Vegetative Treatment Systems Research Articles

Treating Agricultural Runoff with a Mobile Carbon Filtration Unit

Several classes of pesticides have been shown to impair water quality in California, including organophosphates, pyrethroids and neonicotinoids. Vegetative treatment systems (VTS) can reduce pesticide loads and associated toxicity in agricultural runoff, but many water-soluble pesticides such as neonicotinoids are not effectively treated by VTS, and VTS installation is not always an option for growers required to remove non-crop vegetation for food safety concerns. Recent studies have shown that biochar filtration can be used to remove soluble contaminants, especially when coupled with other VTS components. We evaluated a mobile carbon filter system consisting of a trailer-mounted tank containing approximately 600L (~ 180 kg) of biochar. Input water from a 437-hectare agricultural drainage was pre-filtered and treated with biochar during two multi-week study periods. Laboratory toxicity tests and chemical and nutrient analyses were conducted on input and output water. Pesticide concentrations were initially reduced by greater than 99%. Treatment efficacy declined linearly and was expected to remain at least 50% effective for up to 34 weeks. Toxicity was assessed with Ceriodaphnia dubia, Hyalella azteca and Chironomus dilutus. Significant input toxicity was reduced to non-toxic levels in 6 of 16 samples. Some input concentrations of the neonicotinoid imidacloprid and the pyrethroid cypermethrin exceeded organism-specific toxicity thresholds and benchmarks, but the overall causes of toxicity were complex mixtures of agricultural chemicals. Nutrients were not reduced by the biochar. Results demonstrate the utility of biochar in treating agricultural runoff and provide measures of the longevity of biochar under field conditions.

Impact of Vegetative Treatment Systems on Multiple Measures of Antibiotic Resistance in Agricultural Wastewater.

Wastewater is an important vector of antibiotic resistant bacteria and antibiotic resistance genes (ARB/G). While there is broad agreement that ARB/G from agricultural (ag) wastewaters can be transported through the environment and may contribute to untreatable infectious disease in humans and animals, there remain large knowledge gaps surrounding applied details on the types and amounts of ARB/G associated with different agricultural wastewater treatment options and different ag production systems. This study evaluates a vegetative treatment system (VTS) built to treat the wastewater from a beef cattle feedlot. Samples were collected for three years, and plated on multiple media types to enumerate tetracycline and cefotaxime-resistant bacteria. Enterobacteriaceae isolates (n = 822) were characterized for carriage of tetracycline resistance genes, and E. coli isolates (n = 673) were phenotyped to determine multi-drug resistance (MDR) profiles. Tetracycline resistance in feedlot runoff wastewater was 2-to-3 orders of magnitude higher compared to rainfall runoff from the VTS fields, indicating efficacy of the VTA for reducing ARB over time following wastewater application. Clear differences in MDR profiles were observed based on the specific media on which a sample was plated. This result highlights the importance of method, especially in the context of isolate-based surveillance and monitoring of ARB in agricultural wastewaters.

Evaluation of Fecal Indicators and Pathogens in a Beef Cattle Feedlot Vegetative Treatment System.

Runoff from open-lot animal feeding areas contains microorganisms that may adversely affect human and animal health if not properly managed. One alternative to full manure containment systems is a vegetative treatment system (VTS) that collects runoff in a sediment basin and then applies it to a perennial vegetation (grass) treatment area that is harvested for hay. Little is known regarding the efficacy of large-scale commercial VTSs for the removal of microbial contaminants. In this study, an active, pump-based VTS designed and built for a 1200-head beef cattle feedlot operation was examined to determine the effects of repeated feedlot runoff application on fecal indicator microorganisms and pathogens over short-term (2 wk) and long-term (3 yr) operations and whether fecal bacteria were infiltrating into deeper soils within the treatment area. In a short-term study, fecal bacteria and pathogen numbers declined over time in soil. Measurements of total coliforms and Enterococcus counts taken on control soils were not effective as fecal indicators. The repeated application of manure-impacted runoff as irrigation water did not enrich the pathogens or fecal indicators in the soil, and no evidence was seen to indicate that pathogens were moving into the deeper soil at this site. These results indicate that large-scale, active VTSs reduce the potential for environmental contamination by manure-associated bacteria. Also, this study has implications to full-containment systems that apply runoff water to land application areas (cropland) and the fate of pathogens in the soils of land application sites.

