# Preliminary Study on Greywater Treatment Using Nonwoven Textile Filters
## 1 Introduction  
Water is the core of life while humanity is facing increasingly severe water scarcity through population growth, climate change, etc. Water scarcity is already a fact in all continents. According to the United Nations (UN), about three billion people in parts of Asia and Africa will be faced with a water shortage in 2025 [1]. To sustainably protect water resources and to cope with water scarcity, greywater is emerging as a resource that has the potential to reduce stress for water scarcity regions. Greywater consists of sources that are discharged from the laundry, bath, and shower, and kitchen wastewater, excluding wastewater from toilets. Moreover, kitchen greywater contains a high level of nutrients and organic loadings and is often separated to improve efficiency for treatment and greywater reuse [2; 3; 4]. The characteristics of greywater not only depend upon factors such as the living standards, social and culture area of residents, and water shortage level, but also relate to traces found in many categories and production materials of soap, toothpaste, salt, shampoos, and detergents [4]. Indeed, the greywater fluctuated from 60 to 140 dm\({}^{3}\) person\({}^{-1}\) day\({}^{-1}\) in the developed countries, while in the developing countries it amounted to 20-30 dm\({}^{3}\) person\({}^{-1}\) day\({}^{-1}\)[5; 6]. Greywater contributes to more than 50% of total volume of domestic wastewater [2; 4]. However, the composition of organic matter (COD), N, P, and K in greywater is: 29-62%, 9-14%, 20-32%, and 18-22%, respectively [7]. In addition, total suspended solids present in the greywater that depend upon dirt and dust from clothes and zeolite areused in the detergents. The total suspended solids in the greywater range from 170 to 330 mg dm\({}^{-3}\) and the particle size of the solid ranges from 10 to 100 \(\upmu\)m [8; 9]. Greywater is a potential source for reuse because it is less polluted but accounts for a significant volume in household wastewater. Greywater can be treated to reuse for toilet flushing, which has decreased up to 13-41% of total freshwater consumption [10]. Moreover, greywater has a high potential for irrigation because the required quality is not higher than toilet flushing and the plant can take up some nutrients in the greywater. According to [PERSON] [11], household greywater provided enough irrigation for 20 m\({}^{2}\) during months of the dry season, with 11.5 mm day\({}^{-1}\). Greywater reuse has demonstrated efficiency in many regions that are facing water scarcity. An example in Sydney, Australia, where \(3.99\times 10^{7}\) dm\({}^{3}\) year\({}^{-1}\) has been reused by saving \(9.7\times 10^{6}\) dm\({}^{3}\) year\({}^{-1}\) when greywater reuse policy was implemented [12]. Nonwoven fabrics have found application in small wastewater treatment plants since the 1990s, mainly as bulk filters, consisting of pieces of polypropylene nonwoven and hanging or trickling filters [13]. Despite the good treatment results obtained in laboratory conditions, they are not always effective in the field [14]. Intensive wastewater recirculation (up to 700%) is often required. A significant application of nonwoven fabrics (geotextiles) consists of the separation of suspended matter, including activated sludge [15] and biological treatment accompanying wastewater runoff on the nonwoven surface, as well as the use of nonwoven fabrics in the form of biomass carrier [16]. In studies carried out by [PERSON] [17] and [PERSON] [18], nonwovens submerged in aerated reactors were used, with the flow of wastewater taking place mainly at the surface of nonwoven fabrics, not through their pores. A few studies were carried out using wastewater filtration through nonwoven fabric under aerobic or anaerobic conditions, mainly for the recognition of hydraulic properties and the process of clogging [19; 20; 21; 22].