Assessing urban storm water and treating its pollutants through a new green technology system

Abstract

The aim of this research is to assess the quality of urban rainwater in Tripoli and the surrounding areas in North Lebanon, and then treat its pollutants through a new green technology system. Understanding urban stormwater is essential to control and manage rainwater and its impact on the water system. Urbanization results in increased runoff, increased water density, and increased pollutants in local streams and downstream water. This study is divided into two parts: The first part is to assess the quality of urban stormwater in Tripoli and the surrounding areas in North Lebanon in terms of physical, chemical and bacteriological parameters. The values of these parameters are compared with those of Lebanese drinking water and the Environmental Protection Agency standards. A field survey was carried out to study the sites for sampling rainwater, and site filtering, and then the best sites for sampling were determined. Moreover, the statistical analysis of the parameters tested using the Pearson correlation method and the GIS program was used to study the relative contribution of different types of land use to the quality of stormwater. The second part is to design an innovative system (green stormwater system) for sustainable and efficient pollution removal. This stage aims to treat the pollutants that were present in the urban stormwater and allow this water to be used as another source of drinking water and domestic water. The system is designed to remove microbes, nutrients, heavy metals, and polycyclic aromatic hydrocarbons pollutants. The results of the urban stormwater assessment showed that they contain E coli, Total Coliforms, Pseudomonas aeruginosa, BOD5, Nitrite, Potassium, Phosphate, Ammonium, Mercury Acenaphthylene, Phenanthrene, Benzo (a) Pyrene, Indeno (1,2, 3-c, d) Pyrene, in addition to turbidity. The system designed is a filtration system consisting of four different layers; Aqualen fibers, Raschig rings, zeolites, and activated carbon. E coli, Total coliforms, nitrate, nitrite, phosphate and ammonium were tested to study Aqualen fiber layer (AFL) and complete system (CS) efficiencies. The results showed that 95% E coli, 50% nitrite, 82% nitrate, 36% phosphate, 96% ammonium were removed in AFL, while 98% of E coli, 89% of total coliforms, 50% nitrite, 85% nitrate, 50% phosphate and 96% ammonium were removed in CS. The mercury compounds and polycyclic aromatic hydrocarbons detected in stormwater samples could not be tested due to the specific barriers they encountered after the global spread of Covid-19. This study is the first of its kind in Lebanon, with its treatment system design.