Soil Filter Research Articles

Removal of iron, arsenic and coliform bacteria from water by novel constructed soil filter system

The present paper presents results of the study in removal of iron, arsenic and total coliform from drinking water using single-pass constructed soil filter (CSF). Results indicated that arsenic levels ranged from 0.5 to less than 10 μg l −1 levels; iron from 5 to less than 0.3 mg l −1 and coliform from 10 −5 to less than 5 CFU/100 ml. The results revealed very high removal efficiency, i.e., over 99% and water quality as per WHO standard.

Wastewater renovation using constructed soil filter (CSF): A novel approach

Constructed soil filter (CSF) also known as Soil Biotechnology (SBT) is a process for water renovation which makes use of formulated media with culture of soil macro- and microorganisms. CSF combines sedimentation, infiltration and biodegradation processes to remove oxidizable organics and inorganics of wastewater in a single facility. Operating experience shows hydraulic loading in the range of 0.05–0.25 m 3/m 2 h and organic loading up to 200–680 g/m 2 d. The results show increase in dissolved oxygen levels, COD removal (from 352 mg/l to 20 mg/l); BOD removal (from 211 mg/l to 7.0 mg/l); suspended solids removal (from 293 mg/l to 16 mg/l); turbidity reduction (from 145 NTU to 5.3 NTU); iron (from 5 mg/l to 0.3 mg/l); arsenic (from 500 μg/l to 10 μg/l); total coliform and fecal coliform removal (from 145 × 10 5 to 55 CFU/100 mL and 150 × 10 8 to 110 CFU/100 mL respectively), with desired pathogen levels as per WHO standards, i.e. ≤10 3 CFU/100 mL. CSF reveals advantages such as low HRT (0.5–2.0 h), low energy requirement (0.04 kW h/m 3), no pre-treatment, high dissolved oxygen levels in the effluent, no biosludge production, no mechanical aeration and no odor, fish compatible water quality and evergreen ambience.

Treatment of municipal wastewater using laterite-based constructed soil filter

The present study reports the performance of municipal wastewater treatment plant located at Mumbai, India using laterite soil-based constructed soil filter (CSF) system monitored over 17 months. The results indicated increase in dissolved oxygen levels and reduction of chemical oxygen demand (COD) from 135.4 ± 79.4 to 28.8 ± 19.5 mg/L with first order rate constant ( K d) of 0.23 h −1. The bio-chemical oxygen demand (BOD) reduced from 92 to less than 10 mg/L with K d of 0.35 h −1; suspended solids reduction from mean 188 to 12–18 mg/L and turbidity reduction from mean 140 to 5.0 ± 3.4 NTU. The seasonal data showed 3.2 ± 0.9, 2.8 ± 0.4 and 2.85 ± 1.0 log order removal for total coliform, fecal coliform and heterotrophic plate count, respectively. The unique features of the system include a single unit, low HRT, high hydraulic loading, no chemicals, pretreatment and mechanical aeration, odor free, low energy requirement (0.04 kWh/m 3), and green ambience.

Activated soil filters (bio filters) for the elimination of xenobiotics (micro-pollutants) from storm- and waste waters

A technical scale (0.12 m 3) activated soil filter (bio filter) has been used to eliminate diverse xenobiotics (organic micro-pollutants) such as organophosphate flame retardants, and -plasticisers, musk fragrances, DEHP, benzothiazoles and triclosan from water. Model experiments to treat combined sewer overflow, storm water and a post treatment of waste water were performed in controlled laboratory experiments. The indicator compounds were typical for waste water. Diverse chemical compound groups and a wide spectrum from the lipophilic (p K ow = 5.9) to the hydrophilic (p K ow = 2.6) were included. The system consisted of a layer with high organic content (with vegetation to prevent clogging), a sand filter and a gravel drainage layer. The organic layer was spiked with activated sludge to enhance biomass and biodegradation potential. Usually the elimination rates varied from 64% to 99%, with only one compound reaching as little as 17%. For a technical suitability assessment it was calculated how long these filters would be stable in eliminating organic compounds from water. The estimated operating times for such systems was found to be about 100 years for a stack height of 2 m a year in regard to most compounds in this study.

