Treatment of carbofuran-bearing synthetic wastewater using UASB process.

A microbial consortium from a biomixture swiftly degrades high concentrations of carbofuran in fluidized-bed reactors

Abstract: An on-farm biopurification system (BPS) biomixture, with proven capacity to degrade carbofuran (CBF) was used as inoculum for a selective-enrichment process to obtain a bacterial consortium capable of using CBF as a sole source of carbon. Bacterial strains that comprise the consortium were identified as members of the genera Cupriavidus, Achromobacter and Pseudomonas. The consortium was tested in batch bioreactors, with initial CBF concentrations ranging from 50 to 200 mg L−1, in which complete degradation was attained in 16–17 h. Continuous operation of the bioreactor was optimized to achieve conditions of complete removal of up to 100 mg L−1 of CBF at a HRT of 23 h by the microbial consortium. Cross-degradation assays showed that the consortium was also capable of degrading high concentrations of other carbamates such as aldicarb, methiocarb and methomyl in batch bioreactors. The use of this consortium for the treatment of CBF and other carbamates at reactor scale represents a potential approach for the removal of these pesticides from agricultural wastewater, as an alternative to BPS.

Carbofuran removal in continuous-photocatalytic reactor: Reactor optimization, rate-constant determination and carbofuran degradation pathway analysis.

Abstract: Carbofuran (CBF) removal in a continuous-flow photocatalytic reactor with granular activated carbon supported titanium dioxide (GAC-TiO2) catalyst was investigated. The effects of feed flow rate, TiO2 concentration and addition of supplementary oxidants on CBF removal were investigated. The central composite design (CCD) was used to design the experiments and to estimate the effects of feed flow rate and TiO2 concentration on CBF removal. The outcome of CCD experiments demonstrated that reactor performance was influenced mainly by feed flow rate compared to TiO2 concentration. A second-order polynomial model developed based on CCD experiments fitted the experimental data with good correlation (R2 ∼ 0.964). The addition of 1 mL min−1 hydrogen peroxide has shown complete CBF degradation and 76% chemical oxygen demand removal under the following operating conditions of CBF ∼50 mg L−1, TiO2 ∼5 mg L−1 and feed flow rate ∼82.5 mL min−1. Rate constant of the photodegradation process was also calculated b...

Standard methods for the examination of water and wastewater

Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!

Degradation of carbofuran by using ozone, UV radiation and advanced oxidation processes.

Abstract: The degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), a frequently used carbamate derivative pesticide that is considered a priority pollutant, is carried out in batch reactors by means of single oxidants: ozone, UV radiation and Fenton’s reagent; and by the advanced oxidation processes (AOPs) constituted by combinations of ozone plus UV radiation, UV radiation plus H2O2, and UV radiation plus Fenton’s reagent (photo-Fenton system). For all these reactions, the apparent pseudo-first-order rate constants are evaluated in order to compare the efficiency of each process. In addition and by means of a competition kinetic model, the rate constants for the reaction of carbofuran with ozone and with hydroxyl radicals are also determined. The improvement in the decomposition levels of carbofuran reached by the combined processes in relation to the single oxidants, due to the generation of the very reactive hydroxyl radicals, is also established in every process. For the oxidant concentrations applied, the most effective process in removing carbofuran was the photo-Fenton system.

Reductive dehalogenation of chlorophenols by Desulfomonile tiedjei DCB-1.

Abstract: Reductive dehalogenation of chlorophenols has been reported in undefined anaerobic cultures but never before in an anaerobic pure culture. We found that the sulfate-reducing bacterium Desulfomonile tiedjei DCB-1 reductively dehalogenates pentachlorophenol (PCP) and other chlorophenols. The maximum rate of PCP dechlorination observed was 54 mu mol of Cl- h-1 g of protein-1. 3-Chlorobenzoate appeared to serve as a required inducer for PCP dehalogenation; however, neither PCP nor 3-chlorophenol induced dehalogenation. Dehalogenation was catalyzed by living cells, and formate served as a required electron donor. D. tiedjei dehalogenated meta-chlorine substituents of chlorophenols (i.e., PCP was degraded to 2,4,6-trichlorophenol). Generally, more highly chlorinated phenol congeners were more readily dechlorinated, and 3-chlorophenol was not dehalogenated. Growing cultures dehalogenated PCP, but greater than 10 microM PCP (approximately 1.7 mmol g of protein-1) reversibly inhibited growth.

Pesticides in rainwater in the northeastern United States

Abstract: The use of agricultural herbicides in the United States increased 280% between 1966 and 1981; insecticide use also increased, but only by a few per cent1. Since 1981, pesticide use has fluctuated with crop acreage, and shows no clear increasing or decreasing trend2. Compared to their predecessors, currently used herbicides are not very toxic to animals, and both herbicides and insecticides are less persistent and show less tendency to bio-accumulate, but are more soluble in water, and therefore more mobile in the environment. Previous studies of these compounds have reported their movement to the edge of the field by surface transport in rainfall runoff3, their presence in surface and ground water4–9, and their seasonal presence in drinking water supplies4. By contrast, only one previous study10 has reported any of these compounds in rainwater: atrazine was reported in Maryland in concentrations as high as 2.19 μg I−1. The work we report here indicates that many of these compounds are more commonly present in rainfall, at least regionally, than has previously been realized.