Nowadays, minimization of the negative environmental impact of manufacturing processes is considered one of the most challenging problems in various industrial fields. Research communities and environmental legislators are continuously working to address these problems by placing significant efforts in devising new strategies to increase environmental sustainability. One of these problems is the lack of a comprehensive framework that can simultaneously improve economic aspects and lessen the impact on the environment. The need for a mathematical model that can assist firms in reaching suitable investment decisions has become of paramount importance. In this context, this study aims at optimizing the environmental and economic sustainability of batch production systems (i.e. a series of workstations where products are manufactured in batches). To this end, a profit maximization model was created by incorporating constraints such as budget, demand, greenhouse gas emissions and hazardous wastes within the manufacturing stage of product life cycle. Moreover, the model provides detailed guidelines on required improvements in a specific manufacturing system and calculates the investment associated with such implementations. This new approach was tested by using two different software packages and results were probed and discussed in different scenarios to investigate its validity. Sensitivity analysis and simulation results proved the consistency of the proposed mathematical model. In particular, in order to further assess the validity of the model, a pharmaceutical plant was selected as a case study, which also permitted discussion on additional aspects of the problem.

Multipurpose batch manufacturing systems allow a suite of job types to be processed with a fixed set of machines. These types of systems are commonly found in chemical processing, as well as in computer systems and the service industry. In this thesis we consider the problem of sequencing jobs entering the manufacturing system in order to minimize makespan, or total time to complete processing of the jobs. We formulate this problem as a dynamic programming problem and illustrate the computational difficulty of solving this problem. We give a method for simulation of the system by representing each machine in the system as a finite state automata. This allows one to calculate the makespan given a manufacturing system and a sequence. Due to the complexity of the system, we offer an approximation to the problem. We show that the approximation strategy allows refinement. This progressive refinement of the approximation results in a sequence of approximations that approach the true problem. As the approximation is refined, the computational complexity of the approximated problem grows. For a simplified system, we show that the approximation has bounded error. Furthermore, we show that the error bound of the approximation sequence improves as the approximation approaches the true problem. This presents a trade-off between computational complexity and accuracy of the solution. A decision maker using this sequence of approximations can quickly determine a level of approximation based on the amount of computational power available and the accuracy needed in a solution.

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The vast majority of chemical products, both in number and volume, are produced by batch processes. Recent studies show that only six percent of the batch processes were satisfactorily replaced by continuous processes. This clearly shows the importance and permanence of such processes. These plants have a basic characteristic of intermittent production of a product with non-stationary operation, including steps of loading, processing, cleaning and drainage, what makes the project complex. Its use is recommended, or for technological reasons or to meet the need for a dynamic and uncertain market, as it is the case of products with high added value and small demand. An important aspect of this type of plant is its flexibility in producing multiple products in a unique plant. The batch operations are economically justified when a large number of products are produced using similar production paths. Due to the difficulty of predicting the peak and the extension of demand, such settings are frequently modified plant and equipment is usually small and versatile and can be used by a large number of products. Power must be flexible enough to adapt to market needs and product life cycle is usually short. Brazil ranks third in world ranking in sales of personal care products, perfumes and cosmetics. The industry in this sector, in the two study reaches, each year, more consumers. The currently complex and competitive global market requires that companies seek to optimize processes, reduce costs and achieve economies of scale. In view of this, we have the developed a mathematical model of large, from real data, obtained in a Personal Hygiene Industry, providing a practical application to the work on Design and Production Scheduling of Multipurpose Batch Plants, from Professor João Soletti, which enables to perform planning and design of this type of plants. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A grande maioria dos produtos químicos, certamente em número e provavelmente em valor, se não em volume, é produzida por processos em batelada. Recentes estudos mostram que apenas seis por cento dos processos em batelada foram satisfatoriamente substituídos por processos contínuos. Isto mostra claramente a importância e permanência de tais processos. Estas plantas têm como característica básica a produção intermitente de um determinado produto, com operação não estacionária, incluindo etapas de carga, processamento, drenagem e limpeza, o que dificulta o seu projeto. Sua utilização é recomendada, ou por razões tecnológicas ou para atender a necessidade de um mercado incerto e dinâmico, como é o caso de produtos de alto valor agregado e de pequena demanda. Um importante aspecto desse tipo de planta é a sua flexibilidade na produção de múltiplos produtos em uma única planta. As operações em batelada são economicamente justificadas quando um grande número de produtos é realizado utilizando caminhos de produção similares. Devido à dificuldade da previsão do pico e da extensão da demanda, as configurações desse tipo de planta são frequentemente alteradas e os equipamentos são, geralmente, pequenos e versáteis, podendo ser utilizados por um grande número de produtos. A alimentação deve ser flexível, o suficiente, para se adaptar à necessidade do mercado e o ciclo de vida do produto é, geralmente, curto. O Brasil ocupa o terceiro lugar no ranking mundial em vendas de produtos de higiene pessoal, perfumaria e cosméticos. A indústria desse setor, objeto do estudo, atinge, a cada ano, mais consumidores e a natureza do sistema de produção nesse setor é por processo em batelada. Com a atual complexidade do mercado globalizado e competitivo, é necessário que as empresas busquem otimizar processos, reduzir custos e obter ganhos de escala. Em vista disto, desenvolveu-se um modelo matemático de grande porte, a partir de dados reais, obtidos em uma Indústria de Higiene Pessoal, possibilitando uma aplicação prática à tese sobre Dimensionamento e Programação da Produção de Plantas Multipropósito em Batelada, do Prof. João Soletti, que indica como realizar o planejamento e projeto de unidades fabris.