A wastewater purification system includes first purification equipment (101) for receiving wastewater and for outputting first time purified wastewater and sludge, and second purification equipment (102) for receiving the first time purified wastewater and for outputting second time purified wastewater and purification residue. The second purification equipment is based on the reverse osmosis and/or nanofiltration technology. The wastewater purification system further includes combustion equipment (103) for burning the sludge so as to produce heat, and dryer equipment (104) for drying the purification residue with the aid of the produced heat. Hence, the sludge produced by the first purification equipment is used for producing heat for drying the purification residue which is produced by the reverse osmosis and/or nanofiltration technology and whose initial water content is so high that it is problematic to be disposed of without drying.