台灣留學生出席國際會議補助

2010年7月30日 星期五

Evaluation of Bioaugmentation to Improve Wastewater Treatment

論文發表人: 呂紹元(加州大學洛杉磯分校土木與環工系博士班)

 

http://www.weftec.org/

 

生物強化技術(bioaugmentation)可有效改善活性污泥(activated sludge)廢水處理去氮除磷(nutrient removal)能力及去除有害廢棄物(hazardous wastes)。此一技術乃利用高強度廢水培養之菌種(enriched culture)來提升目標污染物(target pollutant)的降解速率。本研究就現今已發表之各生物強化技術分為下列三類建立數值模式以進行比較:1)並聯廢水處理廠(parallel plants)模式;2)離線(off-line)生物培養槽模式(enricher-reactor, 或簡稱ER模式);及3)現場培養(in-situ process)或在線污泥回收模式(簡稱ER-RAS模式)。數值模擬結果顯示兩種生物培養槽之生物強化模式較並聯廢水處理廠更有效率;並聯廢水處理廠可能產生過量污泥並會受限於低溫。而ER-RAS離線模式相比則各有優缺:當污泥停滯時間(solid retention time)略高或溫度較低(<16ºC)ER-RAS表現略佳;而離線模式的優點則在於可處理多種不同的目標污染物而不致造成互相干擾之結果。

 

Bioaugmentation is a proposed method to improve nutrient removal or to enhance the removal of hazardous wastes in activated sludge (AS) processes. Many approaches for bioaugmentation have been developed, and bioaugmentation processes can be classified into several major schemes, such as adding enriched cultures from commercial or "off-site" sources; adding cells produced from other treatment plants or "on-site" reactors, or growing additional biomass in-situ with the ordinary biomass, using special reactor geometry. However, only few studies have compared the benefits among different processes. This paper quantifies the effectiveness of bioaugmentation processes based using experimental results and verified models. In the first part of the paper, we present our lab-scale experiments and simulations with bioaugmentation ranging from 1% to 16% (calculated as mass of augmented cells per unit of indigenous cell mass) to enhance the removal of an aromatic-type hazardous waste. Based upon a similar model, the second part of this paper compares three alternative "on-site" bioaugmentation approaches to improve nitrogen removal in full-scale treatment processes. The three bioaugmentation processes under comparison are: 1) the parallel plant process; 2) the off-line enricher-reactor (ER) process; and 3) the in-situ process. Simulation results suggested that all bioaugmentation approaches can decrease the minimum SRT for nitrification. The parallel plants approach creates the highest concentration of biomass but may fail at too low temperature. The ER-RAS approach would likely be more useful at lower temperature and required less reactor volume while the ER approach would likely be more advantageous in the presence of inhibitory compound(s).