施用尿素和硫酸铵对红壤硝化和酸化作用的影响

通过室内恒温培养试验,研究施用CO(NH2)2和(NH4)2SO4对初始pH值分别为5.14、4.77和4.34的红壤酸化速率和硝化速率的影响。结果表明,施用CO(NH2)2显著增加了3种红壤的硝化速率,从而显著加速土壤酸化。培养结束时,3种红壤pH值较培养过程中最高值分别下降2.14、1.23和0.56。施用(NH4)2SO4抑制了初始pH<5.0的2种红壤的硝化作用,从而显著降低这2种红壤的硝化速率和酸化速率,但显著增加了初始pH>5.0红壤的硝化速率,对其酸化速率则未见显著影响。3种红壤的酸化速率与硝化速率间存在显著线性相关关系。硝化作用是导致农田红壤pH值下降的主要原因之一,但不同氮肥对红壤硝化速率和酸化速率的影响不同。     

除草剂对尿素氮在土壤中转化的影响

在实验室培养条件下研究除草剂草甘膦和丁草胺对尿素氮在菜地土壤中转化的影响。实验设对照、尿素、尿素＋草甘膦和尿素＋丁草胺4个处理,尿素氮用量为200 mg.kg-1（以干土计）,除草剂用量为w（有效成分）=10 mg.kg-1（以干土计）。结果表明,草甘膦和丁草胺对尿素氨化作用不产生抑制作用,甚至出现促进效果。2种除草剂在培养的前2 d均显著抑制硝化作用,但到第4天时显著促进硝化作用（P〈0.05）。草甘膦对反硝化作用表现显著的抑制作用（P〈0.05）,而丁草胺对反硝化作用有极显著的促进作用（P〈0.01）;丁草胺＋尿素、尿素、草甘膦＋尿素处理的反硝化损失量分别占施氮量的16.90%、6.34%和3.66%。可见,除草剂对土壤氮素转化有一定影响,但不同除草剂对氮素各个转化途径的影响有明显差异,不同除草剂品种间影响程度也不同。     

Achievement of high rate nitritation with aerobic granular sludge reactors enhanced by sludge recirculation events

A ratio control strategy has been used to demonstrate the feasibility of this automatic control procedure for the achievement of stable full and partial nitritation. The control strategy assured constant ratio between the dissolved oxygen (DO) and the total ammonia nitrogen (TAN) concentrations in the bulk liquid of aerobic granular sludge reactors operating in continuous mode. Three different set-ups with different reactor capacities were used (3, 110, and 150 L). High strength synthetic wastewaters and reject water were tested with similar performance. Achieved nitrogen loading rates ranged between 0.4 and 6.1 kgN·m^-3·d^-1, at temperatures between 20°C and 30°C. Granular sludge and nitritation were stable in the long term continuous operation of the reactors. Suitable stable effluent for Anammox has been obtained using the desired TAN setpoint (i.e. 50% of influent ammonium oxidation). An existing biofilm model developed incorporating the implemented control loops and validated in a previous publication was used to investigate the effects of the ammonium concentration of the influent and the biofilm density on the achievement of full nitritation. The model demonstrated how sludge recirculation events led to a stable and significant increase of the biomass concentration in the reactor, which in turn resulted in the achievement of high nitrogen loading rates, due to the action of the control strategy. The model predicted an enhancement of stable full nitritation at higher ammonium concentrations in the influent. Poor influence of the biofilm density in the achievement of full nitritation was predicted with the model.     

