. 2020 Dec 14;10(12):421. doi: 10.3390/membranes10120421
© 2020 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Figure 3.
Conventional activated sludge unit system.