The high salt wastewater produced by crude phenol process is difficult to treat due to its high concentration of organics and salts. In this paper, the crude phenol process with replacement reactions is simulated with Aspen Plus to probe the wastewater generation process. A novel treatment process of high atom utilisation and sustainability is then designed to dispose of this wastewater, with the treatment effect analysed by experiment and simulation. In this treatment process, sodium carbonate is acidified by sulfuric acid, and the generated carbon dioxide is recycled back to the crude phenol process. Phenol is extracted from the wastewater, and sodium sulfate is further removed by electrolysis to obtain sodium hydroxide and sulfuric acid, which are used in the production of sodium phenolate and the acidification of sodium carbonate in crude phenol process. Because the proposed treatment process has a high atomic utilisation of carbon dioxide, sodium hydroxide, and sulfuric acid, it is a sustainable and economical process.