Abstract Fenton's reaction-based chemical oxidation is in principle a method that can be utilized for all organic fuel residues thus making it a potential all-purpose, multi-contaminant, in situ application for cases in which storage and distribution of different types of fuels have resulted in contamination of soil or groundwater. Since peroxide breakdown reactions are also expected to lead to a physical transport of the target compound, this secondary physical removal, or rebound concentrations related to it, is prone to be affected by the chemical properties of the target compound. Also, since soil conditions are seldom optimal for Fenton's reaction, the balance between chemical oxidation and transport may vary. In this study, it was found that, with a high enough hydrogen peroxide concentration (5 M), methyl tert-butyl ether–spiked groundwater could be treated even under suboptimal conditions for chemical mineralization. In these cases, volatilization was not only contributing to the total removal but also leading to rebound effects similar to those associated with air sparging techniques. Likewise for diesel, temporal transport from soil to the aqueous phase was found to lead to false positives that outweighed the actual remediation effect through chemical mineralization.
Abstract Background Composting is an aerobic microbiological process that is facilitated by bacteria and fungi. Composting is also a method to produce fertilizer or soil conditioner. Tightened EU legislation now requires treatment of the continuously growing quantities of organic municipal waste before final disposal. However, some full-scale composting plants experience difficulties with the efficiency of biowaste degradation and with the emission of noxious odours. In this study we examine the bacterial species richness and community structure of an optimally working pilot-scale compost plant, as well as a full-scale composting plant experiencing typical problems. Bacterial species composition was determined by isolating total DNA followed by amplifying and sequencing the gene encoding the 16S ribosomal RNA. Results Over 1500 almost full-length 16S rRNA gene sequences were analysed and of these, over 500 were present only as singletons. Most of the sequences observed in either one or both of the composting processes studied here were similar to the bacterial species reported earlier in composts, including bacteria from the phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria and Deinococcus-Thermus. In addition, a number of previously undetected bacterial phylotypes were observed. Statistical calculations estimated a total bacterial diversity of over 2000 different phylotypes in the studied composts. Conclusions Interestingly, locally enriched or evolved bacterial variants of familiar compost species were observed in both composts. A detailed comparison of the bacterial diversity revealed a large difference in composts at the species and strain level from the different composting plants. However, at the genus level, the difference was much smaller and illustrated a delay of the composting process in the full-scale, sub-optimally performing plants.
AbstractHVO has been noted as a more sustainable fuel, not only leading to lower total CO2 emissions, but also resulting in lower emissions of toxic substances upon fuel burning. The environmental impact of HVO and HVO diesel blends when accidentally spilled into the soil and ground water has, however, received little attention. While HVO and diesel exhibit nearly identical viscosity and density, their behavior in soils differs due to varying water solubility and fuel additives. In laboratory- and pilot-scale soil columns and lysimeters, we compared the migration and biostimulation-enhanced degradation of HVO, HVO-diesel blend (HVO15), and fossil diesel over 120 days. Additionally, we investigated the impact of fuel additives on migration by comparing HVO without additives to HVO15 and diesel in wet and dry soil columns over 21 days. Notably, HVO migrated through soil more rapidly and in greater quantities than diesel. In wet soil, 69% of added HVO, 8.4% of HVO15, and 21% of diesel leached through as light non-aqueous phase liquid (LNAPL). Dry soil showed smaller differences in fuel migration, but HVO did not mobilize when water was added, unlike HVO15 and diesel. Biostimulation reduced HVO leaching by 15% more than HVO15 and 48% more than diesel. Overall, HVO's behavior in soil differs significantly from fossil diesel, with factors like lower water solubility, reduced mobilization from dry soil, and higher in situ degradability contributing to its reduced environmental risk compared to fossil fuel alternatives in accident scenarios.