Vegetated Treatment Area Effectiveness at Reducing Nutrient Runoff from Small Swine Operations in Central Texas

<abstract> <b><i>Abstract. </i></b> Numerous modeling and field studies have evaluated the effectiveness of vegetative treatment systems in treating runoff from animal feeding operations; however, none have evaluated the effectiveness of vegetative treatment areas (VTAs) receiving direct runoff from small swine operations. The project objective was to determine whether a sufficiently sized VTA alone can effectively remediate direct runoff from small swine operations (<100 animals). Three study locations were established in 2012, and sampling sites were installed to measure runoff water quantity and quality at the VTA inlet, VTA outlet, and a nearby control. The VTAs reduced runoff volume by 17%-55%, nutrient concentrations by 23%-91%, and nutrient loads by 50%-96%, although some median NO₃-N concentrations and loads increased. The Bell County VTA significantly reduced most nutrient concentrations and loads, many to the level of the control site, which represents “near ideal” performance. The Brazos County VTA also significantly reduced all nutrient concentrations and loads except for NO₃-N, but the reductions were not adequate to match levels at the control. The Robertson County VTA inlet and outlet produced low nutrient concentrations and loads that were similar to the control, which is partially attributed to alternative management of solids and enclosed barn pens. Average soil N and P levels decreased from April 2013 to October 2014, although some nutrient build-up did occur near the VTA inlets in Bell and Brazos County. Based on these results, with proper consideration of design and management factors (e.g., solids management, perennial grass cover and subsequent haying and removal, and nutrient loads/VTA area), VTAs can be practical, environmentally-friendly waste management alternatives.

Vegetative Treatment System Impacts on Groundwater Quality

<abstract><title><italic>Abstract.</italic></title> Increased environmental awareness has prompted the need for improved feedlot runoff control. Vegetative treatment systems (VTSs) provide a cost-effective option that may enhance environmental security by protecting water quality. Vegetative treatment systems are typically designed on the basis of hydraulic performance, which may result in excess application of some nutrients, specifically nitrogen and phosphorus. Groundwater quality monitoring is required to determine the effect, if any, that VTSs have on groundwater. Shallow groundwater (2 to 10 m) quality beneath six VTSs in Iowa was monitored over a four-year period. Monitoring wells were located upgradient, within, and downgradient of the VTSs. Groundwater samples were collected on a monthly basis and analyzed for ammoniacal nitrogen, chloride, nitrate-nitrogen, and fecal coliforms. A trend analysis was conducted to evaluate groundwater response patterns to VTS construction and use. In general, monitoring wells located within and downgradient of the VTS showed increasing trends in chloride and decreasing trends in nitrate concentrations. No trends for fecal coliforms or ammoniacal nitrogen were seen. Statistical analysis was performed to test for concentration differences between upgradient, within, and downgradient monitoring wells. In general, no differences in ammoniacal nitrogen concentration were seen. Fecal coliform concentrations were generally highest at the monitoring well within the VTS, but no difference was found between upgradient and downgradient concentrations. Chloride concentrations were generally significantly higher within and downgradient of the VTS when compared to the upgradient well; nitrate concentrations were generally significantly lower within and downgradient of the VTA than upgradient.

