高鹽廢水中有機物之厭氧處理-化學及微生物分析

Abstract

本研究為探討厭氧處理高鹽分的酸菜加工廢水生產甲烷的鹽耐受度，結合固定化技術與厭氧消化程序，設置包埋式混合厭氧反應槽(Anaerobically entrapped mixed microbial cells reactor, AnEMMCR)；同時運用多源基因體序列分析方法(次世代及Sanger定序)，以瞭解不同處理時槽中菌相的變化情形。實驗時使用河口底泥馴養的菌種，酸菜廢水則來自大埤的酸菜專業區。本研究共進行兩階段的實驗，第一階段 S1-S6 的 6 個試驗由原廢水的 26% 鹽度逐步降低，測試可明顯產甲烷的鹽耐受度；第二階段則進行較長時間的操作測試，S7-S10 的 4 個試驗是以第一階段所得的鹽耐受度操作在不同的有機負荷時觀察反應槽的表現；S11 則是以 10% 的鹽度及 HRT 10 天進行比較試驗。實驗結果顯示，可明顯產氣的最大鹽耐受度為 15%，有 63% 的 COD 去除率以及 0.013-0.032 L CH4/L/d 的甲烷產率；而鹽度 15% S7-S10 的長時間操作測試，COD 去除率介於 57.9-63.3%，甲烷含量平均為 39%，最高可達 41%；而在鹽度降至 10%、HRT 10 天及有機負荷為 1.0 g COD/L/d的 S11 比較試驗則有最佳的表現，可達到所有試驗中最大的 COD 去除率、氣體產率、甲烷產率及甲烷含量，分別為 68.52%、0.122 L/L/d、0.067 L CH4/L/d 及 54.88%。菌相分析結果則顯示在 S7-S11 試驗穩態時，細菌類占絕大部分，Chromohalobacter 及Halanaerobium 為主要優勢菌群，而在甲烷產率最大的 S10 及 S11 試程，發現存在甲烷古生菌Methanosarcina 及嗜鹽古生菌Halobacterium，其相對比例分別為 2.75% 及 2.25%。又Halanaerobium 比例在53-55% 時，可明顯產氣，而當其大於 75% 時(S9 試驗)， pH、產氣量、甲烷比例及甲烷產率皆明顯下降。

An anaerobically entrapped mixed microbial cells reactor (AnEMMCR) which integrated the technology of immobilization and anaerobic digestion was installed to investigate the tolerable salinity for methane production in anaerobic treatment of saline pickled mustard wastewater. Metagenomic analysis (including next generation and Sanger sequencing) was also adopted to study the dynamic microbial community in the reactor for various tests. Inoculums used were acclimated using the estuary sludge and the pickled mustard wastewater was obtained from a specialized manufacturing center in Da-pi Township, Taiwan. Experiment was classified as two phases in this study. The first phase including 6 tests, S1-S6, was designed to find the tolerable salinity by gradually decreasing the influent salinity from the highest value of 26% of raw pickled mustard wastewater till no apparent methane production. The seconde phase was mainly designed for conducting long term operation experiment. Using the tolerable salanity found in the first phase, S7-S10 tests were conducted to evaluate the reactor performance for different organic loadings. Another test, S11, using 10% salinity influent and an HRT of 10 days, was conducted for comparison with previous tests. Experimental results showed the tolerable salinity for methane production was 15% and 63% of COD removal efficiency and 0.013-0.032 L CH4/L/d were achieved under this condition. For tests S7-S10, the long term operation, COD removal efficiency of v 57.9-63.3% and an average 39% of methane content with the maximum of 41% were achieved. The comparison test of S11, using 10% salinity influent, 10 days HRT and 1.0 g COD/L/d organic loading rate, possessed the best performance among all tests, with the highest COD removal efficiency, gas production rate, methane production rate, methane content of 68.52%, 0.122 L/L/d, 0.067 L CH4/L/d and 54.88%, respectively. The results of bacterial community analysis showed Chromohalobacter and Halanaerobium were the dominant bacteria in the steady states of S7-S11. In other aspects, archaea were found in the highest two MPR tests, S10 and S11. The relative abundance of Methanosarcina and Halobacterium were 2.75 and 2.25%, respectively. Besides, significant methane production was observed when relative abundance of Halanaerobium was within the range of 53-55%, but dramatically decrease in pH, gas production, methane content and methane production rate were found when it was larger than 75% (in test S9).