality in the U.S. to connect its biogas to a commercial pipeline.
An example of a direct business-to-biogas partnership comes from Microsoft, which has been developing a demonstration facility in Wyoming that uses biogas from a nearby treatment plant to power its data center.
Along an entirely different path, Google has partnered up with a local wastewater treatment facility in Georgia to use treated wastewater as a natural cooling agent for its Douglas County data center.
It’s also worth noting that the Obama Administration has been encouraging dairy farms and other livestock operators to invest in manure-to-biogas systems. Aside from the energy recovery aspect, the process also resolves environmental issues related to manure disposal by rendering “active” biosolids into an inert material that can be used as an eco-friendly fertilizer or soil enhancer.
[Image: Sewer by Les Chatfield]