The Working Conditions and Optimization of a Large Rainwater Harvesting and Treatment System in an Area at a Risk of Erosion

Abstract The study evaluates the operation of rainwater harvesting and treatment systems (RHTS), receiving effluents from the wholesale market and fuel station (twenty years of observations). Changes of the basic elements of RHT systems (e.g. earthen reservoirs – sealed settler, infiltration reservoir) were characterized and the impact of climatic conditions on the system monitored. The analyses also referred to the stability and work safety of the most important equipment and water treatment efficiency. In the study period, due to the accumulation of erosive phenomena, it was necessary to optimize the system. The infiltration reservoir was considerably modified. At the same time, another reservoir of a similar type was built. The quality of water in the reservoirs were measured in 2008–2010 (before the modernisation) and in 2016–2018 (after the modernisation). Selected physical, oxygen, biogenic and salinity indicators were determined in the water. During the study the harvesting and treatment system had a positive effect on the quality of rainwater runoff – the values of many contaminants were reduced (RHTS 1: suspended solids, nitrogen, iron, potassium; RHTS 2: conductivity, suspended solids, nitrogen). Design and operational errors were noticed that in the long run may contribute to deteriorating the operational efficiency and even lead to a building collapse (intense erosive phenomena). This study clearly demonstrates that building a rainwater management system is a highly site-specific issue.