Wastewater treatment by wetland technology (also known as wet soil leach, leach plant, bio leach ...) has been studied and applied long around the world. Research by wastewater treatment plant wetland vegetation was first made by Seidel (1955) at the Max Planck Institute in Plon, Germany. Since then, this technology has been applied and developed in Europe, America, Australia ... in the years from 1970 to 2000. In our country, the research is done at universities, research institutes in recent years has given the initial results are very encouraging. At the same time, some of the practical applications have been implemented for water treatment and industrial waste in a number of provinces and cities nationwide.
Design a surface flow CWs to treat domestic wastewater for an residential area Group 11 : Đặng Minh Sơn Nguyễn Quang Văn Nguyễn Thanh Tùng Vũ Thị Thu Trang Table of Contents Design a surface flow CWs to treat domestic wastewater for an residential area .1 I Introduction II Designing .5 III.Result IV Conclusion IV References 10 I Introduction Wastewater treatment by wetland technology (also known as wet soil leach, leach plant, bio leach ) has been studied and applied long around the world Research by wastewater treatment plant wetland vegetation was first made by Seidel (1955) at the Max Planck Institute in Plon, Germany Since then, this technology has been applied and developed in Europe, America, Australia in the years from 1970 to 2000 In our country, the research is done at universities, research institutes in recent years has given the initial results are very encouraging At the same time, some of the practical applications have been implemented for water treatment and industrial waste in a number of provinces and cities nationwide Most domestic wastewater in the residential urban, suburban and rural Vietnam are not handled properly Wastewater from toilets only preliminary treatment, unsatisfactory discharge into the environment has been mixed with waste water from the kitchen, bathroom, laundry cause pollution, the spread of diseases Thus, in the present context, where drainage projects and water treatment have not been everywhere, if so, just stop at the drainage situation and overcome the flooding, waterlogging, and also a lot of costs for operation and maintenance of the system, then the study of clean water to households family, or residential areas, with appropriate technology, simple, cost less to build and operate, while ensuring environmental sanitation solutions is a reasonable and feasible In this our presentation, we will introduce to you, the way using horizontal surface flow treat domestic waste water of a residential area of 1000 peple Let make clear what is horizontal surface flow : These systems typically consist of basins or channels, with some sort of subsurface barrier to prevent seepage, soil or another suitable medium to support the emergent vegetation, and water at a relatively shallow depth flowing through the unit The shallow water depth, low flow velocity, and presence of the plant stalks and litter regulate water flow and, especially in long, narrow channels minimize short circuiting II Designing A Domestic wastewater compositions Domestic wastewater contains BOD, SS, NH4+, Nitrogen, Phosphorus, Microorganisms… Compositions Unit Amount pH BOD5 mg/l 6.5 - 8.5 250 – 400 COD mg/l 400 – 700 TSS mg/l 300 – 400 Total Nitrogen mg/l 60 Total Phosphorus mg/l 6.86 Table1: Typically polluted concentration and compositions Wastewater treating is in order to remove contaminants before discharging to the culverts or recycling Water quality after treatment must satisfy the National technical regulation on domestic wastewater–QCVN 14:2008/BTNMT Table2: Value of maximum parameter allowed used for calculating in domestic wastewater Parameter Unit Concentration C A B pH - 5–9 5-9 BOD5 (20oC) mg/l 30 50 Total suspended solid (TSS) mg/l 50 100 Total dissolved solid (TDS) mg/l 500 1000 Sulfur (H2S) mg/l 1.0 4.0 Ammonium mg/l 10 Nitrate (NO3-) mg/l 30 50 Lipid mg/l 10 20 Surface active agents mg/l 10 10 Phosphate (PO43-) mg/l 10 11 Total Coliforms MPN/100 ml 3000 5000 A: concentration of maximum parameter allowed in DWW when discharging into the sources using for activities supply B: concentration of maximum parameter allowed in DWW when discharging into the sources NOT using for activities supply Usually, wastewater after treatment is discharged to the rivers then could be recycled column A will be used for calculating surface flow model Compare between inflow water (not