487037.fig.004a
(a)
487037.fig.004b
(b)
487037.fig.004c
(c)
487037.fig.004d
(d)
487037.fig.004e
(e)
Figure 4: The SEM micrographs of silica fume, raw sewage sludge, and sewage sludge incinerated at 500–950°C.