东江高风险支流污染特征分析和人工湿地处理效果研究

发布时间：2018-09-01 05:18

【摘要】：东江作为饮用水源型河流,承担着供给广东省及香港地区约4000万人生产及生活用水的任务,其水质安全至关重要。高埔小河是东江上游高风险支流,该流域发展快速,工业密集,农田村镇交错,污水管网配套不完善,使得部分生产生活污水直接排入河中。此外,降雨径流作为非点源污染,携带大量地表污染物及农田残留农药进入水体,对高埔小河造成严重污染,进而影响东江水质安全。本研究以高埔小河为研究对象,对氮磷等常规污染物指标及阿特拉津、乙氧喹、异丙甲草胺、抗蚜威、戊唑醇、咖啡因和避蚊胺七种痕量有机污染物指标开展为期一年的监测,分析污染物的时空分布特征,对高埔小河流域进行水质风险评价。选取商住混合区、农业区和工业区三个典型功能区的降雨径流进行监测,分析污染物分布特征,估算降雨径流入河年污染负荷,研究降雨径流对高埔小河污染物的贡献量。采用“组合填料床+波形潜流人工湿地”组合工艺对高埔小河重污染支流河水进行异位生态修复,研究组合工艺对黑臭水体的处理效果。主要结论如下:(1)高埔小河流域常规污染物浓度受季节和水文期的影响较大。CODCr、TN和TP指标均出现枯水期浓度高,丰水期浓度低的现象;溶解氧则是冬季浓度高夏季浓度低。各断面污染物浓度随水流方向呈上升趋势,分析高埔小河干流常规污染物的主要污染源是上游农田径流汇水、中游支流汇水和下游污水厂排水。全年TN和TP(除六月份)的检测值均超过地表水环境质量标准(GB3838-2002)III类标准,部分检测点CODCr浓度超出III类标准值。采用单因子污染指数和多因子加权指数模型分析结果显示高埔小河支流为典型黑臭水体。痕量有机污染物4月前后和8月前后逢作物种植周期浓度较高,枯水期浓度较丰水期的高;上游农田区的降雨径流和中游支流污水的汇入导致污染物浓度逐渐升高,河流水体生物对痕量有机污染物的降解作用不明显;到污水厂排水口下游,由于污水厂排水的稀释作用,痕量有机污染物浓度下降。采用RQ商值法对痕量有机污染物进行生态风险评价,结果表明,七种痕量有机污染物均在环境可接受风险(RQ1)的范围内,其中,中等风险(0.1RQ1)的污染物有阿特拉津、抗蚜威和戊唑醇,低风险(0.01RQ0.1)的污染物有乙氧喹和异丙甲草胺,无风险(RQ0.01)的是咖啡因和避蚊胺。(2)降雨径流中常规污染物浓度较高,商住混合区TN浓度最高,农业区CODCr、TP和SS的浓度最高。工业区由于管网设施完善,地面及时清扫,降雨径流中常规污染物浓度均较低。痕量有机污染物除咖啡因在农田区未检出外,在三个功能区降雨径流中均有检出,且浓度变化范围较大。其分布特征受农药使用、下垫面及降雨参数等影响。农业区检测的痕量有机污染物总量最大,其次是工业区,商住混合区的降雨径流中咖啡因浓度最高。(3)高埔小河流域年污染负荷估算结果为,CODCr年污染负荷最高,达到401448.42kg,TN和TP分别为41466.53kg和5011.23kg。七种痕量有机污染物中,乙氧喹和异丙甲草胺的年负荷最高,分别是444.38g和534.93g。降雨径流作为典型的非点源污染,对高埔小河的污染物贡献量大,应该引起足够的重视,及时采取管控措施,完善管网设施,减少化学农药的使用,改用无毒的生物农药代替,从源头降低河流污染风险。(4)组合工艺对污染物去除效果较好,两组湿地TP去除率都很高,分别为79.66%和79.65%,CODCr去除率为66.74%和72.50%。两组湿地出水CODCr和TP均能实现将河水从劣V类水质提升到地表水IV类的目标。TN的去除率分别为52.04%和45.21%,出水平均浓度较高。检测期间正值冬季,温度较低,微生物和植物的活性较低,导致去除效果不能达到最佳状态。本课题分析高埔小河流域水体及降雨径流中的污染特征,解析污染来源,为河流管理与生态修复提供科学依据。研究了“组合填料床+波形潜流人工湿地”处理重污染河水的效果,为我国河流黑臭水体的生态修复治理提供一定的参考。
[Abstract]:As a source of drinking water, the Dongjiang River undertakes the task of supplying about 40 million people with water for production and living in Guangdong and Hong Kong. Its water quality is very important. In addition, rainfall runoff, as a non-point source of pollution, carries a large number of surface pollutants and pesticide residues into the water body, causing serious pollution to Gaopu River, thereby affecting the water quality and safety of Dongjiang River. Seven trace organic pollutants including oxamide, carbamazole, pentazole, caffeine and mosquito repellent amine were monitored for one year. The spatial and temporal distribution characteristics of pollutants were analyzed and the water quality risk assessment was carried out in Gaopu small river basin. Distribution characteristics, estimation of the annual pollution load of rainfall runoff into the river, study on the contribution of rainfall runoff to pollutants in Gaopu small river, adopt "combined packed bed + waveform subsurface flow constructed wetland" combination technology to carry out heterotopic ecological restoration of the heavily polluted tributary river water of Gaopu small river, and study the treatment effect of combined technology on black and odorous water. The results are as follows: (1) The concentration of conventional pollutants in Gaopu small river basin is greatly influenced by season and hydrological period. The CODCr, TN and TP indexes are high in dry season and low in wet season, while the dissolved oxygen is high in winter and low in summer. The main pollution sources are