The Use of Phosphorus Sorption Isotherms to Project Vegetative Treatment Area Life

<abstract><title><italic>Abstract.</italic></title> Beef feedlots of all sizes are looking for cost-effective solutions to manage feedlot runoff. Vegetative treatment systems (VTSs) are a potential option. VTSs consist of a solids settling structure followed by additional treatment components, such as vegetative infiltration basins (VIBs) and/or vegetative treatment areas (VTAs) that use soil and vegetation to treat nutrients in the applied runoff. Investigations have shown that VTSs can provide a cost-effective means of controlling feedlot runoff; however, their sustainability and life expectancy have not yet been determined. Thus, the objective of this work is to evaluate, based on the VTA’s ability to sorb and utilize phosphorus, the expected phosphorus sink life of VTSs on beef feedlots in Iowa. In doing so, we evaluated three things: (1) phosphorus removal with vegetation harvest, (2) the extent of vertical redistribution of phosphorus in the soil profile, and (3) if a mass balance approach was capable of predicting changes in soil test phosphorus. Vegetation harvest removed 6% to 16% of the applied phosphorus, and a P mass balance did an adequate job of predicting the significant increases in soil P test concentrations. Deep soil cores (1.2 m) showed that phosphorus accumulation tended to be limited to the top 0.3 m but that vertical migration was increasing. Based on this success, we proposed a P mass balance and soil sorption model to project VTA life expectancy and evaluated the sensitivity of the estimated life to different design and management alternatives. The sensitivity analysis showed that phosphorus sorption capacity and loading rate were important, but the critical depth of the soil that can be saturated has the largest impact on VTA life.

Impact of system management on vegetative treatment system effluent concentrations

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems are one potential option, but require performance evaluation for use on concentrated animal feeding operations. The performance of six vegetative treatment systems on open beef feedlots throughout Iowa was monitored from 2006 through 2009. These feedlots had interim, National Pollution Discharge Elimination System permits that allowed the use of vegetative treatment systems to control and treat runoff from the open feedlots. This manuscript focuses on making within site comparisons, i.e., from year-to-year and component-to-component within a site, to evaluate how management changes and system modifications altered performance. The effectiveness, in terms of effluent concentration reductions, of each system was evaluated; nutrient concentration reductions typically ranged from 60 to 99% during treatment in the vegetative components of the vegetative treatment systems. Monitoring results showed a consistent improvement in system performance during the four years of study. Much of this improvement can be attributed to improved management techniques and system modifications that addressed key performance issues. Specifically, active control of the solid settling basin outlet improved solids retention and allowed the producers to match effluent application rates to the infiltration rate of the vegetative treatment area, reducing the occurrence of effluent release. Additional improvements resulted from system maturation, increased operator experience, and the addition of earthen flow spreaders within the vegetative treatment area to slow flow and provide increased effluent storage within the treatment area, and switching to active management of settling basin effluent release.

Comparison of Construction Costs for Vegetative Treatment Systems in the Midwestern United States

Vegetative treatment systems (VTSs) provide an alternative to containment basin systems for beef feedlot runoff control. Beef producers in the Midwestern United States have shown an increasing interest in using VTSs as a perceived lower cost option to containment basin systems. This article reports the actual construction costs associated with 23 VTSs (nine on permitted Concentrated Animal Feeding Operations (CAFOs) and 14 on non-permitted Animal Feeding Operations (AFOs)) and four containment basins located throughout Iowa, Minnesota, South Dakota, and Nebraska. The VTS construction costs are reported on a per head space basis in 2009 adjusted dollars for each system. Cost comparisons are presented for CAFO and AFO facilities, and by system type. Additionally, estimated construction cost comparisons between open feedlots with VTS systems, open feedlots with containment basins, monoslope barns and hoop structures for beef production systems are provided. Results from the cost comparison indicate the average construction cost in 2009 dollars for an AFO or CAFO is $655 per head space for animals housed in a monoslope barn with a concrete floor and $395 per head space for animals housed in a hoop structure. For AFOs and CAFOs, the average cost of an earthen lot with a containment basin costs is $361 per head space, while the average cost of an earthen lot implemented with a VTS is $283 per head space. If only the feedlot runoff control system is considered, VTSs designed for CAFO facilities are less expensive on average to construct ($85 per head space on average) than traditional containment basins ($136 per head space on average). Similarly for AFO feedlot runoff control systems, a VTS was less expensive to build on average ($79 per head space on average.) than a containment basin on a similar facility ($205 per head space). The data indicated on average the least expensive VTS for an AFO is a gravity VTS ($54 per head space average.) followed by a sprinkler VTS ($94 per head space average.) and a pump and gravity VTS ($101 per head space average.). Statistical analysis showed no significant difference between the VTS construction cost per head space of cattle for an AFO compared to a CAFO (p=0.07, alpha=0.05) while there was a statistical difference between system type (p=0.02, alpha=0.05).

