Anammox in a UASB reactor treating saline wastewater

The feasibility of an anammox (anaerobic ammonium oxidation) UASB (upflow anaerobic sludge blanket) bioreactor to treat ammonium-rich brines was investigated in batch and continuous-flow experiments. The evidence from batch tests indicated that the anammox activity was significantly inhibited under highly saline conditions while the inhibition was reversible. Saline shock loading of 30 g NaCl l⁻¹ caused a 67.5% decrease in specific anammox activity (SAA) compared to reference biomass (not exposed to salt). However, the acclimatized biomass displayed a SAA value just 45.1% lower than that of the reference biomass. When transferred from brine to freshwater, the salt-exposed biomass resumed its activity by 43.1%. Subsequent to appropriate acclimatization, careful manipulation nitrite concentration, nitrogen loading rate (NLR), and other operational parameters for 77 days, the results of continuous-flow experiment revealed that under the salinity of 30 g NaCl l⁻¹ the reactor performed well and the substrate removal capacity (nitrogen removal rate, NRR, of 448 ± 15 mgl⁻¹ d⁻¹) was comparable to the condition of freshwater (NRR of 464 ± 13 mgl⁻¹ d⁻¹). However, the anammox UASB bioreactor was prone to malfunction under transient operating conditions.     

三价铁对有机物存在下厌氧氨氧化脱氮的影响

考察了三价铁（2.24~7.84mg/L）存在下厌氧氨氧化系统对有机物的耐受性能,并通过16SrRNA高通量测序技术和定量PCR探究其机理.结果表明,进水COD浓度为50和100mg/L时,4个反应器的氨氮和总氮去除率均较高（>90%）,三价铁的强化作用不明显;进水COD浓度继续升高（150和200mg/L）,厌氧氨氧化受到抑制,三价铁的强化作用逐渐增加;COD浓度为200mg/L时,添加三价铁（7.84mg/L）可将氨氮和总氮去除率由61.3%和79.8%（对照组）提升至71.2%和84.7%.16SrRNA高通量测序技术表明,有机物存在下,污泥微生物群落结构出现变化,主要表现为厌氧氨氧化菌丰度的降低及反硝化菌群的大量增殖,进水添加三价铁可提高浮霉菌（Planctomycetes）的丰度.定量PCR结果表明,三价铁能够提高厌氧氨氧化菌16S rRNA及功能基因hzsB的丰度.     

一体式SNAD废水处理系统的启动和稳定运行控制研究

通过小试实验考察了同步半硝化-厌氧氨氧化-反硝化(SNAD)系统启动和稳定化运行的条件。结果显示,通过控制温度、pH、DO、曝气方式以及碱度与进水氨氮的比值,采用人工富集厌氧氨氧化细菌的方法,成功启动了SNAD系统,并且实现了稳定化运行。氨氮和总氮的去除率均可达到90%以上,平均出水硝酸盐和进水总氮的比例可控制在11%以内。另外,在启动过程中还发现,菌体自溶贡献了大部分化学耗氧量(COD),但随着系统的稳定,菌体自溶现象趋于减小。     

HRT与进水基质浓度对Anammox反应器效能影响研究

以产甲烷颗粒污泥与硝化污泥混合物作为接种污泥,在Anammox-UASB反应器中实现反应器的启动与稳定运行。考察了缩短HRT及进水基质浓度变化对系统的影响。结果显示:缩短HRT能有效提高系统处理能力,但HRT过低会导致处理效果降低,本研究得到的最佳HRT为6 h,此时TN去除率76%,TN容积去除负荷最高,为1.82 kg/(m~3·d)。进水基质比例与浓度对Anammox反应器的稳定运行具有重要影响,当进水中NH_4~+-N与NO_2~--N两者比例约为1且浓度均为500 mg/L时,系统处理能力最佳,TN容积去除负荷为1.55 kg/(m~3·d),且去除率为77%。     

Stoichiometric and molecular evidence for the enrichment of anaerobic ammonium oxidizing bacteria from wastewater treatment plant sludge samples

Anammox enrichments were readily developed from seven municipal wastewater treatment plants (WWTPs) sludge, but not with methanogenic granular sludge from two agro-industrial WWTPs. Only 50 d was required for the first evidence of anammox activity from a return activated sludge obtained from a WWTP operated for nutrient removal. The molar ratios of nitrite and ammonium consumption of approximately 1.32 as well as nitrate and dinitrogen gas product ratios of approximately 0.095 provided evidence of the anammox reaction. The presence of anammox was confirmed by polymerase chain reaction (PCR) using primer sets (PLA46F and AMX820R) specific for anammox bacteria. The 16S rRNA gene fragment of anammox bacteria was detected in seven enrichment cultures (ECs) with demonstrated anammox activity but not in the original inocula from which the ECs were derived and also not in the two methanogenic sludge samples, which indicates the PCR predicted the anammox activity. Two genera, Brocadia and Kuenenia, were successfully identified as the Planctomycetes occurring in the clone libraries of successful anammox enrichments. Brocadia dominated in cultures that were respiked extensively; whereas Kuenenia predominated in cultures that were less aggressively respiked. These findings indicate that respiking management may play an important role on selecting the genus of anammox bacteria. The batch enrichment results clearly illustrate that anammox can be readily enriched from municipal sludge from a wide variety of process operations at WWTPs.     

