Soil Filter Research Articles

Comparative and combined acute toxicity of butachlor, imidacloprid and chlorpyrifos on earthworm, Eisenia fetida

Various pesticides have become widespread contaminants of soils due to their large applications in agriculture and homes. An earthworm assay was used to assess the acute toxicity of butachlor, imidacloprid and chlorpyrifos with different modes of action. Ecotoxicities of these pesticides were compared for earthworm Eisenia fetida separately and in combination in artificial soil and contact filter paper tests. Imidacloprid was the most toxic for E. fetida with LC50 (lethal concentration 50) values three orders magnitude lower than that of butachlor and chlorpyrifos in both tests. The toxicity of the mixtures was compared to that predicted by the concentration addition (CA) model. According to the CA model, the observed toxicities of all binary mixtures were less than additive. However, for all the mixtures in 14d artificial soil test, and mixtures of butachlor plus chlorpyrifos and imidacloprid plus chlorpyrifos in 48h contact filter paper test, the difference in toxicity was less than 30%, hence it was concluded that the mixtures conformed to CA. The combined effects of the pesticides in contact filter paper tests were not consistent with the results in artificial soil toxicity tests, which may be associated with the interaction of soil salts with the pesticides. The CA model provides estimates of mixture toxicity that did not markedly underestimate the measured toxicity, and therefore the CA model is the most suitable to use in ecological risk assessments of the pesticides.

Characterization of domestic gray water from point source to determine the potential for urban residential reuse: a short review

This study aims to discern the domestic gray water (GW) sources that is least polluting, at the urban households of India, by examining the GW characteristics, comparing with literature data, reuse standards and suitable treatment technologies. In view of this, the quantitative and qualitative characteristics of domestic GW originating from bath, wash basin, laundry and kitchen sources are determined and compared with established standards for reuse requirements. Quality of different gray water sources is characterized with respect to the physical, chemical, biological, nutrient, ground element and heavy metal properties. The pollutant loads indicate that the diversion techniques are not suitable for household application and, therefore, treatment is necessary prior to storage and reuse. It is observed that the total volume of GW generated exceeds the reuse requirement for suggested reuse such as for flushing and gardening/irrigation. In spite of generating less volume, the kitchen source is found to be the major contributor for most of the pollutant load and, therefore, not recommended to be considered for treatment. It is concluded that treatment of GW from bathroom source alone is sufficient to meet the onsite reuse requirements and thereby significantly reduce the potable water consumption by 28.5 %. Constructed wetland systems and constructed soil filters are suggested as suitable treatment alternatives owing to its ability to treat highly variable pollutant load with lower operational and maintenance cost, which is more practical for tropical and developing countries.

Survey monitoring results on the reduction of micropollutants, bacteria, bacteriophages and TSS in retention soil filters

A main source of surface water pollution in Western Europe stems from combined sewer overflow. One of the few technologies available to reduce this pollution is the retention soil filter. In this research project, we evaluated the cleaning efficiency of retention soil filters measuring the concentration ratio of standard wastewater parameters and bacteria according to factors limiting efficiency, such as long dry phases or phases of long-lasting retention. Furthermore, we conducted an initial investigation on how well retention soil filters reduce certain micropollutants on large-scale plants. There was little precipitation during the 1-year sampling phase, which led to fewer samples than expected. Nevertheless, we could verify how efficiently retention soil filters clean total suspended solids. Our results show that retention soil filters are not only able to eliminate bacteria, but also to retain some of the micropollutants investigated here. As the filters were able to reduce diclofenac, bisphenol A and metoprolol by a median rate of almost 75%, we think that further investigations should be made into the reduction processes in the filter. At this point, a higher accuracy in the results could be achieved by conducting bench-scale experiments.

