污水生化处理过程中溶解氧的控制方法优劣调研

溶解氧是溶解在水中的分子态氧,它与大气压力、温度等有密切的关系。在污水处理、尤其是生化处理的工艺运行中,溶解氧作为一项至关重要的控制指标,关乎电力资源的消耗、关乎工艺运行能否正常,更关乎处理出水水质。带着这一问题,作者对忻州市污水处理厂生化池的溶解氧的测试方法进行了长时间的探索,得出生化池溶解氧只能直接以在线监测装置或溶解氧便携式测定仪进行测定的结论。     

广州市地表水环境溶解氧时空分布特征分析

为了解广州市地表水环境溶解氧情况,结合广州市2020年40个地表水监测断面溶解氧数据,采用Origin和Excel软件统计分析了广州市中心城区、郊区和及近海区溶解氧时空分布特征。结果表明：(1)溶解氧空间分布特征（即水体溶解氧含量）：中心城区<郊区<近海区;(2)广州市各区溶解氧主要在7月、8月和9月偏低;(3)溶解氧影响因素复杂,受温度、氨氮、上游来水和潮汐等影响。因此,为保障考核断面水质达标,广州市应重点关注第三季度、中心城区考核断面地表水环境溶解氧含量变化影响。     

大型水库水质监测采样和溶解氧的测定

本文选用两种水质采样器，在升钟水库对比采样监测，对大型水库水质监测采样和溶解氧的测定进行讨论。证明一大型水库水质监测采样适宜采样器类型，以及溶解氧水样现场测定的好处。     

空气对采集溶解氧水样的影响

一、前言溶解氧是衡量水质量好坏的一项重要参数。在水环境中,溶解氧低于3 mg/l时,有些鱼类将因缺氧而死亡。在水中,氧的溶解度是很小的,且随水的温度而变化。水中的饱和溶解氧可以查表求得,也可以用下面公式计算:     

水环境质量自动监测中溶解氧偏低的原因探讨

为了弄清楚在水质未受到污染的情况下,水质自动监测中出现溶解氧快速下降然后又快速上升的真实原因。通过分析影响溶解氧的因素、校验自动站仪器设备、实验室比对测试。认为冷空气影响是发生该现象的真实原因。可为监测人员分析溶解氧偏低原因提供参考,为防止误判水环境质量提供帮助。     

乡镇生活污水溶解氧浓度模糊神经网络PID控制系统研究

在乡镇生活污水处理的好氧阶段,溶解氧浓度控制是非常重要的过程,具有滞后性和多干扰等特点,传统控制策略因控制精度较低和自适应能力差而难以满足要求。设计了基于模糊神经网络PID算法的溶解氧浓度控制方案,并在MATLAB中进行仿真。仿真结果表明,该控制方案具有响应速度快、超调量小和抗干扰能力强等优点。     

水中溶解氧光度法测定的初探

摘要本文介绍了水中溶解氧测定的分光光度法,并与标准方Winkler及其修正法进行比较,数理统计结果,无显著性差异。     

石化环境监测LIMS系统中BOD5的组态方法

文章阐述了石化环境监测LIMS系统中BOD5的组态方法。在组态之前,需要根据实际工作中变量的常规取值对BOD5和溶解氧的计算公式进行简化,组态BOD5的LIMS分析方法所需的组态分项包括水样在培养前后的溶解氧浓度等15个,每个分项均应根据数据类型、修约规则、计量单位设置相应的属性,空白样在培养前、后的溶解氧质量浓度用LabWare LIMS的"标准试剂"功能实现组态。BOD5值根据分析方法的计算公式、检出限、测定范围等限定条件编制程序语句计算出最终结果,编程组态后的LIMS分析经反复测试完全正确。     

炼油化工污水处理中活性污泥膨胀原因分析

针对工业废水采用普通活性污泥法处理易出现的丝状菌型污泥膨胀,分析和总结出五种主要膨胀类型:低负荷型、低溶解氧型、营养缺乏型、高硫化物型、pH值不平衡型。对污泥负荷、溶解氧、污水种类、营养成分及pH值和温度的变化等因素对污泥膨胀中菌胶团和丝状菌生长的相互影响进行阐述,给出污泥膨胀理论,并对不同类型的污泥膨胀提出相应的控制方法。     

