Optimization models for shale gas water management

There are four key aspects for water use in hydraulic fracturing, including source water acquisition, wastewater production, reuse and recycle, and subsequent transportation, storage, and disposal. Water use life cycle is optimized for wellpads through a discrete‐time two‐stage stochastic mixed‐integer linear programming model under uncertain availability of water. The objective is to minimize expected transportation, treatment, storage, and disposal cost while accounting for the revenue from gas production. Assuming freshwater sources, river withdrawal data, location of wellpads, and treatment facilities are given, the goal is to determine an optimal fracturing schedule in coordination with water transportation, and its treatment and reuse. The proposed models consider a long‐time horizon and multiple scenarios from historical data. Two examples representative of the Marcellus Shale play are presented to illustrate the effectiveness of the formulation, and to identify optimization opportunities that can improve both the environmental impact and economical use of water. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3490–3501, 2014     

Removal of heavy metals from wastewater by membrane processes: a comparative study

Wastewater containing copper and cadmium can be produced by several industries. The application of both reverse osmosis (RO) and nanofiltration (NF) technologies for the treatment of wastewater containing copper and cadmium ions to reduce fresh water consumption and environmental degradation was investigated. Synthetic wastewater samples containing Cu²⁺ and Cd²⁺ ions at various concentrations were prepared and subjected to treatment by RO and NF in the laboratory. The results showed that high removal efficiency of the heavy metals could be achieved by RO process (98% and 99% for copper and cadmium, respectively). NF, however, was capable of removing more than 90% of the copper ions existing in the feed water. The effectiveness of RO and NF membranes in treating wastewater containing more than one heavy metal was also investigated. The results showed that the RO membrane was capable of treating wastewater with an initial concentration of 500 ppm and reducing the ion concentration to about 3 ppm (99.4% removal), while the average removal efficiency of NF was 97%. The low level of the heavy metals concentration in the permeate implies that water with good quality could be reclaimed for further reuse.     

Closing Water‐Related Loops in High‐tech Polymer Production – Status,Perspectives and Limitations

Chemical production is inherently associated with the use of a significant amount of water. The closure of water‐related loops to recover materials and reuse water has been established in chemical parks for a long time. Circuits can be realized process‐integrated, across legal entities, or even cross‐sectoral. Incentives can be the lack of natural water resources, to use a high water quality or the recovery of valuables. One example is the recovery of NaCl from salt‐containing process water streams to produce chlorine and caustic soda in the chlor‐alkali electrolysis. However, such reuse schemes exhibit technical, economic and ecological challenges. Taking these into account, industry is taking action to research and develop new, environmentally friendly and economically viable processes.     

New quality criteria in wastewater reuse : The case of Gran Canaria

Wastewater reuse plays a key role in this vital cycle of water because it is able to reduce the wastewater spilled. Simultaneously, the supply of water for specific uses is increased. A new regulation (Royal Decree 1620/2007) came into force in Spain in December 2007 and regulates the basic conditions for the wastewater reuse and establishes the required criteria of quality to waters according to use.In the present paper, different kinds of tertiary treatments in reuse of wastewater are described. We focused on the applied tertiary treatments in most wastewater treatment plants of Gran Canaria Island. Particularly, we analysed Hoya del Pozo wastewater treatment plant due to its wide number of technologies and processes.Finally, we reviewed the quality criteria used in the regenerated waters, in agreement with the new regulations.     

