Water Use System Research Articles

Selection of pretreatment process and reverse osmosis membrane for a wastewater reclamation system for the industrial water use

Wastewater reclamation offers an attractive solution to water stress problems these days. Because of health concerns in the reclaimed wastewater as drinking water, most of water reuse projects are focusing on the industrial water use. The key water quality constraint to the industrial water reuse is ionic constituents from nearby industrial complexes. Therefore, the reverse osmosis (RO) process must be the main process for a wastewater reclamation system for the industrial water use. The most important target for the design of an RO-based wastewater reclamation system is to minimize membrane fouling. This study focuses on the selection of pretreatment process and RO membrane to minimize the fouling in the RO process. Since raw water is the wastewater treatment plant effluent, high-quality pretreatment and low-fouling RO membrane should be considered for the design of the whole system. A short-term field test for microfiltration (MF) and ultrafiltration (UF) was carried out to see which process showed better performance in terms of the process stability and the pre-treated water quality. Both MF and UF produced the pretreated water of the similar quality, while UF showed more stable transmembrane pressure data than MF. In addition, a short-term field RO-fouling test was introduced to select the best RO membrane among the three tested membranes in terms of the fouling resistance.

Judicious generation of alternative water network designs with manual evolution strategy

This study is aimed to judiciously generate the desired alternative configurations of a given single-contaminant water-using system under the constraints of minimum freshwater usage, minimum match number and minimum total throughput. A generalized source-shift procedure is proposed for this purpose, which can be applied manually by evolution from a preliminary network which requires minimum freshwater usage. Systematic implementation guidelines are also provided to perform the evolution steps. In addition, the minimum interconnection number can be estimated in advance and the total number of promising alternative solutions can also be determined a priori. Six examples are presented in this paper to demonstrate the effectiveness and benefits of applying our method.

Design of discontinuous water-using systems with a graphical method

A systematic approach using the graphical representation of water use and its system-wide manipulation is proposed for minimising freshwater and wastewater generation for discontinuous water systems. Design interactions of time-dependant water reuse and implications of storage tank in the network design have been fully addressed, and a new targeting and design method has been proposed to provide guidelines for achieving minimum freshwater requirements and to design the configuration of water re-use networks. Design complexity associated with simultaneous consideration of concentration and time constraints has been effectively dealt with in the proposed design method, which clearly provides benefits by reducing water consumptions and maintaining sustainable water usage.

Water Allocation Network Design Concerning Process Disturbance

Water system integration can effectively reduce freshwater consumption and minimize wastewater discharge of a water-using system, but integration makes the resultant water network structurally more integrated among process units. Therefore, to design a flexible water allocation network that is easy to control becomes highly desirable. In this Article, a methodology is presented for water allocation network design with process disturbance taken into account. For a new design, the synthesized network structure can guarantee that the water system consumes minimum freshwater under both normal and disturbance conditions and with minimum number of control streams under disturbance. At the same time, the information needed to adjust flow rate under disturbance will be obtained. For an existing water system, an adjustment scheme under disturbance with minimum freshwater consumption for the existing structure will be obtained. The water network designed by the new methodology has the feature of minimum freshwater ...

Optimization and evaluation of steel industry’s water-use system

In the steel industry, water is mainly used for cleaning and cooling. All these different tasks produce wastewaters that differ not only in quantity but also in quality. This study integrates all water-use processes into a system and applies substance flow analysis to build up an optimization model and an evaluation index system for the water-use network of a steel enterprise. Based on the index system, water-use status of large steel enterprises in China is evaluated and problems in the present water consumption are identified. A contrast analysis between present and optimized water-use is conducted, which then serves as the basis for the network optimization and countermeasure articulation. Finally, an analysis has been made on one of the most important and largest steel enterprise in China. The results indicate that after optimization fresh water consumption can be decreased by 11.1% and wastewater discharge can be decreased by 94.54%.

Modeling climate change impacts on water trading

This paper presents a new method of evaluating the impacts of climate change on the long-term performance of water trading programs, through designing an indicator to measure the mean of periodic water volume that can be released by trading through a water-use system. The indicator is computed with a stochastic optimization model which can reflect the random uncertainty of water availability. The developed method was demonstrated in the Swift Current Creek watershed of Prairie Canada under two future scenarios simulated by a Canadian Regional Climate Model, in which total water availabilities under future scenarios were estimated using a monthly water balance model. Frequency analysis was performed to obtain the best probability distributions for both observed and simulated water quantity data. Results from the case study indicate that the performance of a trading system is highly scenario-dependent in future climate, with trading effectiveness highly optimistic or undesirable under different future scenarios. Trading effectiveness also largely depends on trading costs, with high costs resulting in failure of the trading program.

