Bio-Retention Systems and Vegetated and Bio-Filtration Swales - Assignment Example

Name Instructor Course Date Bio-Retention Systems Introduction Bio-retention is among the best management practice for urban storm water. The system is employed to minimize the impact of urban water runoff during storm events. Prince Gorges County developed bio-retention management in early 1990’s (United States Environmental protection Agency). Bio-retention system utilizes soils, woody and herbaceous plants to remove pollutants from storm water runoff. Additionally, the system remove water pollutants from infiltrating run off via mechanisms like adsorption, precipitation and filtration (Diffuse Pollution Conference Dublin, p.4). Urban storm water runoff occurs abundantly hence the increase of water pollution. The increased impervious surface and loading of toxic contaminants from urban areas towards the receiving water bodies makes the largest water pollution surveyed in the U.S lakes (United States Environmental protection Agency). Total Suspended Soil Total Suspended Soil (TSS) removal requires bio-retention basins. The presences of TSS in storm water happen to be a good indicator of the presences of organic matter, particulate nutrients, heavy metals and other nutrients. The suspended solid materials clog storm water runoff or disrupt aquatic environment. A research conducted using synthetic runoff indicated that after every storm downpour, 91% of sediments collected are TSS mass removal. The retention basin is lined with gravel, sand, and an under drain with which the functionality is to discharge water after treatment. The effectiveness of reducing the pollutants is achieved by treating the first flush of storm water runoff. Penetrates are positioned to remove more than 40% of TSS during the treatment of high pollutants loads in the storm water runoff. The retention basin is currently working effectively in Massachusetts (Bio-retention Basin Removal Efficiency, p.12). Contra wise, using bio-retention particulate matter is captured hence stratification occurs. Finer soil particles are collected in the upper media layer and suspended solids trapped inside the media, altering the system characteristic by reducing the hydraulic conductivity. As per the findings, useful lifespan of bio-retention filter media is limited by clogging which is expected and regularly occur prior to TSS break through. Total Phosphorous and Total Nitrogen TP and TN storm water management is applicable depending on size of bio-retention designed. The pre-treatment is an essential element at this phase since sediments particles need to be trapped before the particles clog the filter bed. Tentatively, grass filter strips, grave diagrams, and stone flow spreaders are basic requirements during TP and TN management (Minami, p. 183). Advisably, innovative or proprietary structure with demonstrated capability of reducing sediments may be used to provide pre-treatment. The TP and TN have good removing rate of impurities in a constructed bio-retention system. Bio-retention systems constructed with the inclusion of plants has a better removal of efficiency than the system without plants. The positive correlation observed between the two nutrients indicates that the removing rate of pollutants is same irrespective of water quantity of initial rainfall runoff. The system shows encouraged results for nutrients retention (Jadlocki, p.48) Biochemical Oxygen Demand and Chemical Oxygen Demand Presences of BOD indicate fecal contamination. The availability of BOD in storm water runoff restricts water use and development, necessitates expensive water treatment, and impairs ecosystem health. The COD can be empirically related to BOD. Chemical Oxygen Demand is an alternative measure of oxygen with same equivalence in organic matter content (International Standards Organization). The samples indicate oxidation through a strong chemical exigent. Increased concentration of dissolved organic carbon creates problems in the production of safe drinking water in a country. BOD is a useful measure to asses the effectiveness of current water treatment processes. Using the bio-retention management system, the polluted water is filtered through biologically active plants and soils. The contaminants from water are removed hence the water is suitable for community consumption (International Standards Organization) Heavy metal removal Copper, zinc and zinc are heavy metal removal during bio-retention system. In series pilot studies indicates that 97% of metal tested are collected from mulch layer in bio-retention system. A series of another pilot research indicates that runoff PH, duration, intensity, and heavy metal concentration have little impact on metal removal efficiency in bio-retention system. The removal of metals is challenging since some metals do not undergo same removal processes. The less collected aluminum metals and arsenic metals indicate that the system is not fully efficient to work along the influent and effluent concentrations of metals. Chances of uncollected metals are likely to exceed the drinking water maximum contaminated level as prescribed by USEPA. Climatic change influences the efficiency of bio-retention. Researchers examined and data indicated that bio-retention enriches its efficiency during the snowmelt seasons compared to other temperate conditions. The heavy metals collected on snowmelt thrive to 90% while other climate conditions indicated only 60% of metals collected (Toronto and Region Conservation Authority). The biometric system has limiting capacity to store the collected method. The potential solution is the harvesting of metals through metal-saturated plant biomass. Higher biomass yields require to be constructed to make plants harvesting viable solution for heavy metal accumulation in bio-retention system. The reason, as per research findings, indicates concentration of metals is available at the plant root within the soil media with a record of capturing 97% of heavy metals on the identified location. With massive researches completed, bio-retention shows a promise for a treatment of storm water use especially during irrigations since heavy metals pose threats to plants survival (Toronto and Region Conservation Authority) Conclusion Conclusively, bio-retention provides opportunity for runoff infiltration, filtration, and storage and water uptake by crops. The bio-retention basin provides the efficient treatment of storm water runoff particularly the minerals available in water. Additionally, the control of bio-retention close to water source shows the