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Sludge that has been treated (e.g., [[Co-composting|Co-Composted ]] or removed from a [[Planted Drying Beds|Planted Drying Bed]], etc.) can be used in agriculture, home gardening, forestry, sod and turf growing, landscaping, parks, golf courses, mine reclamation, as a dump cover, or for erosion control.Although sludge has lower nutrient levels than commercial fertilizers (for nitrogen, phosphorus and potassium, respectively), it can replace an important part of the fertilizer need. Additionally, treated sludge has been found to have properties superior to those of fertilizers, such as bulking and water retention properties, and the slow, steady release of nutrients.
===Design Considerations===
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{{procontable | pro=
- Can accelerate reforestation. <br> - Can reduce the use of chemical fertilizers and improve the water retention -holding capacity of soils. soil <br>- Can accelerate reforestation <br> - Can reduce erosion. <br> - Low cost. costs | con=- May pose public health risk, depending on the quality and application. <br> - Odours are normally may be noticeable (, depending on prior treatment). <br> - May require special spreading equipment. <br> - May pose public health risks, depending on its quality and application <br>- Micropollutants may accumulate in the soil and contaminate groundwater.<br>- Social acceptance may be low in some areas
}}
===Appropriateness===
Although sludge is sometimes criticized for containing potentially high levels of metals or contaminants, commercial fertilizers are also contaminated to varying degrees, most likely with cadmium or other heavy metals. Faecal sludge from pit latrines should not have any chemical inputs and is, therefore, not a high risk source of heavy metal contamination. Sludge that originates at large-scale wastewater treatment plants is more likely to be contaminated since it receives industrial and domestic chemicals, as well as surface water run-offrunoff,
which may contain hydrocarbons and metals. Depending on the source, sludge can serve as a valuable and often much-needed source of nutrients. Application of sludge on land may be less expensive than disposal.