Knollands Septic Tanks & Drainage

septic tank operation

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The septic tank is always full. Clarified effluent is displaced from the tank outlet into the irrigation, soakaway/ distribution system, by the incoming sewage flow.

Within the tank, there are complex internal baffles which are arranged to assist the solids to separate from the liquid. Some solids float, but most settle. Little by little, sludge builds up within the main chamber of the tank.

Floatables, i.e., oils, grease and some faecal constituents, undergo some microbial decomposition and form a floating layer of white brownish scum. In some tank designs this is exposed to the air, and after a period, hardens to form a crust.

Settleable solids sink to the bottom of the tank where they may also undergo some bacterial decomposition acquiring a black colour.

Some of the sewage constituents have the same density as the clarified effluent. Other particles or constituents may be denser but tiny gas bubbles attach to them, thus they become lighter and they stay in the clarified effluent forming a suspension.

Septic tank factsheets:

Septic Tanks

Our range of septic tanks are suitable for both domestic and commercial applications and for populations of 1 up to 500 people. The Knollands Bio-Pure septic tank is an innovative and cost effective solution and as a result is our best selling septic tank.

Drainage systems

Wether it be agricultural drainage coil, twin walled CorriPipe™ or Hunter sewer drains, Knollands can offer quality drainage systems for a number of different requirements and are perfect for use with our range of septic tanks and rain harvesting products.

rain harvesting

Knollands supply mainly Graf Carat S underground tanks due to their quality construction and reliable design. Convenient packages that include everything you need to start rain harvesting result in a simple and enjoyable project that benefits you and the environment.

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