functionality strength of the system. Through paradigm change, the system can be used to optimize and integrate urban planning through management of water cycle to minimize storm water pollution. VEGETATED AND BIO-FILTRATION SWALES Introduction Vegetated and bio-filtrations are open channels engineered to treat storm water. The vegetated swales are open; with low-lying plant, vegetations covering the side’s slopes and the bottom trench that efficiently collect and convey storm runoff towards the discharge points. The vegetated swales provide pollutant removal through settling and filtration in the vegetations lining on the slopes and bottom. Additionally, the system provides the opportunity of volume reduction through infiltration and reduces the velocity to convey storm water runoff (Los Angeles Unified School District Storm water Technical Manual, p.35) Bio-filtration swale is empirically related to vegetated swales. Bio-filtration swales are vegetated in trapezoidal channels with the functionality of receiving and conveying storm water flows. To meet water criteria, pollutants removal occurs through filtration in the vegetation, uptake by plant biomass, sedimentation, adsorption to soil particles and the infiltration through the soil (California Department of Transportation, p.1) Total Suspended Soil Vegetated and bio-filtration swales are effective in reducing total suspended soil (TSS). Studies indicate that the system is very effective in reducing TSS with a removal value ranging from 48% to 98% (Stagge, p.2). The field laboratory studies of TSS indicate that vegetated and bio-filtration swales treat storm water pollutants through sedimentation and filtration mechanism (Jamil, p.2). As such, the particulate removal is governed by Strokes Law and is related to hydraulic residence time and particle size. Total Phosphorous and Total Nitrogen Phosphorous and nitrogen nutrients accelerate eutrophication in receiving water bodies. Varied results indicate challenges faced by the system during nutrients pollutants collection. The contributing agent towards the challenges faced in treatment of storm water is the availability of extraneous organic matter in the vegetations system on use. Fields studies involving phosphorus removal vary greatly. Some studies indicate the vegetation and bio-filtration swales removing a significant total phosphorus from 12% to 60% while other results demonstrate a significant total phosphorus export (Hunho p. 2). tentatively, a study conducted in Florida parking area concludes nitrogen total mass loads was reduced due to storage and infiltration, however the resulting nitrate concentrations are unaffected by vegetated and bio-filtration swale treatment (Rushton, p.2). Heavy metal removal The swale system is effective in removing metals from storm water runoff. Zinc is typically the most removed heavy metal at 96% using the event mean concentration reduction technique. The same technique applies to copper and lead removal at 81% and 94% respectively (kaushal, p.6). Biochemical Oxygen Demand and Chemical Oxygen Demand BOD & COD is designed for aerobic biological species to survive in water. The species require enough BOD to break down organic compounds in water for its continual survival. Pollutants in storm water runoff to oceans and sea hence chances of less dissolved Oxygen in water is high. Less dissolved Oxygen inhibits aquatic life survival. COD is a similar element to BOD but it represents all the amount of Oxygen needed to break down all organic compounds in a sample of water while BOD accounts only for biological process of break down organic compound. The reduction of COD is possible only if the COD concentrations are more than 80 mg/L (Weiss, p.13). Conclusion Conclusively, the COD, TSS, zinc, and lead metals are reduced at least more than 75%. The removal of such pollutants is achieved through infiltration using swale system. As per the research, the findings indicate that the system is able to improve water quality of the storm water run off from Class V to Class III according to the interim National Water Quality Standards of Malaysia. The nutrients pollutant treatment showed variable results of large impulses during a few extreme events. Work Cited Bio-retention Basin Removal Efficiency. Evaluation of Storm water Best Management Practice Effectiveness and Implications for Design. 2013. Project Number PPM 1231 California Department of Transportation. Bio-filtration Swale Design Guidance. 2013. Division of Environmental Analysis Storm Water Program Diffuse Pollution Conference Dublin. Multiple-Event Study Of Bio-Retention For Treatment Of Urban Storm Water Run Off. 2013. Hunho, Kim. Removal of dissolved nitrogen, phosphorous and carbon from storm water by bio-filtration mesocosms. 2014. Water Sci. Technol. 55 (4 International Standards Organization. Water Quality--Determination of Biochemical Oxygen Demand after Five Days. 2013. International Standards Organization. Water Quality--Determination of the Chemical Oxygen Demand. ISO 6060. 2013 Jadlocki, Smith. Pollutant Removal and Peak Flow Mitigation by a Bio-retention Cell in Urban Charlotte, N.C. Jamil, Elier. Sediment transport in grassed swales during simulated runoff events. Water Sci. Technol. 2013. Water Enivron. Res Kaushal, Stack. Increased salinization of Fresh water in the Northeastern United States. 2013. PNAS 102 Los Angeles Unified School District Storm water Technical Manual. 2013. Retrieved from . Minami, Philips. "Water quality improvement through bio-retention media: Nitrogen and phosphorus removal." 2014. Water Environ. Res., 78(3) Rushton, Morrison. Low-impact parking Lot design reduces runoff and pollutants loads. 2013. Wat. Res. Plan. Mgmt. ASCE 127 Stagge, James. Performance of grass swales for improving water quality from highway runoff. 2013. Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA Toronto and Region Conservation Authority (TRCA). "Performance Evaluation of Permeable Pavement and a Bio-retention swale 2013. Seneca College, King City, Ontario." Toronto and Region Conservation Authority, Toronto, ON, Canada. United States Environmental Protection Agency (USEPA). "Total maximum daily loads with storm water sources 2013. A summary of 17 TMDLs." Rep. No. EPA 841-R-13-002, United States Environmental Protection Agency, Office of Wetlands, Oceans and Watersheds, Watershed Branch, Washington, DC. United States Environmental Protection Agency (USEPA). Storm Water Technology Fact Sheet Bio-retention. 2013. Weiss, Peter. The Performance of Grassed Swales as Infiltration and Pollution Prevention Practices. 2013. Read More