Process optimization for zero-liquid discharge desalination of shale gas flowback water under uncertainty

Abstract

Sustainable and efficient desalination is required to treat the large amounts of highsalinity flowback water from shale gas extraction. Nevertheless, uncertainty associated with well data (including water flowrates and salinities) strongly hampers the process design task. In this work, we introduce a new optimization model for the synthesis of zero-liquid discharge (ZLD) desalination systems under uncertainty. The desalination system is based on multiple-effect evaporation with mechanical vapor recompression (MEE-MVR). Our main objective is energy efficiency intensification through brine discharge reduction, while accounting for distinct water feeding scenarios. For this purpose, we consider the outflow brine salinity near to salt saturation condition as a design constraint to achieve ZLD operation. In this innovative approach, uncertain parameters are mathematically modelled as a set of correlated scenarios with known probability of occurrence. The scenarios set is described by a multivariate normal distribution generated via a sampling technique with symmetric correlation matrix. The stochastic multiscenario non-linear programming (NLP) model is implemented in GAMS, and optimized by the minimization of the expected total annualized cost. An illustrative case study is carried out to evaluate the capabilities of the proposed new approach. Cumulative probability curves are constructed to assess the financial risk related to uncertain space for different standard deviations of expected mean values. Sensitivity analysis is performed to appraise optimal system performance for distinct brine salinity conditions. This methodology represents a useful tool to support decision-makers towards the selection of more robust and reliable ZLD desalination systems for the treatment of shale gas flowback water.Keywords: Shale gas flowback water; Multiple-effect evaporation with mechanical vapor recompression (MEE-MVR); Zero-liquid discharge (ZLD); Uncertainty; Risk management; Robust design.3

Review of Hybrid Membrane Distillation Systems

“…It can increase the recovery ratio of water whilst minimizing the volume of concentrated brine [ 129 , 130 ]. As shown in Figure 4 , higher-salinity effluent can be used to generate electricity by coupling it with the pressure-retarded osmosis (PRO) process, the reverse electrodialysis (RED) process, the capacitive mixing (CAPMIX) process, or further treatment to achieve zero liquid discharge (ZLD) [ 131 , 132 ]. It can also be combined with crystallization to recover solid crystals such as sodium chloride and valuable minerals [ 133 , 134 ].…”

Zero-Liquid Discharge Desalination of Hypersaline Shale Gas Wastewater: Challenges and Future Directions

“…Emerging technologies for the ZLD desalination of shale gas wastewater comprise thermal and membrane-based processes. Thermal-based desalination alternatives include multistage flash distillation (MSF), and single/multiple-effect evaporation systems combined with mechanical/thermal vapor compression (SEE/MEE-MVC/TVC) [7]. On the other hand, membrane distillation (MD), forward osmosis (FO), reverse osmosis (RO), and electrodialysis (ED), are promising membrane-based processes.…”

Tectonic Features of the Wufeng–Longmaxi Formation in the Mugan Area, Southwestern Sichuan Basin, China, and Implications for Shale Gas Preservation

“…With the development of exploration and exploitation technology, shale gas, as a clean energy, has become a rising target of natural gas exploration [1][2][3][4]. Several sets of organic-matter-rich shale promote the Sichuan Basin as the main exploration area of shale gas in China, which deepens theoretical study of shale gas exploitation [5][6][7][8]. In particular, the Wufeng-Longmaxi Formation (WLF) organic-matter-rich shale is widely distributed in the Sichuan Basin, which is the main gas producing formation of several large shale gas fields such as Jiaoshiba, Changning, and Weiyuan (Figure 1) [9][10][11][12][13].…”