New Energy World™
New Energy World™ embraces the whole energy industry as it connects and converges to address the decarbonisation challenge. It covers progress being made across the industry, from the dynamics under way to reduce emissions in oil and gas, through improvements to the efficiency of energy conversion and use, to cutting-edge initiatives in renewable and low-carbon technologies.
Thermal hydrolysis improves the efficiency of biogas production
23/3/2022
7 min read
Feature
The production of useful biogas through the anaerobic digestion of waste sludge at wastewater treatment plants is an elegant example of the circular energy economy. But system efficiencies can be improved through the addition of thermal hydrolysis plants, writes Abigail Williams.
In a bid to improve the efficiency of wastewater treatment facilities (WWTF), a growing number of wastewater companies have installed thermal hydrolysis plants (THPs) that enable an increase in the throughput capacity of anaerobic digesters and a rise in the production of biogas, as well as energy recovery from waste ‘sludge’.
Energy potential
As Charlie Walker, Research Director – Technology and Industry at Global Water Intelligence, explains, thermal hydrolysis typically involves three steps. First, waste-activated sludge from the wastewater treatment process is fed to a pulper, which homogenises and preheats the sludge. Next, the sludge is fed into a reactor, where the temperature is raised to around 180°C and pressure of around 5–6 bar, which kills pathogens.
Last, the hydrolysed sludge is fed to a flash tank, where the sudden drop in pressure destroys cells for organic matter to more easily digest. The cooled sludge then goes into an anaerobic digester (AD).