Treatment Classes
1. Primary - Settling and flotation
2. Secondary - Usually aerobic biological treatment
3. Tertiary - Enhanced nutrient removal and disinfection

Tank Functions

· Settling and Flotation

· Anaerobic Digestion

· Storage of Solids

How a Septic Tank Functions

· Provides primary treatment in an on-site wastewater system.

· Wastes enter the first chamber of the tank.

· Heavy solids settle to the bottom of the tank and form a sludge layer.

· Light wastes (grease, hair) float to the top and form a scum layer.

· In a two compartment tank all steps are repeated a second time; this almost invariably provides proper tank treatment.

Things that Degrade a Tank Slowly

· Garbage Disposal Refuse

· Hair

· Laundry Lint

· Powdered Laundry Detergent

· Oil and Grease

Frequency of Pumping

· General Recommendation, every 1-3 years.

· Frequency of pumping is best evaluated at time of service.

What does NOT belong in the tank?

· Cigarette Butts

· Coffee Grounds

· Cooking Fats

· Paints and Chemicals

· Paper Towels

· Sanitary Napkins, Tampons & Applicators

· Disposable Diapers

· Condoms

Tank Materials

· Reinforced Concrete (most new tanks in Michigan)

· Fiberglass

· Polyethylene

· Older Tanks: Steel, Concrete Block, etc.

Water Tightness

· Infiltration

· Ex filtration

·  Water Tight Seals: All Joints, Inlet & Outlet, Riser & Lid

Tank Sizing

· Generally prescribed by the Health Department for individual homes.

· Criteria: Hydraulic Storage

· 2-3 days storage of design flow

· Add solids storage volume

Risers

· Provide easy access

· A must for effluent filters

·  Shallow tanks - short risers

· Joints must be water tight

· Grade away from riser

· Covers must be secure

Effluent Filters - Function

· Reduce suspended solids

· Protect against not pumping

· Control outflow rate

Effluent Filters - Installation Options

· Tank

·  Sump

· Pump Vault

*Size to anticipated flow

Effluent Filters - Cleaning

· No flow while cleaning

· Can be equipped with alarm

Myths and Magic (false information)

·  "A good working septic tank never needs cleaning."

· "Septic tank additives will maintain your septic tank or system."

(At certain times, additives may be helpful. This is best determined at time of cleaning.)