Siew Yoong Leong

Landfill leachate, a complex wastewater generated from municipal solid waste (MSW) landfills, presents significant environmental challenges due to its high organic content and toxic pollutants. This study proposes a sustainable solution by employing the green synthesis of copper oxide nanoparticles (CuO NPs) using durian (Durio zibethinus) husk extract, which serves as a natural reducing and stabilizing agent. This approach transforms agricultural waste into a valuable resource for environmental remediation. The synthesis was carried out under mild conditions, avoiding harmful chemicals and reducing energy consumption. The CuO NPs were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy to examine their morphology, crystallinity, purity, and optical properties. SEM and HR-TEM analyses revealed mainly spherical nanoparticles with an average size of 35–50 nm and minimal aggregation. XRD analysis confirmed the presence of a highly crystalline monoclinic phase of CuO, while the EDX spectrum showed distinct peaks corresponding to copper (72%) and oxygen (28%) by weight, confirming the high purity of the material. Preliminary tests demonstrated the photocatalytic efficiency of the CuO NPs, achieving up to a 79% reduction in chemical oxygen demand (COD) in landfill leachate. These findings underscore the potential of green-synthesized CuO NPs for environmental applications, offering an innovative, sustainable method for wastewater treatment and supporting the advancement of solid waste management practices.

Drying is one of the crucial processes in prolonging the sample lifespan and ease of storage. This research targeted at drying process optimization using response surface methodology (RSM) and analysis of changes in oil isolates from Hermetia illucens prepupae. A total of 13 sets of samples were generated by the central composite design (CCD). The physicochemical properties were characterized by moisture content, crude lipid extraction, peroxide value, iodine value, browning index, and antioxidant activity. Based on the results, the optimum value of moisture loss was 65.31 % (100 °C, 34.70 hours), crude lipid yield was 49.79 % (88.29 °C, 29.82 hours), browning index was measured to have a value of 294.70 (100 °C, 48 hours), and iodine value of 23.70 gI2/ 100g (90.89 °C, 34.82 hours). Meanwhile, the optimum value of peroxide value obtained was 8.20 mEq O2/ kg (100 °C, 48 hours), and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of 76.14 % (99.60 °C, 47.93 hours).

Black soldier fly (BSF) is a sustainable protein source that can be used as feed ingredient as it can convert organic waste into edible feedstuff. This study showed that the prepupae of Black Soldier Fly possessed the higher content of protein and fat that fulfilled the nutritional requirement as a feed. The drying method is vital to remove moisture and produces more shelf-stable feed. In this research, the purpose is to identify the most suitable drying method to produce shelf-stable feed. Vacuum drying was proven to be more suitable in producing shelf-stable feed as compared to microwave drying in accordance with its nutritional composition (fat and protein), antioxidant properties and physicochemical properties of BSF prepupae (BSFP). The experimental BSFP were fed with mixture of fruits peel and flesh, harvested and dried by microwave-oven drying (MD-BSFP) and vacuum-oven drying (VD-BSFP). Based on the experimental results, there is no significant difference in lipid content between MD-BSFP (45.03%) and VD-BSFP (39.23%). However, the crude protein of VD-BSFP (31.00%) was significantly higher than MD-BSFP (16.90%). MD-BSFP and VD-BSFP were still considered as a source of protein (10% of NRV per 100 g of solids) according to FAO standards. Besides, VD-BSFP had a better antioxidant property as it had a lower browning index as compared to MD-BSFP. The present study showed that the water activity of MD-BSFP (0.527) and VD-BSFP (0.494) was below 0.60 which could inhibit the growth of most microorganisms and extend the shelf life of feed. This study suggests that vacuum drying is better than microwave drying in producing shelf stable BSF feed because VD-BSFP was well-established with higher protein content and antioxidant properties, having lower moisture content and browning index.

Insects are gaining popularity in society, especially in light of the recent cultural emphasis on the need of sustainable consumption. Insects’ potential is rapidly developing due to the increasing demands of animal-derived protein and their ability to address environmental challenges. The Hermetia illucens larvae contain high nutritional content of protein and lipid. As such, the nutritional content of this larva is a potential food source and is suitable to be used as novel feed for animal, avian and aquaculture. During this study, the larvae were fed with soy pulp until it reaches a pre-pupae stage. The comparisons of fatty acid profiling were done by harvesting the larvae on the 10^th day, 12^th day and pre-pupae, respectively. After the larvae have been harvested, they are rinsed with distilled water to remove any impurities. Thereafter, the different stages of development of the larvae were dried in an oven at 80°C for 24 hours. Extraction of crude lipids based on different larval development times was performed with n-hexane via soxhlet method. Subsequently, after extraction, a series of lipid analysis were carried to determine the free fatty acid, acid value, iodine value, peroxide value and fatty acid composition. The analyses of lipid were done in accordance with the AOAC methods. Lipid contents of the larvae of different development time indicates that, lipid contents increase from 10^th (28.1%) to 12^th day (31.14%) before it decreases during pre-pupae stage (30.23%). The acid values attained for 10^th day old larvae, 12^th day old larvae and pre-pupae were 9.60±0.48, 89.24±2.28 and 180.28±8.80 mg KOH/g, respectively. Free fatty acid (FFA) value and acid values of lipids are closely related as the rancidity of crude oils is followed by free fatty acid formation due to the decomposing of glycerides in lipids due to the action of lipase. Based on the results, lowest iodine value observed for 10^th day old larvae (22.42±0.14 gI₂/100g) and the highest was observed in pre-pupae (55.38±5.17 gI₂/100g). A higher iodine value indicates the higher amount of double bond in the crude lipid, which depicts the tendency for the oxidation of the oil. The fatty acid profile indicated that the fatty acid was primarily lauric acid.

The growth of black soldier fly larvae (BSFL) has been widely studied by feeding with myriad organic waste materials, transforming the wastes into a high-value