Removal of Hydrophobic Volatile Organic Compounds in an Integrated Process Coupling Absorption and Biodegradation—Selection of an Organic Liquid Phase

Since usual processes involve water as absorbent, they appear not always really efficient for the treatment of hydrophobic volatile organic compound (VOC). Recently, absorption and biodegradation coupling in a two-phase partitioning bioreactor (TPPB) proved to be a promising technology for hydrophobic compound treatment. The choice of the organic phase, the non-aqueous phase liquid (NAPL) is based on various parameters involved in both steps of the process, hydrophobic VOC absorption in a gas?Cliquid contactor, and biodegradation in the TPPB. VOC solubility and diffusivity in the selected NAPL, as well as NAPL viscosity, seems to be the main parameters during the absorption step, while biocompatibility, namely the absence of toxic effect of the NAPL towards microorganisms, non-biodegradability and VOC partition coefficient between NAPL and water were revealed as the key factors during the biodegradation step. The screening of the various NAPL available in the literature highlighted two families of compounds matching the required conditions for the proposed integrated process, silicone oils and ionic liquids.     

Influence of Particle Association and Suspended Solids on UV Inactivation of Fecal Indicator Bacteria in an Urban River

Different cases of bioremediation technique were experimentally investigated here for decontaminating light non-aqueous phase liquid (LNAPL)-polluted groundwater collected from Panipat oil refinery situated in Haryana, India. Natural biodegradation of toluene, the selected LNAPL, was studied first under different varying substrate concentrations at room temperature (21.6?±?0.3 °C). Biostimulation was then studied by mixing the polluted groundwater with a primary treated domestic wastewater for providing nutrients and other supplementary components to the native microbial population. For studying the remaining cases, small-scale wetland having plants of Canna generalis was developed in the laboratory with and without the presence of toluene in the rhizosphere. The wetland system in the presence of toluene was used here for developing the pre-grown microbial cultures to enhance the degradation rate of the LNAPL (bioaugmentation). The plant-assisted biostimulation was studied in the third case by adding the polluted groundwater with the root zone water of the wetland system developed without the presence of toluene. In the fourth case, the biostimulation was coupled with the bioaugmentation strategy by mixing the groundwater with the root zone water of the wetland system developed in the presence of toluene. A comparative account of these four different bioremediation techniques was prepared for their respective rates of biodegradation, duration of lag phases, and the total time of degradation. It was observed that the plant-assisted bioremediation techniques had better performance over the natural biodegradation and biostimulation methods of the considered LNAPL. The plant-assisted biostimulation coupled with the bioaugmentation technique needed almost no acclimatization time and accelerated the rate of degradation almost twofold compared to the natural bioremediation and, hence, is proved to be the best one among the other bioremediation techniques for decontaminating the LNAPL-polluted groundwater. The results of the conducted experiments can be used to obtain vital information on framing the engineered bioremediation planning for LNAPL-contaminated sites.     

Application of Adsorption and Ultrafiltration Processes for the Pre-treatment of Several Industrial Wastewater Streams

In this work ultrafiltration (UF) was coupled with suitable minerals and dried activated sludge for the pre-treatment of several industrial wastewater streams. The aim was to decrease heavy metal concentrations to low levels so that wastewater can be safely discharged into municipal sewers or biological wastewater treatment can take place without biomass inhibition problems. Industrial wastewater originating from metal plating, chemical and textile industries was employed. The experiments were conducted in a reactor where the UF membrane module was immersed. UF reduced the amount of heavy metals, but the performance was variable with removal efficiencies ranging from 20 to 99.7?%, depending on the metal type and on the wastewater initial characteristics. The prevailing wastewater characteristics were the pH, the presence of certain anions, the suspended solids concentration and the presence of competing cations. The addition of activated sludge and/or minerals could further increase heavy metal removal through the process of sorption. UF assisted by minerals could achieve variable colour and COD removal ranging from 22 to 94?% and 58 to > 99.9?% respectively. Minerals resulted in membrane fouling mitigation, while sludge adversely impacted on fouling.     

Influence of rhamnolipids and triton X-100 on the biodegradation of three pesticides in aqueous phase and soil slurries.

