Rhizoremediation of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723

Sphingobium chlorophenolicum is well known as a pentachlorophenol (PCP) degrader. The objective of this study was to evaluate PCP degradation in a loamy sandy soil artificially contaminated with PCP using phytoremediation and bioaugmentation. Measurements of PCP concentrations were carried out using high performance liquid chromatography analyses (HPLC). The toxic effect of PCP on plants was studied through the monitoring of weight plant and root length. The biodegradation of PCP by S. chlorophenolicum in soil was assessed with a bioluminescence assay of Escherichia coli HB101 pUCD607. Bacterial analyses were carried out by plating on Mineral Salt Medium (MSM) for S. chlorophenolicum, MSM for PCP-degrading/tolerant organisms and Trypticase Soy Broth Agar (TSBA) for heterotrophic organisms. The introduction of S. chlorophenolicum into soil with plants showed a faster degradation when compared to the non-inoculated soil. The monitoring of the plant growth showed a protective role of S. chlorophenolicum against the toxicity of PCP. The bioassay confirmed that initial toxicity was lowered while degradation progressed. There was a significant increase of organisms tested in the roots in comparison to those in the soil. This study showed that the presence of S. chlorophenolicum enhanced the PCP degradation in a loamy soil and also it had a protective role to prevent phytotoxic effects of PCP on plant growth. The combined use of bioaugmentation and plants suggests that the rhizosphere of certain plant species may be important for facilitating microbial degradation of pesticides in soil with important implications for using vegetation to stabilize and remediate surface soils.     

高浓度油脂废水的微生物净化处理技术浅析

在简要介绍目前含有高浓度油脂废水的产生和排放现状之后,总结分析了最近几年来一些具有一定代表性的生物处理方法的研究成果,同时提出了今后油脂废水处理技术的一点建议。     

Chlorinated pesticides (2,4-D and DDT) biodegradation at high concentrations using immobilized Pseudomonas fluorescens

Degradation of two chlorinated pesticides (2,4-D and DDT) using a 54-mL glass column packed with tezontle (a low-cost basaltic scoria) was tested. Bacteria were cultured in YPG (yeast, peptone, and glucose) liquid medium at 32 degrees C. The rich medium was pumped during 24 h through the column to inoculate it. Later, the wasted medium was discharged and the pesticide added. Optical densities, TOC, and pesticide concentration were determined. Pesticide removals for 2,4-D (with initial concentration between 100 and 500 mg/L) were about 99%. DDT removal (at initial concentration of up to 150 mg/L) was as high as 55-99%. TOC removals for 2,4-D was in the 36-87% interval, whereas for DDT they were as high as 36-78%.     

Pilot-scale demonstration of a two-stage methanotrophic bioreactor for biodegradation of trichloroethylene in groundwater

A two-stage methanotrophic bioreactor system was developed for remediation of water contaminated with TCE and other chlorinated, volatile, aliphatic hydrocarbons. The first stage of the reactor was a suspended-growth culture vessel using a bubbleless methane-transfer device. The second stage was a plug-flow bioreactor supplied with contaminated groundwater and cell suspension from the culture vessel. The test objectives were to determine the applicability of microbial culture conditions reported in the literature for continuous, pilot-scale TCE treatment; the technical feasibility of plug-flow bioreactor design for treatment of TCE; and the projected economic competitiveness of the technology considering the cost of methane for growth of methanotrophs. The methanotrophic organism used in the study was Methylosinus trichosporium OB3b. Information on system operation was obtained in bench tests prior to conducting the pilot tests. In bench- and pilot-scale tests, variability in the degree of TCE degradation and difficulty in maintaining the microbial culture activity led to short periods of satisfactory biotreatment. Further development of the microbial culture system will be required for long-term operation. During transient periods of high TCE degradation activity, the bioreactor concept proved feasible by exhibiting both a high degree of TCE biodegradation (typically about 90% at influent TCE concentrations of 0.5-4 ppm) and a close approximation to first-order reactor kinetics throughout the length of the reactor. Actual methane usage in the pilot-scale reactor resulted in projected methane costs of $0.33 per 1000 gallons of water treated. This cost theoretically would be reduced by system modifications. The theoretical minimum methane cost was approximately $0.05 per 1000 gallons.     

