Septic & Conservancy Tanks
The Septic Tank is a tank that receives waste from toilets, bathrooms and kitchens. The tank has traditionally two chambers, the primary or solids chamber and the secondary or liquid chamber. There is a French drain or soakaway into which the liquid from the secondary chamber flows. The soakaway is the final treatment of the effluent and will vary in size depending on the size of the tank and amount of people the system is designed for.
NB, where ever possible grey water should not enter a septic tank system, it should be diverted to a separate soakaway, as this has the potential to hydraulically overload the system. It in turn places greater demand on the septic tank system and in the case where the grey water is not diverted a much larger septic tank would be required.
The Primary ChamberIn the primary chamber, the solids in the raw sewerage are settled out while the liquids flow to the secondary chamber. The solids are then broken down by the biomass of bacteria to a liquid. The conditions are mostly anaerobic and thus anaerobic bacteria thrive in this system.
The Secondary ChamberLiquid that flows from the primary chamber to the secondary chamber still contains some solid material that settles out of suspension. The liquid is further treated by bacteria in the chamber to “cleaner” water. This flows out of the septic tank via an outlet pipe to the soakaway.
The Soakaway or French DrainThe clean water from the septic tank then flows to what is known as a soakaway or French drain. The soakaway is a trench which is traditionally filled with rocks or other aggregate. The effluent from the septic tank filters through this bed of rocks where the bacteria have established themselves. If there are any suspended solid particles in this effluent this will settle on the rocks where it will be broken down further by the bacteria before percolating into the soil to the ground water table. Therefore providing a final biodegradation process and polishing of the effluent.
The reasons for a Septic Tank being congested are:
- The use of harsh cleaning chemicals and disinfectants kill off the natural biomass
- Fats and gels biodegrade slowly and as they float and flow through the system to the soakaway where they settle on the rocks, clogging the soil. This prevents percolation and as the effluent can no longer seep away the soakaway begins to fill up and effluent will begin to pool on the surface of the soakaway.
- The tank may be overloaded, it is receiving more effluent than it was designed for and therefore the retention time in the tank is too short for complete biodegradation as the bacteria do not have enough time to assimilate the food. As the solids are not completely broken down they build up in the secondary chamber and the soakaway.
- The inflow of effluent is erratic i.e. holiday homes, in and out seasons etc. The biomass is relative to the incoming food and this controls how well the biodegradation process works and how large the natural biomass is. Without steady conditions or if there are sudden changes in the environment or loading the biomass is not developed or maintained correctly. When bacteria are starved or are old their metabolic rate is lowered, because of the lowered demand for food, the organisms are not capable of maximum food utilisation and struggle when the system is again loaded. Therefore their efficiency per unit volume in biodegrading the new excess load is lowered.
- In many instances vacuum tankers are employed to suck out the effluent from a tank when it is overloaded. In sucking out the liquids, the existing biomass is removed and the tank is left with sludge of old and inadequate bacteria which will not be able to breakdown the fresh incoming effluent fast enough. Once bacteria are full they need time to convert this food in the cell, they synthesise and oxidise the soluble food. Due to the metabolism of old bacteria being low, this results in a slow population growth rate. It can take up to 3 months to re-establish a viable and strong biomass. In the interim solids build up in the system.
A problem septic tank
Over a period of time the primary chamber starts getting an anaerobic and aerobic sludge build-up, which reduces the treatment capacity thereby lowering the biological retention time required. Fats, grease and oil discharge does not have natural bacteria to biodegrade them thus further aggravating the problem.
Solids, fats, oil and grease flow into the secondary chamber and ultimately into the soakaway, which starts congesting the soil and prevents percolation and ponding occurs. When the anaerobic treatment period reduces the waterborne diseases are not killed off and enter into the water source, aquifer, rivers and dams contaminating the water. During the rainy season the water table rises and the water commingles with the sewage in the soakaway further spreading waterborne diseases ultimately rendering them a health hazard to the community.
- Insufficient biological activity to break down the incoming effluent
- An anaerobic and aerobic sludge build up begins to develop
- The solid effluent builds up in the Primary and Secondary Chamber reducing the capacity of the tank this reduces the retention time in the tank (time required to break down the suspended solids)
- Fats and Gels begin to accumulate in the French Drain reducing the capability of the liquid to percolate into the ground
- The liquid effluent builds up and pooling appears on the surface of the ground
- There will be a malodorous odour present
Solution - How Pitking and Fatking work in the Septic Tank:
- The products are a combination of specially selected bacteria designed to breakdown sewerage. The product has a high concentration of bacteria i.e. one billion bacteria per gram. So by applying these bacteria to a tank that is overloaded or congested they will rapidly convert the solids to water and carbon dioxide due to the large amounts of nutrients available to them.
- Due to the bacteria in the product being aerobic, anaerobic and facultative anaerobic they adapt quickly to their environment and thrive in the tank and soakaway.
- Through applying a shock dose of bacteria, the schedule allows for maximum conversion of food to energy and reproduction, the population of bacteria in optimum conditions will reproduce as frequently as every twenty minutes.
- The solids and fats in the primary and secondary chambers will be broken down and the soakaway will be decongested allowing percolation to continue. The final quality of the effluent is improved as the E-coli die off in a healthy environment when they can no longer compete for food, the levels of suspended solids, B.O.D. and C.O.D. are lowered, and therefore Pitking and Fatking will prevent contamination of the ground water.
- By converting the anaerobic environment to aerobic the process will kill off the waterborne diseases that hibernate in the effluent. The bio-augmentation products contain selected bacteria that compete with the cholera bacterium on a food source thereby starving the cholera bacterium preventing it from spreading. Additional bacteria are added that secrete a crystalline toxin that kills off the mosquito and blackfly larvae being a malaria and waterborne disease control.
- Once the anaerobic sludge begins to biodegrade, the malodorous odour will disappear. This can be expected within the first 24 – 48 hours.
A maintenance programme should be implemented once the system is brought under control and the solids are broken down. This will ensure a continual introduction of new, strong and hungry bacteria that will maintain a well-balanced biological activity and prevent any further build up.
A working septic tank
- Sufficient biological activity breaks down the incoming effluent
- The anaerobic and aerobic sludge build up is broken down and a normal anaerobic sludge and aerobic scum will be present
- The suspended solids and fat particles are reduced therefore they do not build up in the soakaway
- The congestion in the soakaway is broken down, allowing for normal percolation
- Varying levels of loading can be controlled by maintaining a viable biomass
Features & Quality Guarantee
- Are Roto-moulded as one integral part to ensure a watertight unit.
- Have heavy-duty reinforced ribs for extra strength.
- Are durable, lightweight and strong.
- Can be linked to increase capacity.
- Have fittings included.
- Have easy access to inlet and outlets.
- Cannot rust or corrode (that would shorten the life expectancy of the units) making it 2 – 3 times more lasting than traditional units.
- Have a removable manhole cover that can be filled with concrete.
- Have an internal baffle for dividing solids and fluids (Septic tanks).
- Have a unique internal pipe and tube system that ensures no unwanted spillage.
- Are resistant to the action of sewer gasses.
- Can easily pumped out if necessary.
We have various sizes to suit your requirement.
High water table & poor installation – the result
Doing it right