廢光碟片濕式回收製程廢液物化處理

The Physi-Chemical Treatment for Wastewater from Disc Wet Recovery Process

葉美鳳(May-Feng Yeh)

指導教授 ： 陳賢焜

崑山科技大學/工程學院/環境工程研究所/碩士(2008年)

https://doi.org/10.6828/KSU.2008.00009

摘要

廢光碟片濕式回收製程中產生高濃度 COD 及高 pH 值廢液，「光碟片」主要可區分為 CD (Compact Disc) 與 DVD (Digital Versatile Disc) 二大類。使用大量液鹼及漂白水攪拌廢光碟片，將光碟片上 UV 硬化膠、染料及金屬反射層剝離聚碳酸酯樹脂，廢液中含有大量懸浮及半溶解性 UV 硬化膠，所以實驗利用土地面積需求小之物化處理流程處理廢液，並找出較經濟有效之流程、藥劑種類及操作參數，將獲取實用之操作控制參數以應用至實廠操作，以增加現場試驗之成功率及符合工業區污水廠進廠限值予以放流。
廢光碟片廢液中 COD 之來源主要為 UV 硬化膠，在濕式回收製程中需利用液鹼使 UV 硬化膠水解而撥離聚碳酸酯樹脂，其單一廢液桶中廢 CD 光碟片廢液及廢 DVD 光碟片廢液各經 4 次取樣分析，pH 值分別為 11.8±0.5、12.0±0.3，COD 分別為 56,000±800 mg/L 及 56,000±1,500 mg/L。
廢 CD 光碟片大多使用鋁及其他微量金屬銀或金做為金屬反射層，經由攪拌過程剝離聚碳酸酯樹脂，而廢液中含有 Al、Ag、Ni 分別為 1.031、2.2×10-3、0.026 mg/L。廢 DVD 光碟片大多使用 Ag 及其他微量金屬做為金屬反射層，廢液中含有Ag、Al、Ni 分別為 0.013、0.056、0.056 mg/L。
本實驗將廢光碟片廢液利用反製程原理降低 pH 值使懸浮及半溶解性 UV 硬化膠還原為膠體狀，再利用混凝沉澱方式將膠體狀 UV 硬化膠去除，藉由氯化鐵、硫酸鐵及硫酸鋁混凝劑做瓶杯試驗，其加藥量為 2,000 mg/L，pH 控制為將先加硫酸將 pH 調整至 4，等其沉澱取上澄液後，再利用液鹼將 pH 調整至 7，廢 CD 光碟片廢液 COD 去除率分別為 86%、79% 及 80%，再以氯化鐵 2,000 mg/L 添加陰離子聚合物 1 mg/L，COD 去除率提升至 88%。廢 DVD 光碟片廢液，氯化鐵、硫酸鐵及硫酸鋁混凝劑加藥量為 1,000 mg/L，COD去除率各別為 92%、86% 及 90%，再以氯化鐵 1,000 mg/L 添加陽離子聚合物 1 mg/L，COD 去除率增加至 93%。
廢光碟片廢液經氯化鐵混凝沉澱後，COD 濃度可降低至 7,000 mg/L，仍未符合符合工業區污水廠進廠限值 (＜650 mg/L)，進而使用氯酸鈉直接氧化法及 Fenton 法以去除剩餘之 COD，其操作條件範圍分別為氯酸鈉加藥量 0.5g/L ~ 50g/L，而最適加藥量為 50g/L，以氯酸鈉直接氧化法處理廢 CD 光碟片及廢 DVD 光碟片廢液，殘餘 COD 分別為 100 mg/L及 200 mg/L，去除率約為 99.8% 及 99.6%，而 Fenton 法 H2O2/Fe2+ 加藥量範圍為 5/2.5g/L ~ 50/25g/L，但是添加進廢液後，廢液中產生細小懸案膠羽，需長時間沉澱，COD去除效率差。
處理廢光碟片廢液在實廠操作流程中建議最先以降低 pH 值至4，再取上澄液調整 pH 至 7，廢 CD 光碟片廢以 2,000 mg/L 氯化鐵及 1 mg/L 陰離子聚合物做為混凝劑，廢 DVD 光碟片廢液以 1,000 mg/L 氯化鐵及 1 mg/L 陽離子聚合物為混凝劑，經由 1 分鐘快混 (100rpm) 及 30 分鐘慢混 (10rpm) 後，藉由混凝沉澱去除廢液中之膠體，再使用 50g/L 氯酸鈉作為氧化劑，反應時間為 10 分鐘，氧化殘餘之 COD。試驗所利用之土地面積要求小，且利用簡單物化處理方法處理廢液，可使設備及操作成本降低，為此試驗之優點。