Using Total Solids Concentration to Estimate Nutrient Content of Feedlot Runoff Effluent from Solid Settling Basins, Vegetative Infiltration Basins, and Vegetative Treatment Areas

Increased environmental awareness has promoted the need for improved feedlot runoff control. The use of vegetative treatment systems (VTSs) to control and treat feedlot runoff may enhance environmental security and protect water quality. Knowledge of effluent nutrient concentrations throughout the vegetative treatment system is required to evaluate system performance and impact on water quality. Previously collected VTS monitoring data has provided the opportunity to investigate relationships between effluent quality parameters. The objective of this study was to evaluate, through correlation and regression, the relationships between total solids, nutrients, and effluent quality indicator concentrations of feedlot runoff at various stages of treatment in a VTS, including solid settling basin, vegetative infiltration basin, and vegetative treatment area effluent. Results of a correlation and primary factor analysis showed that most of the effluent concentrations were strongly correlated to each other, with a single factor capable of describing more than 60% of the total variability of the monitored parameters. Regression equations were developed to relate nutrient content and effluent quality indicator concentrations to total solids concentrations. Results were satisfactory for NH3-N, BOD5, COD, Cl-, TP, and TKN, indicating that total solids concentrations provided significant insight into VTS performance relative to nutrient concentration and effluent quality indicators. A comparison between predicted, based on total solids content, and monitored annual mass release of the parameters was conducted. No statistical difference was found for NH3-N, BOD5, COD, Cl-, TP, and TKN; indicating that effluent volume release along with total solids concentrations could be used to provide an estimate of nutrient mass in solid settling basin, vegetative infiltration basin, and vegetative treatment area effluent.

Comparisons of alternative feedlot runoff management systems

Two vegetative treatment and containment systems were designed in Oliver and Dunn Counties of North Dakota, USA. The results showed that unit costs for the systems designed in Oliver County were 8.83 and 7.18 $/m2 for vegetative treatment system and containment systems, respectively. Same values for Dunn County design were 7.22 and 5.82 $/m2. According to the results, vegetative treatment systems are not always the best practice to manage feedlot runoff. The topography and climate of the location should be carefully studied before making a decision. Key words: Agricultural runoff, vegetative treatment systems, storage pond.

Use of the Soil-Plant-Air-Water Model to Predict Hydraulic Performance of Vegetative Treatment Areas Controlling Open Lot Runoff

Alternative treatment systems to control runoff from open beef feedlots may enhance environmental security and protect water quality. Several Midwestern states have issued National Pollution Discharge Elimination System permits allowing beef feedlots to use vegetative treatment systems (VTSs) to control and treat feedlot runoff. Monitoring VTSs has provided data to validate performance modeling strategies. The objective of this study was to evaluate the ability of the Soil-Plant-Air-Water (SPAW) model to predict the hydraulic performance of vegetative treatment areas (VTAs). Two approaches, one using the field module and the other the pond module of the SPAW model, were investigated. The model results from the SPAW field and pond modules were compared to monitored performance data from five VTAs in Iowa. Modeling statistics were calculated to evaluate SPAW's ability to predict VTA hydraulic performance. Based on the 18 site-years of data collected, the Nash-Sutcliffe efficiency (NSE), percent bias (BIAS), and ratio of the root mean square error to the standard deviation (RSR) were 0.95, 8%, and 0.22, respectively, on an annual basis. The NSE, BIAS, and RSR for the field module were 0.32, 32%, and 0.83, respectively. The results showed that the SPAW model could be used successfully to predict the hydraulic performance of VTAs, with the pond module being more successful than the field module.