Ozone in the United States of America -- State-Of-The-Art

Applications for ozone in the United States have evolved through a lengthy maturation process, which began with drinking water treatment (taste/odor/color removal) in the early 1900s, and grew slowly until acceleration began in the mid-1980s. Although deodorization became a stable market in the 1960s-1970s, these applications were small, for the most part. One of the largest uses for ozone is oxidation of process chemicals in the chemical industry, which began in the USA about the 1940s, and subsequently has spread worldwide. Today, thanks primarily to environmental regulatory pressures which began to impact ozone in the mid-1980s, ozone now is used increasingly in the USA for drinking water treatment and for some municipal and industrial wastewater applications. The U.S. Environmental Protection Agency (EPA) has recognized the growing importance of ozone (> 200 drinking water plants use ozone today), and has appointed IOA representatives to two of its regulatory development committees as stakeholders. Several U.S. cities have installed or are installing wastewater treatment processes for potable reuse purposes, which include the use of ozone. Three full-scale U.S. pulp bleaching plants use tons/day quantities of ozone. Smaller applications for ozone include water treatment for cooling tower waters (biofouling control), swimming pools and spas, marine aquaria, bottled water disinfection and maintenance of high purity waters in the pharmaceuticals and electronics industries. A new application for ozone is in commercial laundries to reduce energy costs and replace chemicals. In mid-1997, a public declaration was made by an expert panel that ozone is Generally Recognized As Safe (GRAS) for contact with foods. This declaration opens the door for ozone to be used in U.S. food processing industries. U.S. research scientists and engineers are at the forefront in studies which define the technical aspects of ozone technologies in a variety of applications employing advanced oxidation, including the treatment of hazardous wastes, groundwater remediation, and process water recovery and reuse in the semi-conductor industry.     

Economic optimization of the water reuse network in batch process industries

Water reuse has proved to be an efficient way to reduce freshwater demand and wastewater generation in process industries. In this paper, a methodology for minimizing the costs associated to water management in batch process industries is presented. This work is based on a previous methodology for freshwater demand minimization, which has been extended to the economical aspects of water management: cost associated to freshwater supply and conditioning, wastewater treatment and disposal, as well as water reuse network investment and operation costs. Water reuse network design is optimized from the economical point of view, minimizing the operation and investment costs associated to the water use.     

Technical efficiency and cost analysis in wastewater treatment processes: A DEA approach

In light of the growing importance of water reuse as an alternative source of water resources in many regional areas, the objective of this paper is to analyse the efficiency of wastewater treatment plants as a basic requisite to improve the potential of the water reuse. The analytical benchmarking methodology Data Envelopment Analysis (DEA) is used to calculate efficiency measurements. An efficiency index is obtained for each plant by means of mathematical programming techniques, aiming to minimise the inputs used in the water treatment process. This indicator is used as a reference to analyse plants' activity through a series of variables including the size of the plant or its cost structure. Given the importance of wastewater treatment in the Valencia Region (Spain), empirical research has been carried out for 338 plants located in this area. We verify the fact that the largest plants run more efficiently than smaller plants, as was to be expected. At the same time, there is evidence that a series of representative variables in the treatment process are clearly linked to efficiency. Maintenance and waste management costs are the most important factors to explain the differences between plants in terms of efficiency. Finally, the benchmarking methodology (Data Envelopment Analysis) is confirmed as a very useful management tool for the study of wastewater sector.     

Integrated water resource management through water reuse network design for clean production technology: State of the art

This article considers new and existing technologies for water reuse networks for water and wastewater minimization. For the systematic design of water reuse networks, the theory of the water pinch methodology and the mathematical optimization are described, which are proved to be effective in identifying water reuse opportunities. As alternative solutions, evolutionary solutions and stochastic design approaches to water system design are also illustrated. And the project work flow and an example in a real plant are examined. Finally, as development is in the forefront in process industries, this paper will also explore some research challenges encountered in this field such as simultaneous water and energy minimization, energy-pinch design, and eco-industrial parks (EIP).     

