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41.
Fishmeal wastewater, a seafood processing waste, was utilized for production of lactic acid and fungal biomass by Rhizopus oryzae AS 3.254 with the addition of sugars. The 30 g/l exogenous glucose in fishmeal wastewater was superior to starch in view
of productivities of lactic acid and fungal biomass, and COD reduction. Fishmeal wastewater can be a replacement for peptone
which was the most suitable nitrogen source for lactic acid production among the tested organic or inorganic nitrogen sources.
Exogenous NaCl (12 g/l) completely inhibited the production of lactic acid and fungal growth. In the medium of COD 5,000 mg/l
fishmeal wastewater with the addition of 30 g/l glucose, the maximum productivity of lactic acid was 0.723 g/l h corresponding
to productivity of fungal biomass 0.0925 g/l h, COD reduction 84.9% and total nitrogen removal 50.3% at a fermentation time
of 30 h. 相似文献
42.
由于难降解有机污染物和外界环境对水处理系统的冲击干扰,污水水质常出现不达标现象。引入外源含有相关功能基因并且具有基因水平转移能力的工程菌株进行生物强化处理是提高污水处理效能的有效措施。污水处理系统中存在能够分泌信号分子的菌体,菌间具有群体感应现象,当种群密度达到感应阈值时,菌体会通过释放信号分子来触发一些群体行为,从而激活相关基因的表达(如生物膜形成、生物发光、抗生素合成和毒力因子表达等)。早期的群体感应技术研究主要集中在信号传递学、微生物社会行为学和医学微生物领域,近年来,在水处理领域也开始有相继报道,研究表明群体感应在污水生物处理中发挥重要作用,并且影响生物强化菌株的定殖和污染物降解,因此群体感应行为调控是生物强化技术成效显著与否的关键因素。本文综述了群体感应及信号分子的作用机制、信号分子释放及存在的影响因素以及群体感应对菌株定殖、微生物群落结构和污染物去除的影响,并对从群体感应角度出发研究生物强化过程进行了展望,旨在为生物强化技术的有效实施及提升污水处理效能提供一种新思路,为深入理解生物强化过程中群体感应调控行为提供理论参考。 相似文献
43.
Courtney M. Gardner Savannah J. Volkoff Claudia K. Gunsch 《Biotechnology and bioengineering》2019,116(11):3063-3071
The consumption of transgenic crops and their by-products has become increasingly common in the United States. Yet, uncertainty remains regarding the fate and behavior of DNA within food matrices once it exits the digestive track and enters into wastewater treatment plants (WWTPs). Because many transgenic crops have historically contained antibiotic resistance genes as selection markers, understanding the behavior and uptake of these transgenes by environmental microbes is of critical importance. To investigate the behavior of free transgenic crop DNA, thermophilic anaerobic batch reactors were amended with varying concentrations of transgenic crop genes (i.e., LUG, nptII, and bla) and the persistence of those genes was monitored over 60 days using quantitative PCR. Significant levels of nptII and bla were detected in extracellular DNA (eDNA). Furthermore, LUG maize marker genes were also detected in the control reactors, suggesting that other crop-derived transgenes contained within digested transgenic foods may also enter WWTPs. Possible bacterial transformation events were detected within the highest dose treatments at Days 30 and 60 of incubation. These findings suggest that within the average conventional digester residence times in the United States (30 days), there is a potential for bacterial transformation events to occur with crop-derived transgenes found in eDNA. 相似文献
44.
