Effective partial nitrification to nitrite by down-flow hanging sponge reactor under limited oxygen condition

Combining the processes of partial nitrification and anaerobic ammonium oxidation (ANAMMOX) is an attractive wastewater-treatment technology for nitrogen removal. In this study we investigated partial nitrification by implementing a closed down-flow hanging sponge (DHS) reactor operated at controlled oxygen concentrations. Basic concept of DHS process is similar to that of trickling filter, in which oxygen concentration can be easily manipulated by controlling airflow to the reactor. The closed reactor was fed with artificial wastewater containing NH(4)Cl and operated with an HRT of 1.5h at 30 degrees C. Oxygen inside the reactor was maintained below 3% (1.2mgDO x L(-1)) (DO-dissolved oxygen) except during the startup periods. Five months of continuous operation showed that there was a strong relationship between oxygen concentration and nitrite production. The ratio of nitrite produced relative to ammonium oxidized increased by decreasing oxygen concentration. Partial nitrification was satisfactorily accomplished under oxygen limitation at around 0.5% in the gas phase (0.2mgDOL(-1)). The system showed a high ammonium-removal rate, at a maximum of 1.46kg NH(4)(+)-Nm(-3)day(-1), even at limited oxygen concentration. We also found that oxygen concentration played an important role in the production of nitrous oxide, which increased with decreasing oxygen concentration.     

SBR恒定曝气量好氧硝化过程动态DO模拟:参数估计及其可靠性评价

提出了一种全新的针对初值常微分方程组系统的全局最优化(遗传算法)结合局部最优化(拟牛顿法)实现参数的鲁棒、快速估计的算法。利用该算法,对所建两步硝化模型中过程溶解氧(dissolved oxygen, DO)的动态变化成功实现了参数估计,相关度达到了0.9955。采用基于Fisher信息矩阵和直接搜索获得的参数置信区间相比较的方法实现了对估计结果的可靠性分析,结果表明采用该方法大部分参数可实现可靠估计,只有少数两个参数可实现估计却不可靠,为动力学系统的参数估计结果提出了一个全新的检验方法。DO模拟结果可以作为软测量手段,对过程中易生物降解COD、氨氮、亚硝态氮、硝态氮的全程变化情况提供充足的过程信息。     

A novel nearly plug‐flow membrane bioreactor for enhanced biological nutrient removal

The feasibility of enhanced biological nutrient removal by a new process called nearly plug‐flow membrane bioreactor (NPFMBR) is studied. Results of long‐term observations showed that average removal degrees of (1) chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) reached 95%, 85%, and 89%, respectively, at the steady operation period. Process success was further corroborated by batch experiments. Data of specific oxygen uptake rates demonstrated the abundance and/or high activities of ammonium oxidation bacteria and nitrite oxidation bacteria in the sludge. Observed specific rates of nitrification, denitrification, phosphorous release/uptake of the sludge were higher than those reported in previous research. Because of the unique flow pattern of sludge and alternant aerobic–anoxic operating conditions in the bioreactor, mass transfer and biotransformation of nutrients were expected to be improved. The NPFMBR could offer a new option for the wider application of MBRs. © 2012 American Institute of Chemical Engineers AIChE J, 59: 46–54, 2013     

生化与Fenton氧化工艺处理焦化废水工艺条件优化

苏州某炼钢集团公司采用除油气浮-A/O-BAF工艺处理焦化废水,当进水COD质量浓度约7 000mg/L时,BAF出水COD质量浓度可达150mg/L左右。采用Fenton试剂进一步对BAF出水进行深度处理,通过试验得到了满足COD≤70mg/L回用要求的最优工艺条件:初始pH值=4,[H_2O_2]/[Fe~(2+)]=4:1,H_2O_2投加量为132mg/L,反应时间1h。     

城市污水连续流A/O系统富氧条件下脱氮特征

基于添加流离填料的连续流A/O生物膜反应器,研究城市污水生物脱氮特征。系统在富氧条件（溶解氧大于1.5 mg·L^-1）下连续运行113 d,氨氮和总氮去除率均稳定在50%。系统稳定运行阶段好氧区和出水均无亚硝酸盐或硝酸盐积累现象,表现出良好的同步硝化反硝化特征。16S rDNA分析表明,实现这一现象的主要功能细菌为好氧区存在的好氧反硝化菌;FISH分析表明,不同好氧区的好氧反硝化菌的活性和相对数量不同。结果证明系统内发生的同步硝化反硝化主要由好氧反硝化作用实现,硝化反应产生的硝酸盐类物质得到去除。根据试验结果与微生物学分析,提出了在富氧水环境中通过同步硝化反硝化途径脱氮的生物膜模型。     

