Poly(hexamethylene guanidine)-poly(ethylene glycol) solid blend for water microbial deactivation

Polyhexamethylene guanidine hydrochloride (PHMG) is a cationic polymeric biocide used in the treatment of contaminated drinking water. This article describes a PHMG controlled release system made from melt blend of PHMG and solid PEG rods. The polymeric blend system gradually dissolves upon contact with running water and release effective and safe doses of PHMG to the passing water. The PEG-PHMG rod units were installed in a water purifier system, and microbial inactivation efficiency was tested according to the WQA certification program against P231/EPA for 250 L, using 25 L of passing water per day with a flow rate of 8-10 min per liter. The released PHMG was analyzed by Raman spectroscopy, and the antimicrobial activity was determined against Escherichia coli and the virus surrogate, MS2. A constant release of 0.35-0.5 ppm PHMG along 250 L of passing water was achieved. Inactivation results exceeded the minimal requirement for bacterial removal of 4-5 log reduction throughout the entire 250L. The rod height correlated with amount of water eroding the rod from bottom surface. Thus, these PEG/PHMG rod unit systems can be used in water purification to provide microbial free drinking water and serve as an indicator for quantity of water passing through the filter.