公共污水污泥特性及堆肥再利用之研究

Characteristic of Public Wastewater Sewage Sludge and it’s Reuse in Composting

陳家榮(Jia-Rong Chen)

指導教授 ： 程淑芬

朝陽科技大學/理工學院/環境工程與管理系/碩士(2014年)

摘要

污泥富大量的有機質、氮和磷等植物生長所需之養分，但因含有多種重金屬，以至於土地施用時必須注意其在土壤中的生物有效性和植物毒性。在許多先進國家將污泥做為肥料或土壤改良劑等土地施用方式是這兩種普遍採用的資源化途徑。本研究以台灣地區三個污水處理廠污泥，新北市林口水資、台中市福田廠及台南市安平廠之污泥進行分析，結果顯示，各廠之乾基重金屬含量Cu平均在217.3~256.3 mg/kg之間；Cr含量在109.2~284.1 mg/kg之間；Cd含量在0.3~9.7 mg/kg之間；Pb含量在54.3~87.4 mg/kg之間；Ni含量在80.6~272.3 mg/kg之間；Zn平均含量在1154.0~2761.7 mg/kg之間。
污泥中各種重金屬之型態分布，Cu含量平均占75.8% 以有機鍵為主；Cr含量平均75.8% 以殘留態為主；Cd含量平均占40.8% 以鐵錳氧化態為主；Pb含量平均占78.2% 以殘留態為主；Ni含量平均占46.2% 以殘留態為主；鋅含量平均占42.2% 以鐵錳氧化態為主。透過污泥與木屑堆肥製作有機肥料有超標之虞的Cu、Cd、Ni及Zn，其鍵結型態大都以鐵錳氧化態、有機態及殘留態之生物有效性較低的型態存在。但隨著堆肥過程中，殘留態Pb含量百分比有減少的現象，而可交換態有增加的情形。
以添加不同比例的污泥堆肥於土壤中之青江菜栽種結果顯示，第二輪植體鮮重之Pb含量介於0.5~0.6 mg/kg之間，而第三輪Pb含量介於0.3~0.9 mg/kg，皆有超過衛生署公告食用作物重金屬Pb含量0.3 ppm之限量值。由栽種第三輪之土壤重金屬Pb鍵結型態分析，Pb大致上在可交換態有較高的分布，為生物有效性最高的部份，也是土壤中移動性較高的重金屬。

關鍵字

生物有效性 ； 鍵結型態 ； 重金屬 ； 污泥 ； 青江菜

並列摘要

Sewage sludge is rich in plant nutrients, but it is also loaded with heavy metals. Prolong use of sewage sludge as fertilizer or soil conditioner may cause phytotoxicity in reducing lead productivity and problem in produce’s palatability. Municipal wstewater sludge from there treatment plants, i.e. Lin-Ko, Fu-Tien and An-Ping in Wstewater Treatment Plants Taiwan were sample of investigated in this study. Results indicated that sewage sludge contains 217.3~256.3 mg/kg for Cu; 109.2~284.1 mg/kg for Cr; 0.3~9.7 mg/kg for Cd; 54.3~87.4 mg/kg for Pb; 80.6~272.3 mg/kg for Ni and 1154.0~2761.7 mg/kg for Zn.
Morphology of bonding from of these metals in sludge is an important factor in determining the bioavailability of the matal. The study shows that most Cu, about 75.8%, exists in organic bond fraction; most Cr, 75.8%, in residual fraction; the largest share of Cd ,40.8%, in Fe-Mn oxides bond; most Pb about 78.2% in residual fraction; the largest share of Ni about 46.2% in residual fraction and Zn is about 42.2% in Fe-Mn oxides bond.
Although sludge and sawdust composting contains Cu, Cd, Ni and Zn with concentrations exceeding the maximum legal limits in organic fertilizer, the dominating bond fraction of these metals are all of low bioavailability, i.e. Fe-Mn oxides bond, organic bond and residual fractions. Composting process, reduces Pb contents in residual fraction, and increases exchangeable fraction.
The bok choy growth reveals that the adding different proportions of sludge compost in soil, the crop of the second round contains Pb ranged from 0.5~0.6 mg/kg on fresh weight basis, while third round contents ranged from 0.3~0.9 mg/kg.These contexts exceed the limit set by the Department of Health for edible crops at 0.3 ppm Pb.
The data also show Pb in produce of the third round primarily prevails in exchangeable fraction which is of highest both in bioavailability and mobility of heavy metals in soil.

並列關鍵字

Bond Fraction ； Heavy Metals ； Sewage Sludge ； Bioavailability ； Bok Choy

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