Incidence and Persistence of Zoonotic Bacterial and Protozoan Pathogens in a Beef Cattle Feedlot Runoff Control–Vegetative Treatment System

Determining the survival of zoonotic pathogens in livestock manure and runoff is critical for understanding the environmental and public health risks associated with these wastes. The occurrence and persistence of the bacterial pathogens Escherichia coli O157:H7 and Campylobacter spp. in a passive beef cattle feedlot runoff control-vegetative treatment system were examined over a 26-mo period. Incidence of the protozoans Cryptosporidium spp. and Giardia spp. was also assessed. The control system utilizes a shallow basin to collect liquid runoff and accumulate eroded solids from the pen surfaces; when an adequate liquid volume is attained, the liquid is discharged from the basin onto a 4.5-ha vegetative treatment area (VTA) of bromegrass which is harvested as hay. Basin discharge transported E. coli O157, Campylobacter spp., and generic E. coli into the VTA soil, but without additional discharge from the basin, the pathogen prevalences decreased over time. Similarly, the VTA soil concentrations of generic E. coli initially decreased rapidly, but lower residual populations persisted. Isolation of Cryptosporidium oocysts and Giardia cysts from VTA samples was infrequent, indicating differences in sedimentation and/or transport in comparison to bacteria. Isolation of generic E. coli from freshly cut hay from VTA regions that received basin discharge (12 of 30 vs. 1 of 30 control samples) provided evidence for the risk of contamination; however, neither E. coli O157 or Campylobacter spp. were recovered from the hay following baling. This work indicates that the runoff control system is effective for reducing environmental risk by containing and removing pathogens from feedlot runoff.

VEGETATIVE TREATMENT SYSTEMS FOR MANAGEMENT OF OPEN LOT RUNOFF: REVIEW OF LITERATURE

Runoff from open lot livestock systems (beef and dairy) defined as Concentrated Animal Feeding Operations(CAFO) must be controlled by systems designed and managed to prevent the release of manure-contaminated runoff for stormsequal to or less than a 25-yr, 24-h design storm. This performance standard has been attained for open lot systems with somecombination of clean water diversion, settling basins, runoff collection ponds, and irrigation systems (baseline system).An alternative approach is to rely on overland flow and infiltration into cropland with perennial forage or grasses fortreatment of open lot runoff. Such vegetative systems have been researched since the late 1960s. This article reviews theresearch literature on vegetative treatment systems (VTS) for managing open lot runoff summarizing available science onsystem performance, design, and management.Based upon this review of the literature, the following conclusions are drawn about the application of VTS to manage runofffrom open lot livestock production systems:<br>(1) Substantial research (approximately 40 identified field trials and plot studies) provides a basis for understanding theperformance of VTS. These performance results suggest that a vegetative system consisting of a settling basin and VTA orVegetative Infiltration Basin (VIB) has the potential to achieve functional equivalency to conventional technologies.<br>(2) The existing research targeting VTS is confined to non-CAFO applications, likely due to past regulatory limits. Uniquechallenges exist in adapting these results and recommendations to CAFO applications.<br>(3) The pollutant reduction resulting from a VTS is based upon two primary mechanisms: 1) sedimentation, typicallyoccurring within the first few meters of a VTS, and 2) infiltration of runoff into the soil profile. Systems relying primarily onsedimentation only are unlikely to perform equal to or better than baseline technologies. System design based uponsedimentation and infiltration is necessary to achieve a required performance level for CAFO application.<br>(4) Critical design factors specific to attaining high levels of pollutant reduction within a VTS include pre-treatment, sheetflow, discharge control, siting, and sizing. Critical management factors include maintenance of a dense vegetation stand andsheet flow of runoff across VTA as well as minimization of nutrient accumulation.

