Towards Flow Heterogeneous Photocatalysis as a Practical Approach to Point-of-Use Water Remediation Strategies

The United Nations and the World Health Organization provide clear guidelines to ensure water security for urban and rural populations. Common contaminants include bacteria and a variety of organic contaminants, such as medications and agricultural runoff. The rapid advancement of point-of-use water treatment is crucial to align with these international recommendations. While some problems are chronic and require long-term solutions, others are transient contamination issues that occur without warning and frequently lead to boil water advisories that can last for extended periods. In these cases, providing reliable water security requires solutions that can be deployed rapidly, are affordable, and can be implemented at the point of use with minimal operator training. Our research explores the state of the art in photocatalysis as a method for purifying water from organic contaminants and bacteria. We present a comparative analysis of various catalysts, supports, and light sources, along with our perspective on the benefits of flow systems. Practical solutions require flow techniques that are portable and can address at least the recommended survival requirements of ~7.5 L per capita per day for small communities, schools, or small hospitals. In this perspective, we propose that flow-compatible modified TiO2 catalysts can offer practical solutions implemented with either solar light or LED sources in the UVA or visible region.