348 Organic waste recycling: technology and management
processes. The conceptual use of APU's to accomplish various treatment
objectives is illustrated in Figure 7.12.
Figure 7.12 Conceptual uses of APUs (aquatic processing units) for the treatment of
wastewater (Tchobanoglous et al. 1979)
The APU's in Figure 7.12 are arranged so that the application is from least to
most complex conceptually. In levels (a) and (b) of Figure 7.12, the APU's are
used for the removal of nutrients, refractory organics, and/or heavy metals. In
contrast to this relatively simple application, the complete treatment of
wastewater is envisioned in level (f).