Windrow composting

Itavara, M. Vilman, M. Venelampi, O. Windrow composting of biodegradable packaging materials. Compost. Sci. Util. 1997, 5, 84-92. 

One source estimated the cost of bioremediating explosives-contaminated soil to be 50 to 400 (1995 dollars) per cubic yard of soil treated. This estimate does not always include all indirect costs associated with treatment such as excavation, permits, and treatment of residuals. A U.S. Army study estimated that to treat less than 10,000 tons of contaminated soil, the cost would be 651 per ton for mechanically agitated composting, and 386 per ton for windrow composting (D17224H, p. 29). 

Two bioassays a) 48h plate incorporation AMES test (Salmonella typhimurium his- (TA 98, 100) b) 7d chronic crustacean test (Ceriodaphnia dubia) Windrow composts from explosives-contaminated sediment leachates Aqueous and organic extraction... 

Griest, W.H., Tyndall, R.L., Stewart, A.J., Caton, J.E., Vass, A.A., Ho, C.H. and Caldwell, W.M. (1995) Chemical characterization and toxicological testing of windrow composts from explosives-contaminated sediments, Environmental Toxicology and Chemistry 14, 51-59. 

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. 

Finally, the Army conducted a study to examine the effectiveness of windrow composting. This study used cow manure, sawdust, and potato waste amendments and required the construction of a concrete pad leachate collection system. Temperatures were maintained at 55°C and the compost was turned once a day. This process produced 98% reductions of explosives contamination within twenty days, and degraded HMX,... 

Figure 8.4 TNT, RDX, and HMX reductions achieved in windrow composting demonstration study at Louisiana Army Ammunition Plant.

Table 8.1 Actual and Percent Contaminant Reductions Achieved in Windrow Composting Demonstration Study at Louisiana Army Ammunition Plant...

Figure 8.5 Comparison of costs for windrow composting mechanically agitated, in-vessel composting (MATV) and incineration of Umatilla Army Depot soils as a function of total soil volume treated.

Windrow composting can effectively be used to bioremediate soils/sediments contaminated with TNT, RDX, and HMX. 

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. 

Preliminary data indicates that windrow composting will provide a high degree of reduction in mobility and toxicity, as was demonstrated for ASP and MAIV technologies. 

The windrow composting technology is relatively simple to implement and operate. Commercially available equipment may be used, although some modifications may be warranted to optimize their characteristics. 

The use of temporary construction shelters can be used for windrow composting. However, particular attention to adequate ventilation is warranted to minimize operation problems. 

With proper containment and manipulation of turning frequencies, windrow composting can be successfully implemented year-round. 

Chemical and toxicological testing showed that nonaerated windrow composting can rapidly reduce extractable explosives, extractable mutagenic activity, and leachable toxicity of explosives-contaminated sediments. It is at least as efficient as the best static pile or mechanically stirred composting methods, based on results of other studies conducted at the same site, and thus is an excellent candidate for remediation of explosives-contaminated soils and sediments. 

The U.S. Army Environmental Center (USAEQ recently completed a demonstration of windrow composting of explosives-contaminated sods at Umatilla Depot Activity (UMDA) in Hermiston, Oregon. This demonstration represented the second phase of field studies conducted at UMDA, and was part of an ongoing effort to develop a composting system which can provide an economical and effective alternative to incineration for the treatment of explosives-contaminated soils and sediments. 

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... 

In addition to the cost savings demonstrated by windrow composting in comparison to other composting methods, there are other, less quantifiable, advantages associated with the use of a windrow system. For example, the windrow system has significantly less process control requirements, and so has less equipment subject to downtime that could lead to system performance variations. Also, the windrow system has demonstrated RDX (99.8% removal) and HMX (96.8% removal) reduction. The other composting systems have not shown this level of destruction. 

Windrow Composting Demonstration for Explosives-Contaminated Soils... 

Windrow Composting Engineering/Economic Evaluation, PB95-200143,... 

Thom KA, Pennington JC, and Hayes CA, 15N NMR investigation of the reduction and binding of TNT in an aerobic bench scale reactor simulating windrow composting, Environ. Sci. Technol., 36, 3797, 2002. 

Griest WH et al., Chemical characterization and toxicological testing of windrow composts from explosives-contaminated sediments, Environ. Toxicol. Chem., 14, 51, 1995. 

The use of green yard waste compost on farmland can lead to a positive environmental impact with lower water usage, lower fertilizer usage, lower herbicide usage, and sequestration. Life cycle impact assessments of environmental concerns from production and application of composted products provide a net positive environmental impact. The use of composting process and products provides a reduction in GHG, human toxicity potential, ecotoxicity potential, and eutrophication potential due to lower use of fertilizers, herbicides, water, and electricity (LCA for Windrow Compost 2006). 

LCA for Windrow Compost (2006) Life Cycle Inventory and Life Cycle Assessment for Windrow Composting Systems, New South Wales, Australia, http //www. epa.nsw.gov.au/resources/warr/2006400 org lcassesswindrowsys.pdf (last accessed June 2014). 

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