Anisotropic Evaporator with a T‐Shape Design for High‐Performance Solar‐Driven Zero‐Liquid Discharge

Abstract

Solar‐driven evaporation is regarded as a sustainable wastewater treatment strategy for clean water recovery and salt condensation. However, achieving both high evaporation rate and long‐term stability remain challenging due to poor thermal management and rapid salt accumulation and blocking. Here, a T‐shape solar‐driven evaporator, composed of a surface‐carbonized longitudinal wood membrane (C‐L‐wood) is demonstrated as the top “” for solar harvesting/vapor generation/salt collection and another piece of natural L‐wood as the support “” for brine transporting and thermally insulating. The horizontally aligned micro‐channels of C‐L‐wood have a low perpendicular thermal conductivity and can effectively localize the thermal energy for rapid evaporation. Meanwhile, the brine is guided to transport from the support L‐wood (“”) to the centerline of the top evaporator and then toward the double edge (“”), during which clean water is evaporated and salt is crystallized at the edge. The T‐shape evaporator demonstrates a high evaporation rate of 2.43 kg m−2 h−1 under 1 sun irradiation, and is stable for 7 days of the outdoor operation, which simultaneously realizes clean water evaporation and salt collection (including Cu2+, CrO42−, Co2+), and achieves zero‐liquid discharge. Therefore, the T‐shape design provides an effective strategy for high performance wastewater treatment.

A self‐salt‐cleaning architecture in cold vapor generation system for hypersaline brines

“…By connecting the evaporator to an expandable polyethylene (EPE) foam, those salt crystals were moved to the foam outside the evaporator 32 . Using this type of guided water flow strategy, solar‐driven evaporation rates of 1.42 ~ 2.43 kg m −2 h −1 10,14,33 were obtained experimentally with minimum requirement in maintenance to regenerate the evaporative surface. The next question is how to enhance the evaporation rate of this type of water‐flow‐driven self‐cleaning strategy since the evaporation rate is proportional to the salt precipitation speed.…”

“…Formation of salt on the absorber hinders stable vapor generation and gradually deteriorates the solar thermal performance (e.g., 11,31,32 ). Recently, self-cleaning strategies were proposed to minimize the maintenance requirement for solar vapor generation (e.g., using prewetting, 10 wood, [33][34][35][36] and specially designed geometry structures). 9,17,24,26,[37][38][39][40][41][42] Figure 1A shows a representative architecture using a controlled water flow to guide the salt transportation within the evaporative materials (e.g., so called the edge preferential salt crystallization).…”

High‐Performance Integrated Solar Steam Generator for Synergetic Freshwater Production, Salt Harvesting, and Electricity Generation

“…Among them, the Na + concentration dropped to 7.32 mg L −1 , a decrease of about four orders of magnitude, and the Mg 2+ , Ca 2+ , and K + concentrations below 1 mg L −1 , in full compliance with the drinking water standards set by the World Health Organization (WHO) ( Figure a). [ 46 ] The rejection of all four ions exceeded 99.5%, indicating the splendid desalination effect for freshwater production (Figure 5b). Furthermore, the effluent purification capacity of solar integrated system was investigated using organic, acidic, and alkaline wastewater as feedwater to extend the availability due to the increasing environmental pollution.…”

Recent advances in structural regulation and optimization of high-performance solar-driven interfacial evaporation systems

“…14d). 276 The brine was guided by the aligned channels in the membrane plane to be transported from the support to the top surface and further to the edge of the T-shape evaporator, where it was finally crystallized and collected. The evaporation rate and salt collection rate of the T-shape evaporator maintained at 1.93 kg m −2 h −1 and 56.6 g m −2 h −1 , respectively, when evaporating 3.5 wt% NaCl solution for 60 h under one sun.…”