膜生物反应器生物降解与膜分离共作用特性研究

膜生物反应器实质是生物降解与膜分离相互影响,共同作用的过程,污泥浓度与通量之间存在一定的相关关系,膜分离对生和性能尤其是细菌活性有着重要的影响,而生物反应器内细菌胞外聚合物,溶解性有机物及微细胶体可能成为形成凝胶层导致通量下降的主要因素。     

Operation of a two-phase partitioning bioreactor for the oxidation of anthracene by the enzyme manganese peroxidase

A study was conducted to determine the potential of a two-phase partitioning bioreactor (TPPB) for the treatment of a poorly soluble compound, anthracene, by the enzyme manganese peroxidase (MnP) from the fungus Bjerkandera sp. BOS55. Silicone oil was used as the immiscible solvent, which contained anthracene at high concentrations. The optimization of the oxidation process was conducted taking into account the factors which may directly affect the MnP catalytic cycle (the concentration of H(2)O(2) and malonic acid) and those that affect the mass transfer of anthracene between the organic and the aqueous phase (solvent and agitation speed). The main objective was carried out in terms of improved efficiency, i.e., maximizing the anthracene oxidized per unit of enzyme used. The TPPB reached nearly complete oxidation of anthracene at a conversion rate of 1.8mgl(-1)h(-1) in 56h, which suggests the application of enzymatic TPPBs for the removal of poorly soluble compounds.     

膜生物反应器处理不同浓度生活污水的研究

通过对毛细管膜在不同浓度的污泥条件下 ,处理生活污水时膜污染情况的研究 ,考察了膜组件水通量随污泥浓度而变化的情况。结果表明 ,在操作压力为 0 .0 2 5MPa、膜面流速为 0 .8m s和温度为 30℃的条件下 ,污泥浓度增大 ,膜水通量随之下降 ,并与污泥浓度呈对数关系。同时 ,表明导致膜污染水通量下降的主要原因为泥饼阻力     

新型高效生物反应器类型和应用

近年来高效生物反应器得到不断发展,出现了多种新型生物反应器.从厌氧升流式生物反应器发展的经验和反应器的特点出发,提出了升流式反应器的结构、三相分离器的形式和污泥颗粒化现象等3个新概念是高效新型反应器的基础,进而在广义升流式污泥床反应器概念的基础上,提出具有传质效率高、处理能力强、有机负荷高以及抗冲击负荷能力强等优点的第三代高效生物反应器概念.     

新型高效生物反应器类型和应用

近年来高效生物反应器得到不断发展，出现了多种新型生物反应器。从厌氧升流式生物反应器发展的经验和反应器的特点出发，提出了升流式反应器的结构、三相分离器的形式和污泥颗粒化现象等3个新概念是高效新型反应器的基础，进而在广义升流式污泥床反应器概念的基础上，提出具有传质效率高、处理能力强、有机负荷高以及抗冲击负荷能力强等优点的第三代高效生物反应器概念。     

Numerical technique for estimating equilibrium concentrations from initial concentrations when using the freundlich adsorption equation

Abstract

The Freundlich equation, X/m = K C_e ^N, is frequently used to express the partitioning of pesticides between solid (soil, sediment) and aqueous phases. When designing adsorption‐desorption experiments, it would be useful to be able to estimate the equilibrium concentration, C_e, in terms of the initial concentration, C_o, if reasonable estimates of K and N can be made. Because of the usual non‐integer nature of N, only a numerical solution of the Freundlich equation is possible for C_e in terms of C_o. A simple computer program is presented which produces almost an exact solution for the value of C_e.     

