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Well-formed floc fully entrains bacteria and other micrometer-sized particles, facilitating sedimentation and filtration.


Evaluations of drinking water treatment process performance, particularly regarding the removal of particles of potential health significance, are of major importance for the protection of public health. However, some of these evaluations may be far from simple, rapid, or unambiguous.


The attached paper, written primarily for the drinking water quality scientist, addresses regulatory issues as it critiques and augments the methods currently used for assessing water treatment process efficiency.


Microscopic Observation: Or to paraphrase Yogi, ‘You can tell a lot by looking ...’


As alternatives (or supplements) to regulatory reliance on turbidity, coliform and heterotrophic plate count organisms, five non-standard parameters, based on the direct microscopic count, were used to evaluate treatment plant organism and particle removal performance. Reductions in the numbers of total bacterial cells, planktonic bacteria, particle-associated bacteria, total particles larger than 3 µm, and nematodes were observed over a calendar year (to observe seasonal temperature effects) at a water plant treating Missouri River water. Subsequent microscopic measures were made of algal cells and colonies and carbon fines.


Of special interest was the pronounced effect of low (winter) source water temperatures on the efficiency of bacterial and particle removals, particularly, by filtration.



We encourage your comments and observations, especially if you have had experience with microscopic methods of particle analysis.

Removal of Total Organic Carbon from Drinking Water Supplies - Part 3


Health effects of a broad assortment of organic compounds in drinking water are clearly difficult to assess. However, efforts to evaluate their significance are ongoing. Meanwhile, water utilities are attempting to monitor TOC compounds and facilitate their removal.

Removal of Total Organic Carbon from Drinking Water Supplies - Part 2


TOC Removal.jpg

Evaluations of TOC reductions at Kirksville, MO; Clinton, MO; and Bloomington, IL serve to illustrate some of the effective, as well as some relatively ineffective, water treatment techniques. In some circumstances, Enhanced Coagulation as well as Granular Activated Carbon appear to be among the latter group.



John O'Connor

Total Organic Carbon

Posted by John O'Connor Nov 25, 2011



Removal of Total Organic Carbon from Drinking Water Supplies - Part 1TOC Northern MO.jpgTotal Organic Carbon in Northern Missouri Public Water Supplies, 1980 and 1989.


Regulations requiring the removal of a portion of naturally-occurring organic carbon compounds from drinking water supplies have created new, and sometimes difficult, challenges for many water utilities.


Part 1 of the attached technical review considers the composition of total organic carbon, its measurement, and USEPA regulations governing its removal. Data is provided on TOC concentrations in Missouri and Illinois drinking waters derived from various water sources.