透過廢液COD還原硫酸鹽以回收硫化鈉之可行性研究

本實驗旨在嘗試利用模擬工業廢液COD將硫酸鹽還原並回收硫化物之研究，針對硫平衡的掌握來解決反應槽內過多硫化氫的困擾，使硫酸鹽還原菌(Sulfate Reducing Bacteria, SRB)將SO42-還原成H2S、HS-、S2-等硫化物。　　透過三次生化產硫潛能試驗(Biochemical Sulfide Potential test, BSP test)找出最適合SRB生長之條件，在第一次BSP試驗中，不同初始濃度(COD 2,000 mg/L及1,000 mg/L)控制組在COD:SO4-S比=10:1時SRB所消耗之COD占比分別為25.81%及73.85%，說明較低濃度情況下SRB與其他厭氧菌競爭更具優勢。在兩次BSP試驗中，SRB均無法順利使用異丙醇(isopropyl alcohol, IPA)，當使用IPA為碳源時，SO4-S僅在高的COD:SO4-S比例會有去除結果，最高去除率僅40%( COD:SO4-S比=20:1)。IPA難以被SRB利用原因推測與水與異丙醇出現分層造成微生物利用上的困難，及異丙醇本身生物可利用性低等特性有關。　　另外，於屏科大後山模場建立厭氧濾床實驗模型(Anaerobic Filter, AF)，從使用蔗糖(SUC)馴養的初始階段到使用以IPA配製合成進流水。SUC階段可以看到在不同的COD負荷下，COD和SO4-S分別皆有較好的去除效果，尤其SO4-S的去除效果在各階段最高可以達到92%。在使用IPA為進料基質後，COD去除率依然保持約48.87%，但SO4-S的去除效率僅剩下16.95%，說明SRB無法有效利用IPA為碳源；且氣體未檢測出甲烷，也排除IPA是因甲烷菌生長代謝而被利用，猜測有其他厭氧菌代替SRB利用IPA(如：酒精發酵之微生物或乳酸菌)，為了解COD和SO4-S再經SRB處理的變化情形，對12月平均數值進行質能平衡，平均進出料COD分別為94.5 g/d 和71.4 g/d，相差的部分為經過槽體後所消耗的COD量，因未發現任何甲烷的產生，故僅使用SO4-S的消耗進行COD的計算，SO4-S消耗需要18.9 g/d的COD，COD回收率為95.66%。平均進出料的SO4-S分別為21.7 g/d及12.2 g/d、槽內的S2-濃度為0.8 g/d、鹼液內硫化物經計算為0.5 g/d以及H2S氣體計算後可得2.2 g/d，得回收率72.53%，判斷可能原因為S2-與金屬離子形成沉澱物，使得出流液的硫化物低估。鹼液吸收瓶可以發現一定濃度的硫化物，說明通過將H2S打入鹼液中可有效的回收產生的硫化物，若將此方法如用於工業上，除了可以降低因H2S毒性造成的安全問題及鏽蝕金屬的問題，對於硫化物的回收也可達到循環再利用的目的。　　本研究另採用高級氧化程序(如:超音波處理)等方式將含IPA及硫酸鹽廢液進行處理，實驗結果發現COD去除率最高可達41.74%，而SO42-去除率最高可達24.16%，說明高級氧化程序能處理含IPA及SO42-之廢水。最終將高級氧化程序結合生物處理系統，先將含IPA及SO42-之廢水進行超音波處理後，再將剩餘廢液與SRB進行反應，發現IPA及SO42-皆有出現去除效果，但COD和SO4-S去除率皆未超過50%，出流水後續還是必需進行其他污水操作單元，增加處理成本。

