waterquality-universityofnorthcarolinawilmington：水的質(zhì)量-北卡羅來(lái)那大學(xué)wilming(編輯修改稿)
2025-02-08 09:01 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 gterm monitoring ? Computer modeling Chesapeake Bay Agreement 2022 ? Bay Program Partners agree to work with the headwater states – Delaware – New York – West Virginia Chesapeake Bay Agreement 2022 ? Continue to improve on previous Nitrogen (N) and Phosphorus (P) goals ? Implemented new water quality standards – Use Total Maximum Daily Load (TMDL) Results ? Between 1985 and 1997 – Annual Phosphorus (P) loads reduced by 8 million lbs – Annual Nitrogen (N) loads reduced by 32 million lbs Results ? Point Source Reduction between 1985 and 1997 – Annual Phosphorus (P) loads reduced by 16 million lbs – Annual Nitrogen (N) loads reduced by 5 million lbs Results ? NonPoint Source Reduction between 1985 and 1997 – Annual Phosphorus (P) loads reduced by 16 million lbs – Annual Nitrogen (N) loads reduced by 1 million lbs Estimated Benefits ? Total Benefits include – Recreation (fishing, boating, swimming) – Commercial (fishing) – Health – Nonuse values – Property values – Regional economic values Estimated Benefits ? People in the Chesapeake Bay Watershed have received benefits that range from $360 million to $ billion in total benefits – Beach users benefits range from $290 million to $ billion – Trailered boating benefits range from $7 million to $84 million Why wetlands for wastewater treatments? ? Water saturated conditions lead to reduced gas exchange ? Less gas exchange contributes to higher anaerobic activity, allowing abundant microbial growth ? Combined, these attributes allow wetlands to transform anic materials into nutrients. Improving Water Quality ? Settling of particulate matter ? Filtration and chemical precipitation through contact of water with substrate ? Breakdown and transform pollutants by microanisms Wetland Systems ? Free Water Surface Systems – Basins or channels – Natural or constructed barrier to prevent seepage – Shallow water depth, low flow viscosity, and presence of the plant stalks to regulate water flow ? Subsurface Flow Systems – Trench or bed with impermeable layer – Built with slight inclination between inlet and outlet – Waste water flows horizontally through rhizosphere of wetland plants ? Wastewater then treated by filtration, sorption, and precipitation processes in the soil and by microbial degradation – The effluent is then collected at the outlet channel and discharged Things to keep in mind when designing a wetland for waste water treatment ? Hydrology most important!! – Climate and weather – High flows by rain and increased snow melt shorten the residence time of pollutants and efficiency of treatment decreases – Heavy rain after period of dryness has greatest impact on treatment efficiency – Freezing temps can reduce efficiency ? Substrates – Soils ? Ideal soil pH for treating wastewater: ? Electrical conductivity – Affects the ability of plants and microbes to process the waste material. – Should be less than 4 for water treatment ? Soil Water control – Soils capacity to retain and remove containments ? Sandy or gravely soils have high porosity values ? High clay content helps retain phosphorus ? Vascular Plants – Stabilize substrates and limit channelized flow – Slow water velocities, allowing suspended materials to settle – Take up Carbon, nutrients and trace elements and incorporate them into plant tissues – Transfer gases between atmosphere and sediments – Most wetlands are monly constructed with eme
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1