Optimal reuse of flowback wastewater in hydraulic fracturing including seasonal and environmental constraints

This article presents a mathematical programing formulation for the optimal management of flowback water in shale gas wells. The formulation accounts for the time‐based generation of the flowback water, the options for treatment, storage, reuse, and disposal. The economic and environmental objectives are considered. The economic objective function is aimed at determining the minimum cost for the fresh water, treatment, storage, disposals, and transportation. The environmental objectives account for the fresh water usage and wastewater discharge. To carry out the water integration, a reuse network including treatment is proposed. Additionally, the model considers seasonal fluctuations in the fresh water availability. A given scheduling for the completion phases of the wells is required to implement the methodology. Finally, an example problem is presented to show the applicability of the proposed methodology. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1634–1645, 2016     

Multilevel strategies for the retrofit of large‐scale industrial water system: A brewery case study

This article presents an approach to designing a large‐scale water system, which integrates water‐using operations and wastewater treatment units in different production sections within the same network. This approach uses a mixed‐integer nonlinear programming (MINLP) model for water reuse and regeneration reuse in batch and semicontinuous processes. The application of this mathematical formulation to large‐scale industrial problems with changing daily production schedule leads to huge and complex mathematical models. Two alternative multilevel strategies are proposed to solve such problems by means of temporal decomposition. The approach is illustrated with a brewery case study that integrates water consumers in two production sections. The results obtained show that, despite the high piping cost, integration of both sections yields better result than the separate water network design in each section. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Process development of treatment plants for dyeing wastewater

A three‐step methodology that integrates experiments, modeling and synthesis has been developed for the systematic development of a plant for treating dyeing wastewater for discharge and/or reuse. First, wastewater characteristics, discharge water standards, and reuse water quality specifications, etc. are collected as input information. Heuristics developed in our industrial practice and gleaned from the literature are used to guide the designer to come up with preliminary flow sheet alternatives. Then, bench‐scale experiments and pilot plant tests for the relevant unit operations are performed. A computer code accepts the bench‐scale and pilot plant experimental data for regression of model parameters and determines the superior process configuration and equipment operating conditions through sensitivity analysis. The workflow among various stakeholders to reach the final design is presented. Possible extension of the methodology to other industrial wastewater treatment plants is discussed. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Optimisation of petroleum refinery water network systems retrofit incorporating reuse,regeneration and recycle strategies

Scarcities in freshwater supply and increasingly stringent rules on wastewater discharges have emerged as major environmental concerns for petroleum refineries. Hence, this work attempts to develop an optimisation framework for refinery water network systems design and retrofit that integrates the complementary advantageous features of water pinch analysis (WPA). The framework explicitly incorporates water minimisation strategies by first postulating a superstructure representation that embeds all feasible flowsheet alternatives for implementing water reuse, regeneration and recycle (W3R) opportunities. Subsequently, a nonlinear programming (NLP) model is formulated based on the superstructure and computational experiments on a real‐world case study are conducted using the GAMS/CONOPT3 modelling language platform. Post‐optimality analysis on the numerical results are performed to achieve the desired water reuse quality, hence presenting a viable framework to aid decision‐making in water network systems synthesis. © 2011 Canadian Society for Chemical Engineering     

Desalination of reclaimed wastewater to prevent salinization of soils and groundwater

The complete utilization of Israel's water potential (safe yield) (1800 Mm³/y) was combined with wide and intensive reuse of most wastewaters (300 Mm³/y), reduced to minimum water outflows to the sea. Irrigation is a “consumptive” type ofwateruse-most ofthe waterbeing “lost” by evapo-transpiration, leavingthe mineral salinity in the soil solution and in the excess (residual) water seeping, penetrating to underlying unsaturated layers on its way to groundwater. Thus, the complete use and reuse of water bring about a high rate of salt accumulation in soils, in the unsaturated zones, and eventually in groundwater. This poses a serious risk of salinization of the country's lands and aquifers. Effects of salinization of soil and water are felt on a time-scale of tens of years. In several regions in Israel, salinization of the soil has already been encountered, and there is a permanent increase in water salinity at the coastal aquifer. Reports of many studies indicate a significant salinity increase in the unsaturated zones and at upper interface layers of the groundwater table. Also, accumulation (fixation) of specific heavy metals can be seen in soils irrigated with reclaimed wastewater. Though negative effects of heavy metals have not been felt up to now, the rate of accumulation predicts such effects in 10 to 30 years of continuing practices of such irrigation. The accumulation of salinity in general, combined with the accumulation of specific elements, can be defined as a chemo-desertifrcation process. Partial desalination (using membrane processes) of reclaimed wastewater is needed to reduce the salinity load, to “purge salt” from the country, and to prevent salinization of land and water to enable sustainable reuse.     

