| 摘要: | 本研究以平鎮淨水場為例，藉沉澱及過濾單元之進、出流水濁度及操作資訊，檢討單元濁度去除成效，推估沉澱污泥、反沖洗廢水(以下統稱為廢污)產量，做為減量策略依據。另一方面，藉隨機採樣，建立廢污物化特性，供後續處置或再利用參考。 研究結果顯示，平鎮場原水濁度，每年至少有63%的機率低於15 NTU，但易因颱風而達上萬NTU。自取水策略改變，原水濁度因颱風而超過10,000 NTU的發生頻率，由4%降至1%。進流水濁度在15~500 NTU時，污泥毯澄清池有最佳的濁度去除成效，沉澱水達成率及單元濁度去除率高於90%；傾斜管沉澱池因溢流堰設計不佳，進流水濁度高於15 NTU時，達成率已低於60%。哈丁式、韋勒式快濾池進流水濁度，宜分別低於3 及6 NTU，且不應超過7 NTU。 中低原水濁度時，污泥毯澄清池沉澱污泥的分別為3,955、5 及172 mg/L；傾斜管沉澱池污泥非每日排除，故污泥的有機物及固體物含量隨時間累積增加，SS、BOD5、COD平均值分別為6,262、35及362 mg/L。平時，兩沉澱單元平均沉澱污泥推估產量，分別為1,975、2,014 kg/day，颱風時期，產量至少為平時的73倍。此外，平鎮場兩過濾單元反沖洗廢水之SS平均值，分別為252、223 mg/L，BOD5平均值低於1 mg/L，COD平均值則分別為17及11 mg/L。哈丁式及韋勒式快濾池反沖洗廢水量，分別為一、二期淨水設備處理水量的0.2~0.3%及1.9~2.5%，顯示平鎮場反沖洗廢水主要來源為韋勒式快濾池，而其反沖洗廢水產量約為哈丁式快濾池反沖洗廢水產量的7~14倍。 直接過濾濁度低於5 NTU的原水，或當原水濁度超10,000 NTU時，藉修正兩階段加藥策略或添加高分子助凝劑，應可降低混凝劑添加量及污泥產量。另一方面，監測韋勒式快濾池反沖洗廢水濁度，除避免濾床過度潔淨，亦可縮減反沖洗時間並降低廢水產量。 This study was to investigate turbidity removal and residuals generation in sedimentation and filtration processes of Ping-Jan Water Treatment Plant. Furthermore, physical-chemical characteristics of residuals were also analyzed. According to the statistical data, the probability of raw water turbidity lower than 15 NTU in Ping-Jan Water Treatment Plant was 63%. However, raw water turbidity might higher than 10,000 NTU due to typhoon events. By changing the location of collecting raw water, the probability of turbidity over 10,000 NTU reduced from 4 to 1%. When influent turbidity was between the range of 15 to 500 NTU, the removal efficiency of turbidity and probability of settled water turbidity in sludge blanket clarifiers below 5 NTU were upon 90%. Moreover, the probability of settled water turbidity in tube settlers below 5 NTU was under 60% resulting from improper design of overflow weir when influent turbidity over 15 NTU. In addition, 7 NTU was the limit for the influent turbidity of Hardinge and Wheeler filters. Consequently, 3 and 6 NTU were suggested for these limits, respectively. For coagulation sludge from sludge blanket clarifiers, the SS was 3,955 mg/L, BOD5 was 5 mg/L, and COD was 172 mg/L. In addition, the characteristics of coagulation sludge of tube settlers including 6,262 mg/L SS, 35 mg/L BOD5, and 362 mg/L COD were increased with settled time. The routine amount of coagulation sludge from sludge blanket clarifiers and tube settlers were 1,975 and 2,014 kg/day, respectively. However, sludge production was 73 times of routine amount during typhoon seasons. The analysis results of the filter backwash water (FBW) produced by Hardinge and Wheeler filters revealed that the SS was 252 and 223 mg/L, BOD5 was <1 mg/L, and COD were 17 and 11 mg/L, respectively. FBW was typically only a small fraction of filtered water volume for Harding and Wheeler filters (0.2~0.3% and 1.9~2.5%, respectively). Additionally, the amount of FBW from Wheeler filters was 7~14 times comparing to that from Hardinge filters. When raw water turbidity was below 5 NTU, direct filtration might decrease PAC dosage in coagulation process and reduce the amount of coagulation sludge. Also, changing the strategy of two-stage coagulation sedimentation and adding flocculent while raw water turbidity was over 10,000 NTU might be reasonable. In addition, monitoring turbidity of FBW from Wheeler filters ensure media wasn’t too clean due to too long backwashing. Therefore, it might keep removal efficiency and reduce the amount of FBW of Wheeler filters. |
