## 1 Introduction
### Background
Industries such as semiconductors, pharmaceuticals, and food and beverage production often require ultra-pure water to avoid contamination of products or processes. To achieve their quality targets, these sectors commonly use membrane technologies, UV disinfection, ion exchange, and ozonation. Disinfection in such cases not only targets pathogens but also prevents biofouling and microbial growth in sensitive equipment. In contrast, industries relying on water for cooling, boiler feed, or cleaning often focus on scaling and corrosion control rather than pathogen inactivation. Chlorination is frequently avoided in these systems because of its high reactivity, which can lead to equipment degradation and the formation of unwanted halogenated byproducts. For example, chlorine can react with organic matter or metals, forming corrosive or toxic compounds that may be detrimental to the factory equipment or products [15]. Therefore, while both municipal and industrial systems aim to improve water quality, their treatment priorities and disinfection strategies are shaped by distinct technical, economic, and regulatory considerations. Rural communities in Latin America and globally often face disproportionately high levels of contaminants due to inadequate treatment systems [16; 17; 18; 19]. Various attempts have been made to create a method for equitable, sustainable water treatment, which could withstand the specific challenges of these remote locations, often experiencing limited access to resources and workforce. Tested treatment methods relied on adapting both well-established and novel treatment technologies to the specific challenges of the remote communities. One example of such a treatment method is the Multi-Stage Filtration method (in Spanish \"Filtracion en Multiples Etapas\", FiME) developed at the Inter-regional Center for Water Supply and Removal (Centro Inter-regional de Abastecimiento y Remocion de Agua, CINARA) operating within the University of Valle, Colombia [20]. FiME systems rely on the slow sand filtration principle and are commonly implemented throughout rural Latin America, due to their robustness and ease of operation. They only require minimum maintenance, as slow sand filtration relies on the microbial action within the _schmutzdecke_--German for \"dirt layer\"--which is a shallow hypogeal biological layer formed just beneath the surface of the sand. In this type of biological filtration, sand serves as a support matrix for the microbial communities, which are the active component in the treatment process [21]. FiME systems, which would be considered a minus approach method according to [PERSON]'s classification, pose challenges related to their large size and maintenance problems. To address this, the Pan-American Center for Sanitary Engineering and Environmental Sciences (Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente, CEPIS), located in Lima, Peru, created another set of guidelines for water treatment plant design [22; 23]. Established in 1968, CEPIS was an environmental technology center established under the Pan-American Health Organization. The mission of this institution was to cooperate with the countries of the Americas in the evaluation and control of environmental risk factors that affect the health of their populations. One of the main contributions developed by the scientists and engineers affiliated with the Center was the creation of a set of designs and recommendations for resilient water treatment systems, based on the conventional coagulation/sedimentation/filtration process [24]. These solutions, known as \"CEPIS plants\", contributed significantly to the efforts made by the countries of Latin America to address their health and environmental challenges. CEPIS technology relied on the conventional water treatment process but was heavily oriented towards passive components, which rely on the flow channel geometry and a creative use of fluid dynamics instead of using mechanical components.