地表水检测中氨氮高于总氮的原因探讨

针对采用国标方法测定同一水样的氨氮和总氮时所出现的氨氮浓度高于总氮浓度的情况，分析了测定方法的准确性，并分析了各影响因素对测定结果的影响。结果表明，消解时间不足造成了总氮测定结果偏低，提出对于成分复杂、色度较高的地表水水样，将消解时间延长至60min可提高测定结果的准确度。     

哈希COD测定仪替代消解液的开发

为了降低COD测定成本、减少试剂污染和缩短测定时间，利用哈希（HACH）仪器开发了测定0～1 000 mg/L COD的消解液。通过计算和对比试验，自配消解液在组成上接近于HACH原装试剂，消解过程的氧化电位与国标重铬酸盐法的氧化电位相当。自配消解液不仅可以替代昂贵的进口试剂，而且样品消解时间由原来的2 h缩短至35 min，特别是在进行突发水体环境污染事件的应急监测时，能够快速提供水体受COD污染的结果。实验证明，采用自配消解液与采用HACH原装试剂及国标重铬酸盐法测定结果相比，数据无显著差异，测定结果     

智能消解/紫外分光光度法测定高氨氮污水中总氮

生活污水中氨氮比例较高(NH+4-N/TN≥90%)时,实验室测得的总氮值经常低于氨氮值。针对这一情况,使用智能消解仪作为消解装置,在消解时间为50 min、消解温度为122℃、碱性过硫酸钾用量(浓度同国标方法)为1.5 mL的条件下,测定结果良好,消除了氨氮测定值高于总氮测定值的现象,同时减少了实验耗时和碱性过硫酸钾用量。     

COD测定仪用消解液的配制与应用

分析了采用COD仪测定COD所用消解液和反应液的紫外－可见光谱特征及其主要影响因素，从而为自配消解液提供了光谱学依据。试验证明采和自配消解液测定COD能大幅度降低分析成本，而且测定精密度与准确度能符合要求。     

污水中总氮和总磷连续测定方法探讨

采用同一消解液消解污水水样,并连续测定水中的总氮和总磷.试验结果表明,只要选择适当的消解液浓度,即可经同一消解液消解后连续测定水中的总氮和总磷.采用该方法分析了标样和各种水样,结果表明,该方法准确、简便且可连续测定水中的总氮和总磷.     

废水中总氮含量低于氨氮含量原因探讨

针对废水水质分析过程中出现的氨氮含量高于总氮含量的情况,对氨氮测定过程和总氮测定过程中的金属离子干扰、标准曲线绘制、消解时间等进行了分析,提出氨氮含量高于总氮含量是由于总氮消解时间不够,导致过硫酸钾的转化不完全造成的。实验结果表明,将总氮消解时间设定为40min可以解决此问题。为提高测定的准确性,在实验中还应注意实验环境、计量器具及高压灭菌锅的密封性等问题。     

水中总氮测定方法的改进

针对目前总氮测定方法GB11894—89消解过程中存在的不安全因素、消解不彻底、双波长测定重现性差等缺点，以水热反应釜代替比色管、烘箱代替高压锅进行消解，并结合酚二磺酸分光光度法对硝酸盐氮的测定进行了改进。采用改进后的方法测定水中的总氮，其相关系数为0．9999，加标回收率为98％～103％，RSD〈5％。试验证明，改进后的方法优化了消解环境，提高了总氮测定方法的稳定性，且灵敏度、准确度、精密度等均令人满意。     

微波消解联合测定水中总磷总氮

探讨了微波消解联合测定总磷、总氮的新方法，确定了碱性过硫酸钾的碱度、加入量和微波消解的最佳条件，氮的回收率为96．5％～102．8％，磷的回收率为94．1％～104．3％。与标准法相比，该方法具有快速、能耗少、操作方便等优点，测定精密度和准确度均令人满意。     

钼酸铵分光光度法测定水中总磷的改进消解方法

在采用钼酸铵分光光度法测定水中总磷时,分别用恒温干燥箱和蒸汽消毒器消解试样,对测定得到的总磷工作曲线和实际水样中总磷的含量进行了对比,结果表明,与蒸汽消毒器消解方法相比,恒温干燥箱消解法同样不存在系统误差,并且操作简便、温度容易控制,同时能够缩短工作时间,且不会出现比色管中试样外溢等现象,测定结果准确.因此,此方法能够替代传统的水样预处理方法,在满足试验精度的前提下达到简化操作的目的.     