Calibration of hydraulic parameters for large-scale vertical flow constructed wetlands

Constructed wetlands for water cleanup have been in use for several years and are promising for cost-efficient remediation of large scale contamination. Within this study, flow conditions in layered vertical soil filters used for remediation of contaminated groundwater were investigated in detail by special discharge experiments and an attuned modeling study. Unsaturated water flow was measured in two vertical flow constructed wetlands for contaminated groundwater treatment at a site in eastern Germany. Numerical simulations were performed using the code MIN3P, in which variably saturated flow is based on the Richards equation. Soil hydraulic functions based on Van Genuchten coefficients and preferential flow characteristics were obtained by calibrating the model to measured data using self-adaptive evolution strategies with covariance matrix adaptation (CMA-ES). The presented inverse modeling procedure not only provides best fit parameterizations for separate and joint model objectives, but also utilizes the information from multiple restarts of the optimization algorithm to determine suitable parameter ranges and reveal potential correlations. The sequential automatic calibration is both straightforward and efficient even if different complex objective functions are considered.

Organic Farm Soil Improves Strawberry Growth But Does Not Diminish Spittlebug Damage

Soil microorganisms are central to the success of low-input agriculture. Among these microbes, arbuscular mycorrhizal fungi (AMF) are integral components of soil communities and are well known for facilitating nutrient uptake by plants. These root symbionts can alter tolerance and resistance of plants to pathogens, and there is mounting evidence that AMF can similarly affect plant-herbivore relations. A greenhouse experiment tested whether inoculation with soil containing AMF alters tolerance of strawberry plants to herbivory by a xylem-feeding insect, the meadow spittlebug Philaenus spumarius. Commercially produced, bare-root ‘Ozark Beauty’ strawberry plants (a day-neutral cultivar) were inoculated with organic farm soil containing AMF spores or with AMF-free soil filtrate and subsequently challenged with one of five herbivore loads. Inoculation with soil increased survival, flowering, runner production, and root and shoot mass. Twenty-four days of spittlebug feeding reduced leaf mass but the negative impact was small compared with positive effects of inoculation with soil containing AMF. Effects of both treatments were additive: compared with AMF-free filtrate, soil inoculum did not alter tolerance of the plant to this xylem-feeding herbivore but did increase plant productivity.

Entfernung von Mikroorganismen durch Bodenfilter für Kleinbadeteiche

"Bathing ponds" are artificial outdoor water pools without disinfection. Whereas in conventional pools, chlorine promptly kills pathogens shed by bathers, such quick inactivation is missing in bathing ponds. We have explored the retention of indicator bacteria and viruses by a vertically operated, reed grown soil filter. After continuously running the filter with wastewater-spiked surface water, we found that the filter retains more than 99 % of the indicator organisms. It has been reported in the literature that the "spontaneous" inactivation of pathogens in water might be very variable depending on sunlight irradiation, water turbidity, etc. On the contrary, the performance of a filter like the one reported here allows filtering the water so as to reliably eliminate 90 % of the spiked microorganisms from the pool water within 24 hours.

NO (nitrogen monoxide) adsorption mechanism by a charcoal filter made from driftwood and waste lumber

Targeting resource management and the effective utilization of waste of plant origin, experiments involving NO (nitrogen monoxide) adsorption by charcoal filter were conducted. The charcoal filter used is made from driftwood into dams and from waste lumber.According to the experimental results, the amount of equilibrium NO adsorption of the charcoal filter was 40-1300 times as much as that of the soil filter used in the previous paper. Based on the experimental results of the NO breakthrough curve from the charcoal filter and the theoretical analysis of the mass transfer process, the NO adsorption characteristics of the charcoal filter were recognized. It was experimentally and theoretically shown that the fundamental main mechanism of the adsorption by the charcoal filter is the surface diffusion into the micro-pores except in the short early stage, during which the Knudsen diffusion in the meso-pores is the main mechanism. A practical equation that properly shows the stepwise change in the adsorption rate was proposed, and the physical meaning of parameters in the equation was explained through interpretation of the adsorption mechanism.The adsorption ability would differ based on the kind of materials involved, and that was left for future work examining the details of the charcoal filter structures.

