The Guadalupe Blanco River Authority (GBRA) began operation of the Western Canyon
Regional Water Treatment Plant (WCRWTP), located in central Texas, in 2006. The facility
utilizes a coagulation / microfiltration membrane process to treat reservoir water. The overarching
goal of the project was to deliver finished water with free chlorine residual to help ensure
compatibility with the existing disinfection practices of wholesale customers. Coagulation was
required to remove organics in order to reduce disinfection byproducts.
Ferric sulfate was initially used as a coagulant. The membrane process experienced shorter than
anticipated runs between chemical cleanings during the initial startup period and subsequent
operations. The membranes also did not return to the expected filtration performance after
cleaning. The clean in place (CIP) chemical waste had to be hauled by truck to a nearby facility,
causing unplanned significant costs. The membrane manufacturer (Pall Corporation), GBRA and Malcolm Pirnie began a
collaborative effort to identify measures to correct the operational challenges. Polyaluminum
chloride (PACl) was considered as an alternative to ferric sulfate. PACl coagulants from several
manufacturers were evaluated. Bench scale testing was performed, and then a rigorous pilot
testing protocol was developed. A close dialogue with the Texas Commission on Environmental
Quality (TCEQ) was required to obtain prompt approval of the pilot testing program. Once
approved, pilot testing was performed utilizing an on-site membrane pilot system. The results
revealed a preferred PACl candidate compared to ferric sulfate.
Numerous operational and design aspects were considered and used to prepare the WCRWTP for
the changeover. The changeover was conducted in July 2007. To date,
GBRA has experienced successful operation using PACl as a coagulant, as indicated by rate of
trans-membrane pressure development and flux recovery after cleaning.
This paper presents the methodologies used to plan for and implement the
coagulant changeover, and the consequences including residuals management, overall cost impacts,
and lessons learned. Includes table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 11/01/2009 |