The effect of surfactants on the biodegradation of trifluralin and atrazine (by Streptomyces PS1/5) and coumaphos (by degrading consortia from a contaminated cattle dip) in liquid cultures and soil slurries was tested at different concentrations of a rhamnolipid mixture (Rh-mix) and Triton X-100 (TX-100). The extent of trifluralin biodegradation in liquid culture was improved at high concentrations of both surfactants. The extent of atrazine degradation dropped in the presence of either surfactant. Coumaphos biodegradation improved slightly at Rh-mix dosages >3000 microM; however, it was readily inhibited by TX-100 at amounts above the critical micelle concentration. In soil slurries, the extent of both trifluralin and atrazine biodegradation was higher in Hagerstown A (HTA) soil than in Hagerstown B (HTB) soil and was not significantly affected by the presence of either surfactant. The onset of trifluralin biodegradation was retarded at higher concentrations of surfactants. In the absence of surfactant, up to 98% of coumaphos in both soil slurries was transformed. At increasing dosages of Rh-mix, the onset of coumaphos biodegradation was retarded, but the removal efficiency of the pesticide increased. Rh-mix and TX-100 depletion was observed during Streptomyces PS1/5 growth in liquid cultures. Rh-mix concentration also decreased during coumaphos biodegradation, whereas TX-100 concentration was not affected. These results suggest that surfactants, added for the purpose of increasing the apparent water solubility of hydrophobic organic compounds, may have unintended effects on both the rate and extent of biodegradation of the target compounds if the surfactants can also be degraded by the microorganisms in the system.     

Na+和K+共存对A2/O工艺脱氮除磷效果及污泥性质的影响

为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na~+、K~+共存对A~2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na~+/K~+摩尔比下A~2/O工艺优势种群的演替规律,以期从微生物角度明确Na~+、K~+共存对含盐废水污染物去除率的影响。结果表明:当进水Na~+/K~+摩尔比分别为2、1和0.5时,A~2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K~+浓度的提高缓解了Na~+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na~+/K~+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K~+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。     

Suitability of Test Chambers for Analyzing Air Pollutant Removal by Plants and Assessing Potential Indoor Air Purification

A unique test chamber system, which enables experiments with plants under highly controlled environmental conditions, was used to examine the pollutant removal efficiency of plants. For this purpose, the removal of two different volatile organic compounds (VOC) (toluene, 2-ethylhexanol) from the air by aerial plant parts of two common indoor plant species (Dieffenbachia maculata and Spathiphyllum wallisii) was monitored. While the control over environmental conditions (temperature, relative humidity, CO₂ content, and light condition) worked very well in all experiments, control experiments with the empty chamber revealed high losses of VOC, especially 2-ethylhexanol, over the test duration of 48 h. Nonetheless, compared to the empty chamber, a significantly stronger and more rapid decline in the toluene as well as in the 2-ethylhexanol concentrations was observed when plants were present in the chamber. Interestingly, almost the same VOC removal as by aerial plant parts could be achieved by potting soil without plants. A comparative literature survey revealed substantial heterogeneity in previous results concerning the VOC removal efficiency of plants. This can be mainly attributed to a high diversity in experimental setup. The experimental setup used in the current study offers an excellent opportunity to examine also plant physiological responses to pollutant exposure (or other stressors) under highly controlled conditions. For the analysis of VOC removal under typical indoor conditions, to obtain data for the assessment of realistic VOC removal efficiencies by plants in rooms and offices, a guideline would be helpful to achieve more coherent findings in this field of research.     

Biodegradation of biodiesel and toluene under nitrate-reducing conditions and the impact on bacterial community structure

Purpose

Biodiesel is a renewable fuel that can be mixed with toluene and be accidentally released into anoxic ecosystems and impact soil microbial communities. Therefore, the aim of the present work was to examine, under nitrate-reduction conditions, the biodegradation of toluene in the presence of two different types of biodiesel (sunflower and rapeseed), and their impact on the bacterial community structure.

Materials and methods

Sediment samples were spiked individually with toluene, biodiesel, and their blends in laboratory-designed microcosms. Sunflower oil biodiesel was produced in the laboratory, while rapeseed oil biodiesel was a commercial product. Degradation of biodiesels and blends was monitored by directly measuring the substrate or indirectly by determining nitrate removal during the course of the experiment. Denitrification rates were estimated with the acetylene inhibition technique. Denaturing gradient gel electrophoresis was used to assess impacts on the bacterial community structure exposed to biodiesels, blends, and toluene.

