Biofilm development in water distribution and drainage systems: dynamics and implications for hydraulic efficiency

Pipeline distribution systems account for the vast majority of the physical infrastructure in the water and wastewater industry. Their effective management represents the primary challenge to the industry, from both an operational and public health standpoint. Biofouling is ubiquitous within these systems, and it can significantly impede their efficiency, through increase in boundary shear and associated flow resistance caused by characteristic change in surface dynamics. Nonetheless, conventional pipeline design practices fail to take into account such effects, partly because research findings that could contribute to upgrade and optimize design practices appear scattered in the literature, and are often offering conflicting views as to its causes. This makes it difficult for the adoption of adequate predictive and preventative measures. The aim of this review is to update and contribute to a better understanding of the development and impact of biofilms and biofouling within water management pipelines, particularly within the academia and the general engineering community. The review has confirmed that the potential impact of biofouling on pipeline performance can be significant and that current design approaches are outdated for biofouled surfaces. Further research on this topic is therefore, essential, to ensure that both current and future systems are as effective as possible, both environmentally and financially. In particular, more advanced mathematical modelling frameworks which include the dynamic and case-specific nature of biofouling should be developed. Such a framework could give rise to a real-time monitoring platform to assist the adoption of more cost-effective approaches to maintain and repair the system.