The Septic Tank
The septic tank plays a vital role in the overall s e p t i c s y s t e m. It is defined as any water tight which implies covered container that is designed in such a way that it first receives the discharge of sewage typically from a residence. It then retains the discharge so that the liquids can be separated from the solids. The solids are broken down for subsequent discharge along with the liquids into the drain field or leach field as it is sometimes called.
The purpose of the tank is therefore to create an environment for the initial onsite treating of wastewater systems. Through its design it promotes the flotation, physical settling and anaerobic digestion of sewage.
Septic Tank Process
Three layers of wastewater form in a septic tank that is properly designed. Heavier solids settle to the bottom and this part is called “sludge.” Lighter solids such as fats and greases float to the top and are called “scum.” There is a layer of liquid between the sludge and the scum and this is referred to as the “clear zone.” A properly sized tank allows for the storage of these accumulated solids until maintenance is performed. Baffles or outlet tees that are part of the tank design prevent the sludge and scum from entering the drainfield.
The solids that accumulate in the tank are comprised of both biodegradable and nonbiodegradable substances. Over time many of the solids wil eventually decompose; however not all will. The process that these solids under go is both anaerobic and facultative operating in an oxygen-deficient enclosure. This is a slow and incomplete process that produces gases such as hydrogen sulfide, methane, carbon dioxide among others.
The anaerobic digestion that occurs in the septic tank is affected by several factors. One of the primary ones is the temperature in the tank with higher temperatures aiding the biological process. However temperatures that are too high can cause the fatty substances, fats, oils, and greases, to liquefy. other factors that contribute to the performance of the tank include the concentration of the incoming wastewater and the pH of that water. If the wastewater contains such things as drain cleaners, paint, harsh chemicals or similarly inappropriate substances, the process can be affected both from a pH and the biological standpoint.
Septic tanks are typically made of concrete, polyethylene or fiberglass. Although steel and redwood have been used in the past, most regulatory agencies now prohibit their use. One of the advantages of the polyethylene and fiberglass tanks is that they can be easily moved by a labor crew. That is not true with concrete tanks which require the use of a boom truck. However both polyethylene and fiberglass tanks are more prone to “floating” than their concrete counterparts. Regardless of what materials are used in the construction, the tank must be structurally sound and watertight.
The structural integrity of the tank will affect its long-term performance. The requirement that the tanks be watertight is necessary in order to protect the environment and to make sure it operates property.
We here at Athens Plumbing & Well Service are experts in the installation and maintenance of septic tanks. Call us at 706-543-1497 to evaluate your septic tank needs.
Athens Plumbing & Well Service
380 Nantahala Ave
Athens, GA 30606