Mutant AFM 2 of Alcaligenes faecalis for phenol biodegradation using He-Ne laser irradiation

He-Ne laser technology was utilized in this study to investigate the response of Alcaligenes faecalis to laser stimulation. The irradiation experiments were conducted by the adjustment of the output power from 5 to 25 mW and the exposure time from 5 to 25 min. The results showed that the survival rate changed regularly with the variety of irradiation dose, and high positive mutation frequency was determined by both the energy density and the output power. The mutant strain AFM 2 was obtained. Phenol biodegradation assay demonstrated that AFM 2 possessed a more prominent phenol-degrading potential than its parent strain, which presumably attributed to the improvements of phenol hydroxylase and catechol 1,2-dioxygenase activities. The phenol of 2000 mgl(-1) was completely degraded by AFM 2 within 85.5h at 30 degrees C. In addition, the cell growth and phenol degradation kinetics of the mutant strain AFM 2 and its parent strain in batch cultures were also investigated at the wide initial phenol concentration ranging from 0 to 2000 mgl(-1) by Haldane model. The results of these experiments further demonstrated that the mutant strain AFM 2 possessed a higher capacity to resist phenol.     

膜生物法降解TNT弹药销毁废水的重要影响因素

采用水解酸化一好氧膜生物工艺对弹药销毁废水中TNT进行降解试验研究。结果表明,共代谢外加碳源对TNT的生物降解影响显著。无共代谢外加碳源的情况下,HRT=40h,TNT的去除率仅为53．4％。有共代谢外加碳源的情况下,外加碳源COD与TNT提供COD比值宜大于4．8,系统对TNT的去除率可高达99％。温度对水解酸化影响重大,当温度低于15℃时,水解酸化对TNT去除率低于33．3％,而当温度高于20℃时,水解酸化对TNT的去除率不小于83％。     

Reduction of surfactant concentrations in static fish tests compared with biodegradation rates in the OECD screening test

The loss of chemicals in static fish tests due to biodegradation has been studied with eight model surfactants whose biodegradabilities in the OECD Screening Test range from 0 to 99 % BiAS removal. There was a good correlation between biodegradation in the fish test and in the OECD Screening Test. Only surfactants with a very high BiAS removal of above 93 % were also degraded quickly in the fish test. Surfactants with less than 80 % BiAS removal incurred losses of less than 20 % in the fish test. These results indicate that those substances which are not lost by volatility or adsorption will be maintained to at least 80 % of their nominal concentration during a 96 hour static fish test.     

Development of a solid phase microextraction-gas chromatography-mass spectrometry method for the determination of pentachlorophenol in human plasma using experimental design

A new method, headspace solid-phase microextraction (HS-SPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS), which was used for the determination of trace amount of pentachlorophenol (PCP) in human plasma was presented. The acetylation derivatization reaction was firstly optimized using a Doehlert design. Then a series of parameters relevant to the headspace SPME procedure, including fiber coating, extraction temperature, extraction time and salt addition, were optimized using a two-level full factorial design expanded further to a central composite design. The validation of method showed that the optimized method had good linearity (R(2)=0.999) within the concentration ranges 0.1-50.0ngml(-1), and was sensitive with the limit of detection of 0.02ngml(-1). Intra- and inter-day precision for pentachlorophenol in human plasma samples were not greater than 11.9% and 12.6%, respectively. The proposed method, to our knowledge, describes the first application of HS-SPME with GC-MS for analysis of PCP in blood plasma sample. Application of the method to real human plasma samples, PCP was successfully detected in some cases at concentration levels 1.2-6.3ngml(-1).     

Comparing the desorption and biodegradation of low concentrations of phenanthrene sorbed to activated carbon,biochar and compost

