Simulation studt on effects of different A/O parut o. s of oxidation ditches on nitrogen removal

采用3种不同曝气模式的模拟氧化沟分别形成2、4、7个缺氧-好氧（A/O）分区,研究了3种工况下氧化沟的脱氮方式和脱氮效果.结果表明,在好氧缺氧区体积比例相同的条件下,A/O分区越多,则好氧区平均DO浓度越小,硝化菌活性越低,在2、7个4、A/O分区的3种工况下的硝化菌活性分别为4.80、和3.73mg·g·h4.65-1-1;A/O分区少,则每一分区的缺氧段和好氧段长,进水后反硝化菌利用的有机物就多,在好氧区中的有机物就少,用于硝化的DO量多,从而硝化和脱氮效果好.试验中3种工况的总氮平均去除率分别为60.14%、47.93%、57%,出水总氮平均浓度分别为17.01、22.17和27.92mg·L-1.在氧化沟工艺中,氮的去除途径主要是缺氧反硝化及同步硝化反硝化（SND）.分区多,则主要通过同步硝化反硝化脱氮;分区少,则以缺氧反硝化脱氮为主,这是由于碳源限制致使同步硝化反硝化的脱氮效率比缺氧反硝化低.     

Comparison of conventional and inverted A2/O processes: Phosphorus release and uptake behaviors

Two full-scale systems operated in parallel, a conventional A²/O system consisting of anaerobic, anoxic and oxic compartments in succession and an inverted system consisting of anoxic, anaerobic and oxic compartments without internal recycle, were compared in terms of their phosphorus removal performance, with an emphasis on phosphate (P) release behaviors, using both operational data and simulation results. The inverted system exhibited better long-term phosphorus removal performance (0.2 ± 0.3 vs. 0.7 ± 0.7 mg/L), which should be attributed to the higher P release rate (0.79 vs. 0.60 kg P/(kg MLSS·day)) in the non-aerated compartments. The P release occurred in both the anoxic and anaerobic compartments of the inverted system, resulting in more efficient P release. Although the abundances of the ‘Candidatus Accumulibacter phosphatis' population in the two systems were quite similar ((19.1 ± 3.27)% and (18.4 ± 4.15)% of the total microbe (DAPI stained particles) population in the inverted and conventional systems, respectively, by fluorescence in situ hybridization (FISH)), the high-concentration DAPI staining results show that the abundances of the whole polyphosphate accumulating organisms (PAOs) in the aerobic ends were quite different (the average ratios of the poly-P granules to total microbes (DAPI stained particles) were (45 ± 4.18)% and (35 ± 5.39)%, respectively). Both the operational data and simulation results showed that the inverted system retained more abundant PAO populations due to its special configuration, which permitted efficient P release in the non-aerated compartment and better P removal.     

污水处理厂升级改造中氨氮控制工艺的研究

文章研究"生物膜+活性污泥"复合工艺,将生物膜法与传统的A2/O污水处理脱氮工艺结合起来,形成了"生物膜+A2/O"复合工艺。2种工艺有机地融合于一个反应系统中,既节省用地又延长污泥龄,使脱氮除磷的效果大大提高。用该工艺处理城市污水,其出水水质符合《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准,用作景观用水和一般回用水,可广泛地应用于污水处理厂的升级改造。     

MBBR-A2O/MBR处理农村生活污水动力学研究

采用MBBR-A2O/MBR(又称BCO-MBR)工艺,对水质特征呈现低碳源高氮磷、水质波动大和日变化系数大等特点的农村生活污水进行研究。对比MBBR-A2O/MBR工艺在5种不同水力停留时间下的(0.42 d、0.50 d、0.75 d、1.25 d、1.50 d)运行状况,挑选出最佳的水力停留时间,并利用Lawrence-McCarty模型构建该工艺的污染物降解动力学方程。结果表明,随着水力停留时间(HRT)的延长,MBBR-A2O/MBR工艺对污染物的去除效果逐渐提升。当HRT为1.25d,CODCr、NH3H、TN、TP平均进水质量浓度分别280.67mg/L、36.88 mg/L、50.59 mg/L、2.51 mg/L时,平均出水质量浓度分别为34.33 mg/L、3.19 mg/L、5.13 mg/L、0.63 mg/L,平均去除率分别可达87.86%、89.92%、89.85%、74.95%。CODCr、NH3H、TN出水质量浓度在城镇污水排放标准一级A限值以下,TP出水质量浓度达到一级B标准,因此确定最佳的HRT为1.25 d。污染物降解动力学计算所得模拟值与实际出水质量浓度测量值拟合度良好,其中CODCr模拟值与平均测量值一致性最高,相对误差在0.02~0.14,NH3H与TN的相对误差分别在0.19~0.60和0.1~0.33。这表明污染物降解动力学方程可以较好地模拟工艺出水的污染物质量浓度。CODCr降解动力学方程常数为Vmax=0.19 d-1,KS=82.97 mg/L;NH3H降解动力学方程常数为Vmax=0.02d-1,KS=8.49 mg/L;TN降解动力学方程常数为Vmax=0.024 d-1,KS=8.10 mg/L。研究的动力学常数与传统活性污泥法动力学常数相比,KS较高,而Vmax较低,导致Vmax较低的主要原因可能是测定的污泥质量浓度高于实际有效的质量浓度。研究对利用MBBR-A2O/MBR工艺处理农村生活污水和传统活性污泥工艺提标改造具有一定的应用参考价值。     

