空压机冷却循环水水质稳定处理

对舞钢空压机冷却循环水水质进行了分析，探讨了循环水系统结垢腐蚀机理。实验确定了水处理药剂及投加药量，解决了水质较差的问题。     

Regression Model for Daily Maximum Stream Temperature

An empirical model is developed to predict daily maximum stream temperatures for the summer period. The model is created using a stepwise linear regression procedure to select significant predictors. The predictive model includes a prediction confidence interval to quantify the uncertainty. The methodology is applied to the Truckee River in California and Nevada. The stepwise procedure selects daily maximum air temperature and average daily flow as the variables to predict maximum daily stream temperature at Reno, Nev. The model is shown to work in a predictive mode by validation using three years of historical data. Using the uncertainty quantification, the amount of required additional flow to meet a target stream temperature with a desired level of confidence is determined.     

High-Frequency Diel Dissolved Oxygen Stream Data Modeled for Variable Temperature and Scale

Diel dissolved oxygen (DO) concentrations and temperature were sensed at high-frequency and modeled in an eastern Iowan stream, Clear Creek, in an agricultural setting. The magnitude of the diel changes in DO and temperature were largest at the upstream (headwater) station. Inclusion of temperature change factors increased the accuracy of modeling results and yielded estimates of the reaeration rate constant, primary production rate, and respiration rate. The DO modeling of the high-frequency measurements (15-min intervals) revealed a temperature-driven nonlinear reaeration process that led to increases in nighttime DO concentrations. The DO modeling results from three sensing stations in the watershed revealed decreasing trends in primary productivity, respiration, and the reaeration rate constant with increasing drainage area. Light extinction from suspended solids was the main factor limiting net primary production. As a result, the P/R ratio also decreased with increasing drainage area. High-frequency sensor data and DO modeling revealed the effects of temperature and watershed scale on the primary factors that dictate diel DO dynamics in a stream setting.     

Role of Stream Restoration on Improving Benthic Macroinvertebrates and In-Stream Water Quality in an Urban Watershed: Case Study

Many stream restoration projects do not include a requirement for long-term monitoring after the project has been completed, resulting in a lack of information about the success or failure of certain restoration techniques. The National Risk Management Research Laboratory, part of the U.S. EPA Office of Research and Development, evaluated the effectiveness of stream bank and channel restoration as a means of improving in-stream water quality and biological habitat in Accotink Creek, Fairfax City, Va., using discrete sampling and continuous monitoring techniques before and after restoration. This project monitored the effects of a 549 m (1,800 linear-ft) restoration of degraded stream channel in the North Fork of Accotink Creek. Restoration, which was intended to restore the stream channel to a stable condition, thereby reducing stream bank erosion and sediment loads in the stream, included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. Results of sampling and monitoring for 2 years after restoration indicated a slight improvement in biological quality for macroinvertebrate indices such as Virginia Stream Condition Index, Hilsenhoff Biotic Index, and Ephemeroptera, Plecoptera, Trichoptera taxa; the differences were statistically significant at 90% level of confidence with the power of greater than 0.8. However, indices were all below the impairment level, indicating poor water quality conditions. No statistically significant differences in chemical constituents and bacteriological indicator organisms were found before and after restoration as well as upstream and downstream of the restoration. The results indicated that stream restoration alone had little effect in improving the conditions of in-stream water quality and biological habitat, though it has lessened further degradation of stream banks in critical areas where the properties were at risk. Control of storm-water flows by placing best management practices in the watershed might reduce and delay discharge to the stream and may ultimately improve habitat and water quality conditions.     

Transient Rainfall-Runoff Loadings to a Partial Exfiltration System: Implications for Urban Water Quantity and Quality

Modification of rainfall-runoff processes by urban infrastructure and anthropogenic activities impacts receiving waters and the surrounding terrestrial environment. Infiltration–exfiltration systems such as a partial exfiltration reactor (PER) when loaded by transient sheet flow have the potential to attenuate the impact of both the quantity and quality of urban runoff. These in situ systems are subject to highly variable water quality and quantity while functioning under variably saturated flow conditions. To improve the understanding of field-scale PER performance as a rainfall-runoff unit operation and process, a two-dimensional (2D) numerical model was used to simulate the effluent hydrograph and water content profiles under transient hydraulic loadings. Richard’s equation was applied in the 2D model using parameters estimated from laboratory experiments and hydrographs measured for an in situ PER. The temporal dynamics of the water content illustrated the ability of the PER to lower peak flow, redistribute volume, and attenuate temporal aspects of the inflow hydrograph. Results demonstrated the role of the PER to attenuate runoff water quantity, while also providing water quality improvements, as illustrated for suspended solids and dissolved Cu. Simulation of historical events for different surrounding soils illustrated the critical role of surrounding soil conditions on PER performance. While the PER demonstrated water quantity attenuation benefits for design storms (1, 2, 5?year return periods), results also illustrate how a given PER design for clayey soils conditions can be limiting for intense events. Evaporation was a dominant mechanism for the drying process in the PER upper layer; with a residual moisture content in the porous pavement layer achieved in less than 2?days in summer for Cincinnati, Ohio.     