Short communication: Survey of animal-borne pathogens in the farm environment of 13 dairy operations

A survey was conducted on 13 dairies to determine the occurrence of 5 animal-borne pathogens (Salmonella enterica, Escherichia coli O157:H7, Campylobacter jejuni, Mycobacterium avium ssp. paratuberculosis, and Cryptosporidium parvum) and their distributions across farm elements (feces, bedding, milk filters, stored manure, field soil, and stream water). Presence of C. parvum was measured only in feces and stored manure. All but one farm were positive for at least one pathogen species, and 5 farms were positive for 3 species. Escherichia coli O157:H7 was detected on 6 farms and in all farm elements, including milk filters. Mycobacterium avium ssp. paratuberculosis was detected on 10 of 13 farms and in all farm elements except for milk filters. Salmonella enterica and C. jejuni were detected at lower frequencies and were not identified in soil, stream water, or milk filters on any of the 13 farms. Cryptosporidium parvum was detected in feces but not in stored manure. Stored manure had the highest occurrence of pathogens (73%), followed by feces (50%), milk filters, bedding, soil, and water (range from 23 to 31%). Association of pathogen presence with farm management factors was examined by t-test; however, the small number of study farms and samples may limit the scope of inference of the associations. Pathogens had a higher prevalence in maternity pen bedding than in calf bedding, but total pathogen occurrence did not differ in calf compared with lactating cow feces or in soils with or without manure incorporation. Herd size and animal density did not appear to have a consistent effect on pathogen occurrence. The extent of pathogen prevalence and distribution on the farms indicates considerable public health risks associated with not only milk and meat consumption and direct animal contact, but also potential dissemination of the pathogens into the agroecosystem.

Hydrolysis of organic phosphorus in soil water suspensions after addition of phosphatase enzymes

Additions of enzymes involved in organic phosphorus (P) hydrolysis can be used to characterize the hydrolyzability of molybdate-unreactive P (MUP) in soil water extracts. Our aim was to test the feasibility of enzyme additions to soil water suspensions with respect to (1) suitable enzyme preparations and (2) recovery of molybdate-reactive P (MRP). To this end, we compared the substrate specificity of seven commercially available enzyme preparations (acid and alkaline phosphomonoesterase, phytase, and nuclease preparations) and optimized the assay conditions in microplates. We then measured MRP release after the addition of the enzymes to soil water suspensions and filtrates of two Swiss grassland soils (midland and alpine). In some cases, commercial preparations of the same enzyme differed in their specificity, presumably due to contamination with other enzymes, and also in their efficiency in soil suspensions. Addition of EDTA to the buffer was required to decrease sorption of released P in soil suspensions. Enzymatic release of P was consistently equal or higher in soil suspensions than in soil filtrates. However, also more dissolved MUP was present in soil suspensions than in filtrates, since the buffer interacted with the solid phase. Of the total dissolved MUP in soil suspensions, 94 and 61 % were hydrolyzable in midland and alpine soil, respectively. More specifically, 60 and 17 % of MUP were in nucleic acids, 6 and 39 % in simple monoesters, and 28 and 5 % in inositol hexakisphosphate in midland and alpine soil, respectively. Thus, we show that the characterization of hydrolyzable organic P in soil suspensions with hydrolytic enzyme preparations may be useful to better understand the availability of soil organic P to enzymatic hydrolysis, but that it requires soil-specific adaptation for optimum P recovery.

Molybdenum(VI) removal by using constructed wetlands with different filter media and plants

The efficacy and capacity of vertical-flow wetland filters on molybdenum (Mo) removal from wastewater was examined, employing reed (Phragmites australis) and cattail (Typha latifolia) as well as different adsorption granular media. Humus, cinder, modified cinder, as well as pyrite were used as filter media. A synthetic effluent with different concentrations of Mo(VI) at different hydraulic retention times was used for simulating Mo leached mine wastewater. Laboratory experiments showed that the equilibrium adsorption data were in agreement with the Langmuir isotherm model, and the maximum Mo(VI) adsorption capacities of modified cinder and pyrite were 10.01 and 6.25 mg/g, respectively. Mo(VI) removal in F5 (combination substrates of pyrite and cinder) was found to be more stable and effective than that of F1 (conventional gravel and soil filter media) during the 14-week experiment. Most of the Mo(VI) was retained in the 10-20 cm of the substrate, and adsorbed by the modified cinder and pyrite. The largest fraction of Mo(VI) retained was the water-soluble fraction on the surface of the pyrite. Cattail was more suitable for Mo(VI) absorption than reed, but the bioaccumulation accounted for a very small portion of the total removal.

