USE OF NONWOVEN GEOTEXTILES FOR REMOVING NUTRIENTS AND SUSPENDED SOLIDS FROM A EUTROPHIC LAKE

摘要

Eutrophication has been identified as one of the leading risks to surface water quality especially for lake water quality in Canada. The objective of the study is to evaluate the effectiveness of nonwoven geotextiles in reducing the nutrients and suspended solids to improve lake water quality. A small scale field experiment was conducted beside a lake by using nonwoven geotextiles as filter media. Custom-made geotextiles were used in different combinations to provide maximum efficiency in removing nutrients and suspended solids (SS) to achieve an acceptable level within a shorter period of time. For an initial turbidity ranging from 4 to 9 NTU, 2 layers of 110 µm pore size filters with 3 layers of 90 um pore size showed the best result at the 7th day of filtration, whereas 2 layers of 110 µm pore size with 3 layers of 75 µm pore size geotextiles had been found to restore the water quality at the 3 rd day of filtration for an initial turbidity ranging from 9 to 14 NTU. The combination of 1 layer of 110 µm pore size with 4 layers of 90 µm pore size showed the best result at the 2nd day during filtration for an initial turbidity higher than 14 NTU. TSS removal correlated with reduction of turbidity, TP and COD concentration. Initial flow rates through the filter decreased with an increase in filter layers and decrease in filter pore size. Geotextiles as filter media have shown potential for improvement of surface water quality in terms of nutrient and TSS removal.