Landfarm performance under arid conditions. 1. Conceptual framework

Area of Science:

• Environmental Science
• Petroleum Engineering
• Soil Science

Background:

• Landfarming is the primary oily sludge disposal method in Saudi Arabia, a major oil exporter.
• Despite its use since 1982, no scientific studies support its efficacy under local arid conditions.
• Oily sludge disposal presents environmental challenges in arid regions.

Purpose of the Study:

• To investigate the dominant degradation mechanisms of oily sludge in landfarm cells under Saudi Arabian environmental conditions.
• To evaluate the effectiveness of landfarming for oily sludge treatment in arid climates.
• To analyze the kinetics of oily sludge degradation, considering natural and enhanced conditions.

Main Methods:

• A comprehensive 12-month field experiment was conducted in Saudi Arabia.
• Oily sludge degradation was monitored in landfarm cells under natural and enhanced conditions (water, nutrients, tilling).
• Analysis focused on the loss of oil and grease (O&G) and specific alkane fractions (C17, C18, branched).

Main Results:

• Weathering (evaporation) was identified as the dominant degradation mechanism, accounting for up to 76% of oil and grease loss.
• Biodegradation was a significant factor in the loss of specific C17 and C18 alkanes, but not the primary overall mechanism.
• Enhanced conditions (water, nutrients, tilling) were applied, but weathering remained dominant.

Conclusions:

• Landfarming in Saudi Arabia's arid climate is primarily driven by physical weathering (evaporation) rather than biodegradation.
• While biodegradation plays a role in degrading specific hydrocarbon fractions, it is not the main contributor to overall oily sludge mass reduction.
• Further research may be needed to optimize landfarming or explore alternative disposal methods for oily sludge in arid regions.