PCB废水破络预处理控制及对AAS-BAF工艺处理效能的影响

发布时间：2017-12-27 01:35

本文关键词：PCB废水破络预处理控制及对AAS-BAF工艺处理效能的影响　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：印刷电路板(PCB)由于制造过程复杂,工艺流程长,用水量大,使得产生的废水污染物种类多,这其中以络合态铜、氨氮、总氮等污染物去除较为困难。本课题选用“硫化钠破络预处理+缺氧活性污泥(AAS)-曝气生物滤池(BAF)”组合工艺对PCB废水进行处理。硫化钠预处理过程中药剂投加控制成为破络过程的关键。本研究中对比了监测ORP或银硫电极电位来调节加药量的破络预处理控制方法,并对方法的可行性进行分析,最后考察连续动态运行组合工艺处理PCB废水的稳定性及其对水中污染物去除情况。研究中对比了监测水中ORP及银硫离子电极电位两种控制PCB废水破络预处理的方法。结果表明,在利用ORP监测控制时,由于其检测过程响应时间长,易受共存离子干扰等原因,在实际应用中存在一定局限性。利用银硫离子电极控制时,准确度和精密度相对较高,响应时间较短,并且受共存离子干扰小,能够实现对铜的破络预处理控制。当初始总铜的浓度在25~150 mg/L范围内变化时,控制电位值为-750 mV,铜可完全去除,此时水中硫离子波动范围为2.6~39.6 mg/L。研究了预处理出水中的硫离子对缺氧活性污泥处理性能及性状的影响。结果表明,硫离子瞬时冲击对缺氧活性污泥反硝化速率会造成抑制,污泥浓度的增加可降低抑制效果。硫离子长期存在时总抑制率为32.3%,单位质量活性污泥反硝化速率长期来看没有明显抑制。硫离子长期存在会使污泥浓度有所降低,并且在一定程度上抑制脱氢酶活性。实际应用中可通过适当提高初始缺氧活性污泥浓度来提高其对硫离子抗冲击能力,从而保证长期运行有较好的处理效果。最后利用“硫化钠破络预处理-AAS-BAF”组合工艺来处理实际PCB废水,并考察了通过监测水中银硫电极电位来控制预处理过程的可行性和长期运行下主要污染物的处理效果。结果表明,利用银硫电极控制电极电位均值为-617 mV时,能够快速发现进水铜的波动,通过电位反馈加药量,实现铜的完全去除。通过调节组合工艺停留时间可实现当HRT为4 h时,污泥回流比50%,硝化液回流比为200%条件下,出水总氮在15 mg/L以下,氨氮出水在5 mg/L以下,COD出水在80 mg/L以下,铜在0.5 mg/L以下,SS在30 mg/L以下,pH出水范围为7.0~8.5之间,均满足相关排放要求。
[Abstract]:Due to the complex manufacturing process, long process flow and large water consumption, printed circuit boards (PCB) cause a lot of wastewater pollutants, including complex copper, ammonia nitrogen and total nitrogen. In this study, PCB wastewater was treated by the combination process of "sodium sulfide pre treatment + anoxic activated sludge (AAS) and biological aerated filter (BAF)". The key of the process is to control the dosage of traditional Chinese medicine in the process of sodium sulfide pretreatment. In this study, we compared the control method of monitoring the dosage of ORP or silver sulfur electrode to control the dosage, and analyzed the feasibility of the method. Finally, we investigated the stability of PCB wastewater and the removal of pollutants in water by continuous dynamic operation combined process. In this study, the methods of monitoring the two kinds of PCB wastewater pretreatment by monitoring the ORP and the silver sulfur ion electrode potential in water were compared. The results show that when using ORP monitoring and control, due to the long response time of the detection process, vulnerable to co existing ion interference and other reasons, there are certain limitations in practical applications. When silver sulfur electrode is used to control, the accuracy and precision are relatively high, the response time is short, and the interference of coexisting ions is small, so that the pretreatment of copper can be realized. When the initial total copper concentration is in the range of 25~150 mg/L, the control potential is -750 mV, and the copper can be completely removed. At this time, the sulfur ion fluctuation range is 2.6~39.6 mg/L. The effects of sulfur ions in the pretreatment effluent on the performance and properties of anoxic activated sludge treatment were studied. The results show that the instantaneous impact of sulfur ions can inhibit the denitrification rate of the activated sludge, and the increase of sludge concentration can reduce the inhibition effect. The total inhibition rate of sulfur ions in the long term was 32.3%, and the denitrification rate of unit mass activated sludge had no obvious inhibition in the long term. The long-term existence of sulfur ions can reduce the concentration of sludge and inhibit dehydrogenase activity to a certain extent. In practical application, we can increase the initial anoxic activated sludge concentration to enhance its impact resistance to sulfur ion, so as to ensure long-term operation with good treatment effect. Finally, the combined process of sodium sulfide pretreatment and -AAS-BAF pretreatment was applied to treat the actual PCB wastewater. The feasibility of controlling the pretreatment process and the treatment effect of main pollutants in long-term operation were investigated by monitoring the potential of silver and sulfur electrode in water. The results show that when the average value of electrode potential is -617 mV, the fluctuation of influent copper can be found quickly, and the total removal of copper can be realized through potential feedback and dosage. By adjusting the combination process of residence time can be achieved when the HRT is 4 h, sludge return ratio of 50%, the nitrification liquid reflux ratio is 200%, the effluent total nitrogen below 15 mg/L, the effluent is below 5 mg/L, the effluent COD is below 80 mg/L, copper below 0.5 mg/L, SS 30 mg/L, pH the water is in the range of 7.0~8.5, all meet the relevant discharge requirements.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X76

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