【作者】 王兴祖；

【导师】 孙德智；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2009， 博士

【摘要】 染料废水由于具有色度高、毒性大、生物降解性差的特点,成为难处理的工业废水之一。光合细菌具有抗逆性强、能处理难降解有机物等独特的优点,因此,光合细菌法可用于染料废水的处理。本论文以自行研发的光生物转盘为主体工艺,研究了缺氧光生物转盘(PRBC)-好氧移动床生物膜(MBBR)组合工艺对偶氮染料废水的处理效能,并对光合细菌纯菌株的脱色特性和介体强化染料脱色的机制进行了研究,最后,通过氧化还原介体强化了组合工艺的处理效果。本论文研制了用于染料废水生物处理的缺氧光生物转盘,该反应器具有光衰减低、不需要进行光合细菌菌体回流等特点。将其与好氧MBBR串联,形成缺氧光生物转盘-好氧MBBR组合工艺,进而用于偶氮染料废水的处理。经过35d左右光生物转盘启动成功,此时废水脱色率和COD去除率均稳定在92%左右。成熟的光生物膜分为内外两层,分别由光合细菌和丝状菌组成,其中,丝状菌对盘片的吸附在整个生物膜的形成中起关键作用。缺氧光生物转盘-好氧MBBR组合工艺适宜的运行条件如下:光生物转盘控制缺氧条件、光照时间≥6h/d、HRT≥10h,相应的MBBR的HRT≥20h。在此条件下,系统脱色率和COD去除率分别达到92%和91%。该组合工艺具有较强的抗染料冲击负荷能力,在染料负荷高达7.2×105mg/(m3·d)时,脱色率和COD去除率仍可达到86%和90%;其中,光生物转盘对色度的去除起主要作用,后续的MBBR起到保证出水水质的作用。组合工艺要求的共基质浓度较低,当染料浓度为100mg/L,共基质浓度在1000mg/L时,系统脱色率即可达到90%。变性梯度凝胶电泳及16S rRNA测序分析表明,光生物膜主要包含沼泽红假单胞菌、万尼氏红微菌、泥生绿菌、褐杆状绿菌以及未培养的蓝细菌等光合细菌和其它细菌。硫酸盐、光照和氧气对光合细菌群落的影响较大。硫酸盐是改变紫色细菌和绿色细菌相对优势的致变因子,高浓度硫酸盐抑制紫色细菌而激活绿色细菌。光照时间和供氧量的增加能够强化光合细菌的优势地位而不改变紫色细菌和绿色细菌的群落结构。从缺氧光生物转盘中分离到一株高效脱色的沼泽红假单胞菌W1,该菌株生长和脱色的最佳条件为:pH≤10;以谷氨酸盐或乳酸盐为碳源,当选择乳酸盐时其浓度应≥500mg/L;以NH4Cl为氮源,浓度应≥100mg/L;盐度≤5%;活性黑5(RB5)浓度≤700mg/L;有光照。在最优条件下,20h内RB5的脱色率可大于95%。菌株W1的偶氮还原酶最适pH值为7.0,最适温度40℃。菌株W1具有较高的蒽醌-2-磺酸钠(AQS)和2-羟基-1,4-萘醌(lawsone)还原酶活性,而对1,2,7-三氨基-8-羟基-3,6-二磺酸萘(TAHNDS)的还原能力相对较弱。研究了偶氮染料RB5在菌株W1作用下的生物脱色,发现RB5的脱色代谢物(DM)能够催化RB5的脱色,表明RB5生物脱色具有自催化作用。在适宜的DM浓度下,RB5在5h内脱色率接近70%。RB5的DM还能够催化其它染料的脱色。优化DM浓度后,直接黄11(DY11)的脱色速率与不加DM的空白相比可提高2.2倍。循环伏安的结果证实,DM具有氧化还原介体的性质。通过对DM的FT-IR和HPLC-MS分析可知,DM中起氧化还原介体作用的物质为TAHNDS。在混合染料脱色时,RB5优先于AR1降解,释放的DM可催化AR1的脱色,使AR1的脱色速率提高近一倍。厌氧硫酸盐还原产生的硫化物能够经由DM的媒介使RB5化学脱色。对于不产生介体的DY11脱色体系,硫化物对脱色无促进作用。硫化物对染料化学脱色后自身转化为单质硫,在厌氧条件下单质硫能被菌株W1重新转化为硫化物,继续还原染料。利用RB5作为内源介体强化工艺对AR1的脱色,在进水存在共基质,酸性红1(AR1)为100mg/L,RB5浓度为150mg/L的条件下,组合工艺脱色率和COD去除率可分别达到91%和94%。缺乏共基质时,RB5抑制AR1脱色。硫酸盐对RB5废水的脱色具有促进作用,硫化物还原RB5后形成的硫单质在生物膜中沉积;对于不能产生介体的DY11废水,硫酸盐对其脱色和COD去除产生抑制作用。投加AQS柱撑类水滑石作介体,在HRT为5h,进水AR1为100mg/L的条件下,组合工艺在18d内的脱色率和COD去除率可分别稳定在89.9%和90%。此外,AQS柱撑类水滑石促使硫酸盐还原率从56%提高到90%。更多还原

