The Influence of Key Elements in Black-Odor Water

Currently, the progress for the treatment of black-odor rivers is not optimistic. One of the main reasons is that the public understanding of the influence of key elements for the formation of black-odor water still remains unclear. Studying the key elements in black-odor water is important to determine the water quality conditions, evolution process, and mechanism underlying the formation of black-odor water, as well as to quantify the degree of black-odor water. In this study, the effect of total organic carbon on dissolved oxygen (DO) and oxidation–reduction potential (ORP) values was studied by artificially simulating black-odor water. The contribution of inorganic sulfur (IS) and organic sulfur (OS) to the formation of black-odor water was discussed. The obtained results show that pure organic pollutants do not cause black-odor water. When the DO content is below 1 mg/L and the ORP value decreases to –200 mv, metal sulfides begin to appear, followed by pungent odors such as H2S and volatile organic sulfur compounds (VOSCs). Both IS and OS contribute to the black-odor water. IS is more likely to form metallic sulfides than OS; however, OS is more likely to produce pungent odors than IS.

Pollution status of volatile organic sulfur compounds causing odor in Xi River and factors influencing spatial distribution

This study investigated the pollution status of volatile organic sulfur compounds (VOSCs) and the factors influencing their spatial distribution in the Xi River in Shenyang, China. A method for simultaneous determination of 14 VOSCs that cause odor in water samples was developed by using purge and trap coupled with gas chromatography and a flame photometric detector. The results indicated that each target compound could be identified from 15 sampling sites, and the total concentration of 14 VOSCs ranged from 2.575 to 52.981 μg L−1. Dimethyl sulfide (DMS) was the most important contaminant with an average concentration of 4.029 μg L−1, a detection rate of 93.33% and a variation coefficient of 0.72. The VOSCs were primarily distributed in suburban and rural sections, and the suburban section was the worst in regard to pollution by VOSCs. Dimethyl trisulfide was primarily distributed in urban and suburban sections of the Xi River due to industrial emissions. Ethanethiol, DMS, and ethyl methyl sulfide, which are typical by-products of microbial anaerobic decomposition from domestic wastewater, were found in abundance in the suburban section. Diethyl sulfide, diethyl disulfide, methyl propyl disulfide, and 1-propyl disulfide representing agricultural nonpoint source pollution were mostly distributed in the rural section.