Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.     

Applications of two-phase anaerobic degradation in industrial wastewater treatment

Prospects for the phased anaerobic treatment of wastewater are extremely promising. With the variety of reactor designs available and the amenability of reactors to modification, existing treatment systems may be replaced or upgraded as required to achieve increased stability, higher loading capacities and greater process efficiencies than single-stage systems. In recent times, various reactor configurations and substrates are applied to two-phase anaerobic process. This paper reviews applications and studies of two-phase anaerobic degradation for wastewater treatment, sums up the performance of application to treating waste from distillery, landfill leachate, coffee, cheese whey and dairy, food, pulp and paper, sludge and solid, etc., and summarises reactor configurations, environmental and operational conditions, and comparisons of two-phase anaerobic digestion with other anaerobic reactors.     

提高厌氧处理甲烷生成量方法的初步探讨

废水厌氧处理因其投资少、运行费用低、耐负荷、耐有毒物质冲击、可间断性运行、污泥产生量少、有可回收能源等优点倍受人们关注。但是 ,其处理效率低于好氧处理的现实却一直在困扰着人们。本文针对这一问题 ,从提高甲烷量的角度 ,提出了几点改进的方法 :消化气回流、消化气回流加氢和消化气回流加氢加热 ,并进行了初步实验。实验结果表明 ,甲烷气生成量和COD去除率都相应地得到了提高。     

常温条件下2种厌氧折流板反应器处理淀粉废水的启动实验

为了研究厌氧折流板反应器在常温下的启动情况,在22.5～30.2℃条件下,对不加填料的5隔室厌氧折流板反应器和加填料的4隔室复合式厌氧折流板反应器同步进行了启动实验。实验用水为高浓度淀粉废水,两反应器采用相同的启动策略,即梯度增加进水COD浓度与降低水力停留时间相结合的方式。两反应器有效容积均为47.8 L,启动初始负荷为0.6 kg COD/(m3.d),逐渐增加到10 kg COD/(m3.d)。实验表明,经过6个阶段87 d的运行,反应器启动完成,并成功培养出颗粒污泥,两反应器对COD的去除率都能达到85%以上。在启动过程中两反应器对COD的去除效率相近。     

污泥厌氧消化前处理技术研究现状及展望

污泥厌氧消化产生的沼气用于发电是一种具有广阔应用前景的垃圾资源化方法.厌氧消化前采用不同的预处理方法能促进污泥内微生物细胞的分解、加速胞内物质的释放、加快污泥的水解速率,这是增强污泥厌氧消化性能的关键.综述了当前研究和应用较多的物理法、化学法和生物法等污泥预处理技术,分析了各种方法的原理、特点、处理效果及应用前景.     

厌氧反应器废水资源化过程在线监测系统

为克服现行厌氧反应器状态离线分析的滞后性,充分利用资源,改进废水排放状态,研究了基于荧光光谱的废水资源化处理过程在线监测系统。系统以厌氧反应器中的关键产物色氨酸、核黄素及辅酶为主要检测组分,自动定位滤波轮并控制脉冲氙灯的闪烁次数,使用光电倍增管采集荧光信号。针对反应产物的混合体系,提出了将三维数据二维化的准三维荧光谱概念,优化获得了的3×3荧光强度矩阵,采用偏最小二乘法并优化其模型参数,实现了反应器中3种关键过程产物的实时在线检测、统计与分析,使其回收率范围达到85%至112%。     

Phenol degradation and microbial characteristics in upflow anaerobic sludge blanket reactors at ambient and mesophilic temperatures

A synthetic wastewater containing phenol as sole substrate was respectively treated at temperatures of 26±1°C and 37±1°C in 2.8 litre upflow anaerobic sludge blanket (UASB) reactors. At the two temperatures, pH 7.0–7.5, with a 1:1 effluent recycle ratio, phenol in wastewater was efficiently degraded in a UASB reactor. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) showed that less shift in the microbial community occurred with the temperature changing. Phenol degradation in wastewater was recommended to select ambient temperature in UASB reactors. The optimal HRT was 12 to 16 hours corresponding to 6.0–4.5 g COD/(l.d) loading rate at ambient temperature in UASB reactors. The distribution of archaeal and bacterial populations in the UASB granular consortium was revealed using fluorescence in situ hybridisation (FISH) technique.     