yet treated) and allowance water according to Regulation (will be outflow water): Compositions Unit Amount Amount (influence) Co (effluence) Ce pH BOD5 mg/l 6.5 - 8.5 250 – 400 5–9 30 COD mg/l 400 – 700 - – 13 times higher - TSS mg/l 300 – 400 50 – times higher Total Nitrogen mg/l 60 30 - Total Phosphorus 6.86 - mg/l Since TSS can be easily removed by filtration or deposition then we consider BOD the main parameter for CW SF calculation B CW calculation Surface calculation In FWS wetlands, removal of the soluble BOD5 is due to microbial growth attached to plant roots, stems, and leaf litter that has fallen into the water Because algae are typically not present if plant coverage is complete, the major sources of oxygen for these reactions are reaeration at the water surface and plant translocation of oxygen from the leaves to the rhizosphere Specific criteria presented below are suitable for low to moderate organic loadings The organic loading should be distributed over a significant portion of the area and not applied at a single point The design water depth should be 600 mm (24 in) (1) or less to ensure adequate oxygen distribution, and partial effluent recirculation might be considered in the summer months to overcome ET losses and maintain design flow rates and oxygen levels BOD5 Removal in FWS Wetlands: C e = A e C o − K T ( A v )1 A s d n Q Where, A = fraction of BOD5 not removed as settleable solids near headworks of the system (as decimal fraction) Av = specific surface area for microbial activity, m 2/m3 As = wetland treatment area, m2 d = design depth of system, m n = porosity of system (as a decimal fraction) Q = average hydraulic loading on the system, m3/day K T = temperature-dependent rate constant KT (in day-1) at water temperature T (oC) A sample calculation for the above coefficients equation yields the following results: • A = 0.52 • K20 = 0.0057 day-1 • Av = 15.7 m2/m3 • d = 0.6m (recommended) • n = Vv/V = 0.75 (Vv & V: volume of voids and total volume) Q = average hydraulic loading on the system, m3/day: Q = 1,000people x 150L/person/day x 80% =120,000L/day =120m /day KT = K20 x (1.1)T-20 = 0.0057 day-1 x (1.1)25-20 = 9.2 x 10-3 Average ToC of water is 25oC K20 is rate constant at 20oC Our purpose is to find CW surface area As Substitution into the formula: 50 = e C o − × ×1 −3 ×1 × A s × × As ranges from 320.67 m2 to 478.36m2 Assume, length : width = : The length is about 32m ~ 38m The width is about 10m ~ 13m Plant and soil In selecting a site for a free water surface wetland the underlying soil permeability must be considered.… Sandy soils are too permeable to support wetland vegetation unless there is a restrictive layer in the soil profile that would result in a perched high ground water table.Highly permeable soils can be used for small wastewater flows by forming narrow trenches and lining the trench walls and bottom with clay or anartificial liner In heavy clay soils, additions of peatmoss or top soil will improve soil permeability and accelerate initial plant growth • Soil Permeability for Free Water Surface Systems • The most desirable soil permeability is 10-6 to 10-7m/s (0.14-0.014 in/hr) Sandy clays and silty clay loams can be suitable when compacted Plant: Canna Hybrid: Strong growth at contaminated wetlands good for NH 4+, NO3-, PO43- removal III.Result Assume, length : width = : The length is about 32m ~ 38m The width is about 10m ~ 13m IV Conclusion - In terms of social topics will contribute to improving the health of communities through clean water and create a good view from the technology underground leach plant - In terms of economic and biodiversity: This type of model wastewater by biological treatment principle does not need to use energy saving will be very effective and economical when applied in practice than other methods In addition, the leach plant can be used as feed for livestock Treated water can circulate to bathe using pigs, barn wash or irrigate crops are good - In terms of biodiversity conservation: Thread has created a good view and contribute to increased biodiversity in areas with abundant types of crops in the leach IV References Basheer, F (2008) Constructed Wetland System for Wastewater Treatment India: Aligarh Muslim University EPA (1988) Constructed Wetlands and Aquatic Plant Systems for Municipal Wastewater Treatment MalaysiaOffice (2003) The use of constructed wetlands for wastewater treatment Selangor, Malaysia: Wetlands International - Malaysia Office National technical regulation on domestic wastewater QCVN 14 : 2008/BTNMT