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A surface flow constructed wetland consisting of seven cells was used to treat the leachates from a decommissioned landfill. Wetland monitoring was performed by evaluating the treatment efficiency of the landfill leachate and the wetland biological integrity of the wetland. The water quality samples were analyzed for iron, manganese, phosphorus (orthophosphate), pH, dissolved oxygen (DO), nitrogen (ammonia, nitrate, nitrite and TKN), chemical oxygen demand (COD), total suspended solids (TSS) and total dissolved solids (TDS). Aquatic macroinvertebrates were examined using Average Score per Taxon (ASPT) via the Biological Monitoring Working Party (BMWP) biotic index, the Ephemeroptera, Trichoptera, Sphaeriidae and Odonata (ETSD) biotic index, abundance of mayflies and trophic structure. Reductions of 49.66, 66.66, 1.91, 46.37 and 8.33% were obtained for manganese, orthophosphate, TSS, TDS and COD, respectively. The nitrite, dissolved oxygen and iron concentrations were not in accordance with the water quality guidelines for aquatic life. ASPT, ETSD, percent abundance of mayflies and trophic structure represented moderate to moderately-poor water quality in comparison to a high quality reference site. Iron had most adverse effect on the biological system of the wetland

The suitability of a passive technology, consisting of filters composed of a mixture of limestone and sandstone rocks, for the treatment of landfill leachates containing 6.6 mg L^ˉ1 iron and 1.8 mg L^ˉ1 manganese were investigated. The limestone and the limestone/sandstone filters successfully removed iron from the prepared solutions. The filters removed on average a minimum of 97.60% of the iron from solution on a daily basis. The removal of manganese from solution was not as efficient as iron removal. The filters removed between 22.22% and 100% of the manganese from solution. Neither the filter type nor the solution type affected the iron and manganese removal efficiencies. Although iron precipitate was evident during the 7 day experimental period, armoring did not affect the removal efficiency of the elements. The pH of the water samples did not exceed 7.7. Therefore, the wetland ecosystem should be able to adjust to water having a slightly higher pH without suffering adverse effects

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The ability of limestone and limestone/sandstone filters to remove dissolved iron and manganese from landfill leachate under field conditions were investigated. The results showed that the precipitation of iron and manganese were affected by temperature and time. Most of iron was removed from solution within the first 10 min at 20oC while the removal of iron from solution took much longer time (50 min) at 5oC. Larger percentage (69%) of manganese was removed from solution within the first 20 min at 20oC compared to that (42%) removed at 5oC. Removal of manganese from solution was affected by the presence of iron while presence of manganese did not affect iron removal from solution. The lower removal efficiencies of manganese showed the slow kinetic of manganese oxidation. The iron and manganese removal rate constants of the limestone filters were higher than those of the limestone/sandstone filters. The pH of the water samples did not exceed 7.7. Therefore, the wetland ecosystem should be able to adjust to water having a slight alkalinity without suffering adverse effects