微波—活性炭协同处理焦化废水的工艺研究

【作者】 李雨；

【导师】 张世敏；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2008， 硕士

【摘要】 中国是世界焦炭生产大国,焦化工业在我国的工业发展中占重要地位。焦化生产在其带来大量优质的冶金用焦的同时,随之产生大量的含有有毒有害物质、组成复杂的焦化废水。本论文在简述国内外焦化废水的处理现状的基础上,以焦化废水为处理对象,采用类似湿式催化氧化的微波-活性炭法来处理焦化废水,以微波作为能量、以实验室自制的椰壳活性炭和再生后的废触媒作为敏化剂对生化前出水和生化后出水进行研究,以提高生化前出水的可生化性及难降解有机物的氧化分解,及解决生化后出水水质超标和不稳定为目的,对微波在焦化废水的处理领域进行积极探索,并在考察各因素对CODcr去除率的影响后,得出优化工艺参数。1.首先通过研究活性炭在微波场中的升温行为、活性炭对焦化废水CODcr的吸附行为、单独微波辐射对CODcr去除率的影响等,确定了微波-活性炭协同处理工艺,并选定了相关的仪器设备。2.通过条件实验,确定了两种体系对焦化废水生化前出水处理的优化条件分别为:1)对椰壳炭处理体系:微波功率700W,辐射时间120s,通气量2L/min,初始pH值为7;2)对再生后废触媒活性炭处理体系:微波功率700W,辐射时间120s,通气量2L/min,初始pH值为3或7。对两种处理体系,增加活性炭投加量可提高COD去除率,但考虑去除率的增加和经济成本,当采用5g时,两种活性炭处理体系的COD去除率在50%左右,结合处理体系对可生化性的影响,活性炭投加量采用5g。在此条件下两种处理体系对生化前出水的COD去除率分别可达到40%,50%左右。3.通过条件实验,确定了两种体系对焦化废水生化后出水处理的优化条件分别为:1)对椰壳炭处理体系:微波功率700W,辐射时间120s,通气量1 L/min,初始pH值为7,活性炭投加量5g;2)对再生后废触媒活性炭处理体系:微波功率700W,辐射时间120s,通气量1 L/min,初始pH值为3或7,活性炭投加量2.5g。在此条件下两种处理体系对生化后出水的COD去除率分别可达到60%,70%左右。4.对比了两种微波-活性炭处理体系处理焦化废水生化前后出水COD去除率的影响,结果表明:微波-废触媒体系效果优于微波-椰壳炭体系。对生化前出水而言,主要原因在于再生后废触媒活性炭的吸波性优于椰壳活性炭,再生后废触媒活性炭在微波场中升温速率更大,在700W微波功率下再生后废触媒活性炭的平均升温速率为95.8℃/min,椰壳活性炭平均升温速率为67℃/min,由此产生的“热点”效应好于椰壳活性炭;对生化后出水而言,一方面鉴于生化处理过程导致长链和杂环化合物的断链和开环,生化后出水中的有机物大部分属于小分子有机物,部分难生化大分子有机物在预吸附过程中和微波-活性炭处理初期得到分解,在处理后期大量的小分子有机物的吸附降解成为对COD变化贡献最大的部分。而两种活性炭的孔径结构分析,再生后废触媒活性炭微孔数量和总孔容要大于椰壳活性炭同。另一方面再生后废触媒活性炭的“类光催化”效应和其“热点”效应要稍好于椰壳炭,故在总体上再生后废触媒活性炭处理体系要好于椰壳炭处理体系。论文的开展为焦化废水的处理提供了有益的探索,同时为微波技术的应用开辟了新的途径。更多还原

【Abstract】 Coking industry occuping a important position in industry developing position of China.A large amount of coking waste water containing pernicious compounds was brought following the production of fine cokes,which contain pernicious compound.In this paper,on basis of a brief summarization of the disposal of coking waste water,a new method which is analogous with wet catalytic oxidation（WCA）was put forward by adopting microwave-activated carbon to dispose the coking waste water.The coking waste water before and after biochemical treatment was treated by microwave（MW）heating and by using coconut shell activated carbon and spent carbon as catalyst.The purpose of this work is to try to improve the biodegradability of the coking waste water before biochemical treatment and the degradability of the some organism,resolve the problem of the pollutant beyond the standard in the coking waste water after biochemical treatment.After the exploration of the effect of each factor on CODcr wipe ratio,the optimal technique parameters were obtained.1.The optimal technique parameters of the coking waste water systems before biochemical treatment disposed by two kind of MW carbons were obtained as follows:1)for microwave-coconut shell activated carbon system:MW power was 700W;radiation time was 120S;ventilate was 2L/min;initial PH was 7.2)for microwave-spent carbon system:MW power was 700W,radiation time was 120S,ventilate was 2L/min,initial PH was 7 or 3.The increase of carbon can approve the wipe ratio of the two systems, but along with the increase of the cost.When the carbon is 2.5g,the wipe ratio of COD_crreaches 40%for MW coconut shell activated carbon system and 50%for MW spent carbon system.2.The optimal technique parameters of the coking waste water systems after biochemical treatment disposed by two kind of MW carbons were obtained as follows:1)for microwave-coconut shell activated carbon system:MV power was 700W;radiation time was 120S;ventilate was 1L/min;initial PH was 7;the AC was 5.0g.2)for microwave-spent carbon system:MV power was 700W;radiation time was 120S;ventilate was 1L/min;initial PH was 7 or 3;the spent carbon was 2.5g.The increase of carbon can approve the wipe ratio for two systems.When the carbon is 2.5g, the wipe ratio of COD_crreaches 60%for MW coconut shell activated carbon system and 70%for MW spent carbon system.3.In comparison of the effect of both microwave-coconut shell activated carbon and microwave-spent carbon on COD wipe ratio of the coking water before and after biochemical treatment,the result indicates that the microwave-spent carbon was more effective than coconut shell activated carbon.For the coking waste water system before biochemical treatment, the different microwave absorption of two kinds of carbon was the reason for the different results of treatment.Under the microwave field,the average heating temperature of coconut shell activated carbon increased as 67℃/min,while the spent carbon increase as 95.8℃/min.For the coking waste water system after biochemical treatment,on the one hand,the biochemical treatment led to the break of carbon chains and the open of rings in long chain and heterocyclic compounds,and most residual organic compounds are small molecules.A part of macromolecular organic compounds were decomposed in the pre-adsorption and pre-treatment of MW-AC.Along with the MW-AC treatment,the absorption and degradation of small molecules become the main contribution to the change of COD. The different pore structures of two kinds of carbon were the primary reason for the different effect of both disposal systems.The spent carbon has more micropores and larger pore volumes than coconut shell activated carbon.On the other hand,the spent carbon has better "homothetic photocatalytic degradation" effect and "heat point" effect than coconut shell activated carbon.Therefore,the treatment of coking waste water by microwave-spent carbon is more effective than that by microwave-coconut shell activated carbon.Therefore,This thesis carried out a actively explore for coking waster water treatment,and open up a new way for microwave application.更多还原