WQA Academy

Total Coliform Rule

 Drinking water regulations require that potable waters for human consumption be free from human-disease-causing bacteria and specific indicator bacteria that are indicative of the presence of these pathogens.  This does not mean that drinking water should be sterile.  Keep in mind that very few species of bacteria are harmful to humans.

Coliform

 Coliform bacteria are a collection of relatively harmless microorganisms that live in large numbers in the intestinal tract of warm-blooded mammals, including man.  They aid in the digestion of food.

Coliform bacteria can also be found in the soil, other animals, insects, etc.   The total coliform group is relatively easy to culture in the lab, and therefore, has been selected as the primary indicator bacteria for the presence of disease causing organisms.

 Coliform bacteria are not pathogenic (disease causing) organism, and are only mildly infectious.  If large numbers of coliforms are found in water, there is a high probability that other pathogenic organisms may be present.  The procedures for isolating pathogenic bacteria are complex and expensive; thus indicator organisms are used to indicate the probable presence of pathogens

Introduction to Microbiology

The science of microbiology is the study of microorganisms and their activities.  It is concerned with their:

• Form
• Structure
• Reproduction
• Physiology
• Metabolism
• Identification

 For the most part, microbiology deals with unicellular microscopic organisms.  In unicellular organisms, all of the life processes are performed in a single cell.  The cell is the basic unit of life.

Commonly used sample collection techniques

 1.    Grab Sample

• Used to describe the collection from a sample tap.

 2.    Subsurface sample

• Used to describe the collection from a treatment basin

 3.    Composite sample

• Samples that are collected and poured into a common container over a specified period of time.
• This type of sample collection is not acceptable for bacteriological analysis.  You cannot determine the extent or time of a single contamination event during the collection period.

 

The EPA has indicated that there is no safe level for Coliform Bacteria. Therefore:

 

The MCL for COLIFORM BACTERIA IS: ZERO (0) under the Presence-Absence Rule.

 

• Multiple Tube Fermentation (MTF) Technique utilizing 5 tubes of 20 ml. Sample each or 10 tubes of 10 ml. sample each.

 

• Presence-Absence (P-A) Coliform Test utilizing a single 100 ml. sample volume

 

• Membrane Filter (MF) Technique utilizing a 100 ml. filter volume.

 

• Minimal Media ONPG-MUG or Autoanalysis Colilert System).

Nuisance Organisms

• Actinomycetes are a collection of nine different groups of bacteria. 
• Taste & odor compounds
• Iron Bacteria associated with Biofouling & Control Strategies
• Sulfur Bacteria & Control Strategies
• Nitrifying Bacteria & Control Strategies

Pathogenic Organisms

 In theory, any organism that can invade the human body and produce a toxic reaction in tissues or organs is a pathogen.

 In practice, outbreaks of waterborne pathogens must occur in two or more individuals.

 Routes of waterborne infection

• Ingestion
• Inhalation
• Body contact
• Penetration

Halogens

 

Elements of Group VII in the Periodic Table are called the halogens.  The name “halogen” is derived from Greek words that mean “salt former.” At room temperature, the halogens exist in physical phases that vary from gas to solid.

 

The halogens combine directly with hydrogen, forming hydrogen halides, all of which are colorless gases

 

Because of their oxidizing power, halogens make superb disinfectants for water treatment.

 

Disinfection is the treatment process used to destroy or inactuate disease-causing (pathogenic) organisms.

 

Disinfection should not be confused with sterilization.  Sterilization is the destruction of all living microorganisms.