Investigation of Heavy Metal Effects on the Anaerobic Co-Digestion Process of Waste Activated Sludge and Septic Tank Sludge

Table 1

Sample labels.

Sample	Content
	19 ppm	40 ppm	60 ppm	80 ppm
Cu	ECS1	ECS2	ECS3	ECS4
Zn	EZS1	EZS2	EZS3	EZS4
Pb	EPS1	EPS2	EPS3	EPS4
Cr	ERS1	ERS2	ERS3	ERS4