Is decline in high altitude eucalypt forests related to rainforest understorey development and altered soil bacteria following the long absence of fire?

Abstract The objective of this study was to identify attributes of the understorey vegetation, soil root biomass, soil chemistry and microbial community that may be associated with tree decline in high altitude eucalypt forests in Tasmania. The sites studied were in healthy eucalypt forest, forest in decline and forest containing dead eucalypts dominated by rainforest, in north‐east (Eucalyptus delegatensis forest) and in north‐west (Eucalyptus coccifera forest) Tasmania. In both regions bare ground, rock and shrubby species were associated with healthy sites whereas decline sites were associated with moss and a tall understorey with a high percentage cover of rainforest species. Healthy sites had low root biomass in the top 10 cm of the soil profile relative to decline and rainforest sites. Seedlings of high altitude species were grown in rainforest soil (0.314% N and 0.060% P) and healthy eucalypt soil (0.253% N and 0.018% P). The four eucalypt species studied had similar root to shoot ratio in the two soils, but the rainforest species, Nothofagus cunninghamii and Leptospermum lanigerum, had higher root to shoot ratio in the healthy eucalypt than in the rainforest soil. We produced three soil filtrates: (i) fungi and bacteria present; (ii) bacteria only present and; and (iii) sterile, from healthy, decline and rainforest sites in north‐east and in north‐west Tasmania and used linseed as a germination bioassay. Filtrates from the north‐east decline and rainforest sites induced a significantly greater dysplastic germination response than healthy sites in (i) and (ii) filtrates, but this was not found in filtrates from sites in the north‐west. We conclude that while the development of a rainforest understorey and elevated soil root biomass in the long absence of fire is generally associated with high altitude eucalypt decline, altered bacterial and/or chemical attributes of soil are not always associated with high altitude eucalypt decline.

Immobilization and mineralization of nitrogen in a saline and alkaline soil during microbial use of sugarcane filter cake amended with glucose

A 42-day incubation was conducted to study the effect of glucose and ammonium addition adjusted to a C/N ratio of 12.5 on sugarcane filter cake decomposition and on the release of inorganic N from microbial residues formed initially. The CO2 evolved increased in comparison with the non-amended control from 35% of the added C with pure +5 mg g−1 soil filter cake amendment to 41% with +5 mg g−1 soil filter cake +2.5 mg g−1 soil glucose amendment to 48% with 5 mg g−1 soil filter cake +5 mg g−1 soil glucose amendment. The different amendments increased microbial biomass C and microbial biomass N within 6 h and such an increase persisted. The fungal cell-membrane component ergosterol initially showed a disproportionate increase in relation to microbial biomass C, which completely disappeared by the end of the incubation. The cellulase activity showed a 5-fold increase after filter cake addition, which was not further increased by the additional glucose amendment. The cellulase activity showed an exponential decline to values around 4% of the initial value in all treatments. The amount of inorganic N immobilized from day 0 to day 14 increased with increasing amount of C added, in contrast to the control treatment. After day 14, the immobilized N was re-mineralized at rates between 1.3 and 1.5 µg N g−1 soil d−1 in the treatments being more than twice as high as in the control treatment. This means that the re-mineralization rate is independent of the actual size of the microbial residues pool and also independent of the size of the soil microbial biomass.

Arsenic and iron removal from water using constructed soil filter—a novel approach

AbstractArsenic poisoning is a global problem. It is known that groundwater in Bangladesh and West Bengal predominantly contains As(III) and concentrations of Fe(II) which are often too low for removal of arsenic in optimum quantities. To eliminate arsenic from drinking water, several basic methods such as coagulation, adsorption, ion exchange, filtration, membrane processes, are reported. To deal with this issue on a small to large scale, we present a novel approach to remove arsenic and iron from water by constructed soil filter (CSF).In CSF, As (III) is oxidized to As(V) by media via natural oxidation and subsequently, arsenic is co‐precipitated with iron. Here water containing arsenic, iron, and phosphate is passed through the CSF media at the rate of 100 ml/min. Results show a mean residence time of 8.6 min and a holdup of 1.85 l. Results of six runs show that with initial As(III) of 300 µg/l and iron concentration of 5–10 mg/l, residual arsenic levels below 10 ppb and residual iron < 0.30 mg/l in water can be achieved.In CSF, no chemicals are needed for the oxidation of As(III) to As(V). The oxidation takes place due to the presence of various oxides such as iron, manganese, aluminum, and the microbial diversity in the media of soil bioreactor. Such a novel technology is also applied for purification of water and wastewater. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.

