NOVELTY - A wastewater treatment system comprises an inlet flow path for receiving wastewater from a source outside the treatment system; a vessel (15) comprising a packed media filter (14) where the wastewater is treated as it flows by gravity through pores in the packed media; a dosing unit for dosing the media with the wastewater; a drain fluidly connected to the vessel for discharging treated wastewater from the vessel; and a unit for cleaning the media through intermittent backwashing and fluidization of the media.    USE - As wastewater treatment system for removing pollutants and pathogens from wastewater and other dirty water sources (claimed).    ADVANTAGE - The system provides a high level of wastewater treatment and physical filtration in a much smaller footprint than conventional unsaturated wastewater filters and without needing secondary clarification treatment. Similar to fine non-backwashing wastewater filters, it provides both physical filtration and aerated biological treatment, but unlike the conventional filters, incorporates backwashing previously only used in high rate saturated filters. The present system is capable of reducing biochemical oxygen demand, suspended solids, and turbidity from wastewater to the very low levels similar to those found in conventional'tertiary'wastewater treatment plants of approximately 10 mg/L for both biochemical oxygen demand and suspended solids. This is accomplished at surface area loading rates from 5 to 20 times as high as conventional fixed media non-backwashing wastewater filters such as biotextile filters and recirculating gravel filters. The present system is also relatively inexpensive because an internal structure is not required as with fixed media filters. Furthermore, it provides a greater specific surface area for microbial growth than many other unsaturated filters because finer media can be used without plugging. The present system also provides an extremely energy-efficient means for transferring oxygen to the aerobic microbes biodegrading the wastewater without the need for large blowers, mixers, or pressurized air diffusers. Supplying sufficient oxygen for aerobic microbes is important for a compact system because aerobic microbes provide a much faster rate of pollutant biodegradation than anaerobic microbes. The amount of treated effluent recycled back to a septic tank either as part of the backwash cycle or as a direct return can be controlled to substantially increase the total nitrogen removal of the combined system due to enhanced biological denitrification in the septic tank.    DETAILED DESCRIPTION - A wastewater treatment system comprises an inlet flow path for receiving wastewater from a source outside the treatment system; a vessel (15) for containing the wastewater, the vessel comprising a packed media filter (14) configured for biological and physical treatment of the wastewater and where the wastewater is treated as it flows by gravity through pores in the packed media; a dosing unit for dosing the media with the wastewater; a drain fluidly connected to the vessel for discharging treated wastewater from the vessel; and a unit for cleaning the media through intermittent backwashing and fluidization of the media. An INDEPENDENT CLAIM is included for method of treating wastewater, involving an accepting step of accepting wastewater into a vessel comprising a packed media filter; treating step where the wastewater is treated during residence in the packed media filter; a draining step of draining treated wastewater by gravity from packed media in the vessel; and a backwashing step of backwashing and fluidizing the media with the treated wastewater.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional side view of the system.    Settleable solids (11)    Filter inlet (12)    Distribution head (13)    Packed media filter (14)    Vessel (15)