市政污水中环形挥发性甲基硅氧烷浓度水平与去除效率

Occurrence and removal efficiency of cyclic volatile methylsiloxanes in municipal wastewater

本研究于2014年10月至11月间对大连市8处污水处理厂(W1—W8)入水、出水中环状挥发性甲基硅氧烷(Cyclic volatile methylsiloxanes,c VMSs)浓度进行了调查,采用超声辅助液液萃取及气相色谱-质谱联用检测方法测定了污水样品中六甲基环三硅氧烷(D3)、八甲基环四硅氧烷(D4)、十甲基环五硅氧烷(D5)、十二甲基环六硅氧烷(D6)的浓度水平.结果表明,入水D3、D4、D5、D6检出率分别为92%、88%、71%、75%;出水检出率分别为61%、96%、63%、58%.入水、出水Σc VMSs平均浓度分别为1135±1600、433±437 ng·L-1,且入水、出水平均浓度均为D5最高,D3最低.入水D3与D4、D6,D4与D5浓度相关性达到5%的显著水平(R2=0.80、0.83、0.82),D3与D5及D5与D6浓度相关性达到1%的显著水平(R^2=0.91、0.85);出水D4与D6浓度相关性达到1%的显著水平(R2=0.93);入水量与入水D3—D6浓度相关性未达到5%显著性水平.c VMSs去除效率范围为28%—100%,对D3—D6去除效率最高的二级处理工艺分别为BAF、BAF、A/O、SBR工艺,去除效率分别为87.3%、69.1%、99.5%、95.1%;最低的二级处理工艺分别为A/O、SBR、SBR、A/O工艺,去除效率分别为68.3%、30.1%、54.1%、72.0%.

Eight wastewater treatment plants （W1--WS） in Dalian were investigated to determine levels of cyclic volatile methylsiloxanes （cVMSs） in their influents and effluents from October to November in 2014. Ultrasound-assisted dispersive liquid-liquid extraction method coupled with GC-MS was emplayed for the analysis of D3, D4, DS, D6 in wastewater. The results showed that, in influent and effluent, detection frequencies of D3, D4, DS, D6 were 92%, 88%, 71%, 75% and 61%,96%,63%,58%, respectively. The average concentrations of cVMSs were 1135± 1600, 433±437 ng·L-1, respectively. D5 and D3 were the compounds found at the highest and lowest average concentration both in influent and effluent. In influent, there were statistically significantcorrelations of the concentrations of D3 with D4 and D6, and D4 with D5 at 95% confidence level （R2= 0.80,0.83,0.82）. Moreover, D3 with D5, and D5 with D6 at 99% confidence level （R2 =0.91,0.85）. In effluent, there were statistically significant correlations of the concentrations of D4 with D6 at 99% confidence level （R2= 0.93）. There is no correlation between water mass flow and cVMSs concentrations in influent. Removal efficiencies of cVMSs ranged from 28% to 100%. Secondary treatment process with the highest removal efficiency was BAF, BAF, A./O and SBR, and removal efficiencies were 87.3%, 69.1%, 99.6%, 95.1%, respectively; The secondary treatment process with the lowest removal efficiency was A/O, SBR, SBR and A/O, and removal efficiencies were 68.3% ,30.1% ,54.1% ,72.0%, respectively.