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Long‐term (from 2005 to 2016) trends in wet SO42− deposition across China are assessed using Ozone Monitoring Instrument (OMI) SO2 columns within the planetary boundary layer. The models for estimating monthly SO42− deposition from precipitation in eight ecological regions are constructed based on SO2 columns and ground‐based measurements. An accuracy assessment shows that the models achieve highly precise predictive values for monthly deposition (R = 0.93, with a relative/absolute error of −0.1/0.3 kg S · ha−1 · month−1). In terms of spatial distribution, SO42− deposition shows substantial variations across China, ranging from 0.9 to 63.9 kg S · ha−1 · year−1, with an average of 10.4 kg S · ha−1 · year−1. Additionally, wet SO42− deposition shows significant seasonal variations, increasing from January to July and then decreasing thereafter. Regarding long‐term trends, the wet SO42− deposition in northern, central, and southern China decreased at rates of 0.009, 0.001, and 0.0009 kg S · ha−1 · month−1, respectively. In contrast, Inner Mongolia, Qinghai‐Tibet, and northwest and northeast China showed increasing deposition trends. In general, the wet SO42− deposition in 2016 decreased by 4.3% from that in 2005 on a national scale, indicating that air quality policies to control SO2 emissions have had some effects on wet SO42− deposition.

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The conventional flue gas treatment technologies require high capital investments and chemical costs, which limit their application in industrial sectors. This study developed a sulfur-cycling technology to integrate sulfide production by biological sulfur reduction and simultaneous catalytic desulfurization and denitrification with HS (HS-SCDD) for flue gas treatment and sulfur recovery. In a packed bed reactor, high-rate sulfide production (1.63 ± 0.16 kg S/m-d) from biological sulfur reduction was achieved using organics in wastewater as electron donors at pH around 5.8. 93% of sulfide in wastewater was stripped out as HS, which can be a low-cost reducing agent in the HS-SCDD process. Over 90% of both SO and NO were removed by the HS-SCDD process under the test conditions, resulting in the formation of sulfur. 88% of the input S (HS and SO) were recovered as octasulfur with high purity. Besides partial recycling to produce biogenic sulfide, excessive sulfur can be obtained as a sellable product. The integrated sulfur-cycling technology is a chemical-saving and even profitable solution to the flue gas treatment in industrial sectors with wastewater available.