Effectiveness of Modified Pumice Stone in the Treatment of Waste Water from Tertiary Hospital

Abstract

Adekunle Adesuyi Ademuwagun, Suraju Adekunle Lateef, Michaela Udioh and Feyisayo Elizabeth Akinjoko

Pharmaceutical contaminants in hospital wastewater, such as paracetamol, aspirin, and ibuprofen, present substantial health and ecological risks, hence the need to be removed efficiently. Conventional wastewater treatment methods are expensive to operate, particularly in developing countries, and not designed to remove pharmaceutical contaminants. A low-cost alternative such as modified pumice stone filtration system is required for treatment of wastewater from hospital sources in developing countries. This study evaluated the effectiveness of modified pumice stone in treating wastewater from hospital sources.

A laboratory-based experimental design was employed, utilizing three continuous filtration system tanks (15 cm × 15 cm × 15 cm). These tanks were filled with coarse sand and granite (CSG), CSG with unmodified pumice stone (CSG/ unmodified PS), and CSG with modified pumice stone (CSG/modified PS). The pumice stones were cleansed, pulverized, sieved, and subjected to physical and chemical modifications to enhance their adsorption capabilities. Wastewater was collected from a tertiary hospital and applied by gravity at a hydraulic loading rate of 0.01 m for 8 days, with a hydraulic retention time of 5 hours. Pharmaceutical concentrations of paracetamol, ibuprofen, and aspirin in the influent and effluent were determined using High-performance Liquid Chromatography (HPLC), and physicochemical parameters were measured using American Public Health Association (APHA) standard methods. Effluent characteristics were then compared to National Environmental Standards and Regulations Enforcement Agency (NESREA) standards for hospital wastewater.

The initial concentrations of paracetamol, aspirin, and ibuprofen in the wastewater were 162.2, 49.7, and 145.2 μg/L, respectively. After four days of treatment, paracetamol concentrations decreased to 106.2, 92.8, and 85.0 μg/L in CSG, CSG/unmodified PS, and CSG/modified PS setups, respectively. Aspirin levels dropped to 32.6, 24.1, and 22.3 μg/L, while ibuprofen concentrations reduced to 96.5, 79.9, and 72.7 μg/L across the same setups. Initial Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Turbidity, Total Nitrogen (TN), and Total Phosphorus (TP) levels in the wastewater were 364.2 mg/L, 428.1 mg/L, 388.1 mg/L, 174.6 NTU, 38.7 mg/L, and 8.7 mg/L, respectively. The COD, BOD, and TSS levels decreased by 40-50%, while TN and TP levels reduced by 35- 45% after treatment. The BOD in the effluent treated with CSG/modified PS was 18.6 mg/L on the eighth day, which was appreciably lower than the 92.1 mg/L in the CSG setup. The COD level also substantially decreased, with the CSG modified PS setup achieving 33.5 mg/L, below the NESREA standard of 80 mg/L. This study demonstrates that modified pumice stone significantly reduces pharmaceutical contaminants and physicochemical parameters in hospital wastewater, making it a cost-effective and efficient option for enhancing wastewater treatment processes.

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