| 摘要: | 本文以關山人工濕地系統為研究對象，探討人工濕地處理鄉村地區汙水之處理效益，以供未來人工濕地功能設計與操作之參考。關山人工地系統位於我國台東縣關山鎮境內，占地6.4公頃，處理水域面積約2.37公頃，處理單元包含截流設施、曝氣氧化塘、密植濕地、開放水域濕地、表面下流動式濕地、草溝、生態池等7個處理單元，設計處理汙水量為5,000 CMD。數據採用2008年8月至2011年11月期間，共計37筆資料，實際每日進流汙水量為1,058～4,662 CMD，平均水力負荷( HLR )為0.11 ± 0.03 m3/m2/day，平均水力停留時間( HRT ) 為7.91 ± 2.52 day。水質數據顯示關山人工濕地系統有效去除汙水中主要汙染物：懸浮固體物(SS)去除效率63.19 ± 12.76 % (2.49 ± 3.36 g/m2/day)、生化需氧量(BOD5)去除效率56.98 ± 16.63 % (1.12 ± 0.61 g/m2/day)、總氮(TN)去除效率62.88 ± 17.65 % (1.76 ± 1.14 g/m2/day)、氨氮去除效率81.55 ± 13.10 % (1.33 ±0.81 g/m2/day)、總磷去除效率66.31 ± 20.21 % (0.11 ± 0.08 g/m2/day)。各單元表現上，曝氣氧化塘儘管只占總水域面積的8.4%，但顯著削減了80 %的懸浮固體負荷、53 %的BOD5負荷，成功扮演人工濕地前處理單元的角色。惟曝氣氧化塘僅能消減20 %的氨氮負荷、4 %的總氮負荷及27.5 % 的總磷負荷，氮磷去除仍須依賴人工濕地的功能。一階去除速率常數(kv)為人工濕地的重要設計參數，本文也計算整個處理系統的各項污染物kv值，SS為0.06～0.42(0.18 ± 0.09) day-1，BOD5 為0.01～0.86(0.19 ± 0.14) day-1，TN為0.03～0.36 (0.16 ± 0.08) day-1，氨氮 為0.06～0.77 (0.29 ± 0.17) day-1、TP為0.03～0.54(0.19 ± 0.12) day-1。SS、BOD5及TP的去除速率常數隨水力負荷增加而提高的趨勢較顯著，總氮及氨氮的去除速率常數隨水溫增加而增加的趨勢較明顯。綜合以上結果，關山人工濕地系統對鄉村地區之生活汙水、畜牧廢水及農業迴歸水等汙水具有顯著成效。
This study investigated characteristics and performance of the Guan-Shan constructed wetland system located in the Guan-Shan Town, Taitung County, so as to provide useful information for designing and operating a constructed wetland. This wetland system occupies about 6.4 ha with water surface area of about 2.37 ha. It includes seven various treatment units arranged in series, i.e., an inflow structure, an aerated lagoon, a surface flow wetland with dense macrophyte, a surface flow wetland with open surface area, a subsurface flow wetland, a grass ditch, and an ecological pond, which was designed to receive countryside sewage with a target influent flow rate of 5,000 m3/d. Data of operational condition and water quality were monitored and collected monthly during the period from August 2008 to November 2011 so that totally 37 sets of data were analyzed in this study. Influent flow rate ranging from 1,058～4,662 m3/d were actually recorded, resulting in an average hydraulic loading rate (HLR) of 0.11 ± 0.03 m3/m2/day and average hydraulic retention time (HRT) of 7.91 ± 2.52 day. Water quality data showed that the Guan-Shan wetland system effectively and significantly removed major pollutants of sewage, achieving 63.19 ± 12.76 % (2.49 ± 3.36 g/m2/day) for suspended solids (SS) removal, 56.98 ± 16.63 % (1.12 ± 0.61 g/m2/day) for 5-day biochemical oxygen demand (BOD5) removal, 81.55 ± 13.10 % (1.33 ±0.81 g/m2/day) for ammonium nitrogen removal, 62.88 ± 17.65 % (1.76 ± 1.14 g/m2/day)for total nitrogen removal, and 66.31 ± 20.21 % (0.11 ± 0.08 g/m2/day) for total phosphorous removal. The aerated lagoon contributed about 80% and 53% of the whole SS and BOD5 removal, respectively, acting successfully a pre-treatment unit prior to constructed wetlands. Nevertheless, it only contributed 20, 4, and 27.5% of total ammonium nitrogen, total nitrogen (TN), and total phosphorous (TP) reduction, respectively. Constructed wetlands did make a major contribution for nitrogen and phosphorous removal.First-order removal rate constant (kv) is one of the most important parameters for designing a constructed wetland. This study also calculated the kv values of the overall treatment system for various pollutants, being 0.06～0.42(0.18 ± 0.09) day-1 for SS, 0.01～0.86(0.19 ± 0.14) day-1 for BOD5 , 0.03～0.36 (0.16 ± 0.08) day-1 for TN, 0.06～0.77 (0.29 ± 0.17) day-1 for ammonium nitrogen, 0.03～0.54(0.19 ± 0.12) day-1 for TP. Apparently, kv values for SS, BOD5, and TP increased with increasing hydraulic loading rate with higher significance, whereas kv values for TN and ammonium nitrogen increased significantly with increasing water temperature. In conclusion, the Guan-Shan constructed wetland system can effectively and consistently improve water quality of countryside sewage that contains domestic wastewater, pig-farm effluent, and paddy-field runoff. |
