Compost made of oil

Solid oil waste should be processed into compost. Specialists of Kazan State University and the Open Joint-Stock Company “Nizhnekamskneft” stick to this opinion. The obtained compost is practically nontoxic, and bio-utilization of waste may be an excellent alternative to harmful waste storage and combustion.

Solid waste of petrochemical production (oil-slimes) belongs to the most persistent environment pollutants. Oil-slimes consist of oil carbohydrates and products of their processing, including asphaltic-resinous substances, as well as phenols, xylols, styrene and multiple other toxic and carcinogenic substances. Of course, oil-refining plants possess slime storage and waste disposal plants, but they do not solve the problem. Therefore, biotechnological methods of oil-slime disposal, including composting, increasingly attract specialists.

As foreign experience shows, the soil containing 3.5 percent of oil carbohydrates, can be purified via composting within 4 to 5 months, while by itself it would be purified within three years. Russian scientists have undertaken their own research.

The proving ground for them was slime accumulators of the ‘Nizhnekamskneftekhim” plant that had been duly operating for more than 40 years. For field trials, the researchers used the upper layer of oil-slime, which had been dried for a year prior to that at a special site. In May, the experimentalists formed compost beds: first, they laid a 30-centimeter layer of wood chips (wood chips representing exhaust biofilter filler material), they put oil-slime on top, then – another layer of aerating agent and a layer of oil-slime. The bed was 140 centimeters high. The site with compost beds had a small slope for redundant liquid drainage.

The slimes of the “Nizhnekamskneftekhim” enterprise are populated with their own microflora that aggressively destroys waste. Appropriate conditions were created for microbes: good airing of compost beds was ensured and nutrients – laprol production wastage– were poured on the beds. In response to the care, microorganisms destroyed major contamination within four months. 14 more months were taken up by degradation of residual, mainly hard-to-reach slime components. In a year and a half after composting had begun, oil carbohydrates concentration in the bed equaled about 12 g/kg, the initial level of contamination making more than 56 g/kg, that is, the decrease was by 85 percent. Content of stable fraction of multiring aromatic hydrocarbons reduced by 90 percent. During the year and a half, the compost toxicity sometimes reduced or sometimes slightly increased, but the final variant turned out to be quite harmless, even red radish grows upon the compost.

This is how the researchers found the way to efficiently neutralize petrochemical slime and to simultaneously utilize two more petrochemical wastes – exhaust biofilter filler material and laprol production wastage. The researchers assume that the process will be improved and they will achieve finer cleaning of petrochemical waste due to interaction of microorganisms and plants. Them the composting technology may be used for recovery of disrupted lands, scrap-heaps reclamation and forest growing on exhausted soils.