Reliability analysis based selection procedure for granular filters with respect to soil boiling condition

Existing granular filter design guidelines are based on the particle size distribution of the base soil and filter material. Though well established, the approach does not provide a means to assess the performance of the existing filters as well as the levels of associated risk with due consideration of variability in soil properties and representative particle sizes. Previously, authors proposed closed form analytical solutions to obtain factor of safety of the base soil–filter material system with respect to soil retention and permeability criteria. The solutions were developed for soil boiling condition that takes into account relevant soil properties such as unit weight, porosity, permeability, particle sizes, angle of internal friction, etc., as well as, existing hydraulic conditions and seepage discharge. In the present work, the proposed analytical solutions are utilized for the reliability analysis of the base soil–filter media system. The variability in the input soil properties is characterized as log normally distributed continuous random variables and combination of Monte Carlo simulations and first order reliability method are utilized for the reliability analysis. Through example applications, it is demonstrated that the reliability based approach is appropriate for considering variability in mathematical framework and for assessing the performance or choice of requisite filter material that has to satisfy the two critical criteria, i.e. soil retention and permeability.

Preliminary Design Aid for Bioretention Filters

A physically based mathematical model is developed in this study for the hydrologic process taking place in a bioretention filter. The hydrologic storage equation is adopted to determine the variation of water depth in the ponding area. The Green and Ampt equations are used to model the movement of water in the underlying storage zone, or soil filter, taking into account the finite depth of the filter. The perforated drain pipes placed at the bottom of a soil filter are represented by atmospheric pressure at this location. The ponding area and the soil filter equations are coupled through the infiltration term. The governing equations are written in terms of a set of dimensionless parameters and are solved numerically by using an explicit finite-difference scheme. The solutions to the dimensionless governing equations are also in terms of dimensionless parameters, and they can be generalized on the basis of the principle of hydrologic similarity. A series of solutions is obtained for numerous and systematically chosen combinations of filter size and hydrologic and soil conditions and is presented in chart form. These charts can be used as a design aid for quick preliminary sizing of new bioretention filters and quick evaluation of existing filters.

An Analysis of Leachate Constituents and Pathogen Destruction in Deer Mortality Static Windrow Composting

Approximately 1.1 million deer–vehicle collisions occur in the United States each year. The predominant methods of disposing of these carcasses (landfill and burial) have several costly disadvantages, including long travel distances to landfills, increasing landfill restrictions, and lack of viable burial areas. Some states have found static compost windrows to be an easy and cost-effective carcass management technique. This type of composting involves the construction of passively aerated static piles, which do not require the materials turning needed with more traditional composting methods. In this study, deer mortality static compost windrows were monitored for 1 year. Windrows were analyzed for pathogen destruction and the degree to which underlying soil filtered leachate contaminants. In response to high windrow temperatures, indicator pathogens Escherichia coli and Salmonella were reduced by 99.99 % the first sampling day (day 7) and ascarids were deemed non-viable by day 77. Soil filtration of leachate was effective in reducing concentrations of ammonia, chloride, and total organic carbon. Nitrate, a contaminant of particular regulatory concern, had an estimated mass contaminant loss of 2.1 kg/ha, compared to the estimated 9 to 50 kg/ha loss from fertilizer application of common agronomic crops. Results of this study indicate that with properly constructed static compost windrows, (1) high temperatures effectively destroy indicator pathogens; (2) the natural filtration of leachate through soil reduces deer mortality contaminant concentrations; and (3) the low volume of leachate (i.e., two percent of the precipitation that fell on windrows) results in nominal losses of nitrate and other contaminants.

