Development of toxicity tolerant water hyacinth (Eichhornea crassipes) for effective treatment of raw sewage

Abstract

AbstractPioneering research efforts in the handling of municipal sewage in developing countries have involved the use of water hyacinth (Eichhornea crassipes) to purify sewage for possible re‐use of the effluent water for domestic purposes. The ability of water hyacinth to remove pollution from raw sewage has been found to be impaired by sewage toxicity. Trials were therefore carried out to adapt water hyacinth to toxicity and thereby increase its ability to remove pollutants from raw sewage. The plants were adapted using an active bio‐degrader consisting of Pseudomonas aeruginosa, Escherichia coli, Klebsiella ozaenae, Klebsiella edwardsiella and Baccillus subtilis. The adaptation progressed through 20, 40, 60 and 80% sewage dilution until plants capable of growth in 100% raw sewage were obtained. Plants were observed for morphological growth and at four weeks, samples were collected for tissue analysis.The plants progressively absorbed nutrients from sewage up to the fourth week, when signs of toxicity were obsereved through wilting, loss of turgidity and reduction in leaf number. However, plants that survived through a series of adaptations under various sewage dilutions exhibited luxuriant growth on raw sewage. In synergy with the active bio‐degrader, the efficiency of the adapted water hyacinth to remove pollutants (nutrients) from raw sewage was enhanced by 93%.