Sewage Treatment

A day in the life of your waste water... It All Starts Here...

…collects in sewer pipes...

…and arrives at your local waste water treatment facility.

Removes 40-50% of the solids PRIMARY TREATMENT Removes 40-50% of the solids

Step 1 in the Waste Water Treatment Process Removal of Solids Chunks of debris, sticks, sand, etc… get caught on the bar screens as the sewage enters the plant. Step 1 in the Waste Water Treatment Process

Next, it goes into the grit chamber sand, grit and heavy solids settle to the bottom

Primary Sedimentation Tank Smaller particles settle; scrapers collect the solid matter plus scum or grease floating on top of the tank

85-90% of pollutants are removed SECONDARY TREATMENT 85-90% of pollutants are removed

The 1st step is AERATION... Microorganisms and oxygen are mixed with the wastewater. Air speeds the growth of the bacteria which eat the waste matter.

SECONDARY SEDIMENTAITON Solids clump together (activated sludge) and settle out for reuse in the aeration tanks. Followed by... SECONDARY SEDIMENTAITON

CHLORINE Added as a disinfectant before the wastewater leaves the plant to kill disease-causing organisms

We’re not done yet! What do you do with all of the ... You know… The ”S” Word NO! SLUDGE!

Digesters The purpose of sludge treatment is to destroy the pathogens Huge tanks in which the sludge is stored to allow it to continue to decompose (15-30 days) Aerobic digestion (treatment) consists of continuously pumping compressed air into a tank Anaerobic bacteria present in the waste convert much of the waste materials to carbon dioxide and methane (natural) gas

Now...what to do with the sludge? Burn it in specially designed plants to prevent air pollution Now...what to do with the sludge? A source of methane for powering small power plants Bury it in approved landfills

What if you are not connected to a sewer line? …then you have a SEPTIC SYSTEM

Septic Tank http://www.co.thurston.wa.us/health/ehoss/images/drainfield.jpg

Septic Tank The septic tank is a settling tank where sewage from the house is stored temporarily so that solid materials settle to the bottom of the tank to form sludge, while grease floats to the top to form a scum layer. The scum and sludge must be periodically removed from the septic tank by simply pumping them out.

Septic Tank http://rps.uvi.edu/CES/septicx.jpg

Drainfield or Absorption Field http://www.co.thurston.wa.us/health/ehoss/images/drainfield.jpg

Drainfield The absorption field is frequently a network of drain lines (pipes with holes in them) that carry wastewater from the septic tank and apply it to the soil. The size of the absorption field varies from site to site, but most are small enough to fit in a backyard and cover and area between 400 and 800 ft2.

Suitable Soils Although effluent can be applied to the surface of any soil, not all soils are able to absorb and purify wastewater. Soils that can be used for waste disposal are permeable, deep, well drained (not waterlogged) and are not on a steep slope. In N. C., state law requires that all soils pass an inspection before a septic system is installed on any property.

The Dos and Don’ts of Septic Maintenance Inspect your tank for signs of sludge buildup. Pump your tank every 2-3 years. Keep a grease can handy. Protect your system from vehicles and encroaching trees and shrubs. Install water saving devices to conserve water. Use non-toxic cleaning products such as baking soda to scrub toilets, or boiling water to help clear clogged drains.

The Dos and Don’ts of Septic Maintenance use a garbage disposal - it adds 50 % more solids to your system. pour automotive oil, cooking oil, grease or paint or paint thinner down the drain. drive vehicles over the septic system/fields. plant bushes or trees over the leach field. use too much water, especially during rainy, wet seasons when the ground is saturated. use drain cleaners and other toxic chemical products. use chemical or biological septic system cleaners which can plug up leach fields and ruin your system.