Statistical Optimization of Bioleaching for Simultaneous Recovery of Cu, Sn, Pb, and Zn from Computer-Printed Circuit Boards

Table 2

Levels of different process variables in coded and uncoded forms for biological leaching studies.

Variables	Name of the process variable	Range and levels
		Low	Centre	High
		−1	0	1
A	Time (hr)	14	21	28
B	Temperature (T) (°C)	24	28	32
C	Pulp density (g/L)	15	20	25