Importance of Field Data in Stream Water Quality Modeling Using QUAL2E-UNCAS

The Stream Water Quality Model QUAL2E-UNCAS is widely used to simulate the dissolved oxygen of streams under steady flow conditions. It is the latest version of a series of water quality models that have a long history in systems analysis in water quality management, and has been applied to a number of streams and rivers around the world. This paper summarizes the conceptual representation of the computer model, briefly reviews a number of applications of the model that have been published in open literature, describes the included uncertainty analysis capability, and discusses the importance of field data in model predictions. Experience with the QUAL2E model has proven the importance of site-specific data to model predictions. An accurate representation of the properties of the system significantly contributes to simulation success.     

Improved Method for Aggregation of Water Quality Subindices

Alternative methods to describe water quality using an aggregate index consisting of subindices for individual water quality variables are examined. Most aggregation methods suffer from three shortcomings: Ambiguity, eclipsing, and rigidity. Ambiguity problems exist when all the subindices indicate acceptable water quality for a given use, but the aggregated index does not. Eclipsing problems exist when the aggregated index fails to reflect poor water quality of one or more water quality variables. Rigidity problems exist when additional variables are included in the index to address specific water quality concerns, but the faulty aggregation function might artificially reduce the value of the water quality index such that it does not accurately reflect the true water quality. As the number of water quality variables increases, the magnitude of the aggregated index decreases raising the issue of ambiguity again. The writers developed a mathematical formulation for aggregate indices that avoids the problems of ambiguity, eclipsing, and rigidity with respect to the number of water quality variables required to be aggregated in a given index.     

Choosing the Right Parameter for Single-Duct Constant Air Volume System Supply Air Temperature Reset

To improve system efficiency under part-load conditions, the supply air temperature set point for a single-duct constant air volume air handling unit (AHU) system is often reset based on either return air temperature or outside air temperature. Both reset strategies make engineering sense as long as the reset schedules are reasonable. Quite often the decision to use one over the other is made with the assumption that they will both achieve some energy savings. However, the impact of these two strategies on AHU energy consumption could be very different. An in-depth analysis and comparison of these two commonly used supply air temperature reset strategies for a single-duct constant air volume system is presented in this paper. It is shown that the reset strategy based on outside air temperature is inherently better than that based on return air temperature, with lower energy consumption and improved building comfort level.     

Steady-State Water Quality Analysis for Pipe Network Systems

In 1993 P. F. Boulos and T. Altman developed an efficient explicit scheme for determining steady state water quality in a distribution system for conservative and zero-order reacting constituents. This approach is extended here to first- and second-order reactions and a general reaction relationship is discussed. Mass balance relationships and nonconservative reaction kinetics lead to a general matrix for constituent analysis. The directed graph that results in steady flow conditions permits single equations to be solved sequentially providing the water quality distribution throughout the system. The method can be used to solve for linear and nonlinear conditions and is demonstrated for first-order decay and growth and second-order decay on a 13-pipe system.     

Modified Larsons Ratio Incorporating Temperature, Water Age, and Electroneutrality Effects on Red Water Release

Corrosion indices have a historical as well as practical relevance in drinking water treatment. The development of reliable indicators of corrosion related problems, like red water, is an ongoing process in the drinking water industry. Due to the complexity of interaction among the physical, chemical, and biological reactions taking place within a typical distribution system, mechanistic models are difficult to formulate. Even if such a model was available, fitting it to actual field conditions would still be an empirical process. Corrosion indices give simplistic generalizations to complex corrosion phenomena. A modified form of the Larson Ratio that includes the effects of temperature and hydraulic retention time is proposed based on apparent color release data available from a 2 year pilot distribution system study.     

