溶解氧对好氧颗粒污泥影响的研究进展

好氧颗粒污泥技术是一种新颖废水处理技术。溶解氧(DO)是好氧颗粒污泥形成和稳定运行的一个重要参数。好氧颗粒污泥需要的曝气量大,能耗高。高曝气量带来的高DO浓度不利于氨氮通过SND去除。当DO扩散在颗粒内部受到限制时,颗粒中心形成的厌氧层不利于颗粒污泥的长期稳定运行。本文系统分析了DO浓度对好氧颗粒污泥影响的国内外研究现状,对好氧颗粒污泥中DO浓度这一重要参数的研究进行了总结。研究在低DO浓度下保持好氧颗粒污泥的稳定性有利于降低运行成本,采取合适的方法降低颗粒内部的扩散限制有利于增强颗粒的稳定性能。     

曝气沉砂池除砂机理分析

针对曝气沉砂池小试装置模型,通过配砂实验对沉砂池除砂率进行统计分析,研究曝气强度与HRT对沉砂池除砂率的影响。实验结果表明,不同曝气强度下,随着HRT变化,除砂率逐渐上升,并最终趋于平衡状态;不同HRT下,曝气强度与除砂率近似呈现一定的线性关系,且随着曝气强度的增大,除砂率降低;在HRT小于1min时,砂粒的运行路径和沉降时间缩短,不利于砂粒的去除;在HRT大于1min时,其中1、3和4min,随着气水比的增加除砂率降低幅度相对较小,曝气所引起的横向环流在一定程度上有利于砂粒的沉降,而HRT为2min时,除砂率降幅却很大,这与砂粒在曝气沉砂池池体断面分布有关,即断面处旋转流速和水平流速的大小变化将影响砂粒的运动;相比曝气强度,HRT对除砂率的影响较大。     

采用间隔流动注射仪测定总氰和氰化物的探讨

采用间隔流动注射的方法对水质中的氰化物进行检测。通过选择合适的锌盐和关闭的紫外灯,将总氰模块应用于易释放氰化物的检测。结果表明,仪器测定的总氰和易释放氰化物的精密度、准确度和加标回收率均满足水质检测的质量控制要求。     

提高水中BOD5测定质量的探讨

介绍了环境空气质量、分析用水、接种液加入量、曝气方法的选择等因素对BOD5测定的影响。提出测定过程中实验室空气质量、分析用水的选择、接种液的选择和加入量以及曝气方法应注意事项,以期得到较为准确的测定结果,提高废水中BOD5测定质量。     

Household organic waste composting using bins with different types of passive aeration

The objective of this study was to study the performances of six 200-L polyethylene bins, each with different design for passive aeration to organic wastes composting. Food scraps and dry leaves (1.6 kg) were added to each bin once a day until the bin was full. Temperatures at the middle portion were measured daily. The compost from each bin was taken once a week for 120 days for analysis of C, N, volatile solids, and a germination index once a week for 120 days. After 120 days, the compost sample from each bin was taken to determine the mass reduction, size distribution, CEC, N, P and K values. The results showed that the temperatures inside the bins were in the ranges of 24 °C-57 °C. The composts in all bins were found to be stable at around 56-91 days. The wastes decayed fastest in bins with lateral and vertical systems of natural ventilation. It took about two months to stabilize the organic wastes, with a 59-62% decrease of mass. The C/N ratio, CEC, N, P, and K values of the final composts were 14.8-16.0, 66-68 cmol/kg, and 1.26-1.50% N, 0.52-0.56% P₂O₅ and 1.66-1.92% K₂O, respectively.     

曝气复氧对底泥氮素生物地球化学循环影响的作用机制研究

通过分析底泥氮污染物释放规律和转化过程,以及底泥生境、氮形态变化和氮循环功能微生物群落结构变化的规律,探讨了不同曝气复氧条件影响底泥氮生物地球化学循环的生物代谢、物理化学联合作用的机制。结果表明：曝气复氧对底泥中氮的生物地球化学循环影响是一个包括微生物代谢作用和物理化学作用的复杂联合作用过程。水体好氧环境的改变主要引起参与底泥氮循环的硝化、亚硝化和反硝化功能菌群群落结构的演变,对异养菌和氨化菌的影响不大,证明环境好氧条件的改变对底泥有机质生物分解产生氨氮的微生物代谢过程影响不大,主要对底泥释放的氨氮硝化、反硝化等生物转化过程产生大的影响。不同溶解氧条件下,底泥释放的氮素在微生物作用下主要以NH4＋-N和NO3--N的形式进入试验体系,并在特定的氧化还原电位（临界值-200 mV）和pH（临界值6.70）条件下通过物理化学作用在底泥中以离子交换态氮（IEF-N）、碳酸盐结合态氮（CF-N）、铁锰氧化态氮（IMOF-N）及有机态和硫化物结合态氮（OSF-N）等不同形态氮相互转化,同时,在氮的转化和循环过程中部分输入上覆水体。在低溶解氧组实验条件下[ρ（DO）〈0.5 mg.L-1],底泥向水体输出氮总量为底泥可转化态氮的19.7%,主要为氨氮,最大释放速率达到289.13 mg.m-2.d-1,释放的质量浓度可达到18.8 mg.L-1;好氧条件下（DO饱和）,底泥向水体输出氮总量为底泥可转化态氮的1.8%;好氧-缺氧条件下为11.7%,主要以N2的形式释出系统。     