超声波—树脂法/封闭回流消解测定污泥总磷

采用超声波--树脂法/封闭回流消解法测定了污泥的TP含量.试验结果表明,采用超声波--离子交换树脂--超声波的程序处理污泥混合液,其Zeta电位＜-30 mV,形成了稳定的污泥悬浮液;其中,在离子交换过程中搅拌时间宜为60 min.在封闭回流消解过程中消解温度为125℃,消解时间为35 min,能使污泥悬浮液中的有机成分完全分解.该方法对不同来源污泥均有良好的测定精密度与准确度,测定结果的相对标准偏差＜2%,加标回收率为97.0%～99.8%.     

等离子光谱法测定城市污泥中总镉、总铬的方法改进

目前检测城市污泥中总镉、总铬的标准方法为<城市污水处理厂污泥检验方法>(CJ/T 221-2005),该方法样品消解时间长、酸用量大,为此改进了样品消解方法,分别采用HNO3-H2O2常压消解、HNO3-H2O2微波消解法处理污泥样品,然后采用等离子光谱法检测污泥中的总镉、总铬.与标准方法的对比试验结果表明,两种方法的相对偏差为0.8%～7.2%.改进的常压消解法的加标回收率:总镉为98.5%～105%,总铬为94.2%～95.6%;微波消解的加标回收率:总镉为104%～106%,总铬为98.5%～102%;改进方法的检出限:总镉为0.000 75 mg/L,总铬为0.002 3 mg/L.     

Biodegradation of the endogenous residue of activated sludge in a membrane bioreactor with continuous or on-off aeration

The goal of this study was to determine the effect of a long sludge retention time on the biodegradation of the endogenous residue in membrane digestion units receiving a daily feed of sludge and operated under either aerobic or intermittently aerated (22 h off-2 h on) conditions. The mixed liquor for these experiments was generated in a 10.4 day sludge retention time membrane bioreactor fed with a synthetic and completely biodegradable influent with acetate as the sole carbon source. It had uniform characteristics and consisted of only two components, heterotrophic biomass X_H and endogenous residue X_E. Membrane digestion unit experiments were conducted for 80 days without any sludge wastage except for some sampling. The dynamic behaviour of generation and consumption of filtered organic digestion products was characterized in the membrane digestion unit systems using three pore filter sizes. Results from this investigation indicated that the colloidal matter with size between 0.04 μm and 0.45 μm was shown to contain a recalcitrant fraction possibly composed of polysaccharides bound to proteins which accumulated in the membrane digestion unit under both conditions. Modelling the membrane digestion unit results by considering a first-order decay of the endogenous residue allowed to determine values of the endogenous residue decay rate of 0.0065 and 0.0072 d⁻¹ under fully aerobic and intermittently aerated conditions, respectively. The effect of temperature on the endogenous decay rate was assessed for the intermittently aerated conditions in batch tests using thickened sludge from tests gave an endogenous decay rate constant of 0.0075 d⁻¹ at 20 °C and an Arrhenius temperature correction factor of 1.033.     

Combined anaerobic and aerobic digestion for increased solids reduction and nitrogen removal

A unique sludge digestion system consisting of anaerobic digestion followed by aerobic digestion and then a recycle step where thickened sludge from the aerobic digester was recirculated back to the anaerobic unit was studied to determine the impact on volatile solids (VS) reduction and nitrogen removal. It was found that the combined anaerobic/aerobic/anaerobic (ANA/AER/ANA) system provided 70% VS reduction compared to 50% for conventional mesophilic anaerobic digestion with a 20 day SRT and 62% for combined anaerobic/aerobic (ANA/AER) digestion with a 15 day anaerobic and a 5 day aerobic SRT. Total Kjeldahl nitrogen (TKN) removal for the ANA/AER/ANA system was 70% for sludge wasted from the aerobic unit and 43.7% when wasted from the anaerobic unit. TKN removal was 64.5% for the ANA/AER system.     

