Treatment Performance and Fate of Heavy Metals in a UASB and Trickling Filter Based Sewage Treatment Process: the Case of Kality Centralized Sewage Treatment Plant, Addis Ababa, Ethiopia
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Date
2023-12
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Addis Ababa University
Abstract
Heavy metals pose a significant challenge to UASB and trickling filter-based sewage treatment plants due to retention, accumulation, limited solid-liquid separation, low sludge production, and anaerobic conditions, posing environmental risks like soil contamination and health issues due to impeded processes and inhibited microorganism activity. The study was aimed to investigating the Treatment Performance and Fate of Heavy Metals in a UASB and Trickling Filter Based Sewage Treatment Process in Kality Centralized Sewage Treatment Plant, Addis Ababa. A study was conducted to measure the levels of heavy metals in effluents and sludge using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES. The results found in the study showed that value of pH, BOD5, COD and TSS were in the range from 6.75±0.04 - 7.54±0.13; 6±0.73 -383.7±74.58 mg/l; 53±2.21 -728.33±121.03 (mg/l) and 1.33±0.19 - 345.33±61.9 (mg/l), respectively. Similarly, NH4-N 20.9±2.56 - 45.4±4.14 (mg/l); TN 52.17±4.24 - 58.2±3.79 (mg/l); TP 26.35±1.77 -27.7±2.31(mg/l); SO4-2- 17.98±2.54 - 48.4±2.65 (mg/l); EC 591.83±31.21 - 855.33±43.7 (μs/cm), while for heavy metals; Pb Below Detectable Limits (BDL); Ag BDL – 63.5±13.5 mg/kg; Ba 60±4.47 μg/l – 1291±58.5 mg/kg; Fe 13.33±3.33 μg/l - 16538.5± 15192 mg/kg; Al BDL - 2358.5±662.5 mg/kg ; Cd 0 μg/l - 0.35±0.15 mg/kg; Cr 0 μg/l - 10.5±0.65 mg/kg; Cu 0 μg/l - 23.85±1.15 mg/kg; Zn 5.45±12.3 μg/l - 165±5.4, and Mn 165 ± 49.5 μg/l - 92.5±3.75 mg/kg. The treatment plant demonstrated exceptional efficacy in reducing physicochemical parameters and heavy metals, meeting the standards set by the Ethiopian Environmental Protection Authority and the World Health Organization, and the attainment of discharge limits for surface water bodies could be attributed to adsorption, precipitation, and bio-sorption processes. To optimize and improve future processes, ongoing data collection and monitoring of seasonal physicochemical parameters and heavy metal levels in the sewage treatment facility would be beneficial.
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Keywords
Fate of Heavy Metals, Treatment Performance, UASB, Sewage Treatment Plant