Modeling of residual chlorine in a drinking water network in times of pandemic of the SARS-CoV-2 (COVID-19)

Abstract

Due to the outbreak of the novel coronavirus disease there is a need for public water supply of the highest quality. Adequate levels of chlorine allow immediate elimination of harmful bacteria and viruses and provide a protective residual throughout the drinking water distribution network (DWDN). Therefore, a residual chlorine decay model was developed to predict chlorine levels in a real drinking water distribution network. The model allowed determining human exposure to drinking water with a deficit of residual chlorine, considering that it is currently necessary for the population to have clean water to combat coronavirus Covid 19. The chlorine bulk decay rates (kb) and the reaction constant of chlorine with the pipe wall (kw) were experimentally determined. Average kb and kw values of 3.7 d− 1 and 0.066 m d− 1 were obtained, respectively. The values of kb and kw were used in EPANET to simulate the chlorine concentrations in a DWDN. The residual chlorine concentrations simulated by the properly calibrated and validated model were notably close to the actual concentrations measured at different points of the DWDN. The results showed that maintaining a chlorine concentration of 0.87 mg L− 1 in the distribution tank, the residual chlorine values in the nodes complied with the Ecuadorian standard (0.3 mg L− 1); meanwhile, about 45% of the nodes did not comply with what is recommended by the WHO as a mechanism to combat the current pandemic (0.5 mg L− 1). This study demonstrated that residual chlorine modeling is a valuable tool for monitoring water quality in the distribution network, allowing to control residual chlorine levels in this pandemic season.

Decay process of free residual chlorine concentration affected by travel time in water distribution systems

“…Appropriate knowledge of the behaviour of FRC concentration as it travels through water distribution systems assists in meeting the minimum and maximum residual disinfectant levels allowed by regulations and also ensures the quality of the water reaching the population. According to the World Health Organization (WHO), water contamination can occur by viruses classified as moderately and highly harmful to health: Hepatitis A and E, rotavirus and more recently the coronavirus (García-Ávila et al, 2021). Thus, public water systems are required to monitor the behaviour and the disinfectant concentration to maintain acceptable levels in more distant areas and to meet the minimum residual chlorine concentration throughout the day, ranging from 0.10 mg L -1 to 0.20 mg L -1 (Ozdemir and Buyruk, 2018;Ababu et al, 2019).…”

“…According to Rossman (2000), the water quality simulation model allows monitoring the growth or decay of a substance due to reactions as it moves along the water distribution network. Chlorine decay models are useful for managers of drinking water supply systems to predict the residual chlorine concentration across the network under various hydraulic conditions (García-Ávila et al, 2021). The degradation of the FRC can be modeled by some known computer software that simulates the hydraulic behavior and water quality in distribution networks.…”

Investigation and disinfection of bacteria and fungi in sports fitness center

“…This type of climate is highly conducive to the breeding and spreading of bioaerosols (Tsai and Liu 2009). Moreover, recent spread of COVID-19 worldwide shows that drinking water disinfection (Garcia-Avila et al 2021) and indoor air purification are extremely important and necessary.…”

Impact of COVID-19 on monthly water consumption on a tropical tourism island: case study of Phuket (Thailand)

“…WHO recommended that the residual concentration of free chlorine should be !0.5 mg/l after at least 30 min of contact time at pH , 8.0 for effective centralized disinfection. García-Ávila et al (2021) developed a drinking water distribution network model for a part of Azogues City, Ecuador, using EPANET software (Rossman 2000) and found that about 45% of the model nodes did not comply with the WHO recommendation. Thus, it is important to assess and optimize the quantity of chlorine in water distribution networks, e.g., Javadinejad et al (2019), Lipiwattanakarn et al (2021).…”