Study on Facile and Full-Scale Reuse Treatment of Wastewater Produced from Tail Gas Oxidation-Absorption Technology of Natural Gas Purification Plant

Abstract

The oxidation-absorption technology of tail gas is perfect for natural gas purification plants to ensure the up-to-standard discharge of sulfur dioxide emissions, but it can produce a large amount of wastewater. In this paper, a facile and full-scale reuse treatment strategy based on the sequential combination of disc tube reverse osmosis and low-temperature and low-pressure evaporation desalination was proposed and studied. The produced light yellow wastewater was acid sulfate-rich organic wastewater, in which sulfate ions (SO42−) existed up to 6479 mg/L, and the chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5), total organic carbon (TOC), ammonia nitrogen (ammonia-N), total nitrogen (TN) and suspended solid (SS) were 207, 71.9, 67.6, 1.28, 70.5 and 20.9 mg/L, respectively. After the reuse treatment, there was COD (6 mg/L), BOD5 (1.4 mg/L), TOC (0.9 mg/L), TN (2.07 mg/L), SS (6 mg/L) and SO42− (90 mg/L) in permeated water, and condensate water with COD (11 mg/L), BOD5 (2.3 mg/L), TOC (4.3 mg/L), SS (2 mg/L) and SO42− (1.2 mg/L) was obtained. Thereby, pollution indexes were reduced after the reuse treatment so as to meet the water quality standard (GB/T18920-2022) in China, and the total water recovery rate reached 98.2 vol%. Ultimately, the priority pollutant migration mechanism during the reuse treatment process was determined.