Bio-treatment: composting

Bio-treatment: composting

Type of treatment: Treatment

Description:
Composting is the biological conversion of organic waste solids into stable, humic material (which contributes to the soil structure as well as its nutritional status).
Composting is achieved by mixing with bulking agents and organic amendments, spreading the oily waste in windrow (or other shapes), regular tilling for oxygenation and addition of nutrients.
 
There are three major designs used in composting.
- aerobic static pile/ compost is formed into piles and aerated with blowers or vacuum pumps,
- use of a vessel similar to a bio-reactor, where the compost is mechanically agitated and aerated,

windrow composting, usually considered the most cost-effective composting alternative


Waste:

Lightly oiled seaweed and vegetation (i.e. biodegradable material), sand may be present


Situation/Possibilities in the country:

May be very easily implemented.


Interest:

- Recovery of natural resource (sand)
- Low cost 
- Larger quantity will result in economy of scale
 


Entry criteria:

Oil with a high asphaltene and resin content degrades slowly due to the molecular recalcitrance of the hydrocarbons while oil with a high aliphatic and aromatic content is a much more nutrient-dependent process and will degrade more rapidly within the adequate environment. It is recommended to carry out a GC/ MS analysis to define the composition of the oil and evaluate its biodegradability.
Usable only for oiled vegetal that are lightly to medium polluted, and should not contain cobble or boulder.


Operational constraints:
Requires personnel, expertise, earth moving equipment, nutriments and large surface of ground, particularly for in-situ treatment options.
The site must meet hydro-geological and physical requirements.
Selection criteria include the following items:
- oil is recovered;
- quires a lot of testing, monitoring, foundation and mechanical work;
- requires large surface area;
- dispersed quantity of contaminated soil increases the cost.

Impacts:

Minimal if suitable monitoring and containment program is implemented.
But possible increase of VOC (Volatile Organic Compound) emissions, and windrow composting has a high dust emission.


Legal constraints:

Refer to waste and oily water / soil legislation.


Efficiency:

Composting is faster than enhanced bioremediation on site: process lasts less than one year (may be 3 to 6 months depending on the degree of pollution of the waste).
Bioremediation degrades aromatics, N-alkanes and iso-alkanes. Resins and Asphaltenes are usually resistant to bioremediation. Cyclic hydrocarbon (Saturated and Aromatics) are partially biodegraded.


Cost:

Costs compare to the cost of land farming (usually less than 50 Euros per ton). However, composting does not require large areas of land and compost can be sold at 15 to 23 Euros per ton (Source: Damien).

published on 2019/12/10 14:45:51 GMT+0 — last modified 2019-12-10T14:45:51+00:00