Morgan L. Petrovich Alex F. Rosenthal James S. Griffin George F. Wells 《Biotechnology and bioengineering》2019,116(3):543-554
Attached growth bioprocesses that use biofilms to remove organic matter or nutrients from wastewater are known to harbor antibiotic resistance genes (ARGs). Biofilms in these processes are spatially heterogeneous, but little is known about depth stratification of ARGs in complex, mixed culture biofilms. To address this knowledge gap, we used an experimental approach combining cryosectioning and quantitative polymerase chain reaction to quantify the spatial distribution of three ARGs (sul1, ermB, and qnrS) and the class 1 integron-integrase gene intI1 in biofilms from a lab-scale rotating annular reactor fed with synthetic wastewater. We also used high throughput 16S ribosomal RNA (rRNA) gene sequencing to characterize community structure with depth in biofilms. The ARG sul1 and the integron-integrase gene intI1 were found in higher abundances in upper layers of biofilm near the fluid-biofilm interface than in lower layers and exhibited significant correlations between the distance from substratum and gene abundances. The genes ermB and qnrS were present in comparatively low relative abundances. Microbial community structure varied significantly by date of sampling and distance from the substratum. These findings highlight the genetic and taxonomic heterogeneity with distance from substratum in wastewater treatment biofilms and show that sul1 and intI1 are particularly abundant near fluid-biofilm interfaces where cells are most likely to detach and flow into downstream portions of treatment systems and can ultimately be released into the environment through effluent. 相似文献
45.
随着有机氟化物在各领域的广泛应用,含氟有机废水处理面临巨大挑战。活性污泥作为有机废水处理的核心技术之一,微生物在其中发挥着极其重要的作用。本综述首先聚焦在活性污泥微生物群落多样性、组成、结构和功能及其与含氟废水类型、处理工艺和处理效率之间的关系,进而讨论了功能微生物降解/转化有机氟化物的途径和作用机制,最后展望了结合分离培养降解有机氟化物的关键微生物,以及微生物组学技术解析活性污泥微生物群落构建、互作、代谢等核心问题,以提高对含氟有机废水微生物降解机理的认识,优化含氟有机废水处理工艺。 相似文献
46.
47.
Due to serious eutrophication in water bodies, nitrogen removal has become a critical stage for wastewater treatment plants (WWTPs) over past decades. Conventional biological nitrogen removal processes are based on nitrification and denitrification (N/DN), and are suffering from several major drawbacks, including substantial aeration consumption, high fugitive greenhouse gas emissions, a requirement for external carbon sources, excessive sludge production and low energy recovery efficiency, and thus unable to satisfy the escalating public needs. Recently, the discovery of anaerobic ammonium oxidation (anammox) bacteria has promoted an update of conventional N/DN-based processes to autotrophic nitrogen removal. However, the application of anammox to treat domestic wastewater has been hindered mainly by unsatisfactory effluent quality with nitrogen removal efficiency below 80%. The discovery of nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) during the last decade has provided new opportunities to remove this barrier and to achieve a robust system with high-level nitrogen removal from municipal wastewater, by utilizing methane as an alternative carbon source. In the present review, opportunities and challenges for nitrate/nitrite-dependent anaerobic methane oxidation are discussed. Particularly, the prospective technologies driven by the cooperation of anammox and n-DAMO microorganisms are put forward based on previous experimental and modeling studies. Finally, a novel WWTP system acting as an energy exporter is delineated. 相似文献
48.
Ivan?Mu?ozEmail author Joan?Rieradevall Xavier?Doménech Lloren??Milà 《The International Journal of Life Cycle Assessment》2004,9(4):272-280
Goal, Scope and Background Gipuzkoa is a department of the Vasque Country (Spain) with a population of about 700,000 people. By the year 2000 approximately
85% of municipal solid waste in this area was managed by landfilling, and only 15% was recycled. Due to environmental law
restrictions and landfill capacity being on its limit, a planning process was initiated by the authorities. LCA was used,
from an environmental point of view, to assess 7 possible scenarios arising from the draft Plan for the 2016 time horizon.
Main Features In each scenario, 9 waste flows are analysed: rest waste, paper and cardboard, glass containers, light packaging, organic-green
waste, as well as industrial/commercial wood, metals and plastics, and wastewater sludge. Waste treatments range from recycling
to energy recovery and landfilling.
Results Recycling of the waste flows separated at the source (paper and cardboard, glass, light packaging, organic-green waste, wood
packaging, metals and plastics) results in net environmental benefits caused by the substitution of primary materials, except
in water consumption. These benefits are common to the 7 different scenarios analysed. However, some inefficiencies are detected,
mainly the energy consumption in collection and transport of low density materials, and water consumption in plastic recycling.