Complex of the means and actions of operative reaction to dangerous displays of harmful substances of the emergency situations

It is proved creations of the complex the means and actions of neutralisation the harmful consequences action of emergency situations, the basic lacks traditional schemes of counteraction to emergency situations are revealed. The full-function block diagramme corresponding means of the counteraction to negative factors technogenic and este-stvennogo origins, including radiating pollution is developed. Means of system of safe water use are developed.

Optimal Design of an Integrated Discontinuous Water-Using Network Coordinating with a Central Continuous Regeneration Unit

A systematic approach is proposed to design an optimal batch water-using network with centralized regeneration in order to deal with coordination of discontinuous water-using operations with one central continuous regeneration unit during multiple repeated batch cycles. The mathematical formulation in weak forms that readily induces process dynamic expressions is established under the framework of continuous time representation, in which a rigorous dynamic model of a tank is embedded. The freshwater consumption and the regeneration flow rates are minimized by a two-stage optimization approach. The integration of the batch water-using system highlights fixed regeneration flow rates and transitional behaviors from the start-up phase to steady state in multiple batch cycles. Optimal network structures and evolution characteristics of residual water and contaminant concentrations in buffer tanks can be achieved through solutions to the nonlinear programming problems (NLP). Four scenarios, including truly batc...

MILP-based initialization strategies for the optimal design of water-using networks

The optimal design of water-using systems involves necessarily the exploitation of all possible water reuse and recycling alternatives. The general problem can be formulated as a non-convex nonlinear program (NLP), but due to the presence of bilinear terms, it may be difficult for local optimization solvers to attain global optimal solutions. To overcome this difficulty, this paper presents two mixed integer linear programming (MILP)-based procedures to generate a few structurally different starting points for the NLP. In both, the problem is decomposed into calculation stages by assuming that the water streams progress in series through the water-using units, with the binary variables selecting which unit belongs to a certain stage. Their main difference concerns the way fixed flowrate units are handled, either separately or in conjunction with a fixed load operation, since the former comprise a linear subsystem. The two algorithms are compared to a closely related LP-based method taken from the literature and to the one employed by the global optimization solver BARON. The results from a large set of example problems confirm their effectiveness in avoiding local solutions despite the small number of starting points. In contrast to the previous method they are easily scalable and, for some of the larger problems, could find better solutions than BARON with significantly fewer computational resources. The results have also shown that the option of tackling one unit at a time is the most favorable.

Synthesis of water-using network with central reusable storage in batch processes

The starting and finishing times of water-using operations in batch plants are dependent on the production planning and scheduling. For maximizing the possibility of water reuse/recycle, or for minimizing the freshwater consumption, central storage facilities in a batch water-using system can collect the reusable water from the earlier operations and then supply the remaining water to the later operations. For a predefined production schedule, this paper presents a mathematical formulation for the synthesis of batch water-using networks with central storage tank(s). Superstructures that incorporate all possible flow connections are built to facilitate the problem modeling. The design problem is formulated as a nonlinear program (NLP) if there is no limitation to water reuse/recycle, or a mixed-integer nonlinear program (MINLP) when forbidding water reuse between assigned water-using units and water recycle of certain water-using units is considered. A published literature example and some adaptation examples are provided to demonstrate the good expectation of the proposed, superstructure-based NLP and MINLP formulations. As supported by the results, superstructures with the design scheme can effectively accomplish the objective of solving the design problem for minimum freshwater consumption and offering the optimal network configuration.

