| 摘要: | 為了改善農村社區家庭污水的汙染問題，環保署經費補助於民國93年台南縣仁德鄉大甲社區設置一座土壤滲濾系統以收集及現地處理該社區產生的生活污水，此自然處理系統場址的地面亦可提供社區居民公園休憩使用。本研究自民國95年4月至96年4月，以一年時間連續紀錄及監測此處理系統的處理水量、水質、生態、及居民利用的情形，以探討土壤滲濾系統對家庭污水的處理效能及處理水質，及評估此生態工法作為鄉村型社區現地處理技術的可行性。
大甲社區的土壤滲濾污水處理系統，場址面積約佔1650 m2，由截流抽水站、流量計量槽、厭氧槽(沉降槽)、土壤濾床、及放流生態池等單元組成。其中，負責污染物淨化的最主要單元為土壤濾床，其面積約1248 m2，屬於地下掩埋式槽體，填充土壤及稻殻濾料作為濾床，上層再填入回填土進行植栽，土壤濾床分三組輪替操作，每次以一組處理廢水。進流污水自截流抽水站送入計量槽，隨後以重力方式流經厭氧槽及土壤濾床，處理水停留於生態池後，流至放流水體或澆灌再利用。
實驗結果顯示，受限於使用土壤作為濾料，顆粒小阻力大，因此土壤滲濾系統無法操作在高的水力負荷。本研究三組濾床中導水能力最佳的一組，其最大水力負荷僅能達0.17 m3/m2/d (m/d)，其餘兩組只能操作在0.04 m3/m2/d (m/d)以下。土壤滲濾系統對於BOD5、COD、PO4及大腸桿菌群等汙染物具有良好的去除效率，整個系統的平均去除效率可達BOD5 77~82%、COD 44~55%、PO4 79~93%、大腸桿菌群 76~87%。處理後放流水之BOD5 濃度全符合放流水標準(<30 mg/L)，而COD所採集的32個樣本中，有31個樣本合符合放流水標準(<100 mg/L)，土壤濾床對大腸桿菌群雖有顯著的去除效率，但處理水質33個分析樣本中有高達28個樣本不符合標準(<2000 CFU/mL)。土壤滲濾系統對TSS、濁度、TN、TP去除成效較低，整個系統的平均去除效率僅TSS 4~29％、濁度15~26%、TN 17~37%、TP 15~33%。不過因進流TSS濃度原本就不高，在33個處理水樣本中，有30個樣本外符合TSS的放流水標準(< 30 mg/L)。
處理過後之放流水除了可提供系統陸生景觀植物的澆灌外，週遭的農民也然樂於取用處理水，作為其農田、園藝灌溉使用。至民國98年中旬止，大甲土壤滲濾系統已持續運轉操作達5年，處理效能及處理後的水質仍相當穩定。
In order to improve the problem facing to domestic sewage in rural community, Environmental Protection Administration Executive Yuan, R.O.C. (Taiwan) offered Da-jia community in Jen-Te Township, Tainan County, a subsidy to set up a subsurface wastewater infiltration system (SWIS) in 2004. It is a natural treatment system for collecting wastewater and operating on-site treatment to meet the requirement of national Effluent Standard; and the ground of the SWIS can also function as a park for residents to spend their spare time. This research had been conducted from April, 2006 to April, 2007 to record and monitor the flow rate of influent and effluent, water quality, ecology and utilization of the SWIS. The treatment performance of the system for improving water quality of domestic sewage was investigated to assess the feasibility of the SWIS as an ecological engineering on-site treatment technology in rural community.
The site of the SWIS in Da-jia community occupies approximately 1650 m2 and is composed of numerous units, including pumping sump, flow metering flume, anaerobic tank (settling tank), soil filter and the eco-pond for discharging treated wastewater. Among them, soil filter, the main unit to purify the pollutants, is an underground tank with surface area of about 1248 m2, and is filled with soil and rice hull as the filtering media. Backfilled soil was filled above the filter for vegetation planting. The soil filter was divided into three beds, which were designated as A, B, C bed and were designed for rotational operation, in which only one filter compartment was operated for wastewater treatment at the same time. The wastewater flowed into metering flume from the pumping sump, and then flowed through anaerobic tank and soil filter by gravity. After the treatment, the treated wastewater entered the eco-pond for reuse in farm-land irrigation and effluent discharge.
The results indicate that the SWIS could not operate under high hydraulic loading due to the inherently high hydraulic resistance, which was induced by the small particle of the soil media used. The C bed reached a highest hydraulic lading up to 0.17 m3/m2/d (m/d), while the other two beds operated only under 0.04 m3/m2/d (m/d). The SWIS exhibited substantial removal of the pollutants such as BOD5、COD、PO4 and total coliforms. The resulting average removal efficiencies of BOD5, COD, PO4 , and total coliform were 77~82%, 44~55%, 79~93%, 76~87%, respectively. After treatment, the BOD5 concentration of the treated effluent consistently satisfied the national Effluent Standard (<30 mg/L). Totally 31 of the 32 samples of the treated wastewater conformed to the Effluent Standard of COD (<100 mg/L). Although the soil filter showed the significant removal efficiency of total coliforms, 28 of the 33 samples of the treated wastewater did not meet the Effluent Standard of total coliforms (<2000 CFU/mL). The SWIS had lower removal of TSS, turbidity, TN, and TP, resulting in removal efficiencies of 4~29%, 15~26%, 17~37%, and 15~33%, respectively. Since the TSS concentration was not high in the influent wastewater, 30 of 33 samples of the treated wastewater still conformed to the Effluent Standard of TTS (< 30 mg/L).
After treatment and purification, the treated sewage offered water to irrigate terrestrial plants in the system. Besides, the farmers nearby were willing to use the treated sewage for irrigation of their farmlands. To the middle of 2009, the SWIS in Da-jia have worked for five years, and its treatment efficiency and the water quality of the treated wastewater are still very stable. |
