【摘要】：隨著污水收集、處理比率的提高,如何妥善處理處置污水處理過程中產(chǎn)生的剩余污泥,避免二次污染,已成為環(huán)保界亟待解決的問題。本研究以城市污水處理廠的剩余污泥為研究對象,通過微波熱解方式制備污泥生物炭,并探索污泥生物炭特性及應用潛勢。探索不同熱解溫度、添加不同化學活性劑對污泥生物炭特性的影響及微波熱解過程污泥中重金屬形態(tài)的變化規(guī)律,同時研究生物炭土地利用潛勢及經(jīng)活化熱解所得生物炭對MB的吸附特性。溫度顯著影響微波低溫熱解制備污泥生物炭。隨著熱解溫度的升高,生物炭的有機質(zhì)含量由原干污泥的74.33%逐漸降至450℃條件下的51.99%,灰分含量則由27.2%增高至49.06%。C元素含量由原干污泥的35.33wt.%提高至400℃條件下的最大值45.48wt.%,同時表面形貌及比表面積等隨著熱解溫度與熱解條件而呈現(xiàn)不同的變化。通過分步提取法研究微波熱解對污泥中重金屬形態(tài)的影響后發(fā)現(xiàn)：微波熱解可使污泥中多種生態(tài)風險高的可溶解態(tài)與可還原態(tài)的重金屬轉(zhuǎn)化為生態(tài)風險小的性質(zhì)穩(wěn)定的殘渣態(tài)。采用三種評價方法對生物炭的重金屬潛在生態(tài)風險進行評價,得出微波熱解對重金屬元素生態(tài)風險的影響存在一定的差異,其中As、Cu、Ni、Zn對環(huán)境的生態(tài)風險明顯降低,而Cr、Pb則不顯著�；瘜W活化劑的添加,可以較顯著的增加生物炭的比表面積,通過KOH的活化在700-C下BET比表面積最大,為467.21 m2/g,在相同的熱解溫度下,不同活化劑活化下BET比表面積大小順序依次為KOHZnCl2H2SO4檸檬酸H3P04。污泥生物炭吸附性能測試結(jié)果表明,生物炭對亞甲基藍的吸附與生物炭的比表面積有一定的關(guān)系,在相同的條件下,各活化劑下所得生物炭的吸附能力順序為KOHZnCl2H2SO4H3PO4檸檬酸。多數(shù)污泥生物炭對MB的吸附行為符合Freundlich等溫方程,說明MB在生物炭表面并非為單分子層吸附。生物炭對MB的吸附更符合Lagergren的二級動力學吸附,且由二級速率方程得出的平衡吸附量與實驗所得的平衡吸附量更接近。通過黑麥草種子發(fā)芽測試實驗,發(fā)現(xiàn)污泥生物炭對黑麥草發(fā)芽具有一定的促進作用,SC350組發(fā)芽率達到了98.15%,比土壤對照組的88.89%要高出9.26%。通過黑麥草的種植,發(fā)現(xiàn)污泥生物炭的添加,對黑麥草生長無負面影響,而相對于直接污泥添加,添加熱解后生物炭的試驗組黑麥草生長狀況良好。利用微波熱解污泥制備生物炭可以實現(xiàn)污泥減量無害和資源化,通過熱解不僅可以降低污泥農(nóng)用的生態(tài)風險,輔助化學活化還可將熱解所得生物炭作為廉價的吸附劑使用,具有較好的應用前景。
[Abstract]:With the increase of sewage collection and treatment ratio, it has become an urgent problem for the environmental protection field to deal with the excess sludge produced in the process of sewage treatment and avoid secondary pollution. In this study, sludge biochar was prepared by microwave pyrolysis from surplus sludge of municipal wastewater treatment plant, and the characteristics and potential of sludge biochar were explored. The effects of different pyrolysis temperatures, the addition of different chemical active agents on the biochar characteristics of sludge and the changes of heavy metal forms in sludge during microwave pyrolysis were explored. At the same time, the land use potential of biochar and the adsorption characteristics of activated biochar to MB were studied. The temperature has a significant effect on the preparation of sludge biochar by microwave pyrolysis at low temperature. With the increase of pyrolysis temperature, The organic matter content of biochar decreased gradually from 74.33% of raw dry sludge to 51.99 at 450 鈩，

本文編號：2189270