四川大学江安校区景观水体水质特征分析

本文以四川大学江安校区景观水体为研究对象,通过近一年,共6次的水质监测采样,研究氨氮、总磷、溶解氧、高锰酸盐指数等水质指标的时空分布特征及变化规律并进行单因子评价。分析了水体富营养化和湖中鱼类的死亡原因并讨论了餐厅排污的影响。研究结果表明:总磷、氨氮和溶解氧是主要污染指标,可导致"水华"、死鱼等问题。最后,提出了相应的治理对策与措施建议。     

Bayesian approach to estimating margin of safety for total maximum daily load development

A Bayesian-updating approach is presented to the estimation of total uncertainty-based Margin of Safety (MOS) for Total Maximum Daily Load (TMDL) calculations. Probability distributions are presented to construct the likelihood function, the prior probability distribution, and the posterior (total uncertainty) probability distribution. The Bayesian-updating approach is demonstrated through a case study for the Lower Amite River, Louisiana. The posterior probability distribution-based on the Bayesian approach updates the standard deviation of summer dissolved oxygen in the Amite River from 1.88 mg/L to 2.10 mg/L when the total uncertainty is considered. Results from the Bayesian-updating approach are compared with two conventional methods. The dissolved oxygen reserve based on a conventional margin of safety of 20% is estimated to be 45,682.26 kg/Day. The second conventional method, where we consider the standard deviation of 1.88 mg/L, produces a dissolved oxygen reserve of 40,516.09 kg/Day. The Bayesian approach yields the dissolved oxygen reserve of 38,614.43 kg/Day with the first level (μ-σ) of MOS, producing a deficit of 5606.65 kg/Day in dissolved oxygen. The dissolved oxygen reserve deficit increases to 23,895.13 kg/Day when the second level (μ-2σ) of MOS is used, which escalated to 42,383.52 kg/Day when the highest level (μ-3σ) of MOS is used. While the total uncertainty-based Bayesian approach is demonstrated for a TMDL development on the Amite River, the overall approach could be applied in any river system with similar available data.     

DISSOLVED OXYGEN MODEL OF A SHORT DETENTION TIME RESERVOIR WITH ANAEROBIC HYPOLIMNION1

ABSTRACT: A vertical dissolved oxygen model was calibrated and verified using independent field data sets from 1972 and 1973 in Lake Lyndon B. Johnson (LBJ), a short detention time reservoir with anaerobic hypolimnion. Ammonia, carbonaceous BOD, conductivity, and temperature were also simulated as state variables. The conductivity results provided a check on the mass balance and the method of entering the inflows to the reservoir model. Emphasis was placed on calculating the sinks of dissolved oxygen in the hypolimnion which could be useful in management decisions.     

Time series in M dimensions: The one-dimensional case: Pollution in the Chicago Sanitary and Ship Canal

A nonstationary time-series model is used to examine the changes occurring at sampling stations on the Chicago Sanitary and Ship Canal. Using data from upstream sampling sites, downstream levels of dissolved oxygen, total dissolved solids, nitrates and nitrites, and ammonia are accurately predicted. The method is simple, insensitive to extreme values, and responsive to changes in the system.     

Industrial experience of process identification and set-point decision algorithm in a full-scale treatment plant

This paper presents industrial experience of process identification, monitoring, and control in a full-scale wastewater treatment plant. The objectives of this study were (1) to apply and compare different process-identification methods of proportional-integral-derivative (PID) autotuning for stable dissolved oxygen (DO) control, (2) to implement a process monitoring method that estimates the respiration rate simultaneously during the process-identification step, and (3) to propose a simple set-point decision algorithm for determining the appropriate set point of the DO controller for optimal operation of the aeration basin. The proposed method was evaluated in the industrial wastewater treatment facility of an iron- and steel-making plant. Among the process-identification methods, the control signal of the controller's set-point change was best for identifying low-frequency information and enhancing the robustness to low-frequency disturbances. Combined automatic control and set-point decision method reduced the total electricity consumption by 5% and the electricity cost by 15% compared to the fixed gain PID controller, when considering only the surface aerators. Moreover, as a result of improved control performance, the fluctuation of effluent quality decreased and overall effluent water quality was better.     

