Wastewater Characteristics



Biochemical Oxygen Demand (BOD)

Presby Environmental - Biological Oxygen CommandBOD is a measurement of how fast biological organisms use up oxygen in a body of water.



Carbonaceous Biological Oxygen Demand (CBOD)

Presby Environmental - Carbonaceous Biological Oxygen CommandCBOD is the amount of oxygen, in mg/L, required by bacteria to oxidize the organic matter or biologic food available in the system. A high CBOD indicates that there will be very little dissolved oxygen available for fish and other aquatic life in the water system tested. This becomes more important if the wastewater will be released near surface water features such as lakes or streams.

Carbonaceous Biological Oxygen Command – 5

Presby Environmental - Carbonaceous Biological Oxygen CommandCBOD5 is averaged over 5 days of carbonaceous, biological oxygen demand.

400X352_totalColiformFecal Coliform is an indicator of bacteria common to the digestive systems of warm blooded animals. The presence of fecal coliform bacteria, measured in colonies per million, indicates the level of disinfection that has taken place in wastewater treatment.

Presby Environmental - The PH ScalepH is a measure of how acidic or basic a substance is. It is a logarithmic scale of 0-14, meaning that each whole number on the scale represents a difference of 10 times. A pH of 7 is considered neutral, neither acidic or basic. pH values below 7 are more acidic. A pH above 7 is basic or alkaline. Therefore, a pH of 8 is ten (101) times more basic than neutral. A pH of 2 is 100,000 (105) times more acidic than neutral. Drinking water should be close to neutral 7. The closer to neutral the pH is, the cleaner the water. Substances with either a very low or a very high pH are generally very harmful to most life forms.

The EPA recommends that drinking water pH is within the range of 6.5 to 8.5. There is no regulation requiring a certain pH for drinking water.

Total Suspended Solids

Presby Environmental - Total Suspended SolidsTotal Suspended Solids is a measurement of the amount of solid particles that are held in suspension and will not pass through a filter.

High enough concentrations of total suspended solids are often visible to the naked eye. Suspended particles usually require a change in temperature, pressure, chemistry, or filtration to separate from the fluids.  These types of changes can occur when the fluids flow from one environment to another.  If the solids drop out of solution in an area where the passage is small enough, they can create clogs or blockages to further flow.  In most cases the warmer the fluid, the more particles and oil-based substances can be held in solution.

Suspended solids in onsite septic systems can diminish treatment effectiveness. Many organic particles can contain compounds that create algae blooms, such as phosphorus.  Other organic compounds may reduce dissolved oxygen and increase oxygen demand in a system, making the environment less capable of supporting life in aquatic conditions.  Surface water that is protected against inflow of these suspended solids is more capable of supporting aquatic life.