厌氧氨氧化-羟基磷灰石颗粒污泥系统的快速启动

为研究厌氧氨氧化-羟基磷灰石（Anammox-HAP）颗粒污泥系统的启动方法,采用厌氧氨氧化膨胀床反应器（AAFEB）,接种少量厌氧氨氧化污泥,通过调控基质浓度和水力停留时间,考察系统内污泥粒径及胞外聚合物（EPS）的变化,同时监测系统的脱氮除磷性能.结果表明,在低上升流速0.213~1.066m/h、Ca/P=5.5物质的量比的条件下,不断提高进水氮负荷,实现了Anammox颗粒污泥系统的启动.总氮、正磷酸盐去除率分别为（78.0±9.8）%、（63.8±9.9）%,总氮容积负荷达2.74kg/（m³·d）,在150d内培养出平均粒径为0.4mm的微颗粒污泥.颗粒的形态特征和元素分布检测表明其为Anammox-HAP颗粒污泥.随着颗粒污泥粒径的增加,EPS中的PS含量基本不变,PN从54.43mg/g增加到137.40mg/g,PN/PS从6.63提高到7.71.EPS中PN占比与粒径之间存在正相关,对污泥颗粒的形成起主要作用.     

尿素废水生物处理技术原理与工艺研究进展

尿素废水的处理是当前亟需解决的难题,其中生物处理法因具有工艺流程短,成本低,抗冲击负荷,不产生二次污染等优点,在尿素废水的处理中备受青睐.本文基于尿素生物水解法原理,从机理上深入分析了脲酶的发展历程,酶学结构与水解机制,并对传统生物尿素脱氮法的应用进行了系统梳理.此外,为了更好地理解厌氧氨氧化菌降解尿素的潜能及在实际工程中的应用,本文分别从微生物学和工程应用的角度总结了相关研究结果.最后提出了尿素废水生物处理研究的建议与展望,以期为实际工程应用提供有力的理论基础和技术支持.     

Fast start-up anammox process using Acyl-homoserine lactones (AHLs) containing supernatant

N-dodecanoyl homoserine lactone (C₁₂-HSL) was detected in the supernatant of an anammox granular sludge reactor (AGSR). C₁₂-HSL could enhance the specific anammox activity of anammox biomass. Adding C₁₂-HSL-containing AGSR supernatant into the continuously stirred tank reactors reduced the start-up time of the anammox process from 80 to 66 days. Moreover, the nitrogen loading rate was also enhanced to 1.6 times that of the control reactor. AHLs could increase the secretion of extracellular polymeric substances and anammox obtained better enrichment with the addition of AHLs-containing AGSR supernatant. Denaturing gradient gel electrophoresis analysis further revealed that AHLs played a role in mediating microbial community parameters. In conclusion, adding AHL-containing supernatant could be an effective and economical way to accelerate the start-up of anammox.     

Microbial nitrogen transformation potential in surface run-off leachate from a tropical landfill

Ammonium is one of the major toxic compounds and a critical long-term pollutant in landfill leachate. Leachate from the Jatibarang landfill in Semarang, Indonesia, contains ammonium in concentrations ranging from 376 to 929 mg N L⁻¹. The objective of this study was to determine seasonal variation in the potential for organic nitrogen ammonification, aerobic nitrification, anaerobic nitrate reduction and anaerobic ammonium oxidation (anammox) at this landfilling site. Seasonal samples from leachate collection treatment ponds were used as an inoculum to feed synthetic media to determine potential rates of nitrogen transformations. Aerobic ammonium oxidation potential (<0.06 mg N L⁻¹ h⁻¹) was more than a hundred times lower than the anaerobic nitrogen transformation processes and organic nitrogen ammonification, which were of the same order of magnitude. Anaerobic nitrate oxidation did not proceed beyond nitrite; isolates grown with nitrate as electron acceptor did not degrade nitrite further. Effects of season were only observed for aerobic nitrification and anammox, and were relatively minor: rates were up to three times higher in the dry season. To completely remove the excess ammonium from the leachate, we propose a two-stage treatment system to be implemented. Aeration in the first leachate pond would strongly contribute to aerobic ammonium oxidation to nitrate by providing the currently missing oxygen in the anaerobic leachate and allowing for the growth of ammonium oxidisers. In the second pond the remaining ammonium and produced nitrate can be converted by a combination of nitrate reduction to nitrite and anammox. Such optimization of microbial nitrogen transformations can contribute to alleviating the ammonium discharge to surface water draining the landfill.