Integrating soil carbon cycling with that of nitrogen and phosphorus in the watershed model SWAT: Theory and model testing

In this paper we describe and test a sub-model that integrates the cycling of carbon (C), nitrogen (N) and phosphorus (P) in the Soil Water Assessment Tool (SWAT) watershed model. The core of the sub-model is a multi-layer, one-pool soil organic carbon (S_C) algorithm, in which the decomposition rate of S_C and input rate to S_C (through decomposition and humification of residues) depend on the current size of S_C. The organic N and P fluxes are coupled to that of C and depend on the available mineral N and P, and the C:N and N:P ratios of the decomposing pools. Tillage explicitly affects the soil organic matter turnover rate through tool-specific coefficients. Unlike most models, the turnover of soil organic matter does not follow first order kinetics. Each soil layer has a specific maximum capacity to accumulate C or C saturation (S_x) that depends on texture and controls the turnover rate. It is shown in an analytical solution that S_x is a parameter with major influence in the model C dynamics. Testing with a 65-yr data set from the dryland wheat growing region in Oregon shows that the model adequately simulates the S_C dynamics in the topsoil (top 0.3 m) for three different treatments. Three key model parameters, the optimal decomposition and humification rates and a factor controlling the effect of soil moisture and temperature on the decomposition rate, showed low uncertainty as determined by generalized likelihood uncertainty estimation. Nonetheless, the parameter set that provided accurate simulations in the topsoil tended to overestimate S_C in the subsoil, suggesting that a mechanism that expresses at depth might not be represented in the current sub-model structure. The explicit integration of C, N, and P fluxes allows for a more cohesive simulation of nutrient cycling in the SWAT model. The sub-model has to be tested in forestland and rangeland in addition to agricultural land, and in diverse soils with extreme properties such high or low pH, an organic horizon, or volcanic soils.     

沼液对甘蓝连作土壤生物学性质的影响

以施用化肥225 kg/hm2为对照,设置两种不同的沼液用量(以纯氮计):沼液I(168 kg/hm2)和沼液II(225 kg/hm2),通过连续3 a的甘蓝种植试验,研究沼液对甘蓝连作土壤微生物区系、土壤酶活性以及土壤养分与土壤酶活性之间的相关性.结果表明:1)施用沼液显著改善了连作土壤的微生物区系,溶磷细菌、解钾细菌、氨化细菌、固氮菌和放线菌的数量显著增加;同时抑制了真菌的富集.两种不同用量的沼液处理较化肥处理的土壤细菌/真菌(B/F)值分别提高了142.7%和202.3%.2)在225 kg/hm2等氮水平下,施用沼液显著提高了土壤的蔗糖酶、磷酸酶和蛋白酶活性,较之化肥处理分别提高了63.96%、137.61%和139.66%;同时显著降低了土壤过氧化氢酶和多酚氧化酶活性.3)土壤养分与土壤酶活性相关性分析表明,有机质含量与土壤脲酶、磷酸酶、蔗糖酶和蛋白酶活性呈显著正相关,与过氧化氢酶活性呈显著负相关,而与多酚氧化酶活性无明显相关性;磷酸酶活性与土壤速效磷含量呈显著正相关;蛋白酶活性与土壤碱解氮、全氮含量呈显著正相关.表4参24     

Oxygen demand for the stabilization of the organic fraction of municipal solid waste in passively aerated bioreactors

Conventional aerobic waste treatment technologies require the use of aeration devices that actively transport air through the stabilized waste mass, which greatly increases operating costs. In addition, improperly operated active aeration systems, may have the adverse effect of cooling the stabilized biomass. Because active aeration can be a limiting factor for the stabilization process, passive aeration can be equally effective and less expensive. Unfortunately, there are few reports documenting the use of passive aeration systems in municipal waste stabilization. There have been doubts raised as to whether a passive aeration system provides enough oxygen to the organic matter mineralization processes. In this paper, the effectiveness of aeration during aerobic stabilization of four different organic fractions of municipal waste in a reactor with an integrated passive ventilation system and leachate recirculation was analyzed. For the study, four fractions separated by a rotary screen were chosen. Despite the high temperatures in the reactor, the air flow rate was below 0.016 m³/h. Using Darcy’s equation, theoretical values of the air flow rate were estimated, depending on the intensity of microbial metabolism and the amount of oxygen required for the oxidation of organic compounds. Calculations showed that the volume of supplied air exceeded the microorganisms demand for oxidation and endogenous activity by 1.7–2.88-fold.     

隔震连续梁桥结构以位移为基础的抗震设计方法

笔者对隔震连续梁桥结构提出了一种以位移为基础的抗震设计方法 ,建立了设计位移反应谱 ,给出了设计步骤 ,该方法可对对称与非对称隔震连续梁桥结构采用相同的设计步骤进行基于位移的抗震设计 ,最后对设计算例用振型分析和非线性时程分析验证了设计结果的合理性