【Abstract】 Dyeing stream is a big challenge in industrial wastewater treatment due to its high chromaticity, high toxicity and biological refractory. Processes employing photosynthetic bacteria (PSB) are demonstrated to take advantages in stress resistance and capability of degrading refractory compounds. In this dissertation, an anoxic photo-rotating biological contactor (PRBC) was developed and combined with an aerobic moving bed biofilm reactor (MBBR) to treat azo dye wastewater, and its treatment efficiency was evaluated. Then the characteristics and decolorization efficiency of photosynthetic bacteria isolated from the anoxic PRBC and the role of redox mediator in the biodecolorization process were studied, respectively. Furthermore, the treatment performance of the anoxic PRBC was enhanced by supplement redox mediators.The anoxic PRBC has no PSB reflux and its luminous decay is low. Azo dye wastewater was treated by the combined process of the anoxic PRBC and the aerobic MBBR. The anoxic PRBC was successfully started up within 35 days. After the success of start-up, the decolorizaiton rate and COD removal rate were both stabilized at approximate 92%. It was found that the stable phototrophic biofilm consisted of two layers: inner layer of photosynthetic bacteria and outer layer of filamentous bacteria, and filamentous bacteria played an important role in the attachment of the biofilm to the disks.The suggested conditions for dyeing wastewater treatment by PRBC-MBBR were: anoxic, illumination time≥6h/d and HRT≥10h, under which the total color and COD removal efficiencies were 92% and 91% respectively. PRBC-MBBR resisted high shocking load of dyes; color and COD removal efficiencies of up to 86% and 90% were obtained even under 7.2×105 mg/m3·d of dyes, and the color removal was mainly attributed to the anoxic PRBC, while the sequential MBBR ensured the water quality of the final effluent. The essential concentration of co-substrate for the decolorization by PRBC-MBBR was low. When concentrations of the dye and the co-substrate were 100 and 1000 mg/L, total decolorization efficiency of 90% was achieved.Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rRNA sequences analysis revealed that the phototrophic biofilm developed in this study consisted Rhodopseudomonas palustris, Rhodomicrobium vannielii, Chlorobium limicola, Chlorobium phaeobacteroides, uncultured cyanobacterium and other bacteria. Sulfate, light and oxygen strongly affected the phototrophic bacterial community. Sulfate was the key factor for switching between purple and green bacteria; high concentration of sulfate was an inhibitor for purple bacteria but a stimulator for green ones. Increases in light time and oxygen supply enhanced the predominance of photosynthetic bacteria in the system, whereas did not change the community structure.An efficient bacterial decolorizer Rhodopseudomonas palustris W1 was isolated from the anoxic PRBC. The results of batch tests of decolorization suggested that to enhance strain W1 growth and its decolorization efficiency, suitable pH level (≤10), carbon source and its concentration (glutamine or lactate recommended,≥500 mg/L when lactate was selected), nitrogen source and its concentration (NH4Cl recommended,≥100 mg/L), salinity (NaCl concentration≤5%), RB5 concentration (≤700 mg/L), and light presence were required. Under that optimal condition, over 95% of color removal efficiency could be achieved in 20 h. The optimal pH for azoreductase from strain W1 was 7.0, and temperature was 40℃. Moreover, strain W1 exhibited high reductase activity of anthraquinone-sulfonate (AQS) and lawsone, but relatively low of 1-2-7-triamino-8-hydroxy-3-6-naphthalinedisulphate (TAHNDS).The biodecolorization of Reactive Black 5 (RB5) by strain W1 was studied and autocatalysis was observed, that is the decolorization metabolites (DM) from RB5 accelerated its own further decolorization. At a suitable DM concentration, the decolorizaton rate was improved to 70% in 5 h. DM from RB5 can also catalyze the decolorization of other dyes. The decolorization rate of Direct Yellow 11 (DY11) was increased by 2.2-fold by supplementing an optimized amount of DM, compared with unamended controls. Cyclic voltammetric(CV) tests revealed that DM could be a rodox mediator. The results of FT-IR and HPLC-MS showed that the active component in DM as a redox mediator was TAHNDS. In the decolorization of a dye mixture of RB5 and AR1, RB5 was decomposed before AR1, and the DM released catalyzed the decolorization of AR1, increasing its rate by 2-fold.DM can mediate the chemical reduction of RB5 by sulfide produced in the anaerobic bioreduction of sulfate. But sulfide did not contribute to the biodecolorization of DY 11 since no redox mediator was produced in this group of azo dyes. Sulfide was oxidized to elemental sulfur during the chemical decolorization of dyes. Under anaerobic condition, sulfur could be readily reduced to sulfide again by W1, which reduced azo dyes repeatedly.When employing RB5 as an endogenic redox mediator, the color and COD removal efficiencies were up to 91 and 94% respectively under 100 mg/L of AR1 and 150 mg/L of RB5 and in the presence of co-substrate. Without co-substrate, RB5 inhibited the decolorization of AR1. Sulfate accelerated the decolorization of RB5 and elemental sulfur produced during the reduction of sulfide accumulated in the biomass. However sulfate had inhibition in the COD removal and decolorization of DY11 because DY11 could not produce redox mediators during its degradation.AQS pillared hydrotalcite was supplemented as an immobilized redox mediator in PRBC-MBBR system. Under HRT of 5h and initial AR1 concentration of 100mg/L, the color and COD removal efficiencies of the two-stage process stabilized at 89.9 and 90% respectively in 18d. In addition, the AQS pillared hydrotalcite improved the sulfate reduction efficiency from 56% to 90%.更多还原