Carbonaceous soil amendments are applied to contaminated soils and sediments to strongly sorb hydrophobic organic contaminants (HOCs) and reduce their freely dissolved concentrations. This limits biouptake and toxicity, but also biodegradation. To investigate whether HOCs sorbed to such amendments can be degraded at all, the desorption and biodegradation of low concentrations of ¹⁴C-labelled phenanthrene (?5 μg L^?1) freshly sorbed to suspensions of the pure soil amendments activated carbon (AC), biochar (charcoal) and compost were compared. Firstly, the maximum abiotic desorption of phenanthrene from soil amendment suspensions in water, minimal salts medium (MSM) or tryptic soy broth (TSB) into a dominating silicone sink were measured. Highest fractions remained sorbed to AC (84 ± 2.3%, 87 ± 4.1%, and 53 ± 1.2% for water, MSM and TSB, respectively), followed by charcoal (35 ± 2.2%, 32 ± 1.7%, and 12 ± 0.3%, respectively) and compost (1.3 ± 0.21%, similar for all media). Secondly, the mineralization of phenanthrene sorbed to AC, charcoal and compost by Sphingomonas sp. 10-1 (DSM 12247) was determined. In contrast to the amounts desorbed, phenanthrene mineralization was similar for all the soil amendments at about 56 ± 11% of the initially applied radioactivity. Furthermore, HPLC analyses showed only minor amounts (<5%) of residual phenanthrene remaining in the suspensions, indicating almost complete biodegradation. Fitting the data to a coupled desorption and biodegradation model revealed that desorption did not limit biodegradation for any of the amendments, and that degradation could proceed due to the high numbers of bacteria and/or the production of biosurfactants or biofilms. Therefore, reduced desorption of phenanthrene from AC or charcoal did not inhibit its biodegradation, which implies that under the experimental conditions these amendments can reduce freely dissolved concentration without hindering biodegradation. In contrast, phenanthrene sorbed to compost was fully desorbed and biodegraded.     

The effects of antibiotic cocktails at environmentally relevant concentrations on the community composition and acetate biodegradation kinetics of bacterial biofilms

Antibiotics and antibacterials are present in water bodies worldwide but little is known about their effects on the biological processes often used to treat water. In this research, the effect of antibiotics on bacterial activity and community structure was investigated by growing biofilms in the presence and absence of a mixture of three compounds (sulfamethoxazole, erythromycin, and ciprofloxacin) in a continuous-flow rotating annular bioreactor fed acetate as a carbon and energy source. Steady-state, surface area-normalized substrate utilization rates for all antibiotic treatments (all at 0.33 μg L^?1, all at 3.33 μg L^?1, and 1 at 3.33 μg L^?1 with the other 2 at 0.33 μg L^?1) were similar to the control experiments. Higher attached biomass levels in the experiments with ciprofloxacin at 3.33 μg L^?1 resulted in lower steady-state biomass-normalized substrate utilization rates in comparison to other runs. Microbial community analyses via automated ribosomal intergenic spacer analysis revealed significant shifts in community structure for the experiments dosed with the highest concentrations of ciprofloxacin, suggesting that the antibiotic selected for more resistant bacterial strains. The results of this research also suggest that mixtures of antibiotics at the sub-μg L^?1 concentrations typically observed in surface waters are unlikely to affect biological process performance, at least in terms of the degradation of easily assimilable compounds. Conversely, changes to community structure and biofilm quantity might be expected with ciprofloxacin at μg L^?1 concentrations.     

Pollutant concentration profile reconstruction using digital soft sensors for biodegradation and exposure assessment in the presence of model uncertainty

A new approach to the problem of environmental hazard assessment and monitoring for pollutant biodegradation reaction systems in the presence of uncertainty is proposed using soft sensor-based pollutant concentration dynamic profile reconstruction techniques. In particular, a robust reduced-order soft sensor is proposed that can be digitally implemented in the presence of inherent complexity and the inevitable model uncertainty. The proposed method explicitly incorporates all the available information associated with a process model characterized by varying degrees of uncertainty, as well as available sensor measurements of certain physicochemical quantities. Based on the above information, a reduced-order soft sensor is designed enabling the reliable reconstruction of pollutant concentration profiles in complex biodegradation systems that can not be always achieved due to physical and/or technical limitations associated with current sensor technology. The option of using the aforementioned approach to compute toxic load and persistence indexes on the basis of the reconstructed concentration profiles is also pursued. Finally, the performance of the proposed method is evaluated in two illustrative environmental hazard assessment case studies.