關鍵字

硫酸鹽還原； COD:SO4-S ；厭氧濾床； SRB ； IPA ；高級氧化程序；超音波處理

並列摘要

The purpose of this study was trying to use simulated industrial waste COD to reduce sulfate and recover sulfide, aiming at the control of sulfur balance to solve the problem of excessive hydrogen sulfide in the reaction tank, made Sulfate Reducing Bacteria (SRB) to reduce SO42- to H2S, HS-, S2- and other sulfides. 　　Through three Biochemical Sulfide Potential test (BSP test) to find the most suitable conditions for the growth of SRB, in the first BSP test, different initial concentrations (COD 2,000 mg/L and 1,000 mg/L) control group When the COD:SO4-S=10:1, the proportion of COD consumed by SRB is 25.81% and 73.85%, respectively, indicating that SRB has an advantage in competition with other anaerobic bacteria at lower concentrations. In the two BSP tests, SRB failed to use isopropyl alcohol (IPA) smoothly. When IPA is used as the carbon source, SO4-S will only be removed at a high COD:SO4-S ratio, and the highest removal The rate is only 40% (COD:SO4-S =20:1). The reason why IPA is difficult to be used by SRB is presumed to be related to the difficulty of microbial utilization caused by the stratification of water and isopropanol, and the low bioavailability of isopropanol itself. 　　In addition,established an Anaerobic Filter (AF) experimental model was in container located at National Pingtung University of Science and Technology, from the initial stage of domestication with sucrose (SUC) to the use of isopropyl alcohol (isopropyl alcohol, IPA) to prepare synthetic influent water for the purpose of hoped that the biological treatment can be used to treat the waste liquid containing high concentration of sulfate and organic matter. In the SUC stage, it can be seen on the different COD loads, COD and SO4-S have better removal effects, especially the removal effect of SO4-S can reach up to 92% in each stage. After using IPA as the feed matrix, the COD removal rate still remains about 48.87%, but the SO4-S removal efficiency is only 16.95%, indicating that SRB cannot effectively use IPA as a carbon source, the gas is not detected as methane, it is also eliminated IPA is used due to the growth and metabolism of methane bacteria. It is speculated that other anaerobic bacteria will replace SRB to use IPA such as alcohol-fermenting microorganisms or lactic acid bacteria. In order to understand the changes of COD and SO4-S after SRB treatment, the average value of December was carried out to balance the mass and energy. The average feed and discharge COD were 94.5 g/d and 71.4 g/d, respectively. The difference is the difference after passing through the tank. The amount of COD consumed was not found to produce any methane, so only the consumption of SO4-S was used to calculate the COD. The consumption of SO4-S requires 18.9 g/d of COD, and the COD recovery rate is 95.66%. The average incoming and outgoing SO4-S are 21.7 g/d and 12.2 g/d, respectively, the S2- concentration in the tank is 0.8 g/d, the sulfide in the lye is calculated to be 0.5 g/d and the H2S gas can be calculated 2.2 g/d, the recovery rate was 72.53%. It was judged that the possible cause was the formation of precipitates between S2- and metal ions, which made the sulfide in the effluent underestimated. A certain concentration of sulfide can be found in the lye absorption bottle, indicating that the sulfide produced can be effectively recovered by pumping H2S into the lye. If this method is used in industry, in addition to reducing the safety problems caused by H2S toxicity and the problem of rusty metal, the recovery of sulfide can also achieve the purpose of recycling. 　　Therefore, in this study, Advanced Oxidation Processes (AOPs) such as ultrasonic treatment were used to treat the waste liquid containing IPA and sulfate. The experimental results found that the removal rate of COD was as high as 41.74%, and the removal rate of SO42- was as high as 24.16%, indicating that the advanced oxidation process can treat wastewater containing IPA and SO42-. Finally, the advanced oxidation process was combined with the biological treatment system. The wastewater containing IPA and SO42- was treated with ultrasonic waves, and then the remaining waste liquid was reacted with SRB. It was found that both IPA and SO42- had the removal effect, but COD and SO4-S removal rate does not exceed 50%, and other sewage operation units must be carried out after the effluent water, which increases the treatment cost.