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Sewage Treatment Plant - BIOROCK - How does it Work
How the BIOROCK Sewage Treatment System Works
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The BIOROCK system consists of a separate settlement tank, which can be an existing traditional brick or concrete septic tank, followed by the BIOROCK sewage treatment plant.
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The raw sewage first enters the settlement tank which separates the solids from the liquid part of the effluent. This tank is ordered seperately at the time of order. This settlement tank is fitted with an effluent filter which prevents solids exiting the tank. New settlement tanks are made for us by Conder and these digest most of the solids anaerobically and only require emptying every 2 to 3 years on average. Existing traditional 2 stage septic tanks can also be used, if they are the correct size and watertight,as this settlement tank and in these cases you would only order the BIOROCK sewage treatment plant.
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The Primary Effluent then enters the BIOROCK sewage treatment plant which uses alternate layers of air passages and natural fibre material contained in nets. This stone fibre is in constant contact with the air to treat the effluent in exactly the same way as Nature treats effluent in the soil or on the margins of a pond.
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Bacteria grow in the stone fibre and digest the organic material as it is trapped in the matrix and the cleaned water trickles through.
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The Stone Fibre is self cleaning and so far, in the 13 years since the current design has been in operation, has not required replacement under normal domestic use. The photo on the right shows the stone fibre under a microscope, The top photo is new stone fibre and the bottom photo is the top layer of the stone fibre after 18 months in the BIOROCK. Note the completely open filter matrix with just the newly trapped solids being digested by the bacteria in the fibres. Sensible care must be taken to ensure that excess fats, oil and grease (FOG) are kept out of the system as far as is possible as it will clog the BIOROCK media and the plant will not work. For commercial kitchens which produce a lot of FOG, a correctly sized grease trap or interceptor needs to be installed prior to the settlement tank.
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Instead of using electricity-guzzling compressors to provide the air, the BIOROCK biofilter sewage treatment plant utilises the wind and natural 'chimney-draft' to pull the air through the plant with no electricity required. This venting of the system is essential in order for the BIOROCK to work. The low end of the chimney has its inlet within 5 metres of the BIOROCK tank and the high end of the chimney usually exits underground and discharges within 10 metres up the side of the house or shed wall, telegraph pole, freestanding pole, etc. as a soil vent pipe. The high air outlet pipe must be 5 metres higher than the top of the air inlet pipe in order to 'draw' the air through the system, which is why it is usually fixed like the soil vent pipe - up the side of the house wall. A freestanding vent can be disguised easily by growing a Honeysuckle, Rose, etc. around it to form a very attractive feature.
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http://www.bing.com/videos/search?q=biorock&mid=2D1A16F21DDCE3281B992D1A16F21DDCE3281B99&FORM=LKVR12
- Please click above to see a video of the process and how the venting works. The video shows a Biorock settement tank wheras we use the Biorock approved Conder tank, but the process is identical - the video is for illustration only. The angles and bends of the venting pipes are not as in the video.
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The Conder settlement tank is included when you order the BIOROCK sewage treatment system package. This is also vented to a separate soil vent pipe (see diagram below) and therefore no smell is emitted from the tank.
Note, there is one vent pipe from the BIOROCK and another one from the settlement tank. You cannot vent both through one 'chimney'.
The final effluent can be discharged either to a soakaway or a watercourse
Never let anyone who is untrained on the BIOROCK system undertake any maintenance on your plant. Unless the BIOROCK is serviced by qualified BIOROCK service engineers, your warranty will be voided. We have seen many extremely stupid things done to the system by so called 'service engineers' and 'drain experts' and these are likely to result in having to replace the entire BIOROCK media.
For high water table sites, ensure that the installation is design by a civil engineer.
You also need a slightly sloping site as the outlet from the BIOROCK is 1740mm below ground.