Ozone Treatment of Defrost Water for In-Plant Reuse

Many fruit and vegetable processing operations are examining technologies to reduce effluent volume and encourage water recovery and reuse. Implementing technologies and programs to promote in-plant reuse and recycling of discharge water is cost-effective and may improve processing efficiency. The efficacy of ozonation of defrost water has been investigated to determine the appropriate treatment level for in-plant reuse at a fruit processing plant in Clovis, California. Treatments of 0.5 ppm and 1.0 ppm of aqueous ozone achieved water quality acceptable for in-plant reuse, while an ozone treatment of 1.0 ppm was needed to significantly (P < 0.05) reduced the microbial load of flume wash effluent.     

Phosphorus recovery from centralised municipal water recycling plants

Depletion of world phosphorus reserves is driving research into options to recover and recycle this essential, non-renewable resource. Phosphate (PO₄³⁻) recovery at centralised wastewater treatment plants can be achieved through biosolids reuse or sidestream precipitation though the PO₄³⁻ levels are low compared with decentralised systems based on source separation. However, the recent growth in membrane based water recycling projects, where reverse osmosis is used to produce high quality water has resulted in the production of liquid waste streams with elevated concentrations of PO₄³⁻. Four recycling scenarios using different membrane processes and anaerobic treatment were compared and the potential PO₄³⁻ recovery via struvite (magnesium ammonium phosphate) from membrane concentrate examined. By incorporating an anaerobic reactor in the process we have been able to investigate the possibility of cogeneration of electricity from methane. Modelling of struvite recovery from membrane concentrate with co-generation indicates a net power requirement of 260 kWh/kg P recovered compared with 510 kWh/kg P for a system without cogeneration at a water consumption level of 250 L/p/d. When water consumption is limited to 80 L/p/d, this scenario compares favourably with literature values for recovery from source separated urine which range from 18 to 43 kWh/kg P.     

Reclamation of wastewater effluent from a chemical fiber plant

An electrochemical method in conjunction with chemical coagulation and ion-exchange treatments is employed to treat the wastewater effluent from a large chemical fiber plant. The effectiveness of the combined methods in treating the wastewater effluent was assessed in terms of water quality for reuse in the manufacturing process. Experiments were conducted to examine the effects of various operating variables of the electro-chemical method, chemical coagulation and ion exchange on the water quality and the optimum operating ranges of those variables were identified. The quality of wastewater effluent after the combined treatments was found to be excellent, better than the reuse standards for the chemical fiber industry.     

基于粒子群优化算法的水分配网络系统综合的最优化研究

The problem of optimal synthesis of an integrated water system is addressed in this study, where water using processes and water treatment operations are combined into a single network such that the total cost of fresh water and wastewater treatment is globally minimized. A superstructure that incorporates all feasible design alterna- tives for wastewater treatment, reuse and recycle, is synthesized with a non-linear programming model. An evolutionary approach--an improved particle swarm optimization is proposed for optimizing such systems. Two simple examples are .Presented.to illustrate the global op.timization of inte.grated water networks using the proposed algorithm.     

