Making Waves

Making Waves: A sea change in treating wastewater – Why thermodynamics supports resource recovery and recycling

Hao, Xiaodi (Beijing University of Civil Engineering & Architecture)
Wu, Daoqi (Beijing University of Civil Engineering & Architecture)
Li, Ji (Beijing University of Civil Engineering & Architecture)
Liu, Ranbin (Beijing University of Civil Engineering & Architecture)
van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology; Beijing University of Civil Engineering & Architecture)

2022

Entropy is a concept defined by the second law of thermodynamics. Applying this concept to the world we live in, entropy production must be minimized and negentropy (negative entropy production) should be accelerated, in order to produce a healthy and stable ecological system. The present wastewater treatment, however, contributes to entropy production. This means that conventional wastewater treatment, without recovery of resource and energy, will gradually but inevitably contribute to a deteriorating ecological balance. When the self-cleaning ability of the natural ecological system is limited, the need to develop sustainable wastewater treatment in order to delay entropy production and accelerate negentropy becomes urgent. Resource and energy recovery from wastewater should be the first priority, as they can contribute significantly towards minimizing entropy production and accelerating negentropy. Sustainable wastewater treatment must focus on recovering recyclable high value-added organic chemicals from wastewater and/or excess sludge to minimize entropy production caused by methane (CH₄, once combusted, is converted into CO₂ - an even higher substance in entropy) via anaerobic digestion. Instead of CH₄, thermal energy present in the effluent can be utilized for heating/cooling buildings and also for drying excess sludge towards incineration to recover more energy. Overall, this can lead to a carbon-neutral operation and even creating a “carbon sink” could be possible for wastewater treatment.

Conventional wastewater treatment (CWWT)
Entropy production
Natural entropy cycle
Negentropy
Resource and energy recovery
Sustainable wastewater treatment (SWWT)

http://resolver.tudelft.nl/uuid:1fceea8c-9745-4137-a0e7-ed9775748976

https://doi.org/10.1016/j.watres.2022.118516

2023-07-01

0043-1354

Water Research, 218

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2022 Xiaodi Hao, Daoqi Wu, Ji Li, Ranbin Liu, Mark C.M. van Loosdrecht