Experimental results and mathematical modelling of an autotrophic and heterotrophic biofilm in a sand filter treating landfill leachate and municipal wastewater

A better understanding of wastewater treatment with soil filters is important to optimise plant operation and reduce the risk of clogging. The article presents results of a treatment concept which uses a combination of SBR and vertical-flow sand filter technology. The SBR was mainly used for denitrification and sedimentation of substances in particulate form. Efficient nitrification was achieved by the planted sand filter. Degradation rates of 10 gNH 4-N/(m 2 × d) were measured for periods with peak loadings. The two-dimensional dynamic model reproduces the biofilm growth and decay of heterotrophic and autotrophic biomass. It is capable of describing the clogging of the sand filter by combining a biochemical and a geometric model. After calibration, the model was used for the calculation of maximum nitrogen degradation performances. Maximum degradation rates of 12 gNH 4-N/(m 2 × d) can be achieved if the COD/TKN ratio is reduced before to a level lower than that of municipal wastewater. The COD was further degraded in the filter than we expected comparing it with activated sludge plants. Within the soil filter a biofilm thickness of up to 110 μm is simulated depending on the embankment of gravel and grains of sand. Sensitivity analysis of model parameters showed the high impact of the maximum autotrophic growth rate, the autotrophic yield, the diffusion coefficient for oxygen and the number of contact points of the single grains of sand.

The diffuse infiltration of road runoff: An environmental improvement

The Laboratory of Engineering and Environmental Geology (GEOLEP) has been mandated by Swiss authorities (Swiss Federal Road Office FedRO) to test a new road runoff management concept. This concept promotes the diffuse infiltration of road runoff into infiltration slopes designed for this purpose. Soils retain particles and contaminants; this lowers the road impact on the environment and simultaneously improves aquifer recharge. This concept has to be adapted to aquifer vulnerability and traffic conditions. Thus, a real-scale experimental station was designed and built in Switzerland to assess the feasibility of this new concept. This station allowed the testing of two lysimeters composed of 80cm of A and B-horizons. Water and chemical fluxes were measured at the lysimeter bases. Road runoff was sampled in a distinct collector. Infiltration of road runoff into the local aquifer was monitored thanks to six piezometers. Water quality and quantity were therefore measured at each step of the infiltration process. Results provided by 112 natural events showed that soil horizons accommodated road runoff flows. The least favourable conditions for contaminant retention are encountered during thunderstorms, when high concentrations of substances deposited on the road are remobilised within a short time and rapidly percolates through soil horizons. Thus, three artificial events were designed to mimic heavy thunderstorms. Concentrations measured in road runoff notably decreased after soil filtration. Substances with high distribution coefficients K d (low mobility) had concentrations reduced to lower values (1/1000 to 1/10,000), while those with high mobility retained similar concentrations even after soil filtration. However, these mobile substances exhibited low concentrations in the underlying aquifer due to dilution. This innovative road runoff management concept can thus be readily implemented outside groundwater protection zones where aquifers are slightly vulnerable; it undoubtedly lowers the environmental impact of roads, does not endanger road integrity, and locally increases aquifer recharge.

Municipal wastewater treatment using novel constructed soil filter system

The study gives a new approach for contaminant removal from municipal wastewater using constructed soil filter (CSF) and presents performance of two CSF units located in Mumbai, India. In this system, natural weathered rock is formulated which combines sedimentation, infiltration and biochemical processes to remove suspended solids and oxidisable organics and inorganics of the wastewater. Results show elevated dissolved oxygen (DO) levels, removal of COD (136–205 to 38–40 mg l −1) and BOD (80–125 to less than 12 mg l −1) suspended solids from 135–203 to 13–18 mg l −1 and turbidity from 84–124 to 8–11 NTU, bacterial removal of 2.4–3.1 log order for Total coliform and Fecal coliform from site I which is almost 8 years old facility, and site II which is 3 years old. Estimated hydraulic retention time of 0.5–1.0 h, hydraulic loading of 0.036–0.047 m 3 m −2 h −1, no pretreatment, high DO levels in the effluent, no bio-sludge production, no mechanical aeration, low energy requirement (0.04 kW h m −3) and green aesthetic ambience are its unique features.

