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

• Main Authors: May-Feng Yeh, 葉美鳳
• Other Authors: 陳賢焜
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/y3f8aw

碩士 === 崑山科技大學 === 環境工程研究所 === 96 === 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.