The Greens Bio Bubble. Bob and Jackie Green are in the process of renovating and extending a large house in Four Marks, Hampshire. Jackie was particularly keen to have a large ornamental fish pond in the garden but she had never thought that it might be possible to use the water they flushed down the loos and emptied from the sinks and washing machines to fill the pond. However, the Greens have installed one of the more innovative sewage treatment plants, the Bio Bubble, which produces such a clean effluent that it can go straight into their pond without further treatment.

Compared to most other package treatment plants, the Bio Bubble is expensive the Greens spent a total of 6,000 installing their Bio Bubble of which about 75% was the cost of the plant and 25% went to the groundworkers doing the installation. However, when it comes to what it actually does, the Bio Bubble is arguably in a class of its own. Its the one treatment plant on the market in the UK which digests the solids as well as the liquids in the waste. Although it falls within the general grouping of activated sludge package plants that is treatment plants which operate by having air pumped through them to speed up digestion the Bio Bubble works in a rather different way which is called Sequential Batch Reaction (SBR).

The foul waste comes into a settlement tank where it is held until the Bio Bubble is ready to get to work when it has reached a certain level, both solids and liquids are then drawn off in one batch into the next chamber where they are subjected to a very high level of bacterial digestion. The resultant effluent is so clean that it is almost drinkable.

There is no need for an annual desludging by tanker as would happen with almost every other treatment plant and septic tank instead, once a year as part of the 120 a year maintenance contract, Bio Bubble extract around two or three wheelbarrows of completely odourless semi-solid matter which the Greens spread straight on the lawn as fertiliser. As it only operates intermittently, the Bio Bubble uses much less electricity than most other package treatment plants which operate continuously.

The majority of Bio Bubbles have been installed on larger community sewage disposal schemes they are used extensively by the National Trust and by such bodies as the RSPCA where they are reckoned to be particularly effective in dealing with dog and cat faeces. Small domestic versions are becoming commonplace too and the Bio Bubble is a particularly suitable solution where space is at a premium. Its one of the few treatment plants to use concrete rings rather than GRP or one of the newer plastics and this means that it can easily be sited under roads or car parking areas. Its rather more hi-tech than many treatment plants and part of the installation is a control panel mounted inside the house which monitors the operation and gives instant feedback should any component fail.