超声波预处理耦合技术改善污泥厌氧发酵产酸的研究

发布时间：2018-10-30 09:41

【摘要】：随着我们城镇污水集中处理率的要求越来越高,相伴污水处理而带来的剩余污泥的量也越来越大。国务院最近颁布的“水污染防治行动计划”对污水厂污泥处理处置提出了新的要求:现有污泥处理处置设施应于2017年底前基本完成达标改造,地级及以上城市污泥无害化处理处置率应于2020年底前达到90%以上。因此,城市污泥处理处置将是未来几年污染控制领域的热点和焦点。污泥厌氧发酵是污泥资源化、减量化与无害化处理一种有效的方式。然而剩余污泥中溶解性有机质含量低、含固率低,可生物降解性较差。单独将剩余污泥进行厌氧消化时污泥的减量与产酸效果并不明显。本文致力于解决水解是污泥厌氧消化的限速步骤这个问题,采用超声波及其耦合技术对污泥进行预处理,达到获得大量溶解性有机质以提高污泥厌氧产酸效能的目的。主要研究结论如下:1)研究了超声波单独预处理污泥时,对污泥破解与厌氧产酸的影响,并优化了超声波处理污泥的参数。结果表明,提高超声波的声能密度和作用时间均能够提高污泥中SCOD与溶解性碳水化合物的含量,并促进了氨氮与磷酸盐的释放。超声波预处理增加了污泥中微小颗粒的含量,并促进了污泥VSS的减量。超声波预处理为污泥厌氧水解提供了大量的初始发酵底物,经过超声预处理的各实验组VFAs的最高浓度均大于对照组;超声预处理减少了污泥厌氧达到最高VFAs浓度的酸化时间;当声能密度为1W/ml时,最佳预处理时间为20min。2)超声波与碱的耦合预处理技术,对污泥破解时有机质释放的影响更加明显。在相同超声波条件下,随着预处理时投碱量(即pH)的升高,污泥中SCOD和溶解性碳水化合物的含量大幅度升高。超声波与碱耦合预处理污泥,提高了污泥厌氧发酵时VFAs的产量,但随着投碱量的提高,污泥厌氧发酵达到最高产酸量的时间有所延长。本实验中,超声波耦合碱预处理污泥的最佳pH为10。3)首次研究了超声波耦合表面活性剂对污泥破解与厌氧产酸的影响。结果表明:随着十二烷基苯磺酸钠(SDBS)或十六烷基三甲基氯化铵(1631)投加量的提升,污泥中SCOD和溶解性碳水化合物的含量逐步升高。在相同超声条件下,投加量相同时,SDBS比1631更加促进了污泥中磷酸盐的释放,并且1631在预处理阶段促进了氨氮的积累。超声波耦合SDBS或1631对污泥进行预处理污泥,提高了污泥厌氧发酵过程中VFAs的产量,但SDBS或1631单独作用时产酸量更高。
[Abstract]:With the increasing demand of sewage treatment rate in cities and towns, the amount of excess sludge brought by wastewater treatment is increasing. The Water pollution Prevention Action Plan recently promulgated by the State Council has put forward new requirements for sludge treatment and disposal in sewage treatment plants: existing sludge treatment and disposal facilities should basically complete the transformation to meet the standards by the end of 2017. The disposal rate of municipal sludge at prefectural level and above should reach more than 90% by 2020. Therefore, municipal sludge treatment and disposal will be a hot spot and focus in the field of pollution control in the next few years. Sludge anaerobic fermentation is an effective way for sludge reuse, reduction and innocuity treatment. However, the content of dissolved organic matter in surplus sludge is low, the solid content is low, and the biodegradability is poor. The effect of sludge reduction and acid production was not obvious when the excess sludge was digested by anaerobic digestion alone. In order to solve the problem that hydrolysis is the rate-limiting step of anaerobic digestion of sludge, a large amount of dissolved organic matter was obtained by using ultrasonic wave and its coupling technology to improve the efficiency of anaerobic acid production of sludge. The main conclusions are as follows: 1) the effects of ultrasonic pretreatment on sludge cracking and anaerobic acid production were studied, and the parameters of ultrasonic treatment were optimized. The results showed that the increase of ultrasonic energy density and action time could increase the content of SCOD and soluble carbohydrate in sludge and promote the release of ammonia nitrogen and phosphate. Ultrasonic pretreatment increased the content of micro-particles in sludge and promoted the reduction of sludge VSS. Ultrasonic pretreatment provided a large number of initial fermentation substrates for anaerobic hydrolysis of sludge. The maximum concentration of VFAs in each experimental group was higher than that in control group, and the acidification time of anaerobic sludge reaching the highest VFAs concentration was reduced by ultrasonic pretreatment. When the sound energy density is 1W/ml, the best pretreatment time is 20min.2) the coupling pretreatment technology of ultrasonic wave and alkali has more obvious effect on the organic matter release during sludge cracking. Under the same ultrasonic condition, the content of SCOD and soluble carbohydrates in sludge increased significantly with the increase of alkali dosage (pH) during pretreatment. Ultrasonic and alkali coupling pretreatment of sludge increased the yield of VFAs during anaerobic fermentation of sludge, but with the increase of alkali input, the time of sludge anaerobic fermentation to reach the most high acid content was prolonged. In this experiment, the optimum pH of supersonic coupling alkali pretreatment sludge was 10. 3) the effect of ultrasonic coupling surfactant on sludge cracking and anaerobic acid production was studied for the first time. The results showed that the content of SCOD and soluble carbohydrate in sludge increased with the increase of sodium dodecylbenzene sulfonate (SDBS) or cetyltrimethylammonium chloride (1631). Under the same ultrasonic condition and the same dosage, SDBS promoted the release of phosphate in sludge more than 1631, and 1631 promoted the accumulation of ammonia nitrogen in pretreatment stage. Ultrasonic coupling of SDBS or 1631 to sludge pretreatment increased the yield of VFAs during anaerobic fermentation of sludge, but the acid production was higher when SDBS or 1631 acted alone.
【学位授予单位】：苏州科技学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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