the runoff catchment of the upper reaches of farmland, the catchment of the middle reaches of tributaries and the drainage of the sewage treatment plants in the lower reaches. The results show that the tributaries of Gaopu River are typical black and odorous water bodies. The concentrations of trace organic pollutants are higher in crop planting cycles around April and August, and higher in dry season than in wet season. The concentration of trace organic pollutants decreased due to the dilution of sewage from the sewage treatment plant. The ecological risk assessment of trace organic pollutants was carried out by RQ quotient method. The results showed that the seven trace organic pollutants were within the range of environmental acceptable risk (RQ1). Risk (0.1RQ1) contaminants are atrazine, Carbendazim and pentazole, low-risk (0.01RQ0.1) contaminants are ethoxyquine and isoprochlor, and risk-free (RQ0.01) are caffeine and mosquito-repellent amine. (2) Rainfall runoff has higher concentrations of conventional pollutants, the highest concentrations of TN in mixed commercial and residential areas, the highest concentrations of CODCr, TP and SS in agricultural areas. Except for caffeine, trace organic pollutants were detected in the runoff of three functional areas, and their concentrations varied widely. Their distribution characteristics were affected by pesticide use, underlying surface and rainfall parameters. The total amount of trace organic pollutants was the largest, followed by the industrial area, and the mixed commercial and residential area had the highest concentration of caffeine in the rainfall runoff. (3) The annual pollution load of Gaopu small river basin was estimated to be the highest, reaching 401448.42 kg, TN and TP were 41466.53 kg and 5011.23 kg, respectively. The annual load of amines is the highest, 444.38g and 534.93g, respectively. Rainfall runoff as a typical non-point source pollution, contributes a lot to the pollutants in Gaopu River. It should be paid enough attention to take timely control measures, improve the pipeline network facilities, reduce the use of chemical pesticides, replace it with non-toxic biological pesticides, and reduce the risk of river pollution from the source. (4) The combined process has a good effect on pollutant removal, and the removal rates of TP and CODCr are 79.66% and 79.65% and 66.74% and 72.50% respectively. The effluent CODCr and TP of the two wetlands can achieve the goal of upgrading river water from inferior V to surface water IV. The removal rates of TN are 52.04% and 45.21% respectively, and the effluent concentration is high. During the winter, the temperature is lower, the activity of microorganisms and plants is lower, so the removal effect can not reach the best state. This paper analyzes the pollution characteristics of water and rainfall runoff in Gaopu small river basin, analyzes the pollution sources, and provides scientific basis for river management and ecological restoration. The effect of constructed wetland on the treatment of heavily polluted river water will provide some reference for the ecological restoration of black and Odorous River water in China.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

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