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低温硝化菌的高效富集及其生物强化效果研究

作者:完美论文网  来源:www.wmlunwen.com  发布时间:2019/10/29 8:02:52  

摘要:由于污水处理厂的硝化系统比较脆弱,受到高温、低温、高氨氮等因素的冲击时易崩溃,进行硝化污泥的富集有助于在硝化系统崩溃时进行快速修复。低温是影响硝化系统的重要因素之一,尤其冬季进水水温低,会对污水处理厂硝化系统产生严重冲击,因此需要研究硝化污泥的耐低温特性。本论文使用完全好氧式膜生物反应器(Membrane Bio-Reactor,MBR)富集一种耐低温硝化污泥,并对其强化特性进行一系列的对比研究,同时将其与耐低温硝化菌的驯化实验进行对比,筛选出最经济的方法。取得的研究成果如下:

(1)研究以高氨氮低有机碳源为培养基质,考察在水温10℃的膜生物反应器中硝化污泥的富集效果,发现富集培养279 d后,获得硝化活性为610.37 mg·(L·d)-1的硝化污泥,其在温度为5℃的环境中时,硝化活性降至10℃下的60%;其在温度为15℃时污泥的硝化活性提高了43%,在20℃时提高了52%。通过分析52d和250d的微生物相变化发现,250d时硝化杆菌属(Nitrobacter)和亚硝化单胞菌属(Nitrosomonas)的相对丰度含量是52d的42倍,说明耐低温硝化菌富集成功。

(2)将(1)中低温硝化污泥应用于受8℃低温冲击的生物处理系统中,投加5% (v/v)上述低温硝化污泥5d后,系统对于氨氮的去除率由70% 提高至99%,出水氨氮浓度达到《中华人民共和国污水综合排放标准》(GB8978--1996)的一级A标准,而使用中温硝化污泥强化的生物处理系统则需15d。上述结果显示了低温硝化污泥富集后用于强化污水生物处理系统、提高其硝化功能启动与恢复速度的可行性。其强化重复试验证明了第一次低温强化试验的准确性,并通过其第二次低温冲击试验结果发现,投加过低温硝化污泥的装置在抵御反复的低温冲击时表现出更好的硝化强化效果。

(3)模拟农村生活污水处理系统,考察低温下低温富集菌在生物膜处理系统和悬浮污泥处理系统中的硝化强化效果对比。在7℃低温冲击下,投加(1)中低温硝化污泥的两组强化反应器仅比对照组早1d使氨氮去除率达到99%以上;而在5℃的低温冲击下,添加低温硝化污泥的强化组对于5℃的低温表现出了很好的适应力,氨氮去除率没有因为低温的冲击而降低,但对照组随着温度的降低其出水氨氮浓度显著升高,5d后氨氮去除率才升至99%。说明低温硝化污泥不仅对低温下崩溃的不同处理工艺有着很好的启动效果,还能够适应农村生活污水这种成分复杂、COD浓度高的污水,处理效果显著。

(4)考察中温富集菌低温驯化的可能性,驯化试验在20℃稳定10天后,氨氮去除率为99%,当温度降至10℃后,出水氨氮浓度由32 mg/L上升至454mg/L,氨氮去除率仅为39%,并进一步降低至19%,表明在相同的氨氮容积负荷下,温度降低使硝化污泥的硝化活性降低了约75%。为了不使驯化过程崩溃,将进水氨氮浓度由600 mg/L降低至200 mg/L,经过36 d驯化后,氨氮去除率由21%提高至75%,此时硝化活性约为305 mg-N/(L·d)。而对比(1)中的耐低温硝化菌富集实验,低温硝化污泥经过31d 的富集,其硝化活性即可达到388 mg-N/(L·d)。低温硝化污泥的富集仍需通过逐步提高氨氮负荷进行富集,直接降低中温硝化污泥的富集温度不能快速获得高硝化活性的低温硝化污泥。

The nitrification function of  the wastewater treatment plantis prone tocollapse when exposed to high temperature, low temperature, and high ammonianitrogen. Compared with general remedy, inoculated with nitrifying activatedsludge could quickly recover the nitrification function. Because of the lowtemperature in winter, the ammonia nitrogen removal reduces which influencedischarge standards. This paper aim to (1) enrich low-temperature-resistantnitrifying sludge in Membrane Bio-Reactor (MBR); (2) evaluate thebioaugmentation efficiency against low temperature; (3) investigate thenitrification activity of mid-temperature nitrifying activated sludge duringthe low temperature domestication process The results show as follows:

(1)   Thenitrification activity and microbial community of activated sludge whichenriched in membrane bioreactor (MBR) with high ammonia nitrogen and loworganic carbon source at 10℃were investigated. The results showed that thenitrifying activated sludge with high nitrification activity of up to 610.37mg·(L·d)-1were successfully enriched in MBR, The nitrification activity wasreduced by 60% with the temperature dropped to 5℃, while increased by 43% and52% with the temperature increased to 20℃ and 15℃,respectively. After enrichedfor 250d, the content of Nitrobacter and Nitrosomonas was 42 times higher thanthat at 52 d.

(2)   Thebioaugmentation test at 8℃showed that the reactor inoculated with 5%(v/v) of10℃-enriched sludge achieved 99% ammonia nitrogen removal within 5 days, whilethe same ammonia nitrogen removal required 15 days which inoculated with mediumtemperature enriched sludge .After bioaugmentaion, the effluent ammonianitrogen concentration reached the first grade A of discharge standard. Theabove results show that the enriched low temperature nitrification sludge couldbe used to recovery the nitrification function in the biological wastewatertreatment system. To scrupulously evaluate the bioaugmentation efficiency, therepeated trial also showed that the enriched nitrifying activated sludge couldenhance the ammonia removal in low temperature.

(3)   Thebioaugmentation efficiency of enriched nitrifying activated sludge to biofilmtreatment systems and suspended sludge treatment systems were investgated.Compared with the control group, ammonia-nitrogen removal reached to 99% in theenhanced systems 1 day ahead at 7℃. When the temperature reduced to 5℃, thenitrification activity in enhanced systems did not decline while it required 5days to up to 99% in control group.These results showed that enrichednitrifying activated sludge could reinforce the nitrification function of ruraldomestic sewage treatment against low temperature.

(4)   Toinvestigate the possibility of domestication the low-temperature-resistantnitrifying sludge. After 10 days stabilization at 20℃, ammonia-nitrogen removalreached to 99%. When the temperature dropped to 10℃, the ammonia concentrationin the effluent increased from 32 mg/L to 454 mg/L, and the ammonia-nitrogenremoval just reached 39%, and sustained decrease to 19%. It was shown thatunder the same ammonia nitrogen volume load, the ammonia-nitrogen removalreduced about 75% when the temperature dropped. In order not to collapse thedomestication process, we take the influent ammonia nitrogen concentration wasreduced from 600 mg/L to 200 mg/L. After 36 days , the ammonia-nitrogen removalincreased from 21% to 75%, and the nitrifying activated sludge was about 305mg-N/(L·d). Compared with the test of enrich low-temperature-resistantnitrifying sludge in (1), the enriched low temperature nitrification sludge after31 days enrichment, the nitrifying activated sludge can reached 388 mg-N/(L·d).Therefore, low-temperature-resistant nitrifying sludge still needs to beenriched by gradually increasing the ammonia nitrogen load. Directly loweringthe temperature can not obtain the low-temperature-resistant nitrifying sludgequickly.

关键词:生活污水;硝化污泥富集;硝化强化;低温冲击

sanitary sewage; nitrifying activatedsludge enrichment; nitrification enhancement; microtherm shocking load

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