Interdependence of ammonia volatilization and nitrification in arid soils

The effect of applied-N (urea) on interdependence of ammonia volatilization and nitrification was studied in twelve arid soils varying mainly in soil texture and CaCO₃. Ammonia volatilization from applied urea was observed only above a threshold N concentration in soil (V_i). Values of V_i ranged from 50 in sandy soils to 250 g N g^-1 in loamy and clay loam soils. Soils with higher CaCO₃ showed lower values of V_i. Concentration of applied-N in soils, in relation to V_i determined its transformation pathway(s). Below V_i, all of the applied-N was nitrified in all soils with a delayed nitrification period ranging from 0 to 5 days. Above V_i, ammonia volatilization was first to start. This reduced NH₄ ⁺ concentration in soil and nitrification started later after the delay period was over. Duration of delay period increased with applied-N, sand content and CaCo₃. Often 80% or more of the total ammonia, volatilized during the delay period. NH₄ ⁺ concentration in soil at which volatilization ended was generally higher than V_i. It was concluded that both ammonia volatilization and nitrification were interdependent only if concentration of applied N was more than V_i. Above V_i only one process predominated at a time as volatilization stopped soon after the start of nitrification even if NH₄ concentration in soil was sufficient to sustain both processes.     

含氮微污染地表水处理技术回顾

微污染水中的氮含量超标不但造成水体的富营养化,而且通过饮水途径危害人体的健康安全。微污染水体脱氮已经成为我国水环境目前亟待解决的问题之一。该文综述了含氮微污染水代表性处理技术及其中的关键性影响因素,并对处理技术发展方向进行了分析讨论。     

外加剩余污泥水解酸化液碳源时曝气生物滤池的生物脱氮性能

利用剩余污泥水解酸化液作为外加碳源研究中部曝气和底部曝气曝气生物滤池(BAF)处理低碳氮比生活污水时的生物脱氮性能。结果表明,碳源与污水投配的流量比以及是否回流对BAF生物脱氮效果影响明显,气水流量比和回流流量比对BAF生物脱氮效果有一定影响;进水NH4+-N、TN质量浓度和COD分别为43.11、45.07、29.2mg.L-1时,中部曝气BAF的NH4+-N和TN去除率分别为99.04%和78.32%,出水COD为32.4 mg.L-1;底部曝气BAF的NH4+-N和TN去除率分别为98.61%和68.99%,出水COD为28.4 mg.L-1。研究表明,BAF在2种运行方式下可获得良好的硝化与反硝化性能,且不会引起二次污染。     

硝酸盐在除磷脱氮中的作用

除磷过程中，厌氧段硝基氮浓度越高、聚磷菌厌氧释磷所受的影响越大；摄磷段存在硝基氮，聚磷菌可以利用其作为替代的电子受体，在不曝气的情况下吸磷。但是，由于以硝基氮为电子受体时聚磷菌对有机物（PHA）利用率较低，所以吸磷的速率和数量均不如氧为电子受体的系统，除磷效率亦较低。研究了厌氧氨氧化反应的几种可能的电子受体，发现硝酸盐、亚硝酸盐、硫酸盐可用作该生物反应的几种电子受体，而醋酸盐是该反应的抑制剂。其中，当亚硝酸盐作为电子受体时，厌氧氨氧化菌混培物转化氨的速率最快。     

CANON工艺的研究现状及面临困难分析

CANON工艺是将Anammox菌与AOB结合到一个反应器中的一种新型节能的脱氮工艺,具有不消耗有机碳源、降低曝气量、降低污泥产量等优点,采用常规脱氮技术处理高氨氮、低C/N的废水,往往面临碳源不足和能源消耗等问题,然而如果能把CANON工艺应用到高氨氮、低C/N的废水领域,将使得高氨氮和低C/N的废水处理产生革命性的改革。本文主要从理论研究、工程应用和面临的问题等3方面分别探讨了CANON工艺。经过分析表明,CANON工艺主要有活性污泥和生物膜2种形式,而颗粒污泥作为活性污泥一种特殊形式,将是今后发展和应用CANON工艺的主要形式,然而CANON工艺主要的问题是亚硝酸盐的来源,而要实现亚硝酸盐的富集就必须综合考虑温度、溶解氧、游离氨的控制,同时也要考虑抑制物对CANON工艺的影响,NH4+-N与NO2--N对其影响有限,但低温与有机物的作用须要考虑。