Biodegradation of Sewage Sludge: Toxic Effects of Heavy Metals

Investigates the fate and toxicity of continuous feeding with increasing dosage of heavy metal ions – Cu, Pb, Zn, Cr(VI) –on biogas production from anaerobic digestion of sewage sludge. The efficiency of the system (as measured by biogas production and volatile organic matter removal rate) was reduced for about 35 days before returning to a steady state with the toxicity ranking Cu > Cr (VI) > Pb>Zn. Also looks at the effect of two “pulse” doses of the metals.