In this century, the shortage of clean water supply is an issue of concern and the problem is expected to become more serious in the future. Consequently, researchers are trying to find the best solution to address this problem by introducing new desalination technologies that are able to accommodate the increasing demand for clean water. One of the new technologies introduced is desalination of seawater through freeze concentration. In this study, progressive freeze concentration (PFC) was implemented to produce pure water in the form of an ice crystal block, leaving behind higher concentration seawater using a coil crystallizer. The effect of operating parameters such as initial concentration and coolant temperature were investigated. Meanwhile, the efficiency of the system was reviewed based on the value of the effective partition constant K which is defined by the ratio of solute in ice and liquid phase. A low value of K indicates when the system is most efficient. In addition, the results for the overall heat transfer coefficient are also presented to observe the heat transfer involved in the system.

Crystallization technique is one of the potential techniques to deal with wastewater treatment. In this work, progressive freeze concentration (PFC) technique was studied for its effectiveness in wastewater treatment from food industry. In PFC, pure water is produced in the form of ice crystal block and leave behind a higher concentration solution. The effect of coolant temperature and stirring speed on the effective partition constant (K) and solute recovery (Y) were investigated. Glucose solution was used as simulated wastewater sample. The best conditions were found at the moderate coolant temperature of -10°C and maximum stirring speed of 500 rpm, resulted in the lowest K value and highest Y, lead to the highest efficiency on the wastewater treatment.

This study focused on the possibility of separating refined, bleached and deodorized palm oil (RBDPO) into olein and stearin by using progressive freeze concentration (PFC) as an alternative method to replace the conventional fractionation process. PFC has the potential to be a more effective technique for olein-stearin separation, with minimal changes in the product’s quality for producing high quality edible oil. Apart from that, it requires fewer unit operations compared to conventional methods. In this research, the parameter of coolant temperature was selected to investigate the performance of PFC using stainless steel crystallizer. In order to determine the system efficiency, effective partition constant (K) was investigated, while the quality of the oil was evaluated by iodine value (IV), slip melting point (SMP) and the percentage of olein yield. From the results, all the determinant parameters were found to be optimum at the coolant temperature of 28°C. At this optimum point, K value, IV, SMP and olein yield were found to be 0.2715, 55.84 wijs, 23.10°C and 67.8537%, respectively.

Natural antioxidants are widely used in food additives, application in functional foods or also known as ingredients that offer health benefits that extend beyond their nutritional value, and pharmaceutical. These natural antioxidants such as carotenoids, vitamins, and polyphenol can be obtained from fruit, vegetables, and traditional herbal medicines. However, there have several issues regarding the conventional extraction method to extract natural antioxidants compounds from food and medicinal plants such as require a large volume of solvent and long extraction time. Therefore, new green extraction methods such as microwave-assisted, ultrasound-assisted, pulsed electric field, enzyme-assisted, supercritical fluid, and pressurised liquid, technologies were studied to overcome these constraints. Thus, different types of extraction and their mechanism in natural antioxidant compounds extraction was further discussed in this study. Besides, the main classes, source of natural antioxidants and their health benefits also were presented in this paper.

Shortages and lack of sources of clean water is a big issue nowadays. This problem happens because of the increment of population that leads to the amount of water usage increases at an alarming rate. Therefore, the sources of water must be explored in order to get a continuous supply of clean water. This paper recommends a new approach to get clean water, which is by purifying the stormwater via progressive freeze concentration (PFC). This method produces a single ice crystal block that contains high purity of water. This paper focuses on the optimization of two operating parameters, which are coolant temperature and operating time. In order to determine the effectiveness of this technology, effective partition constant (K) and concentration efficiency (Eff) were examined. Response surface methodology and central composite design were implemented to find the optimum operating conditions via Statistica software. The best responses for K and Eff obtained were 0.189 and 81.0%, respectively, with the optimum condition at coolant temperature of −8.9 C and operating time at 41.1 min. From the findings, it is proved that PFC has the capability to reduce the concentration of unwanted solute in stormwater and this process has a high potential to be an alternative approach to purify the stormwater. K E Y W O R D Scrystallization, progressive freeze concentration, optimization, stormwater, water treatment