Results and discussion

The results of this study showed that toluene and biodiesel were completely degraded within 10 days. Biodiesel significantly affected the bacterial community structure at a similar magnitude, independently of its origin. Additionally, toluene impacted the bacterial community and denitrification process to a lower extent than biodiesel and a clear decrease in the relative bacterial richness and diversity was shown in samples with biodiesel and blends. To the best of our knowledge, this is one of the first reports describing degradation of biodiesel alone and blends under nitrate-reducing conditions, and also the effects of these compounds on the denitrification process. In addition, due to the recently discovered “oxygenic denitrification” process, the acetylene inhibition technique and nitrous oxide quantification may not be the most adequate tool to estimate denitrification rates. Further detailed studies are advised to understand whether the identified bacterial community shift impacts ecosystem functions.

Conclusions

Our results help to understand the biodegradation of toluene, biodiesel, and their blends in sediments under nitrate-reducing conditions and might be important in implementing bioremediation strategies in anoxic environments.

     

The Potted-Plant Microcosm Substantially Reduces Indoor Air VOC Pollution: II. Laboratory Study

Indoor air-borne loads of volatile organic compounds (VOCs) are usually significantly higher than those outdoors, and chronic exposures can cause health problems. Our previous laboratory studies have shown that the potted-plant microcosm, induced by an initial dose, can eliminate high air-borne VOC concentrations, the primary removal agents being potting-mix microorganisms, selected and maintained in the plant/root-zone microcosm. Our office field-study, reported in the preceding paper, showed that, when total VOC (TVOC) loads in reference offices (0 plants) rose above about 100 ppb, levels were generally reduced by up to 75% (to < 100 ppb) in offices with any one of three planting regimes. The results indicate the induction of the VOC removal mechanism at TVOC levels above a threshold of about 100 ppb. The aims of this laboratory dose-response study were to explore and analyse this response. Over from 5 to 9 days, doses of 0.2, 1.0, 10 and 100 ppm toluene and m-xylene were applied and replenished, singly and as mixtures, to potted-plants of the same two species used in the office study. The results confirmed the induction of the VOC removal response at the lowest test dosage, i.e in the middle of the TVOC range found in the offices, and showed that, with subsequent dosage increments, further stepwise induction occurred, with rate increases of several orders of magnitude. At each dosage, with induction, VOC concentrations could be reduced to below GC detection limits (< 20 ppb) within 24 h. A synergistic interaction was found with the binary mixtures, toluene accelerating m-xylene removal, at least at lower dosages. The results of these two studies together demonstrate that the potted-plant microcosm can provide an effective, self-regulating, sustainable bioremediation or phytoremediation system for VOC pollution in indoor air.     

Heavy metal and volatile organic chemical removal and treatment in on-site wastewater infiltration systems

Solvents, greases, and rinse waters from routine vehicle maintenance contain heavy metals and volatile organic chemicals (VOCs). In Wisconsin, these fluids enter catch basins along with rinsing waters and are discharged to soil infiltration systems drainfields after mixing with domestic wastewaters in a septic tank. The purpose of this study was to monitor heavy metal and VOC removal and treatment in catch basins and septic tanks at four publicly-owned motor vehicle service stations (MVSS). Cadmium, chromium, and lead were found in catch basin wastewater, septic tank effluent, and septic tank sludge at concentrations ranging from 0.002–7.7 mg L^?1. Lead was found in the highest concentration. The highest concentrations of metals were in septic tank sludge. Of the >50 VOCs scanned for in catch basin wastewater, septic tank effluent, and septic tank sludge samples, 29 were found in concentrations that exceeded analytical detection limits. Concentrations of detected VOCs ranged from 1.0–15,800 µg L^?1 and the highest concentrations of VOCs were found in catch basin wastewater and septic tank sludge. Acetone, ethylbenzene, toluene, and xylenes were the most commonly found VOCs at all sampling locations. Thus, heavy metals and VOCs were not completely removed in catch basins and were discharged to septic tanks where removal occured possibly as these contaminants settled with solids in the sludge. The level of treatment was, however, inadequate and heavy metals and VOCs were discharged to drainfields.     

