Cocomposting of Cattle Manure and Hydrocarbon Contaminated Flare Pit Soils

Abstract

The potential of using composting technology to remediate clayey soils with high levels of crude oil contamination was evaluated. An open air windrow comprised of flare pit soil, manure and wood chips was constructed at Olds College, Composting Technology Centre. Aeration and mixing were carried out by a skid steer loader and composting parameters were monitored for ten months. Temperature profile of this windrow gave cyclic patterns of high and low temperature recordings corresponded to the turning events. Most of the microbial metabolic activity occurred within the mesophilic temperature range and the hydrocarbon degrading microorganism populations remained high throughout the trial. Complete removal of BTEX compounds was achieved within six months and extractable carbons from C 5 to C 10 were reduced by 98.7% compared to the initial contaminated soil. Vegetative growth on the composted soil was also evaluated. Barley and timothy plants grown in the composted soil were compared to the control off-lease soil, contaminated soil, and other treatments of varying salinity and organic matter levels. Plant germination, survival, and biomass production was significantly better in the composted soil than in the contaminated soil. Furthermore, barley plants grown in the composted soil were more resilient than those grown in the control off-lease soil.

The use of biosolids in the composting of a crude oil and salt contaminated clay soil.

“…Due to widespread prevalence o f PHCs in modem society, soils contaminated by PHCs are found all over the world. Soils from the Arctic (Whyte et al 1997), Antarctic (Ferguson et al 2003a andb), Middle East (Al-Daher et al 2001), North America (Chaw and Stoklas 2001) and South America (Trindade et al 2005) have been used in published research on the remediation o f PHC-contaminated soils.…”

“…Specifically, soils contaminated with crude oil ), diesel fuel (Van Grestel et al 2003), oily sludges (Kirchmann and Ewnetu 1998), and lube oils (Jorgensen 2000) have been remediated using composting. Soils contaminated with the by-products o f oil exploration and production (flare pits) have also been remediated using composting (Chaw and Stoklas 2001). Nevertheless, there is a relative lack o f published research on composting remediation despite its acceptance in the remediation industry (Shaw et al 1995;Antizar-Ladislao et al 2005).…”

“…Second, the composting process is relatively simple to design and operate and therefore has relatively low costs (Namkoong et al 2002;Choi and Chang 2005;Ouyang et al 2005). Third, after the composting process, the soil can often be returned to the original site or be used at other sites (Chaw and Stoklas 2001).…”

“…Examples include mechanical mixing using a front-end loader or a skid steer loader for larger windrows (Chaw and Stoklas 2001;Parkinson et al 2004) and forced aeration using air blown into the bottom of windrows and smaller piles (Tiquia and Tam 2000). Static piles may be placed over an air duct, allowing for natural air diffusion through all sides or they can be placed on the ground, stopping diffusion from the bottom from occurring but still allowing air flow through the top and sides.…”

“…The bulking agent can improve the oxygenation, porosity, and structure o f the soil (Chaw and Stoklas 2001;Jorgensen et al 2000;Vallini et al 2002). Bulking agents can also reduce the moisture content o f amendments with high moisture contents.…”