State-of-the-Art Review of Pinch Analysis Techniques for Water Network Synthesis

Comprehensive review of water management and wastewater treatment in food processing industries in the framework of water-food-environment nexus

Food processing is among the greatest water-consuming industries with a significant role in the implementation of sustainable development goals. Water-consuming industries such as food processing have become a threat to limited freshwater resources, and numerous attempts are being carried out in order to develop and apply novel approaches for water management in these industries. Studies have shown the positive impact of the new methods of process integration (e.g., water pinch, mathematical optimization, etc.) in maximizing water reuse and recycle. Applying these methods in food processing industries not only significantly supported water consumption minimization but also contributed to environmental protection by reducing wastewater generation. The methods can also increase the productivity of these industries and direct them to sustainable production. This interconnection led to a new subcategory in nexus studies known as water-food-environment nexus. The nexus assures sustainable food production with minimum freshwater consumption and minimizes the environmental destructions caused by untreated wastewater discharge. The aim of this study was to provide a thorough review of water-food-environment nexus application in food processing industries and explore the nexus from different aspects. The current study explored the process of food industries in different sectors regarding water consumption and wastewater generation, both qualitatively and quantitatively. The most recent wastewater treatment methods carried out in different food processing sectors were also reviewed. This review provided a comprehensive literature for choosing the optimum scenario of water and wastewater management in food processing industries.

A Hybrid Methodology to Minimize Freshwater Consumption during Shrimp Shell Waste Valorization Combining Multi-Contaminant Pinch Analysis and Superstructure Optimization

The conservation and proper management of natural resources constitute one of the main objectives of the 2030 Agenda for Sustainable Development designed by the Member States of the United Nations. In this work, a hybrid strategy based on process integration is proposed to minimize freshwater consumption while reusing wastewater. As a novelty, the strategy included a heuristic approach for identifying the minimum consumption of freshwater with a preliminary design of the water network, considering the concept of reuse and multiple pollutants. Then, mathematical programming techniques were applied to evaluate the possibilities of regeneration of the source streams through the inclusion of intercept units and establish the optimal design of the network. This strategy was used in the shrimp shell waste process to obtain chitosan, where a minimum freshwater consumption of 277 t/h was identified, with a reuse strategy and an optimal value of US $5.5 million for the design of the water network.

Research advances on process systems integration and process safety in China

Process systems engineering research focuses on the planning, design, operation, and safety of process systems rather than unit operations. In response to the rapid growth of the chemical process industry in the last 20 years in China, advanced system integration and process safety technologies are investigated and applied for better resource utilization, less environmental impact, and safer working places. In this regard, the review in this article consists of four main achievements: (1) process synthesis, (2) energy system integration, (3) water system integration, and (4) process safety management. The purpose of process synthesis and integration is to improve resource and energy utilization, at the same time lowering by-products and emissions. Optimization is conducted on process structure and operation, following the principles of resource coupling and energy cascade utilization. Typical examples are coupling of coal and hydrogen-rich resources and integration of coal-based polygeneration process of chemicals, electricity, and heat. Energy integration implements the coordinated optimization of total site energy systems. Reviews are made on specific methodologies based on the thermodynamics and applications of design and retrofit in ethylene, oil refining, and synthetic ammonia industries. There are energy savings by 10%–20% and yields increasing by 20%–30%. In addition, waste heat recovery and cold energy utilization are also important research areas. Reviews on the progress of water system integration and its industrial applications are also conducted. It includes the direct reuse, regeneration, and reuse/recycle in water systems and systems with internal water mains. Finally, safety management and technologies are also indispensable technological advancements of the process. The legislation system and the work safety-related standard system have been gradually established and enforced. Process safety research progress is reviewed, and questions are proposed for improving the accident prevention and safety management agenda.

Hybrid Approach for Optimisation and Analysis of Palm Oil Mill

A palm oil mill produces crude palm oil, crude palm kernel oil and other biomass from fresh fruit bunches. Although the milling process is well established in the industry, insufficient research and development reported in optimising and analysing the operations of a palm oil mill. The performance of a palm oil mill (e.g., costs, utilisation and flexibility) is affected by factors such as operating time, capacity and fruit availability. This paper presents a hybrid combined mathematical programming and graphical approach to solve and analyse a palm oil mill case study in Malaysia. The hybrid approach consists of two main steps: (1) optimising a palm oil milling process to achieve maximum economic performance via input-output optimisation model (IOM); and (2) performing a feasible operating range analysis (FORA) to study the utilisation and flexibility of the developed design. Based on the optimised results, the total equipment units needed is reduced from 39 to 26 unit, bringing down the total capital investment by US$6.86 million (from 18.42 to 11.56 million US$) with 23% increment in economic performance (US$0.82 million/y) achieved. An analysis is presented to show the changes in utilisation and flexibility of the mill against capital investment. During the peak crop season, the utilisation index increases from 0.6 to 0.95 while the flexibility index decreases from 0.4 to 0.05.

Recent Developments and Challenges in Optimization-Based Process Synthesis

This article first reviews recent developments in process synthesis and discusses some of the major challenges in the theory and practice in this area. Next, the article reviews key concepts in optimization-based conceptual design, namely superstructure representations, multilevel models, optimization methods, and modeling environments. A brief review of the synthesis of major subsystems and flowsheets is presented. Finally, the article closes with a critical assessment and future research challenges for the process synthesis area.

Using turbidity for designing water networks

Some methods to design water networks with minimum fresh water consumption are based on the selection of a key contaminant. In most of these "single contaminant methods", a maximum allowable concentration of contaminants must be established in water demands and water sources. Turbidity is not a contaminant concentration but is a property that represents the "sum" of other contaminants, with the advantage that it can be cheaper and easily measured than biological oxygen demand, chemical oxygen demand, suspended solids, dissolved solids, among others. The objective of this paper is to demonstrate that turbidity can be used directly in the design of water networks just like any other contaminant concentration. A mathematical demonstration is presented and in order to validate the mathematical results, the design of a water network for a guava fudge production process is performed. The material recovery pinch diagram and nearest neighbors algorithm were used for the design of the water network. Nevertheless, this water network could be designed using other single contaminant methodologies. The maximum error between the expected and the real turbidity values in the water network was 3.3%. These results corroborate the usefulness of turbidity in the design of water networks.