Multiple views of biological stability and optimized coagulation in the control of biostability in traditional water treatment processes: a pilot test

Abstract

This study investigated biological stability in a pilot test of traditional water treatment processes in eastern China. The variations of assimilable organic carbon, biodegradable dissolved organic carbon, bacterial regrowth potential, and total phosphorus were analyzed, and the relationships among them were studied. High-purity aluminum sulfate was added as a coagulant, and the corresponding removal efficiencies of the coagulation–sedimentation unit and the sand filtration unit were evaluated. The experimental results indicate that the removal efficiencies of the dissolved organic carbon (DOC) and UV₂₅₄ both increased as the alum dosages increased in the coagulation and sedimentation process. The removal efficiencies of the biostability indicators of the coagulation and sedimentation process were higher than those of the filtration treatment. The bacterial regrowth potential was correlated with DOC concentration, and the introduction of total dissolved phosphorus into the evaluation of biostability is recommended to help confirm the C:P ratio and to select the appropriate strategy for controlling bacterial regrowth. An explanation for the changes in biostability indicators is provided.

Keywords:

• Biostability
• Assimilable organic carbon
• Biodegradable dissolved organic carbon
• Bacterial regrowth potential
• Total phosphorus

Acknowledgment

This work was supported by the National Water Pollution Control and Treatment Key Technologies R&D Program of China (2011ZX07410-002-1).