AbstractA residential lot impacted by spills from a leaking light heating oil tank was treated with a combination of chemical oxidation and bioremediation to avoid technically challenging excavation. The tank left emptied in the ground was used for slow infiltration of the remediation additives to the low permeability, clayey soil. First, hydrogen peroxide and citrate chelate was added for Fenton's reaction–based chemical oxidation, resulting in a ca. 50% reduction from the initial 25,000 mg/kg average oil concentration in the soil below the tank. Part of this was likely achieved through mobilization of oily soil into the tank, which was beneficial in regards to the following biological treatment. By first adding live bacteria in a soil inoculum, and then oxygen and nutrients in different forms, an approximately 90% average reduction was achieved. To further enhance the effect, methyl-β-cyclodextrin surfactant (CD) was added, resulting finally in a 98% reduction from the initial average level. The applicability of the surfactant was based on laboratory-scale tests demonstrating that CD promoted oil degradation and, unlike pine soap, was not utilized by the bacteria as a carbon source, and thus inhibiting degradation of oils regardless of the positive effect on biological activity. The effect of CD on water solubility for different hydrocarbon fractions was tested to serve as the basis for risk assessment requirements for authorizing the use of the surfactant at the site.
Municipal and industrial waste waters in Finland are treated before their release into the environment. New legislation also requires that waste waters from all households with running water are treated before release, whereas the methods for treatment may vary. In the Tekes-Symbio project VESITURVA research groups at the University of Helsinki, VTT, Tampere University of Technology and Lahti University of Applied Science, in collaboration with companies in the field and municipal stakeholders, pooled their resources in an effort to study and improve waste water treatment. In the case of household waste waters, minimum removal requirements exist only for the bulk components, organic matter (BOD, COD), nitrogen, and phosphorus. While we also monitored the removal of these components in VESITURVA, the main focus was on micropollutants (pollutants that exist in waste water in ng per litre to µg per litre concentrations, for example hormone disruptors, farmaceuticals, musks, components of personal care products etc.) - how they behave and how their removal can be improved. In VESITURVA we tested waste water treatment methods that are based on biofilms colonising the surfaces of matrix materials using multi-phase water treatment systems, where the water passes through two or three reactors. The model substances for the micropollutant removal process were Bisphenol A (BPA), a component used in the plastics industry, and the commonly used polycyclic musk compound HHCB. Two different types of reactors were used for studying the effect of biofilm activity: Rotating Bed Bioreactors (RBBR), where the biofilm develops on plastic beads with a large surface area, and Fixed Bed Bioreactors (FBBR), where wood chips were used as the support. In both cases a continuous or semicontinuous flow of waste water passed through the reactors. In the RBBR set-up, municipal waste water was led through a three-phase treatment process, while in the FBBR artificial grey water was treated in a two-phase process. In both processes, the removal of the bulk components was good, and substantial reductions were also achieved in the case of the model micropollutants. Multi-stage biofilm reactors seemed to be efficient at removing BPA and musk HHCB from waste water. Major parts of the micropollutants were already removed in the first reactors but the model of sequential reactors enhanced the removal of both BPA and HHCB. Diversity of bacterial communities decreased as a function of time suggesting that the bacterial communities in the reactors became specialized over time. The same bacterial groups were dominant in all sequential reactors, but differences were observed at genus taxonomic level. Also, the microbial diversity was similar to that seen earlier studies of waste water treatment microbiology. Carrier material (polyethylene, wood chips) affected the biofilm community profile in FBBR. The performance of FBBR in grey water purification was evaluated in field conditions when the reactor was installed in a detached house. The nitrogen removal efficacy of the reactor was very good and the maximum nitrogen removal efficiency in the system was 84%. Nitrogen removal in grey water treatment system was verified by an evaluation of the abundance of denitrifying microbes. The performance of the grey water treatment system was returned to the original level in 1-2 weeks after the replacement of wood chips, which were used as carrier material. Preliminary results in the laboratory also indicate that nitrogen removal in grey water treatment can be enhanced by using inoculants. Biological waste water treatment based on RBBRs purified car wash waste waters efficiently, while the reduction of surfactants was at least 95% and the reduction of chemical oxygen demand (COD) between 87 and 95% during the sampling period. Efficient waste water treatment allows