Road sediment: characterization and implications for the performance of vegetated strips for treating road run-off

Increasing pressure to mitigate pollution from urban stormwater and road run-off is generating interest in vegetative treatment systems. The treatment performance of these systems depends on the characteristics of the pollutants entering them—for example, whether metals are dissolved or particle bound, and the particle size. This study sought to provide information on the characteristics of sediment derived specifically from road-use activities. A length of roadside gutter was vacuumed repeatedly at 2-day intervals. The samples obtained were found to contain predominantly fine particles (52% <250 μm). Particles <250 μm had the highest metal contents: 181–212 mg Cu/kg, 1073–2080 mg Zn/kg and 251–334 mg Pb/kg. A high percentage of the total metal load was associated with particles smaller than 125 μm (64% of Zn, 57% of Cu and 46% of Pb). These <125-μm particles are generally predicted to be poorly trapped by vegetation. In this study, these smaller particles were also found to have a lower density (<2200 kg/m 3) than normally modelled for sediment (>2600 kg/m 3), and this may further reduce predicted trapping efficiencies. The impact of sediment entering vegetative treatment systems via aerial deposition is also discussed in terms of evaluating such systems for treatment performance.

The performances of vegetative treatment systems for highway runoff during dry and wet conditions

The performances of two different highway runoff treatment systems, a horizontal subsurface flow-constructed wetland and a vegetated balancing pond, are described. Both systems have been assessed by collecting inlet and outlet grab samples during wet and dry weather conditions, and automatically controlled storm event samples have been obtained for the constructed wetland. Removal efficiencies are discussed for BOD (grab samples only), suspended solids, Cd, Cr, Cu, Ni, Pb, Zn, nitrate and sulphate, and explanations are offered for the trends observed under different weather conditions. The large variabilities in the removal efficiencies derived for both treatment systems, based on the analyses of grab samples, make accurate comparisons of the performances difficult and also raise concerns about using this type of sampling approach for this purpose. Treatment systems are required to function satisfactorily during the increased inlet loadings experienced during storm events, and this is shown to be the case for the constructed wetland for the majority of the monitored pollutants. The large removal efficiency ranges for five separate storm events, exhibited by Cu and Pb, are discussed and compared to the other monitored pollutants which showed positive median wet weather removal efficiencies of between 43% and 85%. Despite the existence of performance fluctuations, the generally low monitored inlet concentrations in the highway runoff indicated that the pond discharges did not threaten the environmental quality of the receiving waters.

Sediment accumulation in newly constructed vegetative treatment facilities along a new major road

The A34 Newbury bypass was opened in England in November 1998. This 15 km of roadway has nine constructed vegetative treatment systems incorporating oil separators, silt traps, grass filters for primary filtration and chemical absorption, reed wetlands for secondary biofiltration, a deep water pool and outflow device to control the rate of water discharge into existing watercourses. Two of these facilities discharge stormwater into the Lambourn sites of special scientific interest (SSSI) river. An evaluation of the heavy metal levels in these two ponds (Ponds J and K) has been undertaken in the 39-month period after the opening of the bypass. Motorway-derived contaminants including Pb, Cd, Cu and Zn were evaluated within pond sediment throughout these treatment facilities. Results reveal that heavy metal levels within the treatment system that possesses a well-established reed bed system decrease rapidly though the facility. It is postulated that the high reed biomass within this facility may be primarily responsible for reducing hydraulic flow thus allowing a greater residence time for sedimentation, filtration and bioaccumulation processes.

Drainage from Highways and Other Paved Areas: Methods of Collection, Disposal and Treatment

ABSTRACTDrainage of surface water from paved areas has been a fundamental part of urban planning and highway design for more than 100 years, and many aspects have changed little during this time. However, there have been recent developments in awareness of the need to treat potential pollution from paved surface runoff, as well as the need for flow attenuation and for water quality monitoring. A product of this increased awareness has been the conversion of vegetative treatment systems, traditionally designed to treat domestic and industrial wastewaters, to the treatment of paved surface runoff. The use of vegetative treatment systems for this purpose is as yet relatively untested. This paper therefore provides a brief review of the engineering methods for the collection, transport and treatment of paved surface runoff. It then goes on to describe the different types of vegetative treatment systems which are available, their value and role, and appropriate situations for their use. Finally, consideration is given to the need to monitor the efficiency of these systems in order to establish their effectiveness, and a description is given of monitoring methods which may be appropriate.