热轧薄板淬火水处理水温水质控制工艺

热轧精整热处理薄板是一种非常具有市场潜力的产品,其淬火工艺对冷却水的水温和水质控制要求很高。介绍了一种水温与水质控制工艺,在节约能源、降低投资的同时,达到淬火机冷却水的使用要求,并经过工程实践的检验,是一种应用前景广阔的热处理薄板水处理工艺技术。     

Quality Modeling of Water Distribution Systems Using Sensitivity Equations

In this paper, unsteady water quality modeling and the associated sensitivity equations are solved for water distribution systems. A new solution algorithm is proposed, designed for slow varying velocity and based on a time splitting method to separate and solve efficiently each phenomenon such as advection and chemical reaction. This numerical approach allows simultaneous solution of both the direct problem and the sensitivity equations. Special attention is given to the treatment of advection, which is handled with a total variation diminishing scheme. The general model presented in this study permits global sensitivity analysis of the system to be performed and its efficiency is illustrated on two pipe networks. The importance of the sensitivity analysis is shown as part of the calibration process on a real network.     

蒸发循环水水质与处理浅析

本文针对氧化铝生产循环冷却水系统存在的水质差、温度高、悬浮物含量高、管道设备结垢、堵塞的问题，论述了该系统的水质，结垢机理和堵塞的原因，阐述了循环水系统的改造方案；提出了今后改造和运行中应注意的事项。     

转炉浊环水质稳定处理技术

转炉除尘水水质稳定处理是除尘水实现循环使用的关键。对除尘水特点和水质障碍－－结和了简述，并根据试验室试验筛选出适合转炉除尘水系统中的水质稳定药剂配方并在铁厂实际应用中取得了满意效果。     

Hydrologic and Water Quality Integration Tool: HydroWAMIT

A spatially distributed and continuous hydrologic model focusing on total maximum daily load (TMDL) projects was developed. Hydrologic models frequently used for TMDLs such as the hydrologic simulation program—FORTRAN (HSPF), soil and water assessment tool (SWAT), and generalized watershed loading function (GWLF) differ considerably in terms of spatial resolution, simulated processes, and linkage flexibility to external water quality models. The requirement of using an external water quality model for simulating specific processes is not uncommon. In addition, the scale of the watershed and water quality modeling, and the need for a robust and cost-effective modeling framework justify the development of alternative watershed modeling tools for TMDLs. The hydrologic and water quality integration tool (HydroWAMIT) is a spatially distributed and continuous time model that incorporates some of the features of GWLF and HSPF to provide a robust modeling structure for TMDL projects. HydroWAMIT operates within the WAMIT structure, developed by Omni Environmental LLC for the Passaic River TMDL in N. J. HydroWAMIT is divided into some basic components: the hydrologic component, responsible for the simulation of surface flow and baseflow from subwatersheds; the nonpoint-source (NPS) component, responsible for the calculation of the subwatershed NPS loads; and the linkage component, responsible for linking the flows and loads from HydroWAMIT to the water quality analysis simulation program (WASP). HydroWAMIT operates with the diffusion analogy flow model for flow routing. HydroWAMIT provides surface runoff, baseflow and associated loads as outputs for a daily timestep, and is relatively easy to calibrate compared to hydrologic models like HSPF. HydroWAMIT assumes that the soil profile is divided into saturated and unsaturated layers. The water available in the unsaturated layer directly affects the surface runoff from pervious areas. Surface runoff from impervious areas is calculated separately according to precipitation and the impervious fractions of the watershed. Baseflow is given by a linear function of the available water in the saturated zone. The utility of HydroWAMIT is illustrated for the North Branch and South Branch Raritan River Watershed (NSBRW) in New Jersey. The model was calibrated, validated, and linked to the WASP. The NPS component was tested for total dissolved solids. Available weather data and point-source discharges were used to prepare the meteorological and flow inputs for the model. Digital land use, soil type datasets, and digital elevation models were used for determining input data parameters and model segmentation. HydroWAMIT was successfully calibrated and validated for monthly and daily flows for the NSBRW outlet. The model statistics obtained using HydroWAMIT are comparable with statistics of HSPF and SWAT applications for medium and large drainage areas. The results show that HydroWAMIT is a feasible alternative to HSPF and SWAT, especially for large-scale TMDLs that require particular processes for water quality simulation and minor hydrologic model calibration effort.     

