A consultant (from the latin consultus meaning "legal expert") is a professional who provides expert advice in a particular domain or area of expertise such as accountancy, technology, the law, human resources, marketing, medicine, finance, public affairs, communication, or more esoteric areas of knowledge, for example engineering of different kinds, scientific specialties such as materials science, instrumentation, avionics, and stress analysis.

A consultant is also the term used to denote the most senior medical position in the United Kingdom (e.g., a consultant surgeon).

Ways in which consultants work

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Often a consultant provides expertise to clients who require a particular type of knowledge or service for a specific period of time, thus providing an economy to the client. In other situations, companies implementing a major project may need additional experienced staff to assist with increased work during that period.

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Waste Management & Research current issue

Moving toward COP 15
Savino, A., Hansen, J. A. Mon, 04 Aug 2008 00:00:00 -0000

Modelling waste generation by the telecom sector in Nigeria: the grey side of the impressive outing
Osibanjo, O., Nnorom, I.C., Ogbonna, K.C. Mon, 04 Aug 2008 00:00:00 -0000
Since the introduction of digital mobile technology into Nigeria in 2001, there has been a phenomenal improvement in mobile subscription, service delivery and in the overall penetration of mobile telecommunication into rural areas in the country. For instance, the country's teledensity increased from less than 1% in 2001 to about 25% in 2006 — an increase of more than 3000%. The aim of this paper is to predict improvements in telephone penetration and waste generation by the Nigerian telecommunications sector. This was achieved by regression analysis of available data on telephone subscription in the country. Our estimations indicate that an average of 3 million phones will be retired annually in the country. Considering an economic phone life of 4 years, the over 32 million phones, (weight estimated at about 3200 tons) in use in 2006 would be at their end-of-life (EoL) by 2010. This volume of waste may contain up to 1800 tons of waste plastics, 15 tons of lead and 124 tons of copper. Our derived regression equation also indicates that mobile phone penetration in the country would be about 40% by 2010. This implies that over 55 million mobile phones would be in use by 2010. The grey side of this impressive statistics is that waste generation by the telecommunications sector will also follow this trend. This paper also highlights the need to introduce a framework for the effective management of waste from this sector considering the toxicity of some of the components of mobile phones and accessories and the prevailing inappropriate disposal practices for such potentially `toxic' materials.
The performance of Spanish solid waste collection
Garcia-Sanchez, I.M. Mon, 04 Aug 2008 00:00:00 -0000
In this paper we examine street cleaning and waste collection services in Spanish municipalities with a population exceeding 50 000. The purpose is to identify factors that influence the efficiency of these services. Three input variables (staff, vehicles and containers) and four outputs variables (tonnage, collection points, collection point density and kilometres of surface area washing) are analyzed using an analytical model based on Data Envelopment Analysis (DEA) methodology. These variables, along with non-controllable input variable (Tourist Index), were chosen because they were shown, based on a Tobit regression analysis, to have a statistically significant impact on municipality behaviour. The results obtained show that scale inefficiency was lower than pure technical efficiency, the latter is linked to service management. It was observed that the street-cleaning activity was performed more inefficiently than that of waste collection. Furthermore, it was detected that municipalities can reduce the resources used in rendering this service by 8%. Finally, an estimation using the Mann—Whitney test allows us to conclude that there is no difference between the inefficiencies observed in municipalities managed directly by town councils and those which have been transferred to private companies.
GIS-based modelling for the estimation of municipal solid waste generation and collection
Karadimas, N. V., Loumos, V. G. Mon, 04 Aug 2008 00:00:00 -0000
In the present paper, an innovative model for the estimation of municipal solid waste generation and collection is proposed. This model is part of an extended solid waste management system and uses a spatial Geodatabase, integrated in a GIS environment. It takes into consideration several parameters of waste generation, such as population density, commercial activities, road characteristics and their influence on the location and allocation of waste bins. Ground-based analysis was applied for the estimation of the inter-relations between the aforementioned factors and the variations in waste generation between residential and commercial areas. Therefore, the proposed model follows a unified categorization approach for residential and commercial activities and focuses on the dominant factors that determine waste generation in the area under study. The most important result of the research work presented in the current paper is an accurate estimation of the optimal number of waste bins and their allocation. A new methodology and an appropriate algorithm have been developed for this purpose in order to facilitate routing and waste collection. By using these results, municipalities aware of social, economical and environmental factors, related to waste management, can achieve optimal usage of their resources and offer the best possible services to their citizens.
Nutrients and heavy metals distribution in thermally treated pig manure
Kuligowski, K., Poulsen, T. G., Stoholm, P., Pind, N., Laursen, J. Mon, 04 Aug 2008 00:00:00 -0000
Ash from pig manure treated by combustion and thermal gasification was characterized and compared in terms of nutrient, i.e., potassium (K), phosphorus (P) and heavy metal, i.e., cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn) contents. Total nutrient and metal concentrations were measured using energy dispersive X-ray fluorescence analysis. Acid (HNO3, H2SO4) and water-extractable concentrations were also measured both in non-classified ash and in selected ash particle size fractions using flame atomic absorption spectrometry and colorimetric spectrometry. Results indicate that ash from gasified manure contained more water-extractable K in comparison with combusted manure whereas the opposite was the case with respect to P. Heavy metals Ni, Cr and Cd were present in higher concentrations in the fine particle size fractions (< 30 µm of particle diameter), whereas K, P, Zn and Cu exhibited higher concentrations in the coarser particle size fractions (> 30 µm).
Describing variability of MSW composition data with the log-logistic distribution
Milke, M. W., Wong, V., McBean, E. A. Mon, 04 Aug 2008 00:00:00 -0000
Variations in solid waste composition data are necessary as inputs to solid waste planning, yet uncertainty exists regarding which probability distributions might be generally valuable to describe the variability. Twenty-two detailed analyses of solid waste from British Columbia, Canada, were fitted to distributions using the BestFit software. Alternative distributions were ranked based on three goodness-of-fit parameters and twelve waste fractions. The log-logistic distribution was found to be the most able to fit over the wide range of composition types considered. The results were demonstrated to be insensitive to the number of waste components or to the choice of a two- or three-parameter distribution. Although other distributions were able to better match the waste composition for individual waste types, the log-logistic distribution was demonstrated to fit, overall, a wide variety of waste composition types.

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