活性污泥中细菌对聚丙烯酰胺的生物降解研究

聚丙烯酰胺（Polyacrylamide,PAM）是一类重要的水溶性高分子聚合物,已广泛应用到工农业生产的各个领域和人们的日常生活中。同时,PAM在环境中的残留、迁移和降解对环境的污染也日趋严重,尤其是降解后的单体丙烯酰胺对人类的神经系统有很大的危害。本文从胜利油田的活性污泥中筛选出3株聚丙烯酰胺降解菌,通过比较筛选出一株降解效果较好的菌,命名为AS－2。根据生理生化特性分析,初步鉴定为海球菌属。采用室内培养方法,研究了AS－2对聚丙烯酰胺生物降解的最佳条件。结果表明,当降解时间为5d,pH=8,温度为40℃,碳源为原油,氮源为NaNO3,原油和NaNO3的含量分别为2．5,1．4g·L^-1时,AS-2对聚丙烯酰胺的降解率达到45．23％。通过对聚丙烯酰胺生物降解前后的红外谱图比较,推断出AS-2主要降解了聚丙烯酰胺侧链的酰胺基,将酰胺基降解为羧酸和游离的氡基。用高效液相色谱检测生化后的PAM溶液,未检测出单体丙烯酰胺。     

Bioaugmentation and biostimulation effects on PAH dissipation and soil ecotoxicity under controlled conditions

The degradation of spiked anthracene (ANT), pyrene (PYR) and benzo[a]pyrene (B[a]P) in soil (3000 mg ∑ 3 PAHs kg⁻¹ dry soil) was studied in aerobically incubated microcosms for 120 d. The applied treatments aimed at enhancing PAH removal from the heavily contaminated soils are: (i) bioaugmentation by adding aged PAH-contaminated soil (ACS) containing activated indigenous degraders; and (ii) combined bioaugmentation/biostimulation by incorporating sewage sludge compost (SSC) and decaying rice straw (DRS). The adopted treatments produced higher PAH dissipation rates than those observed in unamended PAH-spiked soils, especially for ANT and PYR in the presence of DRS or ACS (>96%). However, B[a]P was the most recalcitrant hydrocarbon to biodegradation. Extracellular enzyme investigation revealed the existence of ligninolytic activities in all soil treatments, including control but no relationship could be found with PAH dissipation. The ecotoxicological assessment indicated that regardless of applied treatment, PAH-spiked soils were chronically lethal to ostracod Heterocypris incongruens and confirmed the sensitivity of the microcrustacean to the concomitant presence of these three hydrocarbons. Lettuce root elongation inhibition was correlated with PAH level but the presence of SSC conferred a strong phytotoxic capacity to PAH-spiked soils. DRS amendment may constitute a cost-effective alternative for hydrocarbon bioremediation as it has impacted positively on soil microbial activity and enhanced PAH removal with no apparent changes in soil physico-chemical properties.     

Fe3+和Na+共存对缺氧污泥脱氮除磷效率和胞内外聚合物的影响

为了提高多种金属离子共存的含盐废水脱氮除磷效率和生物絮凝性,考察Fe^3+和Na^+共存对A2O工艺缺氧区污染物去除率的影响,研究缺氧区胞内聚合物(Intracellular Polymeric Substances,IPS)和胞外聚合物(Extracellular Polymeric Substances,EPS)的变化,采用气相色谱法与蒽酮比色法分析IPS中聚-β-羟丁酸(Poly-β-hydroxybutyrate,PHB)和糖原含量的变化,结合三维荧光光谱(Three-dimensional Excitation Emission Matrix Fluorescence Spectroscopy,3D-EEM)与傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy,FTIR)探索EPS组成结构的变化,以期揭示共存的Fe^3+和Na^+、IPS及EPS与污泥絮凝性的关系。结果表明:1)单一Fe^3+的加入有助于提高COD、TN和TP的去除率,增加碱性磷酸酶与酸性磷酸酶活性,IPS和EPS总量增多。2)在Fe^3+和Na^+共存的条件下,当Fe^3+浓度为10 mg/L、Na^+浓度为0.5 g/L时,低浓度的Na^+提高了COD、TN和TP去除率,增强了碱性磷酸酶与酸性磷酸酶活性,增加了IPS总量,但是抑制了微生物EPS的分泌,EPS总量下降;当Fe^3+为10 mg/L,Na^+浓度(>1 g/L)继续升高时,高浓度的Na^+导致COD、TN和TP去除率下降,IPS总量降低,但是促进了微生物EPS的分泌,EPS总量增加。3)由FTIR分析可知,Fe^3+和Na^+浓度的变化并未导致松散结合型胞外聚合物(Loosely Bound Extracellular Polymeric Substances,LB-EPS)和紧密结合型胞外聚合物(Tightly Bound Extracellular Polymeric Substances,TB-EPS)的官能团发生明显变化,主要成分始终为蛋白质(Protein,PN)和多糖(Polysaccharide,PS);由3D-EEM分析可知,Fe^3+的加入使三维荧光光谱中出现了可见区类色氨酸峰,Na^+的加入使色氨酸、腐殖酸类物质降解,EPS的成分改变。4)IPS和EPS之间存在竞争生长,IPS/EPS比值较高时,IPS占主导作用,污泥絮凝性能好。     

