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重金屬廢水污染為一嚴重的環境問題，至目前為止一些傳統處理方法雖
可將水質處理達環保規定，但所產生污泥之脫水及其所造成之二次污染仍
是一個嚴重的問題。臺灣地區每年產生大量的電鍍污泥，這些有害事業廢
棄物目前較被認可的處理方式為固化處理，但由於其成本高及固化後產生
體積龐大之固化體，則遭遇無掩埋場肯接受之窘境。日本電氣公司
(NEC) 於 1973 年提出鐵氧磁體法處理含重金屬廢水，在廢水中加入適量
兩價鐵鹽，在特定條件下通入空氣氧化，即可形成安定性高，可通過毒性
溶出試驗，具有磁性之鐵氧磁體，所獲得之鐵氧磁體有可能當磁性材料再
加以利用。本研究以電鍍廢水中常見之重金屬離子如鋅、鉻、鎳、銅、鎘
等，為研究對象製備鐵氧磁體之樣品。首先製備單元系鐵氧磁體由其毒性
溶出試驗之探討瞭解其安定性，進而就溶出量較大的鐵氧磁體進行表面被
覆效果的觀察，再就多元系鐵氧磁體及實際廢水的處理結果加以探討。並
就含重金屬濃度稀薄的電鍍清洗廢水，以中和混凝法觀察沈澱物之沈降性
質以供濃泥操作依據，並測定各系鐵氧磁體的脫水性質，做為過濾操作依
據，以期能應用於實際廢水的處理流程設計之用。實驗結果顯示，鋅系、
鉻系及鎳系鐵氧磁體之重金屬再溶出濃度都很低，溶出率均小於 0.1wt%
，均可符合毒性溶出的管制標準，隨著反應溫度升高，鐵氧磁體之結晶性
變佳，溶出濃度更降低。銅系鐵氧磁體因部分銅離子形成氧化銅，而沒有
嵌入鐵氧磁體結構內，使溶出濃度比其他各系高。鎘系鐵氧磁體由於氫氧
化鎘之水解常數非常小，鎘離子不易納入鐵氧磁體結構內，而以氫氧化鎘
存在使其溶出濃度偏高。多成分系鐵氧磁體之溶出現象與單元系一致，鋅
、鉻及鎳離子溶出濃度均很低，而銅、鎘離子之溶出濃度則偏高。經表面
被覆處理後，銅系、鎘系及多成分系鐵氧磁體之重金屬再溶出濃度均可降
至環保規定以下。重金屬濃度稀薄的電鍍清洗廢水經中和沈澱濃集後，污
泥可直接再添加二價鐵鹽進行鐵氧磁體化反應，並可獲得結晶性良好的鐵
氧磁體產物。 以布氏漏斗試驗測定鐵氧磁體之比抗係數為 106sec2/g 左
右，發現鐵氧磁體之比抗係數較其他污泥都小很多，顯示鐵氧磁體脫水性
佳，利用簡單的脫水設備即可達到良好的固液分離效果。利用上述之結果
可得一適合工業應用之廢水處理流程，不但可將廢水處理達環保規定，其
處理所產生的鐵氧磁體產物為。
Heavy metal ions in industrial wastewater is now be
coming a serious social problem due to its environmental
contamination. Up to the present, sludge produced by
neutralized precipitation process have the possible of
secondary contamination by their redissolution. In Taiwan,
the electroplating plants produce a large quantity of
electroplating sludge yearly. Solidification is a well known
method to treat sludge. And yet, the product volumn of
solidification are very huge. How to landfill the
solidificati on products effectly is a problem which has to be
considered in Taiwan. Since NEC firstly reported the
"ferrite process" in wastewater treatment in 1973, ferrite
process technology has alreadly been put into practical use
to remove heavy metal ions from wastewater. This stduy
concentrates on these heavy metal ions which have strong
tendency in forming ferrites. Firstly, the stability of
ferrites were investigated, from the TCLP (Toxicity
Characteristic Leaching Procedure). The unstabile ferrites was
restablized with surface-coating treatment. The concentration
of heavy metal leaching from Zn-,Cr- and Ni-bearing
ferrites is very low, it can meet the estabilished
pollution control regulations of ROC. The crystallization
of ferrites become better, meanwhile, the concentration of
redissoled metal ions was reduced, with the reaction
temperature rises. However, Cu2+ ions do not incorporate
into the ferrite structure. This is because of CuO phase
formed, a large Cu2+ ions was redissoluted. The hydrolysis
constant of Cd(OH)2 is very low, Cd2+ ions i s difficult to
incorporate into the ferrite structure, and Cd2+ ions was
redissoluted large. After the surface-coating treatment, the
concentration of redissoled metal ions of the unstabe Cu- and
Cd-bearing ferrites were reduced.
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