| 摘要: | 本研究使用的金屬處理廠二級處理的廢水,進行現場模擬試驗,在不同條件下之表面下流動式人工濕地系統(Subsurface Flow, SSF),提升有機物和營養鹽之去除效率,降低廢水處理成本,達到水資源循環再利用的目的.
在人工濕地對污染物質去除效率影響的探討中,嘗試以不同介質(再生活性碳,石英砂,爐石),種植不同植物(香蒲,蘆葦)和水力停留時間(1.5,1,0.5天),以及採曝氣方式操作(蘆葦活性碳)之SSF人工濕地,經由定期採樣分析,著重於有機物質和營養鹽(TOC,COD,BOD5,懸浮固體物,TN,TP)之去除效率探討,以自然方式來達到去除水中污染物質.後續探討之活性碳介質及試驗組,皆使用再生活性碳.
本研究水質分析結果顯示,各試驗組最佳去除效率,TOC去除效率為:蘆葦活性碳組94.3 %>曝氣蘆葦活性碳組93.0 %>香蒲活性碳組91.6 %;COD去除效率為:香蒲活性碳組79.7%,曝氣蘆葦活性碳組79.1%>蘆葦活性碳組68.8%;BOD5去除效率為:香蒲活性碳組89.4 %>蘆葦活性碳組87.3 %>曝氣蘆葦活性碳77.9 %;TN去除效率為:蘆葦活性碳組84.4 %>曝氣蘆葦活性碳組82.2%>香蒲活性碳組75.6 %;TP去除效率為:蘆葦爐石組67.7%>香蒲活性碳組65.7%>蘆葦石英砂組65.4%.
本研究結果顯示,經不同介質之試驗組淨化後,活性碳在有機物質及氮營養鹽之去除效率上,相對於石英砂可提供較穩定的效果,爐石對於磷營養鹽去除效率上,相較於活性碳,石英砂去除效率上較不顯著;大部分的分析結果顯示,在TOC,COD,TN去除效率上,蘆葦組略優於香蒲組(P>0.05),而BOD5可能因進流濃度較低,則呈現香蒲組略優於蘆葦組之現象(P>0.05);在不同水力停留時間(HRT)之下,有機物質,固體物及磷營養鹽,約0.5~1天即可到達最佳去除效率;氮營養鹽則需約1~1.5天.蘆葦活性碳組曝氣與否,對於各項污染物質之去除效率略有提升,但並不顯著(P>0.05),主要原因可能為進流濃度偏低所造成.
In this research, we designed various models of Subsurface Flow System (SSF) to treat wastewater which was previously treated with secondary treatment from a metal processing plant.We intended to enhance the removal efficiency of organic matter and nutrient, to reduce the cost of wastewater treatment, and to achieve the purpose of water recycling.
In an attempt to remove the contaminated substances in the water by a natural way, we constructed subsurface flow system wetlands by using different media (regenerated activated carbon, quartz sand and slag), different plants (cattail and reed) planted on the media, at various hydraulic retention time (0.5 day, 1 day and 1.5 days), with/without aeration at reed activated carbon system. Wastewater was directed to flow through the wetlands under various time period, wastewater was then collected and analyzed for the removal efficiency of the organic substances and Nutrients, i.e., Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), 5 Days Biochemical Oxygen Demand (BOD5), Suspended Solid Substances (SS), Total Nitrogen (TN) and Total Phosphate (TP). Throughout the entire study, the regenerated activated carbon was used as the activated carbon media.
The results revealed the best removal efficiency for the contaminants as the followings: in TOC removal group, reed activated carbon (94.3%) > aerated reed activated carbon (93.0%) > cattail activated carbon (91.6%); in COD removal group, cattail activated carbon (79.7%) > aerated reed activated carbon (79.1%) > reed activated carbon (68.8%); in BOD5 removal group, cattail activated carbon (89.4%) > reed activated carbon (87.3%) > aerated reed activated carbon (77.9%); in TN removal group, reed activated carbon (84.4%) > aerated reed activated carbon (82.2%) > cattail activated carbon (75.6%); in TP removal group, reed slag (67.7%) > cattail activated carbon (65.7%) > reed quartz sand (65.4%).
In summary, activated carbon group has consistent results which are better than quartz sand in the removal of organic substances and nutritional nitrogen salt. Comparing slag group to the activated carbon group and quartz sand group in the removal of total phosphate, the difference in efficiency is not significant. In terms of the removal of TOC, COD and TN, reed is slightly better than cattail (P>0.05); while in the removal of BOD5, cattail is slightly better than reed (P> 0.05). The results could be attributed to the low influent amount of the contaminant. In various hydraulic retention time studies, the contaminants of organic substances, solid substances, and nutritional phosphate salt can be removed within half to one day; while nutritional nitrogen salt will take one to one and a half day to be removed. The aeration in the reed activated carbon group helps slightly in the removal of the contaminants, but not significant (P> 0.05). The results could be attributed to the low influent amount of the contaminants. |
