# Enhancement of a Spent Irrigation Water Recycling Process: A Case Study in a Food Business
## 1 Introduction  
Water is a key resource in the food sector, being paramount for crops, livestock, and cleaning processes. In fact, both water and food, along with energy, form the water-energy-food security nexus, meaning that these three areas usually have an effect on each other [1, 2]. Depletion of groundwater is often unsustainable at both regional and global scales [3]. Approximately 70% of freshwater is currently used for crop irrigation [4]. Water use may be considerably minimized by water reuse [5, 6]. However, improperly treated wastewater can contain high levels of foodborne pathogens. Particularly, spent irrigation water can potentially hold high microbial counts [7]. Therefore, advanced treatment processes are essential to eliminate any potential risks of reusing water [8]. Water-quality properties to consider include colour, dissolved oxygen, electrical conductivity, hardness, pH, suspended solids, and turbidity [9]. There are several techniques to clean water. Filtration is a process where contaminants are removed from the water, reducing the volume of suspended solids and the turbidity of the water. Similarly, the concentration of microbes such as pathogens, viruses, and bacteria must also be reduced to a level that meets relevant legislative guidelines. One form of a solids-removal system often used in water filtration is micro-screen drum filters. Water is filtered by gravity as it passes through drum screens, resultingin a high level of solids removal, whilst maintaining continuous filtration. An optimal micro-screen drum filter should be selected based on the particle-size distribution of the suspended solids in the water and the required water quality [10]. However, there is a limitation to the size of the filtration media that can be adopted due to the gravity feed nature of drum filtration. Another process available to facilitate water filtration is the use of membranes. Membranes are barriers that allow for the selective permeation of different chemical species [11]. For the purpose of water reuse, membranes enable the separation of suspended and dissolved pollutants from water [12]. Membrane-separation processes have received increasing attention as advanced treatment alternatives for wastewater [13]. In 1957, the United States Public Health Service and the American Water Works Association used membranes for coliform bacteria recovery, resulting in the first major application of membrane technology in water treatment [14]. This led to the development and evolution of membrane separation processes that can remove materials of different sizes, such as microfiltration (MF), ultrafiltration (UF), and reverse osmosis (RO) [15]. These processes can be applied across a range of applications in various industries, including sea-water desalination, medical and pharmaceutical processes, food operations, and industrial water reclamation. Thanks to the broad range of treatment options, different water quality levels can be achieved depending on the intended use of the reclaimed water. Membrane separation processes are widely used methods within crop irrigation systems. The basic properties of membranes make them ideal for industrial applications, as they are simple in both concept and operation and operate in mild conditions [11; 16]. They are also low in energy consumption and cheap. In addition, MF and UF are efficient methods for the final clean-up of secondary effluents [11], and combined MF/RO systems can significantly reduce levels of viable bacteria passing to the RO units [17]. RO is a pressure-driven membrane process based on the preferential transport of water through a dense separation layer of a membrane [18]. The RO process is dissimilar to regular filtration because it is not based on filter size. [PERSON] (2001) suggested that in RO, unlike in filtration, it is not membrane pore size nor dissolved particle size that determine the success of the separation process [19].