驯化污泥厌氧还原脱氯促进2,4,6-三氯酚矿化及胞外呼吸脱氯途径

2,4,6-Trichlorophenol Mineralization Promoted by Anaerobic Reductive Dechlorination of Acclimated Sludge and Extracellular Respiration Dechlorination Pathway

厌氧条件下,以乳酸钠为电子供体,2,4,6-三氯酚为电子受体对活性污泥进行驯化,考察了驯化污泥厌氧脱氯的代谢特性.结果发现,污泥可对2,4,6-三氯酚进行高效脱氯,乳酸钠、2,4,6-三氯酚初始浓度为20 mmol·L-1、40~80μmol·L-1时,9~24 h内可实现2,4,6-三氯酚100%初始性降解.中间产物有2,4-二氯酚,但检出浓度较低(<4.22μmol·L-1),4-氯酚和苯酚为主要产物.驯化污泥以脱邻位氯(2,4,6-三氯酚,2,4-二氯酚)降解菌为优势种群,对4-氯酚和苯酚的进一步转化有限.厌氧代谢残留物经好氧污泥处理后,4-氯酚(初始浓度33μmol·L-1)2 h实现100%去除.驯化污泥可快速将Fe(Ⅲ)还原为Fe(Ⅱ),并具有较强的腐殖质(AQDS)还原能力,说明驯化污泥中富集了异化铁还原菌.电子介体[Fe(Ⅲ)和AQDS]明显地加速了脱氯速率,在电子介体的介导作用下,污泥可同步进行胞外呼吸脱氯.

In anaerobic conditions,the acclimation of activated sludge was studied with sodium lactate as the electron donor and2,4,6-trichlorophenol as the electron acceptor. Metabolic characteristics of dechlorination were the focus of this study. The result showed highly efficient dechlorination on 2,4,6-trichlorophenol that the conversion rate reached to 100% in 9-24 h when initial concentrations of sodium lactate and 2,4,6-trichlorophenol were 20 mmol·L- 1and 40-80 μmol·L- 1,respectively. The intermediate product 2,4-dichlorophenol was found in low concentration( < 4. 22 μmol·L- 1). And 4-chlorophenol and phenol were the main products.Ortho chlorophenol( 2,4,6-trichlorophenol,2,4-dichlorophenol) can be converted rapidly by acclimated sludge,while the further conversion of 4-chlorophenol and phenol was limited. The residues of anaerobic metabolism were degraded by aerobic sludge,among which 4-chlorophenol( initial concentration of 33 mol·L- 1) removal rate was up to 100% under aerobic conditions. The acclimated bacteria can rapidly transfer Fe( Ⅲ) and humus( AQDS) into reductive Fe(Ⅱ) and AQH2 DS which indicated that the dissimilatory iron reducing bacteria was enriched in the acclimated sludge. The electron mediator [Fe( Ⅲ) and AQDS] significantly accelerated the dechlorination rate. The acclimated sludge could perform extracellular respiration dechlorination with electron mediators.