Design a surface flow CWs to treat domestic wastewater for an residential area

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 3

II Designing 5

A Domestic wastewater compositions 5

B CW calculation 6

III.Result 9

IV Conclusion 9

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…

5 Total Nitrogen mg/l 60

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

3 Total suspended solid (TSS) mg/l 50 100

4 Total dissolved solid (TDS) mg/l 500 1000

9 Surface active agents mg/l 5 10

10 Phosphate (PO43-) mg/l 6 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. 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

(influence) Co Amount (effluence) Ce

-2 BOD5 mg/l 250 – 400 30 8 – 13 times

higher

-4 TSS mg/l 300 – 400 50 6 – 8 times higher

5 Total Nitrogen mg/l 60 30

-6 Total

-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:

Q

d n s v T K

A e

C o

C e

7 5 1) ( 7.





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, m2/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 =120m3 /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:

1 2 0

7 5 0 6.

0 7.

1 5

1 0 2.

9 7.

0 3 1 7 5

5 2

0



s

A

e

C o

 column A will be used for calculating surface flow model As ranges from 320.67 m2 to 478.36m2

Assume, length : width = 3 : 1

 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 column A will be used for calculating surface flow model 4+, NO3-,

PO43- removal

III.Result

Assume, length : width = 3 : 1

 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:

Ali-garh Muslim University

EPA (1988) Constructed Wetlands and Aquatic Plant Systems for Municipal

Waste-water Treatment

MalaysiaOffice (2003) The use of constructed wetlands for wastewater treatment

Se-langor, Malaysia: Wetlands International - Malaysia Office

National technical regulation on domestic wastewater QCVN 14 : 2008/BTNMT