Toxicity, Synergism, and Antagonism in Anaerobic Waste Treatment Processes

Abstract

Antagonism, synergism, and complexing reactions must be considered in reporting data on toxicity and stimulation in anaerobic waste treatment systems. Low concentrations (< 1 mg/liter) of all heavy metals except iron are extremely toxic, but higher concentrations can be tolerated if sufficient sulfide is present to act as a precipitant. Short chain volatile acids up to 6000 mg/liter have no adverse effect on methane formers. While pH control with alkaline substances can prevent catastrophic failure during digestion, the fundamental cause of imbalance must be corrected for a permanent cure. Light metal cations offer the most difficulty in designing and operating these systems because they can occur in both toxic and stimulatory ranges. An initial attempt to categorize quantitatively toxicity, stimulation, etc. on an absolute basis is presented.