【摘要】：厭氧氨氧化技術(shù)作為一種高效的生物脫氮方法,獲得了大量的研究和一定程度的實踐應(yīng)用,但該系統(tǒng)的運(yùn)行溫度大多控制在中溫范圍內(nèi)(35℃)。而實際廢水溫度往往處于常溫甚至低溫狀態(tài)。為此,研究厭氧氨氧化對低溫的響應(yīng)機(jī)制,進(jìn)而建立高效、穩(wěn)定的低溫厭氧氨氧化系統(tǒng),對拓寬該技術(shù)的應(yīng)用范圍就有重要的意義�；诖�,本文利用實驗室規(guī)模的UASB厭氧氨氧化系統(tǒng),采用梯度降溫方式,研究了溫度變化對厭氧氨氧化活性影響的規(guī)律,考察了整個降溫過程中系統(tǒng)的脫氮性能、污泥理化性質(zhì)和微生物種群結(jié)構(gòu)等變化特征。獲得的主要研究結(jié)論如下:(1)長周期試驗研究表明,隨著溫度降低,系統(tǒng)的脫氮能力逐漸下降,平均總氮去除負(fù)荷從33℃的7.587 kgN m-3 d-3降至13℃和8℃的4.47和3.192 kgN m-3 d-3。各降溫初期的出水水質(zhì)波動明顯,且溫度越低,氨氮、亞硝態(tài)氮的最大出水濃度越高,系統(tǒng)重新恢復(fù)穩(wěn)定所需要的時間也越長。整個降溫過程中,進(jìn)水游離亞硝酸FNA,是系統(tǒng)是否發(fā)生紊亂的關(guān)鍵因素,其限值約為60μg/L,當(dāng)反應(yīng)器內(nèi)濃度高于該值時,系統(tǒng)的脫氮效率也隨之下降。(2)分析了降溫過程中污泥原位活性和非原位活性的變化趨勢,結(jié)果表明,污泥原位活性隨著反應(yīng)器溫度降低而降低,33和13℃反應(yīng)器內(nèi)污泥活性分別為0.102和0.023 gN g-1VSS d-1,這是系統(tǒng)脫氮能力下降的主要原因。不同溫度階段的污泥,其非原位活性均隨溫度的降低而降低,可見降溫過程中污泥的最適生長溫度并未發(fā)生轉(zhuǎn)變,仍在33℃左右。長期處于低溫環(huán)境下的污泥(18、13℃),其在低溫范圍內(nèi)的活性相比穩(wěn)定運(yùn)行于33℃下的污泥,有了顯著的提高,這歸功于污泥在低溫環(huán)境下長期的馴化。根據(jù)阿倫尼烏斯方程,本實驗中的厭氧氨氧化反應(yīng)活化能Ea在23-13和33-23℃下分別為89.6和16.4 kJ/mol。溫度越低,溫度對反應(yīng)的影響越大。(3)溫度下降不僅改變了污泥的外觀顏色、形狀,還影響了系統(tǒng)中胞外聚合物EPS的含量,23℃下EPS總量明顯降低,但反應(yīng)器溫度降至18、13℃后,該值又重新增加,其中相比多糖,蛋白質(zhì)含量波動更大。另外,污泥平均粒徑在溫度從33℃降至28℃后明顯增加(2.693增至3.389 mm),其后隨著溫度的下降而逐漸減小,13℃下減至2.275 mm,相應(yīng)的粒徑最集中的范圍從33℃時的2.5-3mm變成13℃的1.5-2 mm。污泥沉降速度的變化與VSS/SS值呈負(fù)相關(guān)。(4)溫度下降,微生物群落的多樣性呈下降趨勢,13℃時變化顯著。溫度從33℃降至23℃后,浮霉菌門的相對豐度從9.04%逐漸升至16.02%,溫度進(jìn)一步降低至13℃,該值出現(xiàn)了顯著的下降,但是長期13℃馴化后又重新升高至56.34%。微生物屬水平結(jié)果顯示,本實驗接種污泥僅含Candidatus Kuenenia這一種厭氧氨氧化菌,在實驗?zāi)┢?第199天),其在浮霉菌門下的豐度在高達(dá)98%,在總菌種中的豐度為55.18%。整個降溫過程中未發(fā)現(xiàn)其他厭氧氨氧化菌種,反應(yīng)器內(nèi)優(yōu)勢厭氧氨氧化菌種并不會隨溫度變化而改變。另外,qPCR結(jié)果顯示,AMX基因拷貝數(shù)隨溫度下降呈先減后增的趨勢,相反,單位細(xì)胞厭氧氨氧化活性值則先增后增,23℃是溫度關(guān)鍵點(diǎn)。
[Abstract]:Anaerobic ammonia oxidation technology, as an efficient biological denitrification method, has obtained a lot of research and practical application to a certain extent, but the operating temperature of the system is mostly controlled in the range of medium temperature (35 C). However, the actual wastewater temperature is often in the state of normal temperature or even low temperature. Establishing a high efficient and stable low temperature anaerobic ammonia oxidation system is of great significance for widening the application range of this technology. Based on this, the effect of temperature variation on the activity of anaerobic ammonia oxidation was studied by using a laboratory scale UASB anaerobic ammonia oxidation system and a gradient cooling method. The main conclusions are as follows: (1) With the decrease of temperature, the denitrification capacity of the system gradually decreases, and the average total nitrogen removal load decreases from 7.587 kgN M-3 D-3 to 4.47 kgN M-3 D-3 and 3.192 kgN M-3 D-3 at 33 C and 8 C respectively. The lower the temperature, the higher the maximum effluent concentration of ammonia nitrogen and nitrite nitrogen, and the longer the time needed for the system to restore stability. The results showed that the in-situ and Non-in-situ activities of sludge decreased with the decrease of reactor temperature, and the sludge activities in 33 and 13 C reactors were 0.102 and 0.023 gN g-1VSS d-1, respectively, which were the main reasons for the decrease of nitrogen removal capacity of the system. In the same temperature stage, the Non-in-situ activity of sludge decreases with the decrease of temperature. It can be seen that the optimum growth temperature of sludge does not change during the cooling process, but is still around 33 C. According to Arrhenius equation, the activation energy Ea of anaerobic ammonia oxidation reaction in this experiment was 89.6 kJ/mol at 23-13 and 16.4 kJ/mol at 33-23. The lower the temperature, the greater the effect of temperature on the reaction. (3) The decrease of temperature not only changed the appearance and shape of the sludge, but also affected the system. The content of EPS in the medium-sized extracellular polymer decreases obviously at 23 C, but it increases again when the reactor temperature drops to 18 C and 13 C. Compared with the polysaccharide, the protein content fluctuates more greatly. (4) Temperature decreased, microbial community diversity showed a downward trend and a significant change at 13 ~C. The relative abundance of Phytophthora decreased from 9.04% to 9.04% after the temperature dropped from 33 ~C to 23 ~C. The microbial level showed that the sludge inoculated in this experiment contained only Candidatus Kuenenia, an anaerobic ammonia-oxidizing bacterium, and its abundance under Phytophthora was as high as that at the end of the experiment (day 199). No other anaerobic ammonia-oxidizing bacteria were found during the whole cooling process, and the dominant anaerobic ammonia-oxidizing bacteria in the reactor did not change with temperature. In addition, qPCR results showed that the copy number of AMX gene decreased first and then increased with the decrease of temperature. On the contrary, the activity value of anaerobic ammonia-oxidizing bacteria per unit cell decreased. First increase and then increase, 23 C is the key point of temperature.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703

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本文編號：2237137