Additional studies on the use of cracking catalysts in conjunction with activated sludge wastewater treating

A previous study indicated that regenerated spent fluid catalytic cracking catalyst, added to a test activated sludge system, increased the sludge settling rate, decreased the settled sludge volume (compaction), decreased the supernatant (effluent) TOC and increased the supernatant optical clarity. In addition, phosphate levels were markedly reduced in a municipal sewerage a ctivated sludge system. As an extension of this study, fresh, spent, and regenerated cracking catalysts have been examined to determine if the observed activity could be attributed to the carbon and metals deposited on the catalyst during the cracking operation. To do this the earlier studies have been repeated and adsorption isotherm tests have been conducted with fresh, spent and regenerated catalysts. The results indicate that: (1) the carbon and metals on the catalyst surface do not affect the improved settling and compaction of activated sludge observed when the catalyst is present, nor do they affect TOC removals; (2) none of the catalysts tested adsorb soluble TOC to an appreciable extent; and (3) the presence of catalyst, by enhancing compaction, may stabilize the activated sludge system during wet weather conditions.     

Ricinus communis as an Element Biomonitor of Atmospheric Pollution in Urban Areas

Iopromide has been frequently detected in different environmental compartments. However, the biodegradation of iopromide was limited, and significantly different removal efficiencies by various methods were reported. In this study, a Pseudomonas sp. I-24 isolated from activated sludge in a sewage treatment plant was used to degrade iopromide. Four different cosubstrates were selected as the cometabolic carbon and energy sources. The results showed that cosubstrate starch was able to increase catabolic enzymatic activity and enhance iopromide degradation. The degradation efficiency of iopromide was as high as 88.24 %, which was much higher as compared with other cosubstrates (38.58–51.44 %) and blank sample (2.81 %). Additionally, the highest enzymatic activity of 0.182 mU for iopromide degradation was also obtained when adding starch as a cosubstrate, somehow supporting that higher enzymatic activity resulted in higher degradation efficiency for iopromide. Although little was illuminated about the molecular mechanism during the degradation process of iopromide with starch addition, the two-dimensional gel electrophoresis results indicated that the iopromide-degrading cells growing with cosubstrate starch underwent significant physiological changes.     

Hop as an interesting source of resveratrol for brewers: optimization of the extraction and quantitative study by liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Nowadays, hop is used almost exclusively by brewers for bitterness and flavor. Although hop polyphenols have been widely studied in the past decade for their antioxidant activity in the boiling kettle, very little is known about their real impact on health. The discovery of resveratrol in hop pellets highlights the potential health-promoting effect of moderate beer consumption. Here, we have optimized a quantitative extraction procedure for resveratrol in hop pellets. Preliminary removal of hydrophobic bitter compounds with toluene and cyclohexane at room temperature allows 99% trans-resveratrol recovery by ethanol:water (75:25, v/v) solid/liquid extraction at 60 degrees C. Reverse phase liquid chromatography proves an excellent means of separating isomers. In addition, we have compared two mass spectrometry ionization methods-atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI)-in both the positive and the negative modes. On the basis of standard additions applied with the optimized extraction procedure and reverse phase high-performance liquid chromatography-APCI(+)-tandem mass spectrometry, it appears that Tomahawk hop pellets (T90, harvest 2002) contain 0.5 ppm trans-resveratrol, 2 ppm trans-piceid, no cis-resveratrol, and 0.9 ppm cis-piceid.     

