鹼前處理廢棄活性污泥的厭氧消化反應動力模式之研究

Abstract

以廢棄活性污泥作基質來進行厭氧消化反應,在過去已有許多研究;若是將 廢棄活性污泥以鹼劑先處理,化學水解基質的作用會對厭氧消化有何影響, 則是本研究所欲暸解的結果.本實驗是培養四組厭氧反應槽,一組為控制 組,其餘三組則是將廢棄活性污泥以不同的鹼劑量前處理,再飼入半連續式 厭氧消化槽,培養期間共經歷四個水力停留時間(HRT=20 days,13.3 days,10 days 及 7.5 days);與無鹼前處理的情況相較而言,發現基質的 去除率,產氣率,單位基質去除所產生的甲烷量,以及產氣組成中甲烷所含 比例,均有增加.動力模式的推估過程中,可以求得甲烷菌及酸化菌的衰減 速率與生長速率常數,從模式中算出的水解速率常數可知加鹼處理後的 WAS,在經過厭氧消化反應時會有較大的水解速率.實驗進行至水力停留時 間為7.5天時,四組反應槽仍呈現正常的厭氧消化狀態.在實驗過程中所經 的水力時間範圍內,結果顯示以鹼前處理廢棄活性污泥應用於厭氧消化上, 對於基質的去除率及反應速率上,會有較佳的結果 The relative research about the use of waste activated sludge (WAS) as the substrate for anaerobic digestion had widely studied in past few decades.The main purpose of this study is to see the effect of chemical pretreatment on anaerobic digestion. The system adapted in this study is to set four semicontinuous anaerobic digestion reactors,in which one is the control set, ,and the other three are the refrential sets.The control set was fed with WAS without chemical pretreatment,and the three referential sets were fed with WAS pretreated by different concentrations of NaOH.During the four different hydraulitic retention time (HRT=20 days ,13.3 days,10 days,and 7.5 days),we found that the removal of the substrate,the gas production rate,the methane production per unit substrate removal,and the proportion of methane in the gas composition will increase. From the kinetics model we can get the decay coefficient of methanogenesis,the yield coefficient of methanogenesis ,the decay coefficient of acidogenesis ,and the yield coefficient of acidogenesis.The range of the hydrolysis rate can also be computed,which indicated the increase of the hydrolysis rate by chemical pretreatment. When our experiment processed for 7.5 days of hydraulitic retention time,the state of these four reactors still kept normal and stable under anaerobic digestion.And the experimental result indicated that anaerobic digestion with chemical pretreatment was able to increase the effect of substrate removal and the rate of the anaerobic digestion.