Assessment of Water Hyacinth (Eichhornia crassipes) and Osibata (Nymphaea lotus) as Natural Coagulants and Pre-Treatment Materials for Water Quality Improvement

Abstract

Access to safe drinking water remains a major public-health challenge in developing communities where borehole, hand-dug well, and surface-water sources may require additional treatment before use. This study assessed Water Hyacinth (Eichhornia crassipes) and Osibata (Nymphaea lotus) leaf powders and extracts as natural coagulation and pre-treatment materials, while also assessing the antibacterial activity of their extracts. Leaves were collected, washed, shade-dried for approximately two weeks, and milled. Aqueous and ethanolic extracts were prepared by 72-hour maceration and evaluated through qualitative phytochemical screening and agar-well diffusion against seven bacterial isolates. Powdered plant materials were evaluated at doses of 0.5 and 1.0 g per 500 mL of borehole, hand-dug well, and surface-water samples using coagulation–flocculation and settling, after which selected physicochemical and microbiological characteristics were assessed. Both plants contained steroids, saponins, carbohydrates, flavonoids, and alkaloids, while anthraquinones were detected only in Osibata. At 150 mg/mL, ethanolic extracts of both plants inhibited four of the seven bacterial isolates (57.1%). Osibata produced the greatest reported hardness reduction, decreasing well-water hardness from 350 to 7.8 mg/L (97.8%). Microbiological calculations based on the reported colony counts showed reductions of 96.3% and 98.2% in well water treated with Osibata and Water Hyacinth, respectively, and 89.7% and 96.7% in surface water, respectively. In contrast, the reported borehole treatments increased microbial counts. Plant addition also increased TDS and TSS and initially increased turbidity before settling, indicating the need for effective downstream solid–liquid separation. Overall, the findings indicate that Water Hyacinth and Osibata have potential as natural coagulation and pre-treatment materials, with Osibata showing particularly strong hardness-reduction performance; however, the materials should not be regarded as stand-alone drinking-water purification or disinfection agents and require validated downstream filtration and disinfection.