Fe_3O_4@SiO_2复合气凝胶的制备及其对刚果红的吸附

以Fe Cl_3·6H_2O和正硅酸四乙酯为原料,通过溶胶-凝胶法结合醇溶剂热法制备了Fe_3O_4@Si O_2复合气凝胶。采用XRD,FTIR,SEM,EDS等技术对Fe_3O_4@Si O_2的结构进行了表征。考察了Fe_3O_4@Si O_2对刚果红溶液的吸附性能。表征结果显示,Fe_3O_4@Si O_2复合气凝胶是由直径为10~20 nm的近球形颗粒组装而成的具有三维网络结构的纳米材料,比表面积为457.93 m~2/g,平均孔径为10.7 nm。在溶液p H为5、吸附时间为35 min的最佳工艺条件下,采用Fe_3O_4@Si O_2吸附处理质量浓度为10 mg/L的刚果红溶液,刚果红去除率为99.39%,此时溶液中刚果红的质量浓度仅为0.052 mg/L。Fe_3O_4@Si O_2复合气凝胶吸附刚果红后具有较好的解吸和再生能力。     

Co/Al2O3催化剂上CH4的CO2重整反应研究

通过研究不同Ｃｏ负载量的Ｃｏ／Ａｌ２Ｏ３催化剂对ＣＨ４的ＣＯ２重整剂合成气活性的影响,发现Ｃｏ负载量为１３％（Ｗｔ）的Ｃｏ／Ａｌ２Ｏ３活性最好,考察了反应温度,空速,还原温度等对催化剂活性和产物中ＣＯ／Ｈ２比例的影响,结果表明反应温度升高,ＣＨ４的ＣＯ２的转化率均增加,但随空速的增加而降低,还原温度在４００℃时催化剂显示出活性最好,产物中ＣＯ／Ｈ２的比例,随反应条件不同而略有增减。     

Al_2O_3熟料电收尘器若干问题的探讨

Al_2O_3熟料烟气具有含尘浓度高、水分大,CO含量不稳定,粉尘粘结性强、含碱量高等特点,本文结合多年Al_2O_3熟料电收尘器设计改造和运行的经验,对电收尘器设计中的相关问题进行探讨。     

丘陵区稻田N2O排放的特点

1993～1994年在中国科学院红壤生态试验站通过田间试验研究了丘陵区稻田N2O排放的特点结果表明稻田N2O排放主要集中在水分落干期间,淹水状态下几乎没有N2O排放。由于早稻稻草还田,晚稻稻田N2O排放量即使在水分落干期间也不高。稻田N2O排放员随地形降低而逐渐增加,1993～1994年两年中被底、坡腰和坡顶稻田水稻生长期平均N2O-N排放通量分别为10．90、5．60和2．11μg／（m2·h）。     

A2/O系统受低C/N冲击及修复前后的微生物活性研究

利用2套A2/O工艺装置,通过在实际污水中添加铵盐的方式模拟低C/N冲击的不利情况,采取常规工艺调控措施进行修复,研究了冲击及修复前后的微生物活性变化.结果表明,A2/O系统在受到低C/N冲击之后,耗氧呼吸速率(OUR)、脱氢酶活性(DHA)、三磷酸腺苷(ATP)和聚β-羟基丁酸(PHB)4项指标迅速响应,降幅分别为81.8%,87.0%,90.5%和72.9%.提高污泥回流比和减小污泥龄都是有效的修复措施.修复期间,4项指标均呈现先快后慢的回升规律.提高污泥回流比是通过降低冲击负荷的方式实现OUR指标的基本回复,但DHA、ATP和PHB较受冲击前水平还有10%~20%不等的差距.减小污泥龄是通过逐步排出受损污泥来消除冲击的不利影响,过程中A2/O系统的处理效果不佳,但最后4项指标能够完全恢复.     

Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process

The anaerobic-anoxic oxidation ditch (A²/O OD) process is popularly used to eliminate nutrients from domestic wastewater. In order to identify the existence of denitrifying phosphorus removing bacteria (DPB), evaluate the contribution of DPB to biological nutrient removal, and enhance the denitrifying phosphorus removal in the A²/O OD process, a pilot-scale A²/O OD plant (375 L) was conducted. At the same time batch tests using sequence batch reactors (12 L and 4 L) were operated to reveal the significance of anoxic phosphorus removal. The results indicated that: The average removal efficiency of COD, NH4+, PO43-, and TN were 88.2%, 92.6%, 87.8%, and 73.1%, respectively, when the steady state of the pilot-scale A²/O OD plant was reached during 31-73 d, demonstrating a good denitrifying phosphorus removal performance. Phosphorus uptake took place in the anoxic zone by poly-phosphorus accumulating organisms NO2- could be used as electron receptors in denitrifying phosphorus removal, and the phosphorus uptake rate with NO2- as the electron receptor was higher than that with NO3- when the initial concentration of either NO2- or NO3- was 40 mg/L.