Effects of retrofit diesel particulate filters on diesel particulate emissions: a small-scale intervention study

Abstract

Diesel Particulate Matter (DPM) is a significant health hazard in the workplace, particularly in underground mining (UG) settings where diesel-powered machines are utilized for production purposes. Achieving a considerable decrease of DPM exposure in the workplace relies widely on the ability of the industry to apply tried and tested diesel emissions control technologies, in particular the use of diesel particulate filters (DPF) systems. This research report explores the effectiveness of installing and using retrofit DPFs in reducing tailpipe DPM emissions of an existing fleet of diesel-powered machines used in an UG platinum mine in Limpopo, South Africa. In-depth engine exhaust emissions were carried out on 10 trackless mobile machineries (TMMs) fitted with Wall-flow Active regenerating DPFs. Each evaluation was carried out in a stationery mode in the UG workshop whilst the vehicle engine was idling and revving. The data obtained were used to illustrate the effects of DPF systems on exhaust emissions, regeneration, particle size distributions, and the effects on personal DPM (Elemental Carbon-EC) exposures. Significant reductions as a result of the DPF system on mass (mean 84%) and particle number concentration (mean 97%) were achieved. In terms of particle size distribution, both pre and post DPF measurements were similar in shape owing to majority of particles were saturated around the 0.1 µm region. However, the number concentration differed significantly. Personal exposure to EC were also significantly (P<0.0001) reduced with a before and after intervention 90th percentile of 338 and 16.7 ug/m3 respectively. The outcomes of this study were able to demonstrate the benefits of using aftertreatment devices to control diesel exhaust emissions at the source in order to influence concentrations along pathway and at the receptor.