The Columbia Basin Project: Seventy-Five Years Later

The Columbia Basin Project (CBP) is the largest comprehensive reclamation project in the United States. An intertwined system of water diversion, capture, storage, movement, and use for hydroelectric production and irrigation, made famous by the capstone of Grand Coulee Dam, the CBP completely transformed the arid environment of central Washington and the economy of the Pacific Northwest (PNW). As this project stretches now into 75 years of plans, actions, reactions, and potential future actions, there is a surprisingly small amount of literature examining this project and its far-reaching implications. Originally planned as a reclamation project, the CBP morphed over time as values and priorities changed; never achieving completion, approximately two-thirds of the original planned project acreage is currently irrigated, but with escalating ecologic and economic implications. The most obvious ecologic implication has fixated debates about development in the Pacific Northwest, and that is the near annihilation of historic salmon runs due to dam construction. As this question (salmon versus dams) consumes most scholarly literature related to the CBP, we chose instead to examine everything except ecologic implications. This article reviews the existing literature on the CBP from several fields, noting that many economic, social, legal, policy, and agricultural questions remain unanswered after 75 years. Those unanswered questions become particularly important in light of recent discussions within Washington State concerning completing the CBP, thus potentially increasing the size of irrigated lands by one-third in the Columbia Basin Project.

Multi-objective optimization of water-using systems

Industrial water systems often allow efficient water uses via water reuse and/or recirculation. The design of the network layout connecting water-using processes is a complex problem which involves several criteria to optimize. Most of the time, this design is achieved using Water Pinch technology, optimizing the freshwater flow rate entering the system. This paper describes an approach that considers two criteria: (i) the minimization of freshwater consumption and (ii) the minimization of the infrastructure cost required to build the network. The optimization model considers water reuse between operations and wastewater treatment as the main mechanisms to reduce freshwater consumption. The model is solved using multi-objective distributed Q-learning (MDQL), a heuristic approach based on the exploitation of knowledge acquired during the search process. MDQL has been previously tested on several multi-objective optimization benchmark problems with promising results [C. Mariano, Reinforcement learning in multi-objective optimization, Ph.D. thesis in Computer Science, Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Cuernavaca, March, 2002, Cuernavaca, Mor., México, 2001]. In order to compare the quality of the results obtained with MDQL, the reduced gradient method was applied to solve a weighted combination of the two objective functions used in the model. The proposed approach was tested on three cases: (i) a single contaminant four unitary operations problem where freshwater consumption is reduced via water reuse, (ii) a four contaminants real-world case with ten unitary operations, also with water reuse, and (iii) the water distribution network operation of Cuernavaca, Mexico, considering reduction of water leaks, operation of existing treatment plants at their design capacity, and design and construction of new treatment infrastructure to treat 100% of the wastewater produced. It is shown that the proposed approach can solved highly constrained real-world multi-objective optimization problems.

Synthesis of Water Utilization System Using Concentration Interval Analysis Method (II) Discontinuous Process

The first part of the series of this article proposed a systematic method for the synthesis of continuous water-using system involving both non-mass-transfer-based and mass-transfer-based operations. This article, by extending the method, proposes a time-dependent concentration interval analysis (CIA) method to solve the problems associated with the synthesis of discontinuous or batch water-using systems involving both non-mass-transfer-based and mass-transfer-based operation. This method can effectively identify the possibility of water reuse and the amount of water reused under time constraints for minimizing the consumption of freshwater in single or repeated batch/discontinuous water-using systems. Moreover, on the basis of the heuristic method adapted from concentration interval analysis method for the continuous process network design, the network design for the discontinuous or batch process can be obtained through the designs for every time interval. Case study illustrates that the method presented in this article can simultaneously minimize the freshwater consumption in single or repeated batch/discontinuous water system and can determine a preferable storage tank capacity for some problems.

Pinch multi-agent genetic algorithm for optimizing water-using networks

A new genetic algorithm, pinch multi-agent genetic algorithm (PMAGA), is developed for optimizing water-using networks. All agents are fixed on a lattice, and they will compete or cooperate to increase their energy. On the other hand, agents can also increase their energy with knowledge. For single contaminant water-using systems, PMAGA and other algorithms as well as Lingo can find the same minimum freshwater consumption. For multiple contaminants systems, it can find the same or better results in case studies. Moreover, PMAGA is more efficient for much shorter computational time compared with other algorithms, and furthermore, it can yield many water-using networks consuming the same minimum freshwater but with different configurations, whereas Lingo yields only one network. These alternative configurations give more options for industries.

