Low-pressure membrane filtration is typically used to treat surface water after coagulation and
sedimentation. However, recent advancements in membrane technology are making it possible
to incorporate low-pressure membrane filtration directly after coagulation with no sedimentation
required. Due primarily to stringent regulations regarding disinfection byproducts (DBPs) and
upcoming regulations regarding Cryptosporidium, the City of Kerrville, Texas is planning to
expand its 5 mgd conventional water treatment plant (WTP) by installing membrane filtration
combined with chemical coagulation. The source water for the Kerrville WTP is surface water
from the Guadalupe River, which has a range of total organic carbon (TOC) from 1 to 10 mg/L.
To ensure long-term regulatory compliance, direct coagulation with low-pressure membrane
filtration followed by chlorination was selected for treatment of Guadalupe River water.
Enhanced coagulation provides DBP control, membranes enable pathogen removal, and chlorine
provides viral inactivation and a residual disinfectant for distribution. Includes tables, figures.