ABSTRACT
Solar desalination provides a sustainable and eco-friendly solution for purifying wastewater, addressing environmental challenges associated with wastewater treatment. This study focuses on the purification of inorganic contaminants from laboratory chemical wastewater (ICWW) using a spherical solar still (SSS). To enhance the evaporation rate and overcome the impact of heavy metals on absorption efficiency, a carbonized balsa wood (CBW) solar evaporator was employed. Balsa wood pieces, carbonized at 250 °C for 15 min, were arranged in a SSS configuration. The CBW-integrated SSS demonstrated a remarkable freshwater productivity of 2.33 L/m2 for ICWW, surpassing the conventional SSS, which produced only 1.5 L/m2. The presence of heavy metal ions (Na+, Ca+, K+, and Mg2+) in ICWW significantly affected the evaporation rate, and the CBW solar evaporator exhibited an impressive removal efficiency of approximately 99%. Water quality parameters, including pH and chemical oxygen demand (COD), were investigated before and after treatment. The CBW-integrated SSS achieved an outstanding COD removal efficiency of about 99.77%, reducing the COD level from 229.51 to 0.521 mg/L. These results underscore the efficacy of the proposed solar desalination system in purifying ICWW, offering a promising approach to address environmental concerns associated with wastewater treatment.
ABSTRACT
Although solar desalination is a promising approach for obtaining freshwater, its practical application encounters challenges in achieving efficient photothermal evaporation. Recent research has focused on novel configurations of solar absorbers with unique structural features that can minimize heat loss. High-efficiency interfacial solar steam generation (SSG) can be achieved by optimizing the design of the absorber to harness incident heat energy on the top interfacial surface and ensuring a continuous water supply through microchannels. Artificially nanostructured absorbers might have high solar absorptivity and thermal stability. However, the manufacturing of absorbers is expensive, and the constituting materials are typically non-biodegradable. The unique structural configuration of natural plant-based solar absorbers provides a major breakthrough in SSG. Bamboo, as a natural biomass, possesses exceptional mechanical strength and excellent water transport through vertically oriented microchannels. This study aimed to enhance the performance of SSG with a carbonized bamboo-based solar absorber (CBSA). To achieve this goal, we optimized the carbonization thickness of the absorber by varying the carbonization time. Furthermore, the height of the CBSA was varied from 5 to 45 mm to determine the optimal height for effective solar evaporation. Accordingly, the highest evaporation rate of 3.09 kg m-2 h-1 was achieved for the CBSA height of 10 mm and top-layer carbonization thickness of 5 mm. The cost-effectiveness, simple fabrication, and superior desalination performance of the CBSA demonstrate a strong potential for practical applications.
