Determination of the microbiological characteristics and traces of heavy metals in rainwater harvested in urbanized areas to develop their uses: Case study of downtown Souk Ahras, Algeria

Abstract

Rainwater storage tanks designed with diverse materials may host sustainable microbial systems; such systems are found in areas where a potable water source is not readily available. The variations in the water stored can also affect the levels of heavy metals and the physic-chemical parameters. The types of tanks and their composite materials can significantly influence the values of some chemical elements, especially heavy metals, essential nutrients, as well as pH, EC, and turbidity. In this study, two types of tank materials were used for the harvested rainwater systems in Souk Ahras city: concrete and plastic. Twenty-one samples were collected and analyzed for different time scales for both types of tank materials: one week, three weeks, and three months. Results of the determination of the essential nutrients as well as the concentrations of heavy metals, such as lead (Pb), copper (Cu), nickel (Ni), chromium (Cr), iron (Fe), cadmium (Cd), and arsenic (As), were present in moderate concentrations. In addition, pathogens, such as salmonella, yeast, mold spores, fecal coliforms, and streptococci, were undetected in the rainwater samples of all tanks. However, the concrete tanks showed a very interesting resistance to the growth of aerobic germs, where 99.7% of the germs were eliminated by the third week. However, the opposite behavior was recorded after this period.