Characterizing the chemical contaminants diversity and toxic potential of untreated hospital wastewater

Abstract

This study characterizes 21 wastewater samples collected from Al-Amal hospital between the period of 12 April till 8 July 2020. Al Almal is a hospital that provides drug addiction and psychological treatment to patients. Using solid-phase extraction and liquid chromatography with tandem mass spectrometry (LC-MS/MS), chemical contaminants profiles in these wastewater samples were determined in a non-targeted manner. These chemicals were then individually analyzed in an in-silico manner by checking against databases and literature to determine if they were mutagenic. By determining the proportion of mutagenic chemicals against the non-mutagenic ones, we aim to determine if untreated hospital wastewater may potentially negatively impact the downstream municipal biological wastewater treatment process. It was determined that 64% of the identified chemicals were not tested for their mutagenic effect, and hence no prior information is available in the literature and databases. Instead, we further performed in-vitro mutagenicity tests using Ames test to determine if the wastewater sample, with all of its chemical constituents, would be mutagenic. Ames test results showed that majority of the samples were non-mutagenic except for 1 sample that imposed a mutagenic effect on Salmonella enterica serovar Typhimurium TA98 and 3 samples with mutagenic effect on TA100. In addition, 1 sample showed a toxic effect on TA100. However, in all 5 instances, these samples only imposed a mutagenic and toxic effect at high concentrations of > 10x. The findings in this study suggest that a specialty hospital like Al Amal does not contribute substantially to mutagenic wastewater streams to the municipal sewer, and hence unlikely to significantly perturb the downstream biological treatment processes. However, there may still be a need to consider ad-hoc contributions of mutagenic and/or toxic wastewater streams from the hospitals.