Clinton, MO Projects

Investigations of Water Treatment Processes for the Removal of Organic Matter from Sparrowfoot Quarry Water (1997)

Enhanced Coagulation and PAC Addition

A series of experimental bench-scale (jar test) studies were performed in an effort to determine the effectiveness of alternative coagulants, lowered pH and the addition of PAC on achieving enhanced coagulation for increased removal of organic matter from Sparrowfoot Quarry water. In particular, efforts were made to simulate the design treatment process for Clinton, Missouri’s proposed new water purification plant.

Control and treated samples were taken in these studies to determine the degree of removal of TOC and the concurrent reduction in TTHM formation potential (TTHMFP). In addition, turbidity reduction, pH, and alkalinity were monitored through the process.

Sparrowfoot Quarry water was found to contain 6.3 mg C/l. This concentration indicates that the water is derived from surface water and requires treatment for removal of TOC. Direct filtration of the quarry water through a 1 µm membrane reduced TOC by 21% to 5.0 mg C/l. This removal indicates that only 21% of the raw water TOC consists of particulate organic carbon which can be removed by particle removal processes, such as coagulation and sedimentation. Activated carbon was expected to remove additional amounts of dissolved organic carbon (DOC).

Alum coagulation alone removed most of the particulate fraction as well as a portion of the dissolved organic carbon. Dosages of 40 mg/l of the three types of liquid alum tested removed an average of 40% of the TOC. Liquid alum with 9.6% sulfuric acid added achieved the greatest (49%) removal.

Studies were also conducted to evaluate the incremental removal of TOC by five PAC dosages. The average TOC reduction was 50% as compared to 49% for alum alone. The maximum TOC removal observed was 57%. These results indicate that, even at high dosage, PAC has very limited capability for adsorbing the dissolved organic carbon present in Sparrowfoot Quarry water. Alum coagulation concurrent with PAC and sodium carbonate addition resulted in a 44% removal of TOC, the greatest of the removals observed in the three alternative treatment process test series.

In summary, the initial liquid alum coagulation studies averaged 40% TOC removal while the addition of up to 60 mg/l PAC marginally increased TOC removals to 50%.

References

Henry County Water Co.
313 South Washington St.
Clinton, MO 64735
660-885-2157

Relevance

• Evaluation of new drinking water source and proposed new water treatment process
• Missouri’s initial evaluation of enhanced coagulation.
• Assessment of PAC for removal of TOC and TTHMFP