Survey of MBR market: Trends and perspectives in China

Membrane bioreactor (MBR) has gained considerable attention for wastewater treatment and reuse in China in the last two decades. Comparing with the global MBR market, which has an average annual growth rate of 10.9%, the average annual growth rate in China is nearly 100% in recent years. In the past 10 years, publications on MBR researches and applications for wastewater treatment have increased sharply. Over three hundred MBR plants have been successfully applied into practice for different wastewater treatments, such as municipal wastewater, bathing wastewater, restaurant wastewater, landfill leachate, hospital wastewater, petrochemical wastewater and high-concentration industrial wastewater. These plants have capacities ranging from 10 to 100,000 m³/d, among which over 12 MBR plants have capacities exceeding 10,000 m³/d. The largest MBR plant, i.e. Beijing Kunyu River WWPT, which has a capacity of 100,000 m³/d for municipal wastewater treatment and reuse, was constructed in Beijing by Origin Water Technology Co., Ltd. The largest MBR plant for industrial wastewater treatment was located in Tianjin and installed by Motimo Membrane Inc., which has a capacity of 30,000 m³/d. The largest MBR application for industrial sectors was petrochemical wastewater treatment, and over ten MBR plants each exceed a capacity of 5000 m³/d. In South-east China, the constructed MBRs are mostly involved in the high-strength industrial wastewater treatment while in North China MBRs mainly focused on municipal wastewater treatment and reuse.For an MBR commercial application in China, MBR plants were constructed by a lot of home-grown companies such as Tianjin Motimo Membrane Technology Co., Ltd., Beijing Origin Water Technology Co., Ltd. and Omexell Environmental Engineering Co., Ltd. and overseas-funded companies like Zenon-GE and CNC-Simens. Origin Water occupies the majority of the MBR market in China, whereas CNC-Simens and Zenon-GE have a larger number of installations in other parts of China. MBR unit key suppliers in China are Zenon (Canada), Mitsubishi-Rayon (Japan), Toray (Japan), Kubota (Japan), Norit (Netherlands), Motimo (China) etc.Due to more stringent regulations and wastewater reuse strategies, it is expected that a significant increase in MBR plant capacity and a widening of application areas will occur in the future.     

Disinfection of recycled red‐meat‐processing wastewater by ozone

Ozonation of a real red‐meat‐processing wastewater was conducted in a semi‐batch reactor to explore the possibility of the water reuse. The experimental results revealed that ozone was very effective in disinfection of the red‐meat‐processing wastewater. After 8 min of ozonation with an applied ozone dose of 23.09 mg min^?1 liter^?1 of wastewater, 99% of aerobic bacteria, total coliforms and Escherichia coli were inactivated. Empirical models were developed to predict the microbial inactivation efficacy of ozone from the CT values for the real red‐meat‐processing wastewater. A correlation was also derived to estimate the CT values from the applied ozone dose and the ozone contact time. The results also revealed that under the ozonation condition for 99% inactivation of aerobic bacteria, total coliforms and E coli, the decrease in the chemical oxygen demand and the 5‐day biological oxygen demand of the wastewater were 10.7% and 23.6%, respectively. However, ozonation under this condition neither improved the light transmission nor reduced the total suspended solids (TSS) despite of the decolorization of the wastewater after ozonation. Copyright © 2005 Society of Chemical Industry     

Ozone Treatment of Secondary Effluent at U.S. Municipal Wastewater Treatment Plants

Ozone is a strong oxidant used to treat a variety of constituents in potable water, wastewater, water reuse, and industrial water treatment applications. Ozone is effective at oxidizing a wide range of organic and inorganic compounds and disinfection. Well-known in potable water treatment, with about 400 US installations and 3,000 world-wide, ozone has limited application at wastewater treatments, with less than 10 operating facilities in the US. The ability of ozone to significantly reduce low level concentrations of trace organic compounds, including endocrine disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs), and other emerging contaminants have increased interest in applying ozone in potable water and wastewater treatment. Treating at the point source discharge rather than the water supply intake may be more effective. A recent American Water Works Research Foundation (AwwaRF) report indicated high removals of many EDCs and PPCPs at typical disinfection doses. Several wastewater utilities have installed or are in the process of installing ozone to treat secondary effluent. These utilities are using ozone in a variety of ways: as a primary disinfectant, for treatment of microconstituents, and in combination with other processes (e.g. membranes and UV) to produce high-quality water for indirect potable reuse (IPR). The different applications, treatment goals and basis of process selection are compared and contrasted. Secondary benefits of ozone treatment of secondary effluent, including the use of off-gas in biological treatment is also discussed.