Pressurised Sand Filter Wastewater Treatment Plants

Operation

Typically, in pressurised sand filter wastewater treatment plants in France, the waste water flows into a septic tank first. This septic tank requires a filter to hold back solids. Then the anaerobic filtered septic tank effluent flows into a holding chamber that contains a pump or pumps to pressurize liquid material through small diameter pipes. These small diameter pipes are pre-drilled with holes of a particular diameter in order to achieve a particular squirt height and velocity. Then the under pressure anaerobic filtered septic tank effluent is forced into the intermittent sand filter wastewater treatment plant.

The intermittent sand filter itself consists of several layers of sand and/or gravel that must contain specific sieve characteristics and cleanliness. Once the pressurized anaerobic filter septic tank effluent has passed through the intermittent sand filter wastewater treatment plant it travels to the disposal site. The filtered anaerobic septic tank effluent is treated and filtered as it passes through the intermittent sand filter by the microorganism attached to the sand, by the aerobic condition of the intermittent sand filter (ISF), and by the sands ability to hold onto suspended solids.

To keep the intermittent sand filter small diameter pipes clean in larger commercial waste water treatment plant situations there are often recirculation tanks and pump systems to hold some of the ISF's effluent to be used to backwash the pipes. Over months and years of service the sand bed has the potential to become saturated with suspended solids held by the sand. This condition, if not addressed, may cause the sand bed to go anaerobic or smelly. To keep this from occurring, there may be installed a system of an air pump to air feed lines to force atmospheric air into the bottom of the sand bed.

Service & Maintenance

• pressurizing the lateral pipe lines - utilizing a bottle brush each lateral pipe line should be cleaned every six months
• checking for pumping out of septic tank every six months
• checking of pump screen and cleaning every six months
• Sand bed may need to be removed, transported to sanitary land fill, every 2-5 years

Environmental Benefits

Correctly performing pressurised sand filter wastewater treatment plants in France (WWTP s) with sophisticated control systems can bring significant environmental benefits and clean results compared to traditional anaerobic treatment methods such as fosse septiques and normal sand filter configurations. Whether the often complicated arrangement of pumps and electronics, which require reasonably frequent attention, can be considered ecologically defendable, remains to be decided.

Conclusion

With pressurised sand filter type wastewater treatment plants in France, there is some question whether the disposal of the polluted sand will be readily available in the future at a reasonable cost. This solution to your wastewater treatment does not offer any significant advantages over other wastewater treatment plants and the long term reliability and cost can be questioned too.

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