Many architects and engineers are now specifying a sewage treatment plant followed by a tertiary treatment module in place of a large percolation area.
Tertiary treatment modules include the following;
Sand Filters – Sand filters are very effective. They are layers of certified silica sands and gravels installed to EPA designs. Limitations of sand filters are that they can be large, are expensive to install and they require a certain degree of skill by the installer.
Coconut filters – There are some new products on the market now that use waste organic material like peanut shells and coconut shell fragments to treat wastewater. These systems come in a tank preinstalled. Drawbacks of the systems are that they use waste organic filter material that needs regular replacement. Suppliers may tell you otherwise, but our advice is read the small print and get it in writing! The only advantage versus a sand filter is that they are tank based systems to they are simple to install.
Filterpod Units – Biocell offers filterpod tertiary treatment units for tertiary treatment. Certified to EN12566-3 and EN12566-7. The systems come plug and play as a small tank that can be installed in place of a percolation area. The filter media is synthetic – so none of the problms that you get with organic filter media as discussed above. Far better value and easier to install than sand filters.