# Application of Ultrafiltration for Recovery of Bioactive Phenolic Compounds from Rose Wastewater
## 1 Introduction  
The food industry generates vast amounts of byproducts from the processing of fruits, vegetables, beer, wine, and essential oil crops and are often treated as environmental pollutants, despite their potential [1]. Current practices, including the landfilling or incineration of these waste products, contribute to greenhouse gas emissions and waste mismanagement, highlighting the need for innovative approaches to minimize their environmental impact [2]. Recycling wastewater has become essential, creating an urgent demand for the development of more efficient and cost-effective wastewater treatment techniques [3]. Circular economy approaches promote the valorization of these byproducts, extracting bioactive molecules such as phenolic compounds, fibers, and lipids for use in various industries [4]. Such advancements not only reduce waste but also create new revenue streams, aligning with global sustainability goals for waste reduction and resource efficiency [5]. The pursuit of bioactive compounds from plant-based materials has grown significantly due to their diverse application in the food, pharmaceutical, and cosme industries [6]. Plants, especially their by-products, offer a storage of secondary metaboliteslike polyphenols, which are known for their antioxidant, antimicrobial, and therapeutic properties [7; 8]. Among these, polyphenols are particularly valued for their ability to neutralize free radicals and support human health by reducing the risk of diseases, such as cardiovascular ailments, cancer, and diabetes [9; 10]. One of the symbols of the Republic of Bulgaria, alongside yogurt, is rose oil. Cultivated _Rosa damascena_ Mill. is grown in the Rose Valley due to favorable climate conditions [11; 12]. Hydro distillation and steam distillation are among the oldest and most commonly used methods for extracting essential oils, including rose oil [13; 14]. The process of rose oil distillation generates a significant amount of waste byproducts, which often remain unused, and pose serious environmental challenges [10]. Aromatic products derived from Bulgarian rose blossoms, such as concrete, absolute essential oil, and rose water, find widespread application in fine perfumery, cosmetics, and medicine [11]. The sustainable utilization of byproducts from the essential oil industry, in particular those derived from _Rosa damascena_ Mill., has become a key focus of research due to their significant environmental and economic implications [8]. The processing of _Rosa damascena_ Mill. generates substantial byproducts rich in flavonoids and tannins, which have potential applications as natural additives in the food industry. The byproducts from rose oil distillation are rose petals and rose wastewater [10; 15]. They are an abundant resource of polyphenols, flavonoids, and antioxidants, making them highly suitable for different applications [16]. Recent research on extraction techniques, including microwave-assisted extraction [17], enzyme-assisted extraction [18], and membrane-based methods [19], have enabled the efficient recovery of these compounds. These technologies not only enhance the yield and purity of polyphenols but also contribute to sustainable waste management practices, transforming byproducts into valuable resources [8]. Furthermore, innovative uses of these extracts include their incorporation into functional food and natural preservatives, addressing growing consumer demands for sustainable and health-promoting solutions [16]. Ultrafiltration is a sustainable technology widely used in the recovery and concentration of valuable compounds, including bioactive molecules, from food and beverage industry byproducts [20]. This process has proven effective at separating and concentrating valuable bioactive compounds while simultaneously reducing the environmental impact of industrial effluents [21]. Its advantages include low energy consumption, gentle processing, and the ability to operate without the need for chemical additives [22].