Primary Study On Odorous Organic Sulfides In Typical Polluted Rivers And Municipal Wstewater Treatment Plants In Guangzhou Urban

Odors emitted from polluted water bodies are concerning great attention and playing an important pole in environmental protection. However, being restricted by special charactertics of volatile organic sulfides (VOS), there is even no detailed report in China. In this paper, we studied the VOS distributed in different municipal polluted rivers and wastewater treatment plants (WWTP) separately, which include methanethiol (MT), carbonyl sulfide (COS), dimethyl sulfide (DMS), carbon disulfide (CS₂) and dimethyl disulfide (DMDS). Furthermore, different techniques applied in odor control system were assessed and the impact scopes made by odor were predicted. Major results are below:1. VOS distributed in gas phas on wastewater surface were sampled with a modified dynamic flux chamber, and conventional activated carbon adsorptive pipe was substituted with high pressure fresh air as inlet gas. The target compounds dissolved in wastewater were purged out by a purging vessel with high pure nitrogen gas and then were analyzed with the same detecting method as gas samples.2. As the tipical polluted rivers, Shijing River and Liuxi River were chosen as the studied object. The results indicated that the emission flux presented a fluctuated variation with the water quality of riverwater. For all VOS, COS has the highest concentration value, which ranged from 51.6-92.2μg/m³, 17.8-69.7μg/m³ for DMS, 11.6-14.8μg/m³ for CS₂ , 8.1-59.7μg/m³ for DMDS, and the order of emission was COS>DMS> DMDS > CS₂ ; as to the Liuxi River, the concentration of COS was 0.11-3.26μg/m³, 0.20-3.13μg/m³ for DMS, 0.11-1.23μg/m³ for CS₂, and 0.13-1.74μg/m³ for DMDS, the order of emission was COS> DMS>CS₂> DMDS。Furthermore, the variation of VOS emission in 24hr presented two obvious peaks, this result was consistent with the variability of water quality in riverwater.3. MT, DMS, COS, CS₂, DMDS distributed in water body and atmosphere were carefully identified and quantified at different treatment units in different WWTPs. The results showed that different units have the different concentrations for each compound. For all VOS, in gas phase, DMS has the highest concentration, which ranged from 0.66-5.41 mg/m³, 0.01-0.21 mg/m³ for COS, 0.66-5.41 mg/m³ for DMS, 0.03-0.44 mg/m³ for CS₂, and 0.06-1.61 mg/m³ for DMDS; In wastewater, the concentration of DMS ranged from 23.7-308.2mg/m³, 0.1-2.2 mg/m³ for COS, 1.4-23.3 mg/m³ for CS₂, 0.3-106.8mg/m³ for DMDS, and 113.1-216.8 mg/m³ for MT, respectively. The order of emission was DMS > DMDS > CS₂ > COS。Furthermore, the results also indicated that different treatment process produce different VOS, and excessive disoved oxygen contribute to restrain the production potential.4. For the control techniques of odor pollution in WWTPs, we take the Datansha WWTP as the example and assess the efficiency of different odor pollution control system. The results indicate that bio-soil technique and biofiltration technique can effectively degrade the VOS, and the removal rate are all over 80%, but only about 50% for equal-ion technique.5. Under the prediction with corresponding predicting model, the concentrations at the distance over 30 m far away from downwind riverbank has been greatly decreased and lower than its odor threshold value. The scope of malodor impact from WWTPs was about 80 m away from border, and the highest concentration is on the place where is 89.25 m far away from the borderline of WWTP in the downwind.