Applicability of the Arrhenius model for ammonia oxidizing bacteria subjected to temperature time gradients

The aim of this work is to identify the range of applicability of Arrhenius type temperature dependence for Ammonia Oxidizing Bacteria (AOB) subjected to temperature time gradients through continuous titrimetric tests. An innovative online differential titrimetric technique was used to continuously monitor the maximum biologic ammonia oxidation rate of the biomass selected in a pilot scale membrane bioreactor, as a function of temperature time gradients. The monitoring technique is based on the measurement of alkalinity and hydrogen peroxide consumption rates in two parallel reactors operated in non-limiting substrate conditions for AOB; both reactors were continuously fed with mixed liquor and in one of them AOB were inhibited with allylthiourea. The effects of temperature decrease rates in the range 1 to 4°C·h⁻¹ were evaluated by controlling the titrimetric reactor in the temperature range 10°C–20°C. The dependence of growth kinetics on temperature time gradients and the range of applicability of Arrhenius model for temperature dependency of AOB growth kinetics were assessed. The Arrhenius model was found to be accurate only with temperature gradients lower than 2°C·h⁻¹. The estimated Arrhenius coefficients (θ) were shown to increase from 1.07 to 1.6 when the temperature decrease rate reached 4°C·h⁻¹.     

太湖不同湖区无机氮转化潜力

采集太湖梅梁湾和东太湖的水样和积物,在实验室内模拟研究不同湖区水体中溶解性无机氮(DIN)短期内的转化潜力.研究结果表明,太湖藻型湖区(梅梁湾)和草型湖区(东太湖)水体中存在着强烈的硝化作用,NH 4-N和NO3-N含量之间表现出显著的负相关关系(P＜0.05或P＜0.01),NH 4-N质量浓度下降速率为0.08～0.19 mg·L-1·d-1.在同样的试验条件下,藻型湖区硝化速率高于草型湖区.NH 4-N初始浓度越高则硝化速率也越高,不添加外源氮时硝化速率随着时间的推移而逐渐降低.藻型湖区的反硝化作用强于草型湖区.室内模拟试验20 d后,沉积物中TN含量平均下降了3.7%,东太湖水样中平均下降26.7%,梅梁湾平均下降42.2%.湖泊沉积物是进行反硝化作用的重要场所.短期内DIN的转化潜力反映了不同湖区氮素转化速率,也反映了不同生态类型水体对湖泊氮素转化的影响.     

巢湖十五里河沉积物硝化速率的城乡梯度变化及相关性

2017年7月—2018年5月,在巢湖十五里河干流城乡梯度方向的5个采样点位,按两月一次的频率采集表层沉积物及其上覆水.在此基础上,开展沉积物硝化速率城乡梯度变化规律分析,并识别主要影响因素.结果表明:①十五里河水体氮磷污染严重,并具有氨氮浓度相对较高的污染特点;②潜在硝化速率(PNR)变幅为0.003～0.021μmol·g~(-1)·h~(-1),均值为0.011μmol·g~(-1)·h~(-1),没有表现出明显的城乡梯度规律;③表面硝化速率(ANR)变幅为0.73～15.23μmol·m~(-2)·h~(-1),均值为4.19μmol·m~(-2)·h~(-1),也未表现出明显的城乡梯度规律;④十五里河沉积物硝化速率季节性变化规律明显,基本表现为:夏季春季秋季冬季,但5个采样点之间硝化速率的差异性程度不完全相同;⑤PNR与上覆水水温相关性较为显著,ANR与上覆水中NH~+_4-N和NO~-_3-N存在显著相关性,沉积物中对PNR和ANR影响较为显著的因素都是TN、NH~+_4-N和pH.     

High nitrite accumulation and strengthening denitrification for old-age landfill leachate treatment using an autocontrol two-stage hybrid process

