Biodegradation of phthalate esters in polluted soil by using organic amendment

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Phthalate esters (PAEs) are common pollutants.
• Biodegradation of PAEs in soil and sludge is crucial for environmental remediation.
• Understanding factors influencing PAE degradation is essential.

Purpose of the Study:

• To investigate the biodegradation of di-n-butyl phthalate (DBP) and di-(2-ethyl hexyl) phthalate (DEHP) in sludge and soil.
• To assess the impact of sewage sludge addition on PAE degradation in soil.
• To determine the effect of sludge particle size on PAE biodegradation.

Main Methods:

• Addition of DBP and DEHP to sewage sludge and subsequently to soil.
• Fractionation of sludge based on particle size (0.1-0.45 μm to 500-2000 μm).
• Monitoring of PAE degradation rates and identification of dominant microbial strains (Rhodococcus sp. and Microbacterium sp.).

Main Results:

• Sewage sludge demonstrated significant capacity for PAE biodegradation.
• Addition of sewage sludge to soil enhanced the degradation of PAEs.
• Smaller sludge particle sizes exhibited higher PAE degradation rates within sludge, but this effect diminished upon soil amendment.
• Microbial strains F4 (Rhodococcus sp.) and F8 (Microbacterium sp.) were consistently dominant.

Conclusions:

• Sewage sludge is a viable medium for PAE biodegradation.
• Amending soil with sewage sludge improves PAE removal efficiency.
• While particle size influences degradation in sludge, its impact is less significant when sludge is incorporated into soil.
• Specific microbial communities, including Rhodococcus sp. and Microbacterium sp., play a key role in PAE degradation.