水庫淤泥及淨水污泥再利用製磚之研究

Abstract

因台灣地小人稠，大量的水庫淤泥及淨水污泥等廢棄污泥採用掩埋方式並不是良好之處置方法，為能有效利用此類廢棄污泥，本研究嘗試將大量的水庫淤泥及淨水污泥利用燒結程序做資源化利用。 由實驗得知，水庫淤泥燒結體在燒結溫度為1050℃，燒結時間為45分鐘時，其燒結磚體在比重、吸水率及抗壓強度等方面皆可符合中國國家標準（CNS）所規範之一級磚標準，而淨水污泥燒結體在燒結溫度為1100℃、燒結時間15分鐘時，其燒結磚體亦可符合CNS規範之一級磚標準。但考量經濟成本方面，水庫淤泥較適合做製磚之原料。 從試體成型壓力的研究得知，增加成型壓力可有效降低燒結體之吸水率。由實驗得知，水庫淤泥燒結體在成型壓力為550 kg/cm2，燒結溫度為1100℃時，燒結時間為60分鐘時，其燒結體物性可符合鋪路磚之要求，另外，因一般鋪路磚的燒製溫度為1100∼1300℃，故此操作條件下燒製之水庫淤泥燒結體亦具有良好的經濟效益。 由探討混合污泥燒結體作為鋪路磚之實驗得知，混合污泥中淨水污泥比例達到40∼50％時，可有效降低燒結體之軟化。當混合污泥燒結體在成型壓力為220 kg/cm2，燒結溫度為1150℃，燒結時間為60分鐘，混合污泥燒結體符合鋪路磚之規範。 不管是淨水污泥或水庫淤泥，其都含有微量之重金屬，故當兩種污泥之燒結磚體應用在環境中，其重金屬是否溶出為我們所關心之問題，由燒結磚體之毒性特性溶出程序（TCLP）分析結果得知，磚體之重金屬溶出濃度均遠小於法規標準。故在本研究中，我們證明水庫淤泥及淨水污泥燒結體可做為一般建築磚之使用。

In Taiwan, because of limited land available, landfill is not a feasible method for disposing water treatment plant (WTP) sludge and dam sediment. For efficient and economic management of these wastes, sintering process was attempted to reuse the solids in brick and pavior-making. Dried samples of water treatment plant sludge, dam sediment, and their mixtures of various proportion were molded and fired at various temperatures. The sinter quality was examined to study the most adequate firing condition and the optimal combination of WTP sludge and sediment mixture. Our result shows that less energy is involved in the brick-making of dam sediment. At molding pressure of 220 kg/cm2, the sinter of the dam sediment fired at 1050℃ for 45 minutes meets the first level brick of Chinese National Standard(CNS), while that of the water treatment plant sludge fired at 1100℃ for 15 minutes is required to meet the same standard. Increasing the molding pressure reduce the water absorption of the sinter. When the molding pressure of sample is increased to 550 kg/cm2, the sinter of the dam sediment fired at 1100℃ for 60 minutes can meet the general standard for paving, which provide an alternative for dam sediment reuse since the paving-making is conducted between 1100℃ and 1300℃. Because the water treatment plant sludge alone is not a good material in making bricks, an alternative has been explored by mixing the two solid wastes in various ratios before the firing. When 40% to 50% dam sediment is replaced with the water treatment plant sludge, molded at 220 kg/cm2, the sinter fired at 1150℃ for 60 minutes meet the general standard of a pavior. The sinters of both WTP sludge and dam sediment can be safely used as bricks and paviors because that the concentrations of heavy metals in the TCLP leachate are much lower than the Regulatory limitations of the ROC EPA.