sewage treatment system 10 in accordance with the invention this sewage treatment system is especially designed for purification of sanitary wastewater here the plant containers are indicated by reference number 56 there are several plant basins provided in plant container 56 and these are populated with plants of different species the wastewater to be purified is sent initially into a feeder tank 58 via a feed unit not shown in fig2 from there the wastewater goes in flow direction 34 to the plant basin 60 in which there are plants of species juncus inflexus arranged the water passes through the plant basin 60 from right to left at the left end of plant basin 60 there is a crossover line 62 only shown schematically by means of an arrow by which the wastewater goes to plant basin 64 plant basin 64 contains plants of two different species carex acutiformis and iris pseudacorus here the plants are arranged in separate rows only shown schematically by reference number 66 across the direction of flow 34 and alternating with each other in succession the direction of flow of the wastewater in plant basin 64 is from left to right at the right end of plant basin 64 is another crossover line 67 through which the wastewater flows into plant basin 68 which contains plants of species f2 the wastewater flows from the right end of plant basin 68 to.