以水庫底泥與花生殼製作生物炭陶粒之研究

本研究以水庫底泥與有機資材製成一種具有保水性的新型生物炭陶粒介質，並探討燒結溫度(600℃、800℃與1000℃)、有機資材添加比例(0%、5%、10%與15%)與燒結氣氛(空氣燒結與氮氣燒結)對生物炭陶粒各項理化性質的影響。實驗結果與商用介質(發泡煉石與火山岩屑)比較，提出最適生產條件與栽培介質配方。實驗結果發現燒結溫度愈高，陶粒燒結作用變得明顯，其燒結過程的粉體熔融、礦物改變與孔隙分布等改變，致使陶粒之機械強度增加，降低陶粒水份持留與養分含量。燒結氣氛的不同，造成對有機資材添加的明顯差異，在空氣燒結樣本中，有機資材添加主要作為發泡劑增加孔隙，增加孔隙可造成陶粒機械強度降低，但增加水份持留；在氮氣燒結生物炭陶粒樣本中，添加有機資材以生物炭形式留存，雖同樣因孔隙生成使機械強度下降，但不僅碳氮養分明顯留存，其保水能力亦較空氣燒結陶粒更具優勢。相較於商用陶粒，生物炭陶粒抗壓強度介於0.2 MPa 至10.0 MPa 之間，兩種商用介質則分別是1.2 MPa 與 1.6 MPa，雖然大部分生物炭陶粒抗壓強度相對較差，但仍具一定物理穩定結構。生物炭陶粒的植物可利用水分介於 8.6 %至 46.1 % 之間，兩種商用介質的植物可利用水分僅為 2.3%，且生物炭陶粒對植物可利用水分的保留時間可達商用介質的3倍。生物炭陶粒的氮含量介於 0.02 % 至 0.2 % 之間，兩種商用介質皆無法檢測出氮含量。因此，利用生物炭陶粒做為栽培介質，可較市面上的商用介質更具保水與養分提供之栽培優勢。綜合以上結果，生物炭陶粒的最適配方可以分為兩種情況，一為常用盆栽栽植環境，建議可以800℃混合10%有機資材之生物炭陶粒使用，在此條件下，生物炭陶粒可提供更佳的養分含量以及水分持留能力；另一情況則是需求長期使用，就如大樓樓頂的綠屋頂環境，此時建議1000℃混合15%有機資材之生物炭陶粒使用，高溫生物炭陶粒可提供如商用陶粒之穩定結構，且因生物炭混入而具明顯養分含量與水份持留優勢。

關鍵字

生物炭；陶粒；水庫底泥；農業廢棄物；栽培介質

並列摘要

In this study, a new type of biochar-based cermasite with water-retentive properties was produced from reservoir sediment and organic materials. The sintering temperature (600℃, 800℃ and 1000℃), the proportion of organic materials (0%, 5%, 10% and 15%) and the sintering atmosphere (air sintered and nitrogen sintered) were investigated to determine the effects of these factors on the physicochemical properties of the biochar-based ceramsite. The experimental results were compared with commercial media (commercial ceramsite(Com-1) and volcanic rock(Com-2)), and the optimal production conditions were suggested. The results indicated that the increase of sintering temperature led to a series of changes of biochar-based cermasite, including powder melting, pore size distribution, mineral composition, etc. High sintering temperatures improved mechanical strength but reduced water retention and nutrient contents. Differences in the sintering atmosphere had different effects on the organic materail amendments. In the aerobic sintering ceramsite, the organic material would be burned out and thus increased the pore volume of ceramsite, reduced the mech-anical strength but increased water retention capacity. In the anaerobic sintering ceramsite, the organic materials would be pyrolysised as biochar, and thus reduced mechanic strength as well but increasing water retention capacity and carbon and nitrogen nutrients. The compressive mechanic strength of biochar-based cermasite was between 0.2 MPa and 10.0 MPa, while the two commercial media were at 1.2 MPa and 1.6 MPa, respectively. Although most of the biochar-based cermasite had lower mechanic strength, they still maintain-ned an adequate strength. The plant-available water content of biochar-based cermasite ranged from 8.6% to 46.1%. In comparison, the plant-available water content in commercial media was only 2.3 %. The plant-available water retention time of biochar-based cermasite was up to three times of the commercial media. The nitrogen content of biochar-based cermasite was bet-ween 0.02% and 0.2%, while no nitrogen content could be detected in the commercial media. Therefore, the biochar-based cermasite had advantages over commercial media, particularly water retention and nutrient contents, over the commercial media. We proposed two types that the most suitable sintering conditions for making growing media. First, the sediment ceramasite, mixed with 10% organic material at 800℃, would provide better nutrient content and water retention capacity for the potted plants. Second, the sediment ceranmsite, mixed with 10% organic material at sintering at 1000℃, would be suitable for long-term use, such as green roof. Thus, the biochar-based cermasite should have advantages over the commercial media, particularly in nutrient contents and water retention.