On the use of graphical method to determine the targets of single-contaminant regeneration recycling water systems

Water system integration with regeneration recycling can reduce freshwater consumption and wastewater discharge to the maximum extent. In this paper, by analyzing the limiting composite curve of a single-contaminant water system, a method is proposed to construct the optimal water supply line for regeneration recycling. Accordingly the targets for regeneration recycling water systems are obtained. The targets in sequence are the minimum freshwater consumption (the minimum wastewater discharge), the minimum regenerated water flowrate, and the optimal regeneration concentration. The post-regeneration concentration is taken to be fixed in the sequential targeting procedure. The interactions of these targets are analyzed, and formulas for calculating these targets are proposed. The results show that for a single-contaminant regeneration recycling water system, the minimum freshwater consumption is determined by the shape of the limiting composite curve below the post-regeneration concentration. The optimal regeneration concentration is defined as the minimum regeneration concentration at the minimum freshwater consumption and the corresponding minimum regenerated water flowrate. The minimum regenerated water flowrate and the optimal regeneration concentration are both related to the geometrical features of the limiting composite curve of the water-using system and to the post-regeneration concentration. The optimal regeneration concentration has no direct relationship with the pinch concentration.

Challenging Activities of the Western Tottori General Office to Undertake the New National Project for Conserving Agricultural Water-use System

Challenging Activities of the Western Tottori General Office to Undertake the New National Project for Conserving Agricultural Water-use System

Determining the Pinch Point and Calculating the Freshwater Target for Water-Using Systems with Single Contaminant

In this paper, the pinch point(s) and the freshwater target(s) are investigated for water-using networks with single contaminant. A new method is proposed to determine the pinch point(s) based on the features of the pinch point before target calculation. With the known pinch point, it is only necessary to carry out detailed calculation for the allocation of the pinch-source stream(s) to the demand stream(s) just below the pinch, in the freshwater target calculation. This reduces the calculation effort, especially for the networks with many streams. The results of this work agree with that obtained in the literature.

A conceptual decomposition of MINLP models for the design of water-using systems

The work presents a systematic methodology for the design of industrial water systems that combines principles of water-pinch (Wang and Smith, 1994a, 1994b) with mathematical programming techniques that enable the imposition of practical constraints and the generalisation of the conceptual tools into multi-contaminant problems. A superstructure model is formulated as an MINLP and solved via decomposition. Layout constraints and flowrates compatible with existing networks can be enforced. Elements of capital and operating cost, including piping are analysed. The solution strategy is based upon a penalty-based search, coupled with an iterative projection procedure. The approach is tested and illustrated on several examples.

Graphically Based Optimization of Single-Contaminant Regeneration Reuse Water Systems

In this paper, graphical method is employed to optimize single-contaminant regeneration reuse water systems. On the concentration-mass load diagram, three categories of water-using systems with regeneration reuse are analyzed in terms of the geometric features of limiting composite curve. Total regeneration and partial regeneration are identified first. Then based on sequential optimization and at a specified post-regeneration concentration, the optimal water supply lines for regeneration reuse systems can be constructed. The optimal water supply line corresponds to minimum freshwater consumption, minimum regenerated water flowrate and minimum contaminant regeneration load. Formulas for calculating these targets are summarized and interactions of these parameters are discussed. The concepts of limiting points for regeneration reuse, which are the counterpart of pinch for direct reuse, are proposed to indicate the bottlenecks of a water system with regeneration reuse. Different locations of the limiting points for different systems underlie that the optimal regeneration concentration can be greater than, equal to or smaller than the pinch concentration of the system.

The design of water-using systems in petroleum refining using a water-pinch decomposition

Water reuse and recycling offer substantial potential for savings in petroleum refining, as the water volumes processed are large. Presently, there is a lack of methods to systematically screen and analyze design alternatives using a total systems approach. Such an approach would consider effluent treatment, recycle of treated water and freshwater distribution simultaneously. The paper contributes with a systematic methodology that empowers conceptual engineering and water-pinch [R. Smith, Chemical Process Design and Integration, 2nd ed., John Wiley & Sons, 2005; Y.P. Wang, R. Smith, Wastewater minimization, Chem. Eng. Sci. 49 (7) (1994) 981–1006; Y.P. Wang, R. Smith, Design of distributed effluent treatment systems, Chem. Eng. Sci. 49 (18) (1994) 3127–3145.] with mathematical programming methods. The method focuses on petroleum refineries explaining trade-offs and savings between freshwater costs, wastewater treatment, piping costs and environmental constraints on the discharge.