超声破解促进污泥高温厌氧消化研究

城市污水厂的剩余污泥经槽式超声波反应器预处理后,被投加到小型高温厌氧反应器中进行消化处理,通过改变投配率来控制厌氧消化时间,研究超声破解对高温厌氧消化反应速率和效率的影响。试验结果表明,与未经预处理的污泥相比,超声破解能够明显提高污泥高温厌氧消化的生物气产量及对有机物的去除率。控制组在停留时间为20d时对TCOD的去除率为37.29%,而破解污泥在第8天时的去除率就达到了39.60%。这表明污泥经超声破解后其厌氧消化性能得到改善,超声破解不但可以提高厌氧消化对有机物的去除率,而且可以缩短反应时间,在不影响厌氧消化反应正常进行的条件下,还实现了污泥的减量化。     

Comparing the anaerobic digestion of Ascophyllum nodosum,the organic fraction of municipal solid waste and white rice in batch reactors

The biogas potential of marine macroalga Ascophyllum nodosum was compared with the organic fraction of municipal solid waste (OFMSW) and white rice to determine the applicability of the feedstock for anaerobic digestion. For OFMSW three dry matter contents were compared, 3%, 10% and 25%, to determine the effect of dry matter on methane yield. Biogas was evolved in each system, but the rate of evolution of biogas changed with moisture content. The highest total methane yield was obtained from 3% OFMSW but A. nodosum yielded more methane at 176±37.62 L/kg VS than white rice and the drier anaerobic digestion of OFMSW. The substrates were digested using wastewater treatment plant inoculum to determine gas yield and gas quality under batch mesophilic digestion conditions.     

智能组件模块化CODcr在线监测仪重复性的研究

阐述了CODcr在线监测仪的方法原理和单元构造,描述了该仪器基于智能组件库技术的消解模块和滴定模块.并通过实验研究其重复性,分别对含COD100、500、1500和5000 mg/L 的标液进行分批多次测量,分析数据得出该仪器的重复性符合标准.     

Mechanisms of floc destruction during anaerobic and aerobic digestion and the effect on conditioning and dewatering of biosolids

Laboratory anaerobic and aerobic digestion studies were conducted using waste activated sludges from two municipal wastewater treatment plants in order to gain insight into the mechanisms of floc destruction that account for changes in sludge conditioning and dewatering properties when sludges undergo anaerobic and aerobic digestion. Batch digestion studies were conducted at 20 degrees C and the dewatering properties, solution biopolymer concentration and conditioning dose requirements measured. The data indicated that release of biopolymer from sludges occurred under both anaerobic and aerobic conditions but that the release was much greater under anaerobic conditions. In particular, the release of protein into solution was 4-5 times higher under anaerobic than under aerobic conditions. Both the dewatering rate, as characterized by the specific resistance to filtration and the amount of polymer conditioning chemicals required was found to depend directly on the amount of biopolymer (protein + polysaccharide) in solution. Little difference in dewatering properties and conditioning doses was seen between the two activated sludges from different plants. Differences in the cations released between anaerobic and aerobic digestion suggest that the digestion mechanisms differ for the two types of processes. Enzyme activity data showed that during aerobic digestion, polysaccharide degradation activity decreased to near zero and this was consistent with the accumulation of polysaccharides in aerobic digesters.     

城市污水处理厂剩余污泥厌氧消化试验研究

以北京市某污水处理厂的剩余污泥为研究对象，对该污泥的理论产气量进行了估算，考察了投加接种污泥和未投加接种污泥条件下污泥厌氧消化的产气情况，并分析了污泥消化前、后的泥质特点。结果表明：与未接种条件相比，污泥厌氧消化前采用投加接种污泥的方式可大大促进消化反应的进行，加快污泥的产气速率，使厌氧消化周期缩短近1／4，但对污泥的总产气量影响较小；在厌氧消化正常运行条件下，污泥产气量达到总产气量的90％时所需反应时间约为16d，可将其作为污泥厌氧消化工艺较为理想的消化周期；剩余污泥的消化性能差、产气率低、试验产气量占理论产气量的比例〈50％，在工程上单独的剩余污泥不宜采用厌氧消化工艺处理。     

自配消解液分光光度法测定污水中COD

以自配消解液代替成本较高的HACH专用试剂,采用分光光度法测定了污水中的COD浓度,对影响测定结果的诸多因素进行了试验研究,确定了最佳操作条件。对比试验结果表明,该方法的测定结果与标准方法无显著性差异,适用于污水中COD浓度的测定。