Waste conversion system with a low-temperature carbonizing chamber heated by flue gases and with a gas purification plant, in which, for removing problematic substances, the low-temperature carbonizing chamber is heated by flue gases of a high-temperature melting chamber which is supplied with, in particular, liquid wastes. The flue gases, after leaving the low-temperature carbonizing chamber, are conducted to the gas purification plant. The low-temperature carbonizing gases are conducted into the melting chamber.