Rhizofiltration for the enhancement of biofuel production

Abstract

The effectiveness of water hyacinth (EichhorniaCrassipes) in the remediation of municipal wastewater and production of bioethanol was compared with water lettuce (Pistia Stratiotes) and water spinach (Ipomoea Aquatica). Preliminary test using hydroponic system was conducted in order to measure the parameters required at the laboratory scale continuous experimental rig configuration (hydraulic retention time and flowrate). The experiment using the experimental rig was conducted for 18 d for each of the aquatic plant. Water lettuce showed a better removal performance compared with water hyacinth and water spinach. Water lettuce was able to remove 92% of nitrogen and 87% of phosphorus. Besides, water lettuce also showed higher BOD removal of 98.3% followed by water hyacinth 93.9% and then water spinach 89.6%. For COD removal performance, water lettuce treated COD up to 98% followed by water hyacinth 94.2% and water spinach 89.9%. The biomass harvested from water hyacinth, water lettuce and water spinach was 772 ± 37 g/kg, 794 ± 75 g/kg and 702 ± 69 g/kg, respectively. The DNS test was conducted to measure the reducing sugar from the plant biomass. The concentration of sugar produced by water hyacinth was 21.2 ± 2.7 g/L-m2, while water lettuce was 23.5 ± 3.8 g/L which is higher than water hyacinth's sugar production. Water spinach produced the lowest sugar concentration with only 15.5 ± 3.3 g/L. The production of biofuel was estimated based on known theories. Water lettuce produced 0.13 ± 0.01 g/g bioethanol while water hyacinth produced 0.12 ± 0.01 g/g of bioethanol. Due to the low concentration of sugar, water spinach managed to produce only 0.10 ± 0.02 g/g bioethanol. Water lettuce showed better performance in comparison with water hyacinth in the remediation of wastewater and subsequent production of biofuel.