高锰酸钾预氧化对剑水蚤DBPsFP的去除特征研究

以剑水蚤为试验对象,研究在不同条件下,高锰酸钾预氧化对剑水蚤代谢产物在氯化消毒过程中消毒副产物前体物的去除特征.研究表明:随高锰酸钾投加量的增加,水合氯醛(CH)、1,1,1-三氯丙酮(1,1,1-TCP)、三氯甲烷(TCM)总体呈上升趋势,二氯乙酸(DCAA)逐渐减少,而三氯硝基甲(TCNM)、1,1-二氯丙酮(1,1-DCP)、二氯乙腈(DCAN)和三氯乙酸(TCAA)先上升后下降,在本试验高锰酸钾投量范围内,高锰酸钾浓度为5mg/L时 CH、TCNM、DCAN、TCAN、DCAA、TCAA和1,1-DCP的去除效果最佳,去除率最高可达72.2%;延长预氧化时间,DCAN、DCAA、TCAA浓度逐渐降低,TCM、CH浓度逐渐升高,TCNM、TCAN、1,1,1-TCP浓度先升高后降低,而1,1-DCP浓度先迅速下降后逐渐升高,预氧化时间宜控制在20min;pH<7可有效抑制TCM的生成.pH=7时TCAA达到最小值,而1,1-DCP含量最高,pH>7有助于1,1-DCP的减少,CH、DCAA、DCAN、TCAN、TCNM和1,1,1-TCP随pH的增加而减少.在pH=9时生成量均最小, 最高去除率为80%;最佳温度为30℃,随着温度的升高,DCAA、TCAA和TCM浓度有所增加,1,1-DCP、DCAN和1,1,1-TCP生成量减少,在20℃时,CH的浓度最小,而TCAN的浓度最大.

The removal characteristic of DBPsFP by potassium permanganate preoxidation during chlorination of Cyclops metabolite

During chlorination process, the Cyclops metabolite would produce disinfection by-products. The objective of present study is to investigate the disinfection by-products precursors removal characteristics by potassium permanganate preoxidation under different conditions. The research indicates that: along with the increasing dosage of potassium permanganate (KMnO4), the concentration of 1,1,1-trichloropropanone (1,1,1-TCP), chloral hydrate (CH), chloroform (TCM) content increases, while the concentration of dichloroacetic acid (DCAA) decreases, this index for chloropicrin (TCNM) increases in the first place while decreases after it reaches its peak. In our experiment, when the KMnO4dosage exceeds 5mg/L, CH, TCNM, DCAN, TCAN, DCAA, TCAA and 1,1-DCP would reach their best removal efficiency, which could exceed 72.2%. The optimum preoxidation time is 20minutes. With the prolonged preoxidation time, the concentration of DCAN, DCAA and TCAA decreases, while the same item of TCM and CH changes in the opposite way. The concentration of TCNM, TCAN and 1,1,1-TCP firstly increases and then decreases. On the contrary, the concentration of 1,1-DCP decreases at first and then increases continuously. pH also has a significant impact on removal efficiency. When pH is lower than 7, TCM generation would be restrained. When pH is 7, TCAA would exceed its lowest concentration while 1,1-DCP would exceed its highest concentration. It would contribute to the decrease of 1,1-DCP with pH above 7. And when pH is higher than 7, the concentration of CH, DCAA, DCAN, TCAN, TCNM and 1,1,1-TCP decreases along with the increase of pH. The removal efficiency would reach its highest value of 80% when the pH is 9. With the increase of temperature, the concentration of DCAA, TCAA and TCM increases, while 1,1-DCP, DCAN and 1,1,1-TCP decreases correspondingly. Furthermore, CH firstly increases and then decreases. TCAN shows the opposite trend to CH. By analyzing the removal characteristics of most DBPsFP indicate that the optimum temperature is 30℃.