A review of odour assessments in the raw rubber processing industry

Abstract

Understanding and managing the generation of odour nuisances throughout the raw rubber processing industry are vital to reduce the impact on the community. This paper aims to review literature on odour studies and management in the raw rubber processing industry. The generation of odour is typically associated with microbial reactions occurring in non-rubber components. The most offensive compound groups commonly discussed in the literature are sulfur derivatives and volatile fatty acids due to their unpleasant characteristics and low-odour threshold. Major sources of these odorants are from effluent treatment of the latex processing plant and exhaust gas from the drying process at the block rubber processing plant, respectively. However, studies performed on the composition of rubber emissions also reported the presence of other compound groups such as aldehyde, ester, amine and aromatic, which could potentially contribute to the odour emissions. Single or multiple odour assessment methods can be applied based on the objective of the odour assessment. Olfactory and chemical testings were generally applied to evaluate the odour concentration, offensiveness and identification of potential odorants, while odour wheel and dispersion modelling were employed to assess the impact on the community. Odour legislations mainly used olfactory techniques and dispersion modelling to control the odour emissions by limiting the odour release at a tolerable limit. Numerous mitigation measures have been studied and performed upstream and downstream of rubber processing, such as utilising biological methods and aerated effluent treatment that produces less odour, chemical substitution and installation of wet scrubber to reduce the odour emissions from drying process. Nevertheless, the literature is lacking studies conducted at the industrial scale on odour generation and mitigation where knowledge can be applied to develop an appropriate odour management strategy in the current industrial scenario to mitigate the odour effectively.