剩余污泥厌氧发酵混合物提高低C/N污水处理效果

为了避免剩余污泥厌氧发酵液利用时泥液难分离的问题,探讨了直接将发酵混合物用作外加碳源处理低碳氮比(C/N)污水的可行性。为此,首先对比了酸性(pH值=4.0±0.2)、中性(不控pH值)、碱性(pH值=10.0±0.2)条件下长期运行的剩余污泥厌氧发酵混合物的特性;其次,分别考察了碱性厌氧发酵混合物的不同投加量(0、10、20、30、50、100、200 mL),在反硝化及释磷过程中的利用。结果表明:碱性条件下溶解性化学需氧量(soluble chemical oxygen demand,SCOD)和短链脂肪酸(short-chain fatty acids,SCFAs)产量要远高于酸性和中性条件的,其中C/N比和C/P比分别高达18.9和57.0,更适合作为外加碳源利用。反硝化过程中,当初始NO_3~--N=(15.0±0.5)mg/L时,最佳投加量为30 mL,此时NO_3~--N去除率为100%;释磷过程中,最佳投加量为20 mL,此时最大净释磷量为22.8 mg/L。剩余污泥碱性厌氧发酵混合物用作外加碳源是可行的,既解决了碳源不足及剩余污泥处理的双重问题,又简化了传统发酵液利用时泥液分离的操作步骤,适用于处理低C/N比乡镇生活污水。     

Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L^?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.     

Removal of Copper and Cadmium Ions from Diluted Aqueous Solutions by Low Cost and Waste Material Adsorbents

The sorption of copper and cadmium ions using activated carbon,kaolin, bentonite, diatomite and waste materials such as compost,cellulose pulp waste and anaerobic sludge as sorbents is reported. Equilibrium isotherms were obtained for the adsorption of these metals in single and binary solutions. Bentonite presented the highest adsorption capacities for both copper and cadmium. A competitive uptake was observed when both metals are present; copper being preferentially adsorbed by all materials with theexception of anaerobic sludge. Equilibrium data were fitted toLangmuir and Freundlich models, with satisfactory results for most of the adsorbent-metal systems studied.Of all the adsorbents studied, bentonite and compost presentedthe highest removal efficiencies, reaching 99% for copper whencadmium is also present, for initial solution concentrations ofup to 100 mg L^-1. Anaerobic sludge has a greater preferencefor cadmium, even in the presence of copper, with removal efficiencies of 98% for similar concentrations to those mentioned above.     

蚯蚓对造纸污泥的养分和重金属处理效应研究

造纸污泥含有大量的养分和重金属等物质。试验采用室内培养试验,研究不同蚯蚓投放量对污泥中养分和重金属的处理效应。结果表明:蚯蚓的最佳投放量为中等投放量(22.5 g kg-1)。经过84天处理后,造纸污泥中有机质大量分解,最高分解率为24.95%;全量N、P、K的含量增加,其最大增量分别为2.65 g kg-1、0.64 g kg-1和0.32 g kg-1;碱解氮、速效磷、速效钾的最大减幅依次为24.78%、30.40%和10.77%。经蚯蚓处理后造纸污泥中重金属Mn、Cu和Zn的最大去除率依次为28.80%、28.80%和35.34%,蚯蚓体内Mn、Cu和Zn最高增加了8.03%、23.49%和27.06%,Mn、Cu和Zn的K值均小于1.0,其中Mn>Zn>Cu,说明蚯蚓对重金属Mn、Cu和Zn有明显的去除效应。     

Successful Biodegradation of a Refractory Pharmaceutical Compound by an Indigenous Phenol-Tolerant <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Strain

This study provides an alternative solution for the bioremediation of a recalcitrant pharmaceutical micropollutant. Clofibric acid (CLA) was chosen as target molecule, because of its environmental persistence and resistance to wastewater treatment technologies. The aim of this study was to investigate the potential of a phenol-resistant Pseudomonas aeruginosa strain isolated from the activated sludge to degrade CLA. In order to evaluate the effect of acclimation process with glucose as carbon co-substrate, two protocols were performed, in which the transfer of the inoculum is carried out either in the exponential growth phase or in the decline phase. The results showed a removal efficiency of CLA of 35% when cells in the decline phase were used for inoculation. In contrast, a very low removal yield (10%) was achieved when cells harvested in the exponential phase were used as inoculum. This work is the first one reporting on the capability of this bacterium to remove this drug. The obtained data showed that the isolated strain is able to degrade target molecule and might be a promising agent for the elimination of this refractory compound.