Optimisation of wastewater treatments through combined geomaterials and natural soil filter: modelling tools

The main objective of this study is the establishment of innovative purification systems through the conceptualisation of reactive barriers in soil for artificial recharge of groundwater with treated wastewater. Numerical integration of hydrodynamics and biogeochemical processes controlling the effectiveness of this engineering system is applied to design soil column experiments. This leads to the elaboration of a combined aerobic/anaerobic environment to ensure the successive nitrification of rich ammonium wastewater and the denitrification mechanisms reducing NO3– according to heterotrophic denitrification and pyrite oxidation. A MIN3P reactive flow and transport model is used to reproduce an experimental flow-through column. Calculated concentrations of CH2O and NO3− are consistent with experimental results. Agreement between model and experimental results makes it possible to understand major processes taking place in the column and optimises future treatment experiments.

Combined wastewater feed directly into final clarification – advantage for receiving rivers

With a view to a reduction of the discharge from combined water outflow, the increase of the influent to a wastewater treatment plant can be an efficient solution, for cases in which the discharge concentration of the wastewater treatment plant would not deteriorate significantly as a result. Through bypassing the aeration with combined water and a direct feed of the combined water into the final clarification (Mina-Process) the specific sludge volume loading, which is significant to the efficiency of the final clarification, will not be raised. But the adsorption capability of the aerated sludge, the sedimentation effect of the final clarification, and the partial recirculation over return-sludge can be used for an elimination of suspended solids, chemical oxygen demand (COD), ammonia and phosphate from the combined wastewater. In large-scale tests in Wilhelmshaven (160,000 PE), removal efficiencies for the elimination in the bypass of 75% of COD, 60% of ammonia and 89% of suspended solids were reached. In comparison with conventional procedures for combined water treatment (e.g. storage volumes, soil filter) the Mina-Process has the possibility to achieve a highly efficient and economical combined water treatment by using the capability of existing clarifiers.

Acidification and loss of organic matter in context with soil filtration function

One of the most important soil ecological functions is inactivation of soil pollutants. The potential of soil for immobilization of inorganic pollutants is dependent on the total amount of the inorganic pollutants in the soil and the potential of soil sorbents which are sensitive to the pollutants sorption. The minimum data set for assessment of the soil's ability to immobilize inorganic contaminants in soil profile includes the following: total content of inorganic contaminants, pH value, content and quality (optical parameters Q4 6) of organic matter, humus layer thickness and soil texture. The decline of pH value (acidification) and organic matter content and also deterioration of organic matter quality can bring negative influence and change the sorption potential of soil. Actual changes of dynamic parameters were applied in sorption model in the Banska Bystrica region of Slovakia. The decline of pH and organic matter content as well as the increase of soil organic matter optical parameter shift Fluvisols from medium category into very low category of sorption potential on 3.8% of grassland area. This result shows that soil degradation processes will cause a decline of soil sorption potential. Therefore, optimization of dynamic soil parameters belongs to the very important tasks in soil management.

Discrete numerical modeling of particle transport in granular filters

Granular filters are an essential component in earth dams to protect the dam core from seepage erosion. This paper uses the particle flow method (PFM) to study the mechanism of particle transport in a base soil–filter system. The distributions of the eroded base-soil particles in different filters are traced and analyzed. The eroded mass and intruding depth of the eroded particles into the filters are obtained under different times and hydraulic gradients. The simulation results show that the eroded mass and intruding depth of the base-soil particles into the filter are related to the representative particle size ratio of the base soil to the filter, hydraulic gradient and erosion time. The numerical predictions are also compared with the empirical filter design criterion. The results show that the particle flow model provides an effective approach for studying the filtration micro-property and the erosion mechanism in a base soil–filter system, which is useful for filter design.

