TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The polyphosphate storing microorganisms are anaerobic polyphosphate storing microorganisms. The treated solid material is sewage sludge ash, industrial waste, soil material, sludge, landfill soil or liquid manure. The feedstock is anaerobically conditioned sewage sludge.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The treatment of the solid material is carried out at a pH of 2-3.5, preferably 2.2-2.5, and at a temperature of 15-37, preferably 20-30 degrees C. The treatment takes place under the addition of oxidizable sulfur. The process further comprises enrichment of sulfur-oxidizing microorganisms by culturing in an aqueous feedstock, which contains anaerobic polyphosphate storing microorganism, treating the heavy metals- and phosphorus-containing solid with the acid leaching liquid obtained in the step (a) under aerobic conditions to release heavy metals and phosphate from the solid and to uptake phosphate released by the polyphosphate storing microorganisms contained in the culture, and removing phosphorus-enriched biomass. The solid material is located in a percolator (3), through which acid leaching liquid is percolated, which contains leaching active sulfur-oxidizing microorganism and anaerobic polyphosphate storing microorganism. The percolated leaching liquid is continuously led back into the percolator. The treatment is carried out under the supply of fresh leaching active and polyphosphate storing microorganism. The separation of the biomass enriched with phosphorus takes place, when the concentration of phosphate in the leaching liquid reaches a minimum amount. Besides the biomass enriched with phosphorus, the leaching liquid enriched with heavy metals and/or the solid material having less heavy metals are isolated. EXAMPLE - Anaerobically conditioned sewage sludge (2 l) was placed in a first stirring reactor under stirring (250 revolution per minute (rpm)) and enriched with polyphosphate storing microorganism and aerated with compressed air containing oxygen and carbon dioxide. Then the treated sludge was mixed with elemental sulfur (10 g/l) and the enrichment carried out at 25 degrees C without the addition of other nutrients. The pH value was measured daily to control the bacterial growth. Then the mixture was centrifuged at 25000 rpm for 20 minutes to collect the supernatant having the pH of 2.3-2.4. The supernatant (more than 800 ml) still containing the polyphosphate storing microorganism was enriched with leaching active sulfur-oxidizing microorganism. The enriched supernatant as a leaching solution was transferred into a second stirring reactor. The second stirring reactor was connected to a percolator having glass frit, where the leaching of the solid material was carried out, in which sewage sludge ash (2 g) was used. After the leaching treatment, the accumulated phosphorus-enriched biomass was collected using centrifugation.