First Report of Leaf Spot, Shoot Blight, and Stem and Collar Canker of Rhododendron spp. Caused by Phytophthora citricola in the Czech Republic.

During the summer and autumn of 2006, a disease of rhododendron plants (Ericaceae) was found in nurseries and public gardens in several areas of the Czech Republic. Leaves of damaged plants showed dark brown-to-black lesions extending along the mid-rib and commonly spreading to petioles and shoots. The infected shoots turned black and died. The cankers on branches, stems, and collars were characterized by reddish, brownish, or blackish discoloration. The disease was identified on Rhododendron catawbiense, R. repens, and other Rhododendron spp. After plating pieces of symptomatic tissue on PARPNH medium (2), several isolates of a homothallic Phytophthora sp. were acquired. Ten representative isolates of the pathogen were cultivated on V8A plates and examined for cultural and morphological characteristics. Colonies had a stellate pattern of growth with sparse aerial mycelium at 20°C; optimum temperature for growth was 25 to 28°C, minimum was 4°C, and maximum was 33°C. Radial growth was 14 mm per day at 20°C on V8A. The isolates produced terminal, spherical, smooth-walled oogonia, which were 19 to 37 μm in diameter. Oospores were plerotic (17 to 32 μm) with walls 2 to 4 μm thick; antheridia were paragynous. Single, terminal, noncaducous, semipapillate sporangia were formed on simple (occasionally sympodial) sporangiophores in nonsterile soil filtrate. The sporangia (28 to 61 × 24 to 35 μm, L:B ratio 1.5) were mostly obpyriform, rarely obovoid, or ovoid-ellipsoid. Morphological and cultural characters resembled those described for Phytophthora citricola Sawada (1). The ITS sequences of the rDNA of the two representative isolates (GenBank Accession Nos. EF194772 and EF194773) showed 100% homology to P. citricola sequences obtained from GenBank, thus the identity was confirmed as P. citricola. Both specimens were deposited in CCF (Culture Collection of Fungi, Charles University, Prague, Czech Republic). To confirm the pathogenicity of isolates, Koch's postulates were tested using 40 3-year-old potted rhododendron (R. catawbiense and R. repens) plants and the two P. citricola strains deposited in CCF. Surfaces of attached healthy leaves were disinfected with 95% ethanol and gently abraded with a sterile scalpel near the mid-rib. Agar plugs from the margin of a 5-day-old colony grown on carrot agar were placed on leaf surfaces and also inserted under flaps of stem tissues made with a sterile scalpel. The leaves and stems were then sealed with Parafilm. Control plants were treated in the same manner with sterile agar plugs. All plants were watered with deionized water, covered with a plastic bag, and maintained in a greenhouse at 21°C for 6 weeks. All inoculated plants exhibited necrotic lesions on leaves and stems around the points of inoculation after 4 days, whereas the control plants remained healthy. The pathogen was consistently reisolated from symptomatic plants. P. citricola is well known as a pathogen of rhododendron (1), but to our knowledge, this is the first report of P. citricola on Rhododendron sp. in the Czech Republic. P. citricola has been found at five different locations and in the most frequently isolated Phytophthora spp. from rhododendron in the Czech Republic.

The influence of temperature on nutrient treatment efficiency in stormwater biofilter systems

Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source in urbanised areas has to be treated in order to reduce its nutrient loads. Biofilters which use soil filter media, biofilms and plants, are a good treatment option for nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2 degrees C, +8 degrees C, control at +20 degrees C) which may cause special problems regarding biofilter performance. It was shown that particle-bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NO(x) was produced in the columns. This behaviour can be explained with both insufficient denitrification and high leaching from the columns.

