Potential of Local Algae Genera in Removing Nitrates from Wastewater: A Case Study of Uasin Gishu County, Kenya
Main Article Content
Keywords
Nitrates, waste water, Spirogyra, Zygnema, Oedogonium, efficiency, treatment
Abstract
Increased population growth in urban areas has resulted in production of large volumes of wastewater. This has had an effect on the efficiency of treatment of the wastewater, leading to discharge of poor-quality effluent into the environment. The main objective of the study was to determine the use of selected algae to remove nitrates from secondary-treated wastewater. In this study, local filamentous algae genera (Spirogyra, Zygnema and Oedogonium) were collected from Kesses, Uasin Gishu County, Kenya and cultured in sewage under laboratory conditions at Moi University. Wastewater samples were obtained from Moi University's stabilization ponds, including anaerobic, facultative, and maturation ponds, which treat wastewater from university facilities. Systematic sampling was conducted at multiple points in the ponds following EPA protocols, using composite samples made up of grab samples collected at 30 cm subsurface depth. After initial analysis, the first maturation pond, with adequate nutrient levels, was selected for culturing algae. The algae were grown under laboratory conditions, and nitrate removal was monitored daily for seven days. The concentration of nitrates removed by the algae was quantified daily for seven days. The collected data was coded into SPSS version 26 and analyzed using descriptive and inferential statistics. The study found that wastewater characteristics varied across the ponds, with nitrate concentrations decreasing significantly in the maturation ponds. Spirogyra, Zygnema, and Oedogonium algae effectively removed nitrates from wastewater, with Spirogyra achieving the highest reduction (6.56 mg/L to 0.83 mg/L by day four). Friedman and Mann-Whitney tests confirmed significant differences in nitrate removal across the days and between algae genera, with Spirogyra showing the highest nitrate removal efficiency, particularly on day two (65.39%). The study recommends that local authorities and wastewater treatment facilities should consider integrating algae-based bioremediation techniques into existing treatment systems to improve effluent quality while reducing reliance on chemical treatments.
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