Occurrence and Health Risk of Heavy Metals and Microorganisms in Wastewater Collected from selected Eateries in Lekki, Lagos, Nigeria

Abstract

The number of eateries is growing around the world because they provide jobs and food to urban people who do not have time to cook. However, there are concerns that eatery wastewater may contain hazardous compounds and microorganisms. In view of the above, this study determined the chemical characteristics, heavy metal concentrations, and microbiological loads of wastewater collected from three eateries in Lekki, Lagos, Nigeria. The human exposure to heavy metals via oral and dermal contact, as well as the hazard quotient of daily exposure to these heavy metals, was also calculated. The chemical characterization revealed that nitrate, ammonia, and phosphate levels in all of the wastewater samples were above the limits of the Federal Environmental Protection Agency, while sulphate levels were normal. Copper, lead, cadmium, nickel, and chromium levels were within the permissible levels, but zinc was above the limits in the three eateries. The average daily oral and dermal exposure to heavy metals was normal, while the hazard quotient of daily dermal exposure to zinc and chromium in the three eateries was abnormal (> 1). In all of the eateries, bacterial and fungal levels were above permitted limits, but no coliforms were found. The results imply that the wastewater from the three eateries are hazardous and could pose environmental and health hazards. It is recommended that eatery owners treat wastewater before releasing it into the environment.