催化臭氧化处理难降解制药废水研究

【作者】 蔡哲锋；

【导师】 方土；

【作者基本信息】 浙江大学 ， 环境工程， 2004， 硕士

【摘要】 制药废水具有COD值高且波动性大，可生化性差，毒性大等特点，直接采用生化方法处理制药废水效果欠佳，因而必须对其进行预处理，降低废水对微生物的毒性，提高废水的可生化性，使其适于生化处理。本实验考察了臭氧化联合SBR法工艺对制药废水的降解效果，研究了催化剂对提高处理效率的作用，比较了反应器设计优化对去除率的影响，并对降解机理进行了研究，得到了如下结论： 1、臭氧对制药废水预处理作用较好，能够改善废水的可生化性。一次进水600ml，用浓度为71mg/L的臭氧气处理3h，隔20min取样，测定水样的pH、COD、BOD和色度等因素。结果显示：臭氧对废水色度的去除效果很好，在10min中内即可从320倍下降为零；COD按照一级反应规律被去除，即反应时间越长，臭氧对废水的去除效果越好，处理3h后出水COD值从4220mg／L下降到2087mg／L，去除率达到50.5％；废水的pH值由12.8下降到5.8，变化较大，说明臭氧处理后有酸性物质产生；废水B／C比提高较为显著，由原水的0.18上升到0.35，说明臭氧氧化能够改善废水的可生化性。 2、过渡金属氧化物有很强的催化作用，可大大缩短臭氧化预处理时间。本实验采用Mn、Cu、Fe、Co、Pd氧化物作为催化剂，用活性炭纤维作载体，非均相催化臭氧化处理制药废水，结果显示，过渡金属氧化物均能有效提高臭氧的氧化效率，用71mg／L的臭氧气对600ml废水进行预处理，在40～60min之间即能达到良好的反应效果。如Fe氧化物催化臭氧化7min废水的色度即全部消除，40min后废水的COD去除率即可达到62.1％，超过了单用臭氧处理废水3h的去除率，此时废水的B／C比为0.36，已经具有较好的可生化性。在催化剂中，Pd、Fe、Co氧化物具有相对更好的催化效果，40min后COD去除率分别可以达到57.3％、62.1％和62.9％，B／C比分别提高到0.33、0.35和0.35，其中Fe氧化物尤佳，因此，可以选用Fe氧化物作为本实验废水的催化剂，不仅较易获得，而且成本较低。实验还对影响催化臭氧化的初始pH值、臭氧用量、催化剂投量、反应时间、初始污染物浓度等诸因素进行了考察，发现除了碱性条件对催化臭氧化预处理制药废水有普遍的促进作用外，其它因素都与特定的废水浓度相关联，存在最佳值，因而确定了相对于某一特定浓度下的最佳反应条件：在废水初始COD浓度为4220 mg／L条件下，选用氧化铁为催化剂，投加量3.6mg/L，控制臭氧气流量4OL/h，初始PH值12.5左右，反应时间为40min。在此条件下，出水COD可下降为1565mg/L，去除率62.9%，B/C比提高到0.35，可生化性得到了改善，pH值降为9.4左右，色度在反应7min后即可全部消除。 3、用催化臭氧化/SBR联合工艺处理实验制药废水，可以达标排放。预处理出水调节PH值为7一7.5，进入SBR反应器进行处理，反应器直径Zoonun，有效容积为4L，用蠕动泵、搅拌器和时控开关实现自动控制，一个周期12h，其中进水1 smin，厌氧搅拌Zh，曝气sh，沉淀1.sh，排水15min，水力停留时间(HRT)48h，控制水温巧一200C。系统稳定运行后，十个周期出水平均Coo为25Omg/L，去除率达到84.工%，抽样检测BOD<50 mg/L，出水可以达到国家二级排放标准，联合工艺全过程c0D总去除率达到94%。 4、对臭氧化苯胺的反应机理进行研究，发现至少存在两个降解途径。苯胺广泛应用于制药工业，也是本实验废水中含有的物质。只含有苯胺的废水经臭氧处理后，用高效液相色谱进行分析，出现了苯醒和硝基苯等物质的特征峰线，因此可以推测臭氧降解苯胺的可能途径至少有两条:o:N+O-白|OH·HOZ·夕刻于。中— OCOz 5、对反应器进行设计优化，可以提高臭氧氧化效率。实验设计制造了新的反应器，将直径由loollun缩小到50咖，高径比从2:1提高到8:1，同时改用更细密的砂芯布气装置，发现在处理等量废水和其它反应条件不变的情况下，臭氧对废水的coD去除率提高到74.2%，优化后处理效果改善较为显著。 6、将催化臭氧化与活性碳十臭氧、HZOZ十臭氧等工艺进行比较，预处理效果分别为催化臭氧化>HZ氏+臭氧>活性碳+臭氧。更多还原