An autocontrol two-stage hybrid process was developed to treat landfill leachate. Biological nitrogen removal with nitrification and denitrification via nitrite pathway was split into two stages. The first stage was designed for the high nitrite accumulation and was composed of two hybrid bed reactors (Hybrid I and Hybrid II) and a coagulation–flocculation reactor having effective volumes of 120 L and 80 L, respectively. The second stage was designed for strengthening denitrification and included a single 80 L reactor. The carriers of the hybrid bed reactors were composed of fixed multiple flexible carriers and suspended particle carriers. Dissolved oxygen (DO), pH value, oxidation–reduction potential (ORP) and temperature were used as online fuzzy control parameters of the automatic control system. The concentration of nitrite in Hybrid I and Hybrid II could reach 411 mg L⁻¹ and 604 mg L⁻¹, respectively. Ammonia removal has reached maximal rates of 0.061 kgNH₄⁺-N (m³ h)⁻¹ and 0.041 kgNH₄⁺-N (m³ h)⁻¹, respectively. A maximum nitrite removal rate of 0.211 kgNO₂⁻-N (m³ h)⁻¹ was observed during the strengthening denitrification. The running time of one cycle was not fixed and was actually controlled by the system. The results indicated that the running period was more closely related to influent ammonia concentration than influent COD concentration. The aeration times could be shortened and the energy could be saved. The autocontrol two-stage hybrid process is therefore an economical and effective way for landfill leachate treatment.     

停曝时间比对亚硝化颗粒污泥形成的影响

室温下(22~28℃),采用R1、R2、R3三组相同的SBR反应器接种MLSS、SVI值分别为3 500 mg·L-1、162 m L·g-1的具有良好亚硝化性能的絮状活性污泥,研究了不同停曝时间比(1∶2、1∶1、2∶1)对亚硝化颗粒污泥形成的影响.实验表明,R1、R2和R3分别于103、82、64 d实现了亚硝化污泥的颗粒化,运转至85 d时,亚硝化率分别可达86%、98%、96%,R1、R2和R3的SVI值降低至89、75、58 m L·g-1,MLSS增加至2 314、2 781、2 946 mg·L-1.结果表明,在停曝时间比为1∶2~2∶1的范围内,停曝时间比越大,越有利于污泥颗粒化;停曝时间比为1∶2时,由于无法抑制NOB,反应器中污泥亚硝化性能下降,且污泥的沉降性能先变好后变差,在停曝时间比为1∶1~2∶1范围内,停曝时间比越大,污泥的沉降性越好,同时可以保持系统良好的亚硝化性能.另外,停曝时间比越大,微生物分泌的PN、PS越多,且在亚硝化颗粒形成阶段,厌氧末的PN小于好氧末PN,亚硝化颗粒成熟阶段厌氧末的PN大于好氧末PN,而在运行期间,厌氧末的PS一直大于好氧末PS.     

模拟评价亚硝化-厌氧氨氧化生物膜工艺中氧的消耗

前期模拟研究显示,溶解氧是控制亚硝化-厌氧氨氧化生物膜工艺的关键因子.因此,作为一个设计参数,曝气量在工程上便显得尤为重要.生物膜工艺曝气量取决于发生在生物膜内各种反应(硝化、常规反硝化及厌氧氨氧化)的耗氧与氧补偿以及生物膜的厚度等.由于在生物膜内存在着基质扩散梯度,所以,通过试验方法确定净耗氧量十分困难,甚至难以实现.正因如此,数学模拟技术被用来评价这一在工艺设计和运行管理中具有实际意义的问题.模拟试验结果显示,不同的工艺及生物膜参数会导致不同的耗氧曲线.这些信息有助于亚硝化-厌氧氨氧化生物膜工艺的设计及运行.     

悬浮生物填料床处理微污染原水硝化试验研究

对采用新型悬浮填料床处理微污染原水硝化过程进行了探讨分析了自然挂膜条件下的工艺启动过程，研究了不同工况条件下，悬浮填料床硝化效果。通过春、夏、秋和冬季的中试运行效果表明：在温度适宜、停留时间60min、填料填充率50％条件下，氨氮平均去除效率达到77．60％，定义了氨氮填料表面负荷指数判断氨氮去除效果，水温对硝化的影响较大，在低于20℃时，氨氮填料表面负荷随温度呈指数增长，高于该温度时则增长缓慢，但能维持较高水平；浊度对本工艺硝化影响较小；实验表明原水中氨氮浓度较低，硝化反应符合一级反应，其反应速率常数为0.75h^-1。