Uncertainties of stormwater characteristics and removal rates of stormwater treatment facilities: Implications for stormwater handling

Stormwater runoff is a major contributor to the pollution of receiving waters. This study focuses at characterising stormwater in order to be able to determine the impact of stormwater on receiving waters and to be able to select the most appropriate stormwater handling strategy. The stormwater characterisation is based on determining site mean concentrations (SMCs) and their uncertainties as well as the treatability of stormwater by monitoring specific pollutants concentration levels (TSS, COD, BOD, TKN, TP, Pb, Cu, Zn, E.coli) at three full scale stormwater treatment facilities in Arnhem, the Netherlands. This has resulted in 106 storm events being monitored at the lamella settler, 59 at the high rate sand filter and 132 at the soil filter during the 2 year monitoring period.The stormwater characteristics in Arnhem in terms of SMCs for main pollutants TSS and COD and settling velocities differ from international data. This implies that decisions for stormwater handling made on international literature data will very likely be wrong due to assuming too high concentrations of pollutants and misjudgement of the treatability of stormwater. The removal rates monitored at the full scale treatment facilities are within the expected range, with the soil filter and the sand filter having higher removal rates than the lamella settler. The full scale pilots revealed the importance of incorporating gross solids removal in the design of stormwater treatment facilities, as the gross solids determine operation and maintenance requirements.

Effects of Normal Pressure on the Clogging Behavior of Geotextile and Gap-Graded Soil Filtration Systems

The applied loads have a significant role on the filtration property of soil and geotextile systems. This paper investigates the effects of normal pressure on the clogging behavior of geotextile and gap-graded soil filtration systems. The experimental results show that the clogging potential increases as the normal pressure increases. And a critical value for the normal pressure may exist. When the applied normal pressure is less than the critical value, the normal pressure has significant effects on the filtration systems. However, when the applied normal pressure exceeds the critical value, effects of the normal pressure on the soil-geotextile filtration systems are minor.

하천 수질정화를 위한 실험실 규모 다단식 토양여과 시스템에서 오염물질 제거에 미치는 운전인자의 영향

In this study we investigated the effects of operational parameters of a multi-layered soil filtration (filter depth, filtration velocity, and continuous/intermittent operation) on removal of pollutants in river water. As filter depth increased removal of all the pollutants (COD, TP, TN, and NH4-N) was increased because the increase in filter depth increased in contact time between media and pollutants. The removal of TP and NH4-N more increased with the increase in filter depth, comparing to the biological COD removal which was performed only in the top layer, since the removal mechanism of TP and NH4-N was physicochemical process occurring throughout the whole layers. However, the reduction in filtration velocity resulted in decrease of removal all the pollutants removal due to shorter retention time. Biological COD removal was more influenced with the reduction in filtration velocity (longer retention time), than the removal of TP and NH4-N. Because biological process was occurred only in the top layer which has relatively shorter retention time, comparing with physicochemical process occurred throughout whole media. Therefore, it is desirable that the operation parameters be controlled toward increasing retention time, in order to achieve efficient pollutants removal. The change in operation mode (continuos vs. intermittent operations) did not provide significant effects on the pollutant treatment efficiency by the multi-layered soil filtration system. Our findings suggest that for stable long-term operation it should be considered keeping conditions for biological activity and accelerating clogging.

