Effect of Activated Carbon Amendment on Bacterial Community Structure and Functions in a PAH Impacted Urban Soil

ABSTRACT: We collected urban soil samples impacted by polycyclic aromatic hydrocarbons (PAHs) from a sorbent-based remediation field trial to address concerns about unwanted side-effects of 2 % powdered (PAC) or granular (GAC) activated carbon amendment on soil microbiology and pollutant biodegradation. After three years, total microbial cell counts and respiration rates were highest in the GAC amended soil. The predominant bacterial community structure derived from denaturing gradient gel electrophoresis (DGGE) shifted more strongly with time than in response to AC amendment. DGGE band sequencing revealed the presence of taxa with closest affiliations either to known PAH degraders, e.g. Rhodococcus jostii RHA-1, or taxa known to harbor PAH degraders, e.g. Rhodococcus erythropolis, in all soils. Quantification by real-time polymerase chain reaction yielded similar dioxygenases gene copy numbers in unamended, PAC-, or GACamended soil. PAH availability assessments in batch tests showed th

Aerodynamic Properties of Biochar Particles: Effect of Grinding and Implications

This study reports the aerodynamic properties of ground biochar particles produced from the slow pyrolysis of mallee biomass at 400 °C, considering grinding times from 10 s to 16 min. The data show that extensive grinding (e.g., ≥ 1 min) substantially increases the amounts of particulate matter with an aerodynamic diameter of <10 µm (PM10) and <2.5 µm (PM2.5) in the ground biochars. Whereas the aerodynamic particle size distribution (PSD) of PM10 in biochar after grinding for 10 s shows no obvious peak, a bimodal PSD is observed for PM10 in the biochars after grinding for 1-16 min. The results suggest that care must be taken during biochar grinding to minimize the PM10 and PM2.5 produced. PM10 and PM2.5 in a biochar should also be quantified to assess environmental risks during biochar transport and applications

Is sustainability certification for biochar the answer to environmental risks?

Biochar has the potential to make a major contribution to the mitigation of climate change, and enhancement of plant production. However, in order for biochar to fulfill this promise, the industry and regulating bodies must take steps to manage potential environmental threats and address negative perceptions. The potential threats to the sustainability of biochar systems, at each stage of the biochar life cycle, were reviewed. We propose that a sustainability framework for biochar could be adapted from existing frameworks developed for bioenergy. Sustainable land use policies, combined with effective regulation of biochar production facilities and incentives for efficient utilization of energy, and improved knowledge of biochar impacts on ecosystem health and productivity could provide a strong framework for the development of a robust sustainable biochar industry. Sustainability certification could be introduced to provide confidence to consumers that sustainable practices have been employed along the production chain, particularly where biochar is traded internationally