麥粕與下水污泥快速堆肥及其應用

Abstract

台灣每年生產啤酒量約三十萬公噸，其中麥粕產量約六萬噸。由於麥粕仍含有大量未糖化之有機物，包括蛋白質及碳水化合物等，其後續處理相當不易。此外國內生活污水及工廠所排放之污水量逐年增加，污水處理後衍生出大量污泥影響到水及土壤的品質。因此必須發展出一套預處理及回收的方法來處理麥粕及下水污泥。好氧堆肥是一種簡單、經濟的生物處理技術，能分解有機物質將其轉變為有經濟價值的有機肥料或是土壤調節劑。由於污泥中所含的有機物質較少，若單一以污泥作為堆肥的材料，所得到的堆肥成品品質較差。有鑑於此，本研究以添加麥粕的方式增加基質中的有機物，以期能達到廢麥粕與下水污泥減量及資源化的目的。 根據實驗結果顯示，由溫度、二氧化碳產率及揮發性固體物損失率之結果可推測麥粕與下水污泥中之有機物可在 5-7 天內完全達到分解。此外，本研究採用中央合成設計 (CCD) 配合反應曲面法 (RSM) ，以改變操作條件 (摻合比、含水率)的方式，進行多組實驗，探討不同操作條件對於堆肥中反應變數 (碳分解率、總揮發性固體物損失率) 的影響，以評估最佳操作條件。實驗之結果顯示麥粕與下水污泥快速堆肥最佳生物降解之摻合比約在 35-40% 之間，而含水率在 55-60% 之間，其碳分解率及總揮發性固體物損失率符合二階多項式模式。 在生物吸附實驗方面，以不同初始重金屬濃度之方式探討腐熟堆肥吸附Cu (Ⅱ) 及Pb (Ⅱ) 的能力，得到對 Cu (Ⅱ) 和 Pb (Ⅱ) 的最大吸附能力分別為 0.58 及 0.10 mmol/g，其吸附模式則較符合 Langmuir isotherm。

Barley dregs wastes accounts for about 20% of the 300,000 tons of beer production per year in Taiwan. The disposal of barley dregs wastes is difficult due to the restrictive characteristics of barley dregs, such as high protein, carbohydrates and cellulose contents. The large amounts of sewage sludge are discharged by households and industry which gradually increases to affect the water and soil quality. Therefore, it is necessary to develop pretreatment and recycling methods for barley dregs wastes with sewage sludge. Consequently, the reduction and reclamation of barley dregs and sewage sludge would achieve simultaneously by using aerobic composting process. From the results of temperature, CO2 evolution rate and volatile solid loss rate showed that the organic matters in the barley dregs and sewage sludge could be completely biodegraded within 5 to 7 days. A central composite design (CCD) and response surface methodology (RSM) were applied to investigate the influence of operational conditions (mix ration and moisture content) on the properties of product obtained (carbon decomposition rate and TVS loss rate) in order to determine the optimaum operating conditions for the composting of barley dregs with sewage sludge. The range of the independent variable measured was 35-40% for mix ratio and 55-60% for moisture content. A second-order polynomial model consisting of two independent variables was found to accurately describe the carbon decomposition rate and TVS loss rate. The adsorption capacity of compost product for Cu (Ⅱ) and Pb (Ⅱ) was studied at various initial metal ion concentrations (from 10 to 250 mg/L). The biosorption data fitted better with Langmuir adsorption isotherm model. Batch experiments showed that the maximum adsorption capacities of compost for lead and copper were 0.58 and 0.10 mmol/g, respectively.