Variation among plant species in pollutant removal from stormwater in biofiltration systems

Biofiltration systems use vegetation to improve efficiency of pollutant removal from stormwater, but little is known of how plants vary in their capacity to improve biofilter effectiveness. We used a pot trial of 20 Australian species to investigate how species vary in the removal of pollutants from semisynthetic stormwater passing through a soil filter medium. Effluent levels of total suspended solids (TSS), Al, Cr, Cu, Pb and Zn were similarly low for vegetated and non-vegetated soils, with reduction to <1–12% of levels in the stormwater input. N and P effluent concentrations were generally lower from vegetated than non-vegetated soils, but total N increased on average in effluent of both vegetated and non-vegetated soils relative to stormwater input. Effluent concentrations varied 2–4-fold among species for TSS, total N and P, total dissolved N (TDN), organic nitrogen and Cu, to more than 20-fold for NO x , NH 4 +, Mn, Pb and Fe. Species also varied markedly in pollutant removal per root mass (a means of standardising for plant size), with 18–50-fold variation among species in effluent concentrations of total P and N, TDN and organic N, to >150-fold variation in NO x and NH 4 +. Hence, choice of plant species may have marked effects on biofilter effectiveness.

Interaction of oxygen concentration and retention of pollutants in vertical flow constructed wetlands for CSO treatment

The EU Water Framework Directive (WFD) calls for a good quality of all water bodies. Retention soil filters (RSF) have been developed to treat discharges from combined sewers systems. RSF have proved over the past 15 years to be the most effective measure to meet the EU WFD standards, especially for small or particularly sensitive receiving waters, which require an enhanced reduction of emissions from combined sewer overflows (CSOs). The paper presents results from laboratory-scale experiments, in which the oxygen measurement in the filter plays a main role. The results show remarkable differences in oxygen concentrations in different filter depths. The highest oxygen consumption takes place in the upper part of the filter. In the lower part the re-aeration of sewage from the soil air dominates. This indicates that the biological activity is limited to the upper part of the filter. The availability of oxygen in the filter is a sign for degradation of wastewater compounds (ammonium, COD) under certain conditions and already takes place during the filter operation. The removal of ammonium especially cannot be strictly divided into phases of sorption during the loading and oxidation during the dry period any more.

Biodegradation of chlorobenzene in a constructed wetland treating contaminated groundwater

Monochlorobenzene (MCB) is an important groundwater contaminant world-wide. In this study, a horizontal subsurface flow constructed wetland with an integrated water compartment was fed with MCB contaminated groundwater originating from the local aquifer. Analysis of spatial concentration dynamics of MCB and oxygen was combined with isotope composition analysis of MCB for assessing in situ biodegradation. Removal of MCB was most effective in the upper layer of the soil filter, reaching up to 77.1%. Trace oxygen concentrations below 0.16 mg L(-1) were observed throughout the wetland transect, suggesting a considerable limitation of aerobic microbial MCB degradation. Enrichment of 13C in the residual MCB fraction at increasing distance from the inflow point indicated microbial MCB degradation in the wetland. The observed isotope shift was higher than expected for aerobic MCB degradation and thus pointed out a significant contribution of an anaerobic degradation pathway to the overall biodegradation.

Wastewater treatment with activated pre-clarifier and planted soil filters

With a series of buffer tank, activated pre-clarifier (SBR) and planted soil filters, it is possible to get a stable degradation and good effluent values in the case of unsteady inflow and changing concentrations. In the process presented here the activated pre-clarifier is working as a denitrification tank and the soil filter as a nitrification reactor. An automatic control manages the storm-water runoff, the water-recirculation returns the nitrate and provides a minimal feed. Experiences with this plant from 1999 to 2005 are given in this paper, research has been done in the project "Planted soil filters as a Biotechnological Process", founded by the German Federal Environment Foundation (DBU). A full scale pilot plant was built to treat wastewater from composting sides, with a 42 m3 SBR and a bed area of 2 x 550 m2 of the planted soil filters. Now, after six years of operation, the results are still satisfactory. Besides this pilot plant, landfill leakage and municipal wastewater have been treated in a technical scale plant with the same process in an 80 L SBR and 0.75 m2 vertical flow soil filter with good results.