二元驱污水配聚黏损影响因素分析及控制方法

含油污水中活泼金属离子会对聚合物产生不同程度的降解,导致注入液的黏度损失较大。室内试验表明:水中二价铁、二价硫及硫化亚铁在溶解氧存在的情况下,均会大幅降低聚合物溶液的黏度,0.5mg/L的二价铁或二价硫、1mg/L的硫化亚铁,黏度损失在15%左右。溶解氧为5.17mg/L时,加入9mg/L的二价铁,聚合物溶液的黏度仅为5.48mPa.s,黏度损失超过95%。为减少上述因素对聚合物黏度的影响,利用陈化法、曝气法及化学氧化法等方法均能有效降低含油污水配聚过程中的黏度损失率。     

提高测定含油污水中COD准确度的探讨

根据自身工作实践,介绍了测定水中COD应注意的几个主要问题,如水样pH的调整、溶解氧含量的调整及确定稀释倍数的方法。特别提出:对于含石油类较高的水样时,应先用重铬酸钾法测定CODCr ,再确定稀释倍数。     

DROUGHT EFFECTS ON WATER QUALITY IN THE SOUTH PLATTE RIVER BASIN,COLORADO1

ABSTRACT: Twenty‐three stream sites representing a range of forested, agricultural, and urban land uses were sampled in the South Platte River Basin of Colorado from July through September 2002 to characterize water quality during drought conditions. With a few exceptions, dissolved ammonia, Kjeldahl nitrogen, total phosphorus, and dissolved orthophosphate concentrations were similar to seasonal historical levels in all land use areas during the drought. At some agricultural sites, decreased dilution of irrigation return flow may have contributed to higher concentrations of some nutrient species, increased primary productivity, and higher dissolved oxygen concentrations. At some urban sites, decreased dilution of base flow and wastewater treatment plant effluent may have contributed to higher dissolved nitrite‐plus‐nitrate concentrations, increased primary productivity, and higher dissolved oxygen concentrations. Total pesticide concentrations in urban and agricultural areas were not consistently higher or lower during the drought. At most forested sites, decreased dilution of ground water‐derived calcium bicarbonate type base flow likely led to elevated pH and specific‐conductance values. Water temperatures at many of the forested sites also were higher, contributing to lower dissolved oxygen concentrations during the drought.     

Exploratory Analysis of the Winter Chemistry of Five Lakes on the North Slope of Alaska1

Abstract: Lakes are important water resources on the North Slope of Alaska. Freshwater is required for oilfield production as well as exploration, which occurs largely on ice roads and pads. Since most North Slope lakes are shallow, the quantity and quality of the water under ice at the end of winter are important environmental management issues. Currently, water‐use permits are a function of the presence of overwintering fish populations, and their sensitivity to low oxygen concentrations. Sampling of five North Slope lakes during the winter of 2004‐2005 shed some light on the winter chemistry of four lakes that were used as water supplies and one undisturbed lake. Field analysis was conducted for oxygen, conductivity, pH, and temperature throughout the lake depth, as well as ice thickness and water depth. Water samples were retrieved from the lakes and analyzed for Na, Ca, K, Mg, Fe, dissolved‐organic carbon, and alkalinity in the laboratory. Lake properties, rather than pumping, were the best predictors of oxygen depletion, with the highest dissolved‐oxygen levels maintained in the lake with the lowest concentration of constituents. Volume weighted mean dissolved‐oxygen concentrations ranged from 4 to 94% of saturation in March. Dissolved oxygen and specific conductance data suggested that the lakes began to refresh in May.