Ndeke Musee

The antibacterial effects of engineered nanomaterials: implications for wastewater treatment plants

Nanotechnology is currently at the forefront of scientific research and technological developments that have resulted in the manufacture of novel consumer products and numerous industrial applications using engineered nanomaterials (ENMs). With the increasing number of applications and uses of ENMs comes an increasing likelihood of nanoscale materials posing potential risks to the environment and engineered technical systems such as wastewater treatment plants (WWTPs). Recent scientific data suggests that ENMs that are useful in, for example, medical applications due to their novel physicochemical properties, may also cause adverse effects to the bacterial populations used in wastewater treatment systems. In this review, the toxicological effects of titanium nanoparticles (nTiO(2)), zinc oxide (nZnO), carbon nanotubes (CNTs), fullerenes (C(60)) and silver nanoparticles (AgNPs) to bacteria were examined. The results suggest that the potential ENMs risks to bacteria are non-uniform (need to be assessed case-by-case), and are dependent on numerous factors (e.g. size, pH, surface area, natural organic matter). Currently available data are therefore insufficient for evaluating the risks that ENMs pose in WWTPs. To fill these knowledge gaps, we recommend scenario specific studies aimed at improving our understanding on: (i) estimated volumes of ENMs in effluents, (ii) the antibacterial sensitivity of cultures within WWTPs towards selected ENMs, and (iii) processes improving the stability of ENMs in solutions. Two factors that merit consideration for elucidating the potential risks systematically are the toxicity mechanisms of ENMs to bacteria, and the influencing factors based on inherent physicochemical properties and environmental factors. Furthermore, the complexity of behaviour and fate of ENMs in real WWTPs requires case studies for assessing the ENMs risks to bacteria in vivo. The current laboratory results derived using simplified exposure media do not reflect actual environmental conditions.

New methodology for hazardous waste classification using fuzzy set theory Part II. Intelligent decision support system.

In part 1 of this paper, factors that influence hazards and eco/toxicity in composite hazardous wastes were described. In part 2, a computer-aided decision support tool based on fuzzy set theory is proposed to support the classification of composite wastes. Given the chemical properties, the nature of microorganisms that may be present, the behaviour of chemicals in humans and ecosystems, and the quantities of wastes, the computer-aided tool automatically classifies the waste as benign, partially hazardous, hazardous or highly hazardous. The functionality of the computer-aided decision tool is demonstrated through nine worked examples and the results are discussed in detail.

A Fuzzy - Based Methodology for Aggregative Waste Minimization in the Wine Industry

The wine industry generates large quantities of waste annually, including organic solid wastes (solids, skins, pips, marc, etc.), inorganic solid wastes (diatomaceous earth, bentonite clay, perlite), liquid waste (cleaning wastewater, spent cleaning solvents, cooling water), and gaseous pollutants (carbon dioxide, volatile organic compounds, ammonia, sulphur dioxide, etc.) (Chapman et al., 2001; Musee, 2004a; Musee et al., 2007). Several factors give rise to these diverse waste streams (Musee, 2004a; Musee et al., 2007), however, only the most salient ones are highlighted here. Firstly, wine production evolved from a cottage industry to a global industry. Because of their antiquated origin, the design and development of many wineries made no provision for in-plant modern waste minimization (WM) approaches. Secondly, because the wine industry is dependent on an agricultural feedstock (grapes), the resultant waste streams tend to have a high concentration of organic material. This is because the grape feedstock cannot be altered, replaced, or eliminated before the vinification process begins – if the finished wine quality is to remain consistent. And finally, although auxiliary process feedstock, such as filter aids and diatomaceous earth are essential for clarifying the wine, they cannot be incorporated into the final product. Consequently, the clarification agents constitute part of the waste streams generated from the wine industry. In view of these unique constraints facing the wine industry, among others, necessitates the development of appropriate WM strategies to address the waste management challenges facing the wine industry (Musee et al., 2007). In recent years, there has been continuous pressure on the operating profits of wine makers, mainly owing to increasing competitiveness in the global wine market. This can be attributed to increased variety of wine brands, rise in operational and input material costs, as well as the emergence of an onerous environmental regulatory framework in many wine producing countries (Bisson et al., 2002). Notably, the impact of stringent environmental legislation on the cost of production is expected to continue to be a key determinant in the international competitiveness of wine products (Katsiri & Dalou 1994; Massette, 1994; Muller, 1999). This, and a combination of other powerful intrinsic and external drivers should motivate the wine industry to consider the possibility of incorporating WM strategies as an integral part of wine making processes. As such, the identification and implementation of appropriate WM strategies should be part of the drive to reduce the cost of wine production – particularly in the context of ensuring its future sustainability.