關鍵字

廢光碟片回收 ； UV 硬化膠 ； 混凝沉澱 ； 化學氧化

並列摘要

The pre-crushed disc (Compact Disc, CD and Digital Versatile Disc, DVD ) was first immersed with the alkaline liquid containing hypochlorite to solve the UV lacquer, dye and the metal reflex layer from the poly-carbonate-ester resin. The waste-liquid originated from this procedure containing high COD concentration and pH. This study treated both the waste liquid with coagulation and the oxidation process in order to search the operation parameters in the disc-recovery plant.
After about 4 times of investigation, it was found that the CD waste liquid containing 56,000 ± 800 mg/L COD, pH of 11 ± 0.5 , and some metals of Al, Ag and Ni contents of 1.031, 2.2×10-3 and 0.026 mg/L individually, while the DVD waste water contained 56,000 ± 1,500 mg/L COD, pH of 12 ± 0.3 , and some metals of Al, Ag and Ni contents of 0.056, 0.013 and 0.056 mg/L individually.
After being acidified with hydrogen chloride, form pH 12 to low pH the CD and DVD waste liquid was approved that the lower pH arriving, the much more grey glue material precipitated with the COD removal percentage up to 81% for CD and 89% for DVD in the supernatant for pH 2. It was also found that that the COD removal efficient was increased with the decreasing of the pH value and the increasing addition of coagulant in the jar test with agent of ferric chloride, ferric sulfate and aluminum sulfate individually. The supernatant of pH 4 was then alkalinized to pH 7 for flowing coagulation treatment. The suggestion for economical coagulant addition were 2,000 mg/L for ferric chloride, ferric sulfate and aluminum sulfate with the COD removal of 86, 79 and 80% respectively. Concurrent addition of ferric chloride 2,000 mg/L and anionic polymer 1 mg/L for CD waste liquid the COD removal increased to 88%.
The suggestion for economical coagulant addition were 1,000 mg/L for ferric chloride, ferric sulfate and aluminum sulfate with the COD removal of 92, 86 and 90% respectively. Concurrent addition of ferric chloride 1,000 mg/L and add cationic polymer 1 mg/L for DVD waste liquid the COD removal increased to 93%.
After the coagulation and sedimentation for 1~2 hr with ferric chloride and polymer, the residual COD in the supernatant was 7,000 mg/L, which was further oxidized by chloric acid or Fenton agents. The COD removal efficient increased up to 99.8% for CD and 99.6% for DVD with the increasing dosage of chloric acid from 0.5 (g/L/g/L) to 50 (g/L/g/L) , and the economical dosage were suggested as chloric acid 50 g/L which resulted in the residual COD of 100 mg/L for the CD waste liquid and 200 mg/L for DVD the waste liquid in the reaction duration 10 minutes. The Fenton method H2O2/Fe2+ dosage from 5/2.5 (g/L/g/L) to 50/25 (g/L/g/L)resulted in much suspension material that was difficult to settle.

並列關鍵字

disc-recovery ； UV lacquer ； jar test ； the coagulation and sedimentation ； the chemical oxidation

參考文獻

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