The remaining flows, mixed waste and wastewater sludge, are the ones causing the major environmental impacts, by means of
incineration, landfilling of partially stabilised organic material, as well as thermal drying of sludge. With the characterisation
results, none of the seven scenarios can be clearly identified as the most preferable, although, due to the high recycling
rates expected by the Plan, net environmental benefits are achieved in 9 out of 10 impact categories in all scenarios when
integrated waste management is assessed (the sum of the 9 flows of waste). Finally, there are no relevant differences between
scenarios concerning the number of treatment plants considered. Nevertheless, only the effects on transportation impacts were
assessed in the LCA, since the plant construction stage was excluded from the system boundaries.
Conclusions The results of the study show the environmental importance of material recycling in waste management, although the recycling
schemes assessed can be improved in some aspects. It is also important to highlight the environmental impact of incineration
and landfilling of waste, as well as thermal drying of sludge using fossil fuels. One of the main findings of applying LCA
to integrated waste management in Gipuzkoa is the fact that the benefits of high recycling rates can compensate for the impacts
of mixed waste and wastewater sludge.
Recommendations and Outlook Although none of the scenarios can be clearly identified as the one having the best environmental performance, the authorities
in Gipuzkoa now have objective information about the future scenarios, and a multidisciplinary panel could be formed in order
to weight the impacts if necessary. In our opinion, LCA was successfully applied in Gipuzkoa as an environmental tool for
decision making. 相似文献
49.
Koji?Mori Ryozo?Iriye Mutsunori?Hirata Kazuhiro?TakamizawaEmail author 《Biotechnology and Bioprocess Engineering》2004,9(6):482-489
Bacillus species were observed and quantified by molecular approaches, using the 165 rDNA primers/probes, in a wastewater treatment
plant designed for the purpose of stimulating the growth ofBacillus species. The plant has been operating as a test plant since 1997 in the city of Ina, Japan, with excellent treatment performance.
Observations byin situ hybridization, usingBacillus-specific probes, indicated thatBacillus strains were inhabited in the plant and their numbers decreased during the treatment process. Similar results were obtained
from a quantitative PCR analysis using aBacillus-specific primer set, and the amount of DNA originating from variousBacillus species was maximally 1.91% of the total DNA in the wastewater treatment tank. Clone library analysis using theBacillus-specific primers suggested that, while the population was noticeably increased, the phylogenetic diversity of the increasingBacillus species was very low. 相似文献
50.
Competition strategies for the decolorization of a textile-reactive dye with the white-rot fungi Trametes versicolor under non-sterile conditions 总被引:11,自引:0,他引:11
A variety of white-rot fungi can oxidize textile dyes under sterile conditions; however, an important consideration for their use in treating wastewater containing textile dyes is whether similar degrees of treatment can be achieved under non-sterile conditions. Four strategies were investigated for their potential in optimizing the use of the fungus Trametes versicolor in non-sterile culture for treating wastewater containing the diazo textile dye C.I. Reactive Black 5 (RB5). Three strategies with suspended culture were designed to increase the decolorization activity in suspended culture from a given amount of T. versicolor inoculum based on its tolerance of low pH (pH reduction in medium), production of extracellular enzymes (use of suspended enzymes alone), and its ability to produce enzymes independent of growth (nitrogen limitation in medium). The results showed that reduction of the medium pH to 3 did not suppress bacterial growth, while enzyme production by T. versicolor ceased. The use of the extracellular enzymes alone would allow the decoupling of the process of fungal growth from wastewater treatment; however, the enzyme activity of an enzyme suspension decreased rapidly under non-sterile conditions. The strategy of limiting nitrogen in the medium to suppress bacterial growth has potential together with the fourth strategy, the cultivation of fungi on organic solids to produce inocula for a decolorization process under non-sterile conditions. A high degree of decolorization of RB5 under non-sterile conditions was achieved with T. versicolor grown on grains as sole substrate. The rate of decolorization was dependent on the amount of fungal inoculum used. 相似文献