油脂及盐对餐厨垃圾产VFAs的影响研究及工程示范

发布时间：2019-01-07 09:52

【摘要】：传统方式处理餐厨垃圾存在效率低、成本高的问题,而采用厌氧定向产酸工艺处理餐厨垃圾可以获得大量富含挥发性有机酸(VFAs)的发酵液,可以替代乙醇和乙酸作为污水处理厂污水及垃圾填埋场渗滤液脱氮除磷的外加碳源,但我国餐厨垃圾中含有较高浓度的NaCl和油脂,会影响VFAs的产生。本文研究了餐厨垃圾中NaCl及油脂对其厌氧发酵定向产酸的影响并开展了示范工程的应用研究,主要研究成果如下:通过小试研究了NaCl和油脂对餐厨垃圾厌氧产酸的影响,考察了发酵过程中VFA浓度、有机酸组分、TS/VS、SCOD/氨氮及几种碱金属离子浓度的变化。实验结果表明,NaCl对厌氧发酵产酸有抑制作用,当NaCl浓度超过6.0g/L后,对产酸的抑制强度迅速增强,至12.0g/L时几乎不产酸,但NaCl对厌氧发酵类型影响不显著,各批次均为丁酸型发酵;油脂对产酸亦有明显的抑制作用,表现为降低产酸量并使产酸过程滞后,当油脂添加量为35g/L时,最大VFA浓度降低了68.0%,产酸滞后39.4h,并且油脂会促使厌氧发酵类型向丙酸型转变。盐与油同时存在时,盐的抑制与油的抑制相互之间存在部分拮抗作用,即当餐厨垃圾中同时存在一定量的油脂及盐时,其对产VFA的综合抑制强度是介于相同含量油脂或盐单独存在条件下的抑制强度之间。此外,各组发酵体系中VFA组分的变化呈现相同的规律,均以乙酸、丙酸及丁酸为主要组成成分,丁酸所占比例在发酵初期迅速增加后趋于稳定,而乙酸与丙酸所占比例在整个发酵过程中变化不大。此外,发酵体系中的Na+浓度会随发酵时间的增加而逐渐上升,其上升的幅度和时间与发酵产酸量及时间吻合。研究结果表明,实际餐厨垃圾产酸前宜进行脱油脱盐预处理,使NaCl含量低于6.0g/L、油脂含量低于15.0g/L,并于发酵第2~3d提取发酵液。在小试研究的基础上设计并建设了处理规模为3.5t/d的示范工程,发酵底物为餐厨垃圾与厌氧污泥的混合物,其TS为128.2 g/L,VS为107.4g/L,经过5天发酵,VFAs产量达到最大值21.8g/L,与小试实验的理论值相近,证明餐厨垃圾厌氧产酸技术具有实际工程应用的可行性。
[Abstract]:The traditional treatment of kitchen waste has the problems of low efficiency and high cost. However, a large amount of fermentation liquid rich in volatile organic acid (VFAs) can be obtained by anaerobic directed acid production process. Ethanol and acetic acid can be used as carbon sources to remove nitrogen and phosphorus from sewage and landfill leachate. However, high concentration of NaCl and grease in Chinese kitchen waste will affect the production of VFAs. In this paper, the effects of NaCl and grease in kitchen waste on directed acid production by anaerobic fermentation were studied. The main research results were as follows: the effects of NaCl and grease on anaerobic acid production of kitchen waste were studied in a small scale. The changes of VFA concentration, organic acid component, TS/VS,SCOD/ ammonia nitrogen and several alkali metal ions during fermentation were investigated. The results showed that NaCl could inhibit the production of acid by anaerobic fermentation. When the concentration of NaCl exceeded 6.0g/L, the inhibition of acid production increased rapidly, and almost no acid was produced at 12.0g/L, but the effect of NaCl on the type of anaerobic fermentation was not significant. All batches were fermented with butyric acid; The effect of oil on acid production was also obvious, which was as follows: the amount of acid production was decreased and the process of acid production was delayed. When the oil was added with 35g/L, the maximum concentration of VFA decreased 68.0 and the acid production delayed 39.4 hours. And the fat can promote the anaerobic fermentation type to propionic acid type change. When salt and oil exist at the same time, there is some antagonism between the inhibition of salt and the inhibition of oil, that is, when there is a certain amount of oil and salt in the kitchen garbage, The comprehensive inhibition intensity of VFA was between the same content of oil or salt and the same content of oil or salt. In addition, the changes of VFA components in each fermentation system showed the same regularity, with acetic acid, propionic acid and butyric acid as the main components, and the proportion of butyric acid tended to be stable after a rapid increase in the initial stage of fermentation. However, the ratio of acetic acid to propionic acid changed little during the whole fermentation process. In addition, the concentration of Na in fermentation system would increase gradually with the increase of fermentation time, and the range and time of the increase was consistent with the amount of acid produced by fermentation and the time of fermentation. The results showed that the pretreatment of desalination and desalination should be carried out before the actual kitchen waste produced acid, so that the NaCl content was less than 6.0 g / L, the oil content was less than 15.0 g / L, and the fermentation broth was extracted on the 2nd day of fermentation. On the basis of the pilot study, a demonstration project was designed and built for the treatment of 3.5t/d. The fermentation substrate was a mixture of kitchen waste and anaerobic sludge, with a TS of 128.2 g / L vs 107.4 g / L, and fermentation for 5 days. The maximum output of VFAs was 21.8 g / L, which was close to the theoretical value of the small scale experiment. It was proved that the anaerobic acid-producing technology of kitchen waste had the feasibility of practical engineering application.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X799.3

【相似文献】