Biodegradation behavior of agricultural pesticides in anaerobic batch reactors

This study explored the biodegradation potential of two agricultural pesticides (2,4-D and isoproturon) as well as their effect on the performance of the anaerobic digestion process. Three 3.5 L batch reactors were used, having the same initial isoproturon concentration (25 mg/L) and different 2,4-D concentrations (i.e. 0, 100, or 300 mg/L, respectively). All systems were fed with equal amounts of primary sludge and digested sludge and operated at the low mesophilic range (32 ± 2°C). Following an acclimation period of approximately 30 days, complete 2,4-D removal was achieved, whereas isoproturon biodegradation was practically negligible. The presence of 2,4-D did not have a direct effect on acidogenesis since soluble organic carbon [expressed either as volatile fatty acids (VFAs) or as total organic carbon (TOC)] peaked within the first 10 days of operation in all bioreactors. Utilization of VFAs however appeared to follow two distinct patterns: one pattern was represented by acetate and butyrate (i.e. no acid accumulation) while the other was followed by propionate, isobuturate, valerate and isovalerate (i.e. acid accumulation, duration of which was related to the initial 2,4-D concentration). On the whole, all reactors exhibited a successful digestion performance demonstrated by complete VFAs utilization, considerable gas production (containing 45 to 65% methane by volume), substantial volatile suspended solids (VSS) reduction (42 to 50%), as well as pH and alkalinity recovery.     

Biodegradation behavior of agricultural pesticides in anaerobic batch reactors

This study explored the biodegradation potential of two agricultural pesticides (2,4-D and isoproturon) as well as their effect on the performance of the anaerobic digestion process. Three 3.5 L batch reactors were used, having the same initial isoproturon concentration (25 mg/L) and different 2,4-D concentrations (i.e. 0, 100, or 300 mg/L, respectively). All systems were fed with equal amounts of primary sludge and digested sludge and operated at the low mesophilic range (32 +/- 2 degrees C). Following an acclimation period of approximately 30 days, complete 2,4-D removal was achieved, whereas isoproturon biodegradation was practically negligible. The presence of 2,4-D did not have a direct effect on acidogenesis since soluble organic carbon [expressed either as volatile fatty acids (VFAs) or as total organic carbon (TOC)] peaked within the first 10 days of operation in all bioreactors. Utilization of VFAs however appeared to follow two distinct patterns: one pattern was represented by acetate and butyrate (i.e. no acid accumulation) while the other was followed by propionate, isobuturate, valerate and isovalerate (i.e. acid accumulation, duration of which was related to the initial 2,4-D concentration). On the whole, all reactors exhibited a successful digestion performance demonstrated by complete VFAs utilization, considerable gas production (containing 45 to 65% methane by volume), substantial volatile suspended solids (VSS) reduction (42 to 50%), as well as pH and alkalinity recovery.     

Gas chromatographic studies on the biodegradation of nitrobenzene and 2,4-dinitrophenol in the nitrobenzene plant wastewater

The biodegradation of nitrobenzene (NB) and 2,4-dinitrophenol (DNP) in NB plant wastewater has been studied using acclimated activated sludge in a batch bioreactor. The gas chromatographic (GC) monitoring shows simultaneous utilization of these two substrates, and both NB and DNP were ultimately biodegraded. The primary and ultimate biodegradation rates using GC and COD methods, respectively, are compared and reported.     

生产性IC反应器厌氧颗粒污泥的生物学特征

IC反应器以絮状污泥接种用于处理酒糟废水,运行至第180d时分别测定反应器第1、第2反应室颗粒污泥的VSS、产甲烷活性、胞外多聚物和辅酶F420等各项生物学指标。结果表明反应器内颗粒污泥具有较强活性,反应器COD去除率基本稳定在95%以上,出水COD不超过1000mg/L。     

城市生活污水厌氧生物处理发展现状

回顾了国内外污水厌氧生物处理工艺的发展情况,着重分析了中国城市污水的特点以及厌氧生物处理工艺在城市生活污水处理中的应用情况。     

Recycled and virgin plastic carriers in hybrid reactors for wastewater treatment.

The reduction of organic and nitrogen pollution of wastewater was investigated in two hybrid reactors and compared with the reduction obtained by using a conventional activated sludge reactor (ASR) run as a control. Both HR-1 and HR-2 were activated sludge systems where a low-density carrier, P1 (polyethylene) for HR-1 and P2 (recycled plastics) for HR-2, was added. Firstly, the three reactors were operated at 10 days Suspended Solid Retention Time (SRT(SS)), leading to a complete nitrification. Secondly, the SRT(SS) for each reactor was lowered to 3 days. Nitrification was lost for the ASR but remained complete for HR's. Respirometric techniques were used to measure fixed or suspended biomass activities for heterotrophic and autotrophic biomass. More than 90% of the autotrophic activity was found on the supports whatever the SRT(SS) used. The results may underline the role of the carrier geometry or surface characteristics on the autotrophic/heterotrophic microorganism distribution.     