提高连铸浊环水水质浅析

介绍了太钢板坯连铸水处理系统的工艺流程，分析了连铸浊环水水质存在的问题。通过对冷却塔部分、铁皮坑、水泵调速等改造，以及选用新的水质稳定剂，使水质明显好转。     

Identifying Outliers in Correlated Water Quality Data

Evaluating water quality data for outliers is a good quality control/quality assessment procedure whether the data are used for monitoring or for modeling. Often water quality data are correlated, e.g., carbonaceous biochemical oxygen demand (CBOD) has some correlation with NH3. Univariate methods for identifying outliers do not consider the correlation between variables and may identify too many data points as outliers or miss observations which have extreme ratios between variables, e.g., a raw wastewater sample with relatively low CBOD but high NH3. Testing for outliers using multivariate methods such as the Mahalanobis distance, Jackknife distance, p-values, or Hadi’s automatically incorporates the correlation or covariance between variables and is fundamentally more correct. Such multivariate methods can better identify potential outliers and avoid eliminating valid data.     

Optimal Wasteload Allocation Procedure for Achieving Dissolved Oxygen Water Quality Objectives. I: Sensitivity Analysis

A method is presented to compute sensitivities of in-stream dissolved oxygen (DO) with respect to perturbations in the load vector and the reaction coefficients that make up the eutrophication cycle. It is shown that the direct sensitivity method, i.e., the repetitive solution of the direct problem, produces the desired information, however at a large computational cost. The utilization of the adjoint sensitivity method proves to be a much more efficient way to compute these sensitivities as large subsets of the sensitivity information domain can be easily extracted with just a few runs. It is found that for the given problem setup, in-stream DO is most sensitive to ammonia, effluent DO, algae, and carbonaceous biochemical oxygen demand (CBOD) loads. Additionally, the computed sensitivities vary considerably in their general trend over the simulation time. Sensitivities also are computed with respect to the reaction coefficients (26 total) that govern the interdependency of all constituents. Sediment oxygen demand proves to be the coefficient with the highest influence that is three orders of magnitude higher than the next set of coefficients comprised of reaeration, CBOD degradation, nitrification, and denitrification. All other coefficients have a negligible influence on DO concentrations. Computations are carried out using a two-dimensional model formulation applied to a long rectangular channel with varying width and slope and periodic but unsteady flow conditions.     

Water Quality Aspects of Irrigation and Drainage: Past History and Future Challenges for Civil Engineers

This paper presents a brief history of irrigation and drainage related to ASCE activities on its Jubilee. This paper discusses legislation and policies that affect irrigation and drainage practices, water quality constituents of increasing concern in irrigation and drainage practices, and presents a prognosis on the future of declining freshwater resources available for irrigated agriculture and growing water quality problems in irrigation and drainage. Civil engineers in ASCE’s Irrigation and Drainage Division have compiled an 80-year history of highly meritorious service and accomplishments. In the next millennium, civil engineers will face a formidable challenge in managing and protecting the precious freshwater resources in the U.S.     

Comparison of the Monod and Droop Methods for Dynamic Water Quality Simulations

The Monod method is widely used to model nutrient limitation and primary productivity in water bodies. It offers a straightforward approach to simulate the main processes governing eutrophication and it allows the proper representation of many aquatic systems. The Monod method is not able to represent the nutrient luxury uptake by algae, which consists of the excess nutrient uptake during times of high nutrient availability in the water column. The Droop method, which is also used to model nutrient limitation and primary productivity, takes into account the luxury uptake of nutrients. Because of the relative complexity of the Droop method, it has not been systematically adopted for the simulation of large stream networks. The Water Quality Analysis Simulation Program (WASP) version 7.1 was updated to include nutrient luxury uptake for periphyton growth. The objective of this paper is to present the new nutrient limitation processes simulated by WASP 7.1 and to compare the performance of the Droop and the Monod methods for a complex stream network where periphyton is the main organism responsible for primary productivity. Two applications of WASP 7.1 with the Droop and Monod methods were developed for the Raritan River Basin in New Jersey. Water quality parameters affecting the transport and fate of nutrients were calibrated based on observed data collected for the Raritan River total maximum daily load. The dissolved oxygen and nutrients simulated with WASP 7.1, obtained with the Droop and Monod methods, were compared at selected monitoring stations under different flows and nutrient availability conditions. The comparison of the WASP 7.1 applications showed the importance of using the Droop method when periphyton was the main organism responsible for primary productivity. The data simulated with the Droop method resulted in good agreement with the observed data for dissolved oxygen, ammonia-nitrogen, nitrate-nitrogen, and dissolved orthophosphate at the selected stations. The Monod method was not able to capture the diel dissolved oxygen variation when nutrients were scarce, and it resulted in unrealistic diel variations of nutrients at times of strong primary productivity at some locations.