Rapid determination of 226Ra in environmental samples

A new rapid method for the determination of 226Ra in environmental samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for emergency response or routine sample analyses. The need for rapid analyses in the event of a Radiological Dispersive Device or Improvised Nuclear Device event is well-known. In addition, the recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid analyses for radionuclides in environmental samples in the event of a nuclear accident. 226Ra (T1/2 = 1,620 years) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The new method to determine 226Ra in environmental samples utilizes a rapid sodium hydroxide fusion method for solid samples, calcium carbonate precipitation to preconcentrate Ra, and rapid column separation steps to remove interferences. The column separation process uses cation exchange resin to remove large amounts of calcium, Sr Resin to remove barium and Ln Resin as a final purification step to remove 225Ac and potential interferences. The purified 226Ra sample test sources are prepared using barium sulfate microprecipitation in the presence of isopropanol for counting by alpha spectrometry. The method showed good chemical recoveries and effective removal of interferences. The determination of 226Ra in environmental samples can be performed in less than 16 h for vegetation, concrete, brick, soil, and air filter samples with excellent quality for emergency or routine analyses. The sample preparation work takes less than 6 h. 225Ra (T1/2 = 14.9 day) tracer is used and the 225Ra progeny 217At is used to determine chemical yield via alpha spectrometry. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory radium particles are effectively digested. The preconcentration and column separation steps can also be applied to aqueous samples with good results.

The review of non-conventional technologies applied in the Czech Republic

Non-conventional technologies are commonly used in the Czech Republic for wastewater treatment, especially for small municipalities (up to 500 PE). Three main types of non-conventional technologies are applied: stabilization ponds, soil filters and constructed wetlands. Within the research project of Czech Ministry of the Environment, authors have observed 14 localities for two or more years. In this article all three types of non-conventional technologies will be described. At the same time detailed results of the monitoring will be presented with the accent to treatment efficiency comparison of these technologies in parameters COD, BOD5, SS, NTOT and PTOT. Operational experiences of non-conventional technologies will also be described, especially critical moments which can negatively influence the treatment efficiency.

Activated soil filters for removal of biocides from contaminated run-off and waste-waters

Building facades can be equipped with biocides to prevent formation of algal, fungal and bacterial films. Thus run-off waters may contain these highly active compounds. In this study, the removal of several groups of biocides from contaminated waters by means of an activated soil filter was studied. A technical scale activated vertical soil filter (biofilter) with different layers (peat, sand and gravel), was planted with reed ( Phragmites australis) and used to study the removal rates and fate of hydrophilic to moderate hydrophobic (log K ow 1.8–4.4) biocides and biocide metabolites such as: Terbutryn, Cybutryn (Irgarol® 1051), Descyclopropyl–Cybutryn (Cybutryn and Terbutryn metabolite), Isoproturon, Diuron, and its metabolite Diuron-desmonomethyl, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro- n-octylisothiazolinone and Iodocarbamate (Iodocarb). Three experiments were performed: the first one (36 d) under low flow conditions (61 L m −2 d −1) reached removal rates between 82% and 100%. The second one was performed to study high flow conditions: During this experiment, water was added as a pulse to the filter system with a hydraulic load of 255 L m −2 within 5 min (retention time <1 h). During this experiment the removal rates of the compounds decreased drastically. For five compounds (Cybutryn, Descyclopropyl–Cybutryn, Diuron, Isoproturon, and Iodocarb) the removal dropped temporarily below 60%, while it was always above 70% for the others (Terbutryn, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro- n-octylisothiazolinone). However, this removal is a considerable improvement compared to direct discharge into surface waters or infiltration into soil without appropriate removal. In the last experiment the removal efficiencies of the different layers were studied. Though the peat layer was responsible for most of the removal, the sand and gravel layers also contributed significantly for some compounds. All compounds are rather removed by degradation than by sorption.

Microwave digestion of hardly dissoluble samples

This paper describes a method for digestion of hardly dissoluble samples such as soil, sand, glass fiber and cellulose filters via microwave. The evaluation of this method was conducted by automatic TDCR liquid scintilation counter Hidex 300 SL. The alpha tracer 244Cm was used for the assessment of efficiency. The decomposition of samples was realized by MWS 4 Speedwave (Berghof, Germany) with the method determined to be simple, safe and very effective as evidenced by high chemical yield.