单组分垃圾厌氧降解初期的产气规律及恶臭特征

研究了垃圾单组分(蛋白类和糖类)厌氧降解初期的产气动态规律和恶臭特征。结果表明,糖类物料厌氧降解的累积产气量大于蛋白类物料,各物料的气体排放动态曲线不同,酪蛋白和淀粉物料呈现Monod型曲线,而纤维素物料呈现2次Monod型曲线;蛋白类物料降解产生的恶臭气体成分更丰富,且动态变化曲线有多种形式:硫化氢、磷化氢和硫8的浓度变化曲线呈单峰型,聚硫醚浓度曲线呈S型,挥发性脂肪酸(VFAs)呈Monod型曲线;臭气强度分析结果表明,蛋白类物料产生的臭气强度高于糖类物料。单组分垃圾产气规律和恶臭特征的研究结果为开发高效恶臭原位控制技术提供了理论基础。     

生活污水中糖类测试方法研究

分别用蒽酮比色、苯酚-硫酸及气相色谱法3种测试方法测试了上海市某生活小区生活污水的糖类组成.试验结果表明,蒽酮比色法测试糖类浓度的准确性与精确性优于苯酚-硫酸法,但不能得出污水中糖类的详细组成情况;与蒽酮比色法和苯酚-硫酸法相比,气相色谱法不仅能得出污水中糖类的详细组成,而且还具有较高的精密度.气相色谱法测得的生活污水中各种单糖,如木糖、甘露糖、葡萄糖、半乳糖、鼠李糖、核糖、岩藻糖的质量浓度分别为8.25、 6.02、5.52、4.80、4.44、4.41、2.66 mg/L.     

两相厌氧在浆粕废水处理工程中的应用

浆粕废水组分较为复杂,废水治理具有一定的技术难度,采用两相厌氧、间歇式活性污泥法和物化处理组合工艺可以取得较好的效果。生产运行表明两相厌氧工艺对CODCr、BOD5的去除效率分别达67%～78%和82%～87%,生物水解使挥发酸提高了23～34倍。根据水质和水量的变化情况,及时调整其操作参数可使水解池维持良好的运行状态。     

Rapid anaerobic degradation of toxaphene in sewage sludge

We studied the degradation of technical toxaphene in anaerobic sewage sludge from a municipal waste water treatment plant. Chlorobornanes, chlorocamphenes and related compounds were rapidly degraded, with degradation rates in the order of decachloro>nonachloro>octochloro>heptachloro approximately = hexachloro compounds. The half-lives of individual congeners ranged from <1 day to several days. We also studied the degradation of technical toxaphene in previously sterilized sludge (control), and found it was slower than in the anaerobic sludge. The chlorobornanes that degraded most rapidly in the non-sterilized anaerobic sludge were those with gem chloro substitution on the 6-member carbon-ring, including the toxic congeners, Toxicant A and B. Non-gem chloro substituted congeners, like the biologically persistent P26 and P50, also degraded, but less rapidly. Toxaphene degradation in sewage sludge proceeded primarily via reductive dechlorination, leading to HxSed, HpSed, TC2 and other persistent metabolites. Enantioselective determinations indicated little, if any, enantioselectivity in the formation and/or degradation of these compounds. The isomer and enantiomer profiles of the hexa-, hepta-, and octachlorobornanes are similar to those observed in sediment from the Baltic Sea, suggesting that technical toxaphene is the source of these compounds and that its composition was changed via similar anaerobic degradation pathways.     

厌氧颗粒污泥反应器对丙酸和丁酸冲击负荷变化的响应研究

采用升流式厌氧污泥床（UASB）反应器,对增大进水浓度和增大进水流量过程中,颗粒污泥对丙酸和丁酸冲击负荷变化响应进行了研究。实验表明,进水浓度从2 000 mg COD/L提高到5 000 mg COD/L,丙酸去除率骤降,而丁酸降解相对稳定;在保持进水浓度为3 000 mg COD/L的条件下,增大进水流量,负荷从7.5 kg COD/（m3.d）升高到15 kg COD/（m3.d）时,丙酸降解率骤降,丁酸降解率仍然相对稳定。实验结果符合降解热力学理论和传统抑制动力学的未解离挥发性脂肪酸理论,并发现改变反应器运行条件能够加剧未解离酸的抑制作用。同时提出了探讨厌氧过程中丙酸积累导致厌氧反应器运行失败的基础理论原因。     

Aerobic and anaerobic membrane bioreactors for municipal wastewater treatment.

An aerobic bioreactor and an anaerobic bioreactor, each coupled with a microfiltration membrane filter (MBR), were operated at different hydraulic retention times (HRTs) with primary effluent from the City of Elmhurst, Illinois, municipal-wastewater-treatment plant. The soluble chemical oxygen demand (COD) removal performance of the anaerobic MBR system was similar to that of the aerobic MBR under the same operational conditions, without the added cost of aeration. The results indicated that the solids deposition rate on the membrane surface was lower in the case of anaerobic MBR compared to the aerobic MBR, indicating possible lower loss in water-flux rates. This research found that an anaerobic MBR is a feasible and economical option for municipal-wastewater-treatment plants seeking COD removal by a biological process followed by a separate nitrification and denitrification system.