【Abstract】 Since the pharmaceutical wastewater has kinds of compounds, low biodegradability, the important pollutants such as COD are out of criterion, the treatment of pharmaceutical wastewater is considered the one of the most difficult treatments for the most of pharmaceutical companies. So, in order to improve its biodegradability, we should pretreat the water. In these experiments, we treated the special pharmaceutical wastewater with the ozonation process coupled with SBR, then studied the effect of catalyst to increase treatment efficiency, researched the principle of the degradation and compared the redesigned reactor to old one. At last, we achieved several conclusions following.1, Ozone is preferable to pharmaceutical wastewater’s pretreatment and can improve its biodegradability. We pretreated 600ml this water with 71mg/L ozone, sampling every 20min, then determined its factors such as pH, COD, BOD and chroma, The results show that ozone has very good removal effect to chroma, it can wipe off almost all the chroma in 10min, dropped from 320 to 0. COD was removed responding to stair reaction law, in another word, more time, better removal effect, and it dropped from 4220mg/L to 2087mg/L after 3 hours’ treatment, the degradation rate reached to 50.5%. pH changed greatly from 12.8 to 5.8,it showed that there was acidity substance come into being. B/C increased a little notably from 0.18 to 0.35, it made out that ozone can improve its biodegradability.2, The catalysis of transition metal oxide is very powerful, and can greatly shorten the pretreated time of ozonation. We introduced the oxide of Mn, Cu, Fe, Co and Pd as catalyzer, and used active carbon fibre as carrier, then pretreated the refractory pharmaceutical wastewater by Heterogeneous Catalytic Oxidation. The results are that transition metal oxide can greatly advance the efficiency of ozonation. If we pretreated 600ml this water with 71mg/L ozone, it ,very soon in 40~60min, can reach favorable effect. For instance, if we use Fe oxide as catalyzer, chroma will be entirely eliminated in 7min, and COD removal rate can attain 62.1%, more than therate of using single way of ozone treating 3h, and on the temporary, the B/C is 0.36. At those kinds of catalyzer, using Fe, Co and Pd oxide in pretreatment will have comparatively good catalyze effect, COD removal rate can attain partly 57.3%, 62.1% ’ and 62.9%, B/C increased partly to 0.33, 0.35 and 0.35, and Fe was especially best among the three. So this experiment selected Fe oxide as ozonation catalyzer, not only for its good effect, but also for its low cost and easily obtaining. Furthermore, we studied the influenced factors of pretreatment such as original pH, ozone dosage, catalyzer casting quantity, reaction hour and original contamination concentration, and found that all factor were correlated to a given concentration of wastewater, expect alkalescence condition can accelerate pretreatment effect prevalently, so there must exist a best-of-all reaction condition, and the condition to a given COD concentration of wastewater is that original COD is 4220 mg/L, Fe oxide is 3.6mg/L, ozone airflow is 40L/h, original pH is 12.5, and reaction hour is 40min. On this condition, COD of outflow water fell to 1565mg/L, and its removal rate can reach 62.9%, on the temporary, B/C unproved to 035, pH dropped to 9.4, and chroma eliminated in 7min.3, If the refractory pharmaceutical wastewater was treated by the catalytic ozonation process coupled with SBR, it can let flow reaching the mark.. We accommodated pH of the outflow into 7~7.5, then put it in a SBR reactor for deeper treatment which diameter is 200mm and available dimension is 4L, using vermiculation pump, beater and time-controlling switch for automation. An react cycle was 12h composing of 15min’s inflow, 2h’s mix, 8h’s charge, 1.5h’s deposition and 15min’s drainage. HRT was 48h and the temperature was 15~20C. After the system running stable, we measured COD and BOD of outflow. The average COD of ten cycles’ was 250mg/L, correspondence with 84.1% removal rate,更多还原