Wastewater treatment system and wastewater treatment method

The silicon processing wastewater by injecting carbon dioxide gas and carbon dioxide injection means 3 to obtain the raw wastewater, the wastewater tank 2, the filter membrane 11 for filtering the raw wastewater, feed to feed the raw wastewater to the filter membrane 11 a liquid pump 9, when the amount of the raw wastewater in the wastewater tank 2 is below the reference amount, concentrated water, or concentrated water and filtered water as well as transported to the drain tank 2, the pH of the raw wastewater 4 and adjusted to filter membrane 11 circulating liquid feed control means 30 which can be fed to the .0～6.5 a wastewater treatment system 20 that includes a.