US EPA

1959309 

Journal Article 

Bioremediation: Use of composts and composting technologies 

Fermor, T; Watts, N; Duncombe, T; Brooks, R; Mccarthy, A; Semple, K; Reid, B 

2000 

833-839 

WOS:000088226800107 

Bioremediation is the use of biological treatments, in this case, microorganisms, to remove hazardous chemicals from the environment. Over the past decade, we have used mushroom composts and composting strategies for the biodegradation of xenobiotics and remediation of polluted soils. This work has concentrated on chlorophenols eg. pentachlorophenol (PCP), polycyclic aromatic hydrocarbons (PAHs) eg. anthracene, phenanthrene and benzo[a] pyrene and aromatic monomers eg. benzene. A series of tools have been developed for bioremediation experiments using different amounts of compost or compost/soil mixes: flask respirometers (10-100g), bench composters (1 kg) and environmentally controlled compost bins (40 kg).



Mineralization of [UL-C-14] PCP has been demonstrated in mushroom composts incubated at 30 degrees C for 4 weeks with an initial PCP concentration of 50mg kg(-1). Pre-enrichment using PCP at 500mg kg(-1) for 3 months on a 30 kg scale induced PCP mineralization activity in composts. Low abiotic values confirmed that microbial activity was responsible for the disappearance of PCP. The effect of chlorophenol application on the microflora of Phase II mushroom compost was characterised. Enrichment for fluorescent pseudomonads required the presence of tri- or more highly chlorinated phenols, but we were unable to recover any pure cultures of bacteria that could mineralize PCP in isolation. Uncooked spent mushroom compost (SMC) gave the highest mineralization rates for PCP, and generally neither toxic intermediates eg. chloroanisoles nor polymerization products eg. dibenzo-p-dioxins were detected. SMC can also be used successfully in the treatment of chlorophenol-contaminated soils. Even though PCP had been present in the soil for many years, excavated soil was remediated almost completely within 3 weeks as shown by GC-ECD data. This was supported by application of a novel Vibrio natriegens bioassay for PCP, which also demonstrated that the the gross toxicity of the soil had been ameliorated. Further studies showed that Phase II compost could also be induced to degrade freshly added phenanthrene. The extent of mineralization (65% after 50d.) was greater than in uninduced compost (6%). However the application of compost - whether induced or not - does not seem to influence removal of aged phenanthrene from soil. In contrast to chlorophenols, PAHs are strongly hydrophobic compounds that exhibit significant partitioning in soil organic carbon resulting in a reduction in bioavailability and hence bioremediation potential. BTEX compounds (benzene, toluene, ethylbenzene and xylenes) are toxic, water soluble and mobile petroleum components found mainly in aviation fuel, diesel and refined petroleum products. Following a 3 month enrichment in the presence of BTEX compounds, the extent of [U-C-14] benzene mineralization in pasteurised SMC increased with increasing incubation temperature (18 degrees C<37 degrees C<50 degrees C). In the absence of a pre-enrichment period, benzene mineralization was minimal. On the basis of this accumulated evidence, the potential of composting technology for remediating land contaminated with a range of xenobiotic pollutants remains high.