automatic car washes to recycle water used for washing. The main challenges for the quality of purified water seems to be optimal nutrient input and an on-line monitoring system for water quality. We conclude that waste water treatment technology based on microbial biofilms is an efficient alternative, at least in smaller units suitable for single family homes. Although not tested in VESITURVA, we believe that the units and the technology can be upscaled and adapted to at least cover the needs of several families or a small village. Furthermore, the results regarding removal of the micropollutants tested were promising, and it is likely that many other organic micropollutants would behave similarly in multi-phase biofilm treatment systems. ; Municipal and industrial waste waters in Finland are treated before their release into the environment. New legislation also requires that waste waters from all households with running water are treated before release, whereas the methods for treatment may vary. In the Tekes-Symbio project VESITURVA research groups at the University of Helsinki, VTT, Tampere University of Technology and Lahti University of Applied Science, in collaboration with companies in the field and municipal stakeholders, pooled their resources in an effort to study and improve waste water treatment. In the case of household waste waters, minimum removal requirements exist only for the bulk components, organic matter (BOD, COD), nitrogen, and phosphorus. While we also monitored the removal of these components in VESITURVA, the main focus was on micropollutants (pollutants that exist in waste water in ng per litre to µg per litre concentrations, for example hormone disruptors, farmaceuticals, musks, components of personal care products etc.) - how they behave and how their removal can be improved. In VESITURVA we tested waste water treatment methods that are based on biofilms colonising the surfaces of matrix materials using multi-phase water treatment systems, where the water passes through two or three reactors. The model substances for the micropollutant removal process were Bisphenol A (BPA), a component used in the plastics industry, and the commonly used polycyclic musk compound HHCB. Two different types of reactors were used for studying the effect of biofilm activity: Rotating Bed Bioreactors (RBBR), where the biofilm develops on plastic beads with a large surface area, and Fixed Bed Bioreactors (FBBR), where wood chips were used as the support. In both cases a continuous or semicontinuous flow of waste water passed through the reactors. In the RBBR set-up, municipal waste water was led through a three-phase treatment process, while in the FBBR artificial grey water was treated in a two-phase process. In both processes, the removal of the bulk components was good, and substantial reductions were also achieved in the case of the model micropollutants. Multi-stage biofilm reactors seemed to be efficient at removing BPA and musk HHCB from waste water. Major parts of the micropollutants were already removed in the first reactors but the model of sequential reactors enhanced the removal of both BPA and HHCB. Diversity of bacterial communities decreased as a function of time suggesting that the bacterial communities in the reactors became specialized over time. The same bacterial groups were dominant in all sequential reactors, but differences were observed at genus taxonomic level. Also, the microbial diversity was similar to that seen earlier studies of waste water treatment microbiology. Carrier material (polyethylene, wood chips) affected the biofilm community profile in FBBR. The performance of FBBR in grey water purification was evaluated in field conditions when the reactor was installed in a detached house. The nitrogen removal efficacy of the reactor was very good and the maximum nitrogen removal efficiency in the system was 84%. Nitrogen removal in grey water treatment system was verified by an evaluation of the abundance of denitrifying microbes. The performance of the grey water treatment system was returned to the original level in 1-2 weeks after the replacement of wood chips, which were used as carrier material. Preliminary results in the laboratory also indicate that nitrogen removal in grey water treatment can be enhanced by using inoculants. Biological waste water treatment based on RBBRs purified car wash waste waters efficiently, while the reduction of surfactants was at least 95% and the reduction of chemical oxygen demand (COD) between 87 and 95% during the sampling period. Efficient waste water treatment allows automatic car washes to recycle water used for washing. The main challenges for the quality of purified water seems to be optimal nutrient input and an on-line monitoring system for water quality. We conclude that waste water treatment technology based on microbial biofilms is an efficient alternative, at least in smaller units suitable for single family homes. Although not tested in VESITURVA, we believe that the units and the technology can be upscaled and adapted to at least cover the needs of several families or a small village. Furthermore, the results regarding removal of the micropollutants tested were promising, and it is likely that many other organic micropollutants would behave similarly in multi-phase biofilm treatment systems.
