Education
Cost Comparion
Convetional Treament vs Wetland Assimilation
Convetional Treatment with Sand Filteration
Conventional treatment method depends on inputs from outside including
chemicals and other capital investment. In adition to the capital cost, engineering, land,
filtration system and pumps, there are operations and maintence cost such as electricity,
labor and chemicals.
| Item | Raw Unit | Unit | Cost ('92 $) | |
| Capital Cost | Land | 1,170 | '92$/MGD | 1,780 |
| Transfer Pump | 72,000 | '92$/MGD | 109,800 | |
| Filter & Equipment | 296,000 | '92$/MGD | 451,000 | |
| Engineering | 76,000 | '92$/MGD | 115,900 | |
| Recurrent Cost | Electrical Energy | 176,514 | kwh/yr | 126,940 |
| Labor | 45,825 | '92$/yr | 470,790 | |
| Chemicals | Polymer | 1,700 | '92$/yr | 17,465 |
| Lime | 11,147 | '92$/yr | 114,520 | |
| Clearance | Sludge Disposal | 1,700 | '92$/yr | 17,465 |
Wastewater Assimilation Process
Free energies of the natural system drive the cycles of production, use, degradation,
and reuse. The major functions are physical settling, filtration, chemical precipitation, and
adsorption, and biological metabolic process. Thus, burial, storage in vegetation, and
denitrification are major functions of wetlands in assimilating treated effluent.
| Item | Raw Unit | Unit | Cost* ('92 $) | |
| Benefits | Nutrient Removal | 1,419,495 | '92$ | |
| Wetland Maintenance | 65 | '92$/ha | ||
| Additional NPP Increase | 207 | dry wt.g/m2/yr | ||
| Total Benefits | 2,329,022 | |||
| Capital Costs | Pump Station | 68,000 | '92$/MGD | 103,700 |
| Force Main | 2,000 | ft.@40$/ft. | ||
| Survey of Property | 5,000 | '92 $ | 5,000 | |
| Monitoring | 125,000 | 92 $ | 125,000 | |
| Recurrent Cost | Property Lease | 6,000 | '92 $/yr | 61,642 |
| Operation & Maintenance | 8,600 | '92 $/yr | 88,353 | |
| Total Cost | Benefit / Cost | 5.02 |
Typical Permit Limits
Typical Permit for Water Quality of Municipal Wastewater in Louisiana
| Category | Without Wetland | With Wetland |
| NH3-N (avg, mg/L) | 10 | n/a |
| BOD5-N (avg, mg/L) | 10 | 30 |
| TSS (avg, mg/L) | 15 | 30 |
| Fecal Coliform (avg, col/100mL) | 10 | n/a |
| pH | 6-9 | 6-9 |
Typical Wastewater Loading Rates
Population served and loading rates for four wetland wasterwater assimilation facilities.
|
Community |
Typical town |
||||
|
Parish |
St. Mary |
St. Martin |
St. Bernard |
Lafourche |
|
|
serving population |
2,500 |
6,500 |
17,000 |
8,700 |
|
|
wastewater generation |
1.00 |
1.00 |
1.44 |
4.00 |
1.86 |
|
(MGD) |
|||||
|
total nitrogen loading |
0.96 |
1.87 |
2.03 |
7.76 |
2.14 |
|
(g/m2/yr) |
|||||
|
total phosphorus loading |
0.11 |
0.94 |
0.43 |
3.88 |
0.38 |
|
(g/m2/yr) |
|||||
|
total wetlands |
1,012 |
1,475 |
1,536 |
1,425 |
1,362 |
|
(ha) |
|||||
|
distance btwn plant & |
0 |
0 |
40 |
2,520 |
640 |
|
wetlands(meters) |
|||||
|
ownership of wetlands |
private |
city |
private |
private |
private |
Removal Efficiency
Removal efficiency of nutrients in wetland wastewater assimilation
| Removal Efficiency** | Amelia | Breaux Bridge | St. Bernard - Riverbend | Thibodaux | Typical Town |
| BOD5 | 88 | 42 | 49 | 60 | |
| Fecal Coliform | 69 | 69 | |||
| NO3-N | 93 | 99 | 96 | ||
| NH4-N | 94 | 92 | 94 | 93 | |
| TKN | 84 | 78 | 79 | 80 | |
| PO4-P | 68 | 68 | 68 | ||
| Total P | 81 | 73 | 65 | 73 |