Aerated static pile

In contrast, composting processes utilize a mixture of solids and yard waste under controlled environmental conditions to produce a disinfected, humus-like product. Three common composting systems are a horizontal agitated reactor, a horizontal nonagitated reactor, and an aerated static pile system (nonproprietary). Compost can be marketed as a soil conditioner in competition with such products as peat, soil, and mulch. Although a large potential market exists, significant effort is required to penetrate this market. Yard waste revenue of 6.50/m (S5/yd ) and product revenue of 2.00/m ( 1.50/yd ) appear to be reasonable market values based on various studies reported on the Web. 

The static pile system is an intensive biotreatment because the pile of organic waste and bulking agent is intensively aerated using blowers and air diffusers. The pile is usually covered with compost to remove odor and to maintain high internal temperatures. The aerated static pile process typically takes 21 days, after which the compost is cured for another 30 days, dried, and screened to recycle the bulking agent. 

Figure 1. Aerated static pile for ex situ bioremediation of chemically contaminated soil. Adapted from Rynk (1992). Reprinted with permission from Northeast Regional Agricultural Engineering Service (NRAES), Cooperative Extension, Ithaca, New York.

Windrow composting performance was comparable to, or better than, previously tested aerated static pile (ASP) and mechanically agitated in-vessel (MATV) composting in terms of the rate and extent of explosives removal. 

The U.S. Army conducted an economic evaluation of windrow composting versus the aerated static pile, and a mechanically agitated invessel composting system (MAIV). 

The results of this economic evaluation show that windrow composting treatment costs are less than aerated static pile or mechanical composting. The MAIV composting system is comparable on a cost-per-ton basis to incineration at 290/ton of soil treated compared to 300/ton for incineration. The greatest cost savings in comparison to incineration are seen by the windrow composting system at 187/ton. The aerated static pile system "treatment only" costs are estimated at 236/ton. All estimates... 

The aerated static pile method involves forming compostable materials into large piles, which are aerated by drawing air through the pile or forcing air out through the pile. The pile is not turned. 

Composting. This is an aerobic, thermophilic treatment process in which contaminated material is mixed with a bulking agent it can be carried out using static piles or aerated piles. 

Figure 8.2 is a schematic of an in-vessel, static-pile composting device. In mechanically agitated, in-vessel composting, contaminated material is aerated and blended with carbon-source materials in a mechanical composter. These devices have been used at municipal sewage treatment facilities and applied to explosives waste. 

Figure 8.3 is a schematic of a mechanical composter. Windrow composting is similar to static-pile composting except that compost is aerated by a mechanical mixing vehicle, rather than a forced air system. 

Figure 8.1 Schematic of static-pile composting, showing the compost pile, protective shelter, forced aeration system, and leachate collection pad.

Composting. Lyocell fibres have been found to degrade completely after six weeks in a static aerated compost pile. Synthetic fibres tested... 

The prepared mix is put into a tunnel in a static aerated pile, where a 16 day active composting phase takes place. The compostable bag fragments, separated during the screening and mash separation steps, start their degradation here. Part of the process water from the AD is added to keep the moisture constant and to evaporate part of the excess water from AD. 

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