Monitoring of activated sludge settling ability through image analysis : validation on full-scale wastewater treatment plants

In recent years, a great deal of attention has been focused on the research of activated sludge processes, where the solid–liquid separation phase is frequently considered of critical importance, due to the different problems that severely affect the compaction and the settling of the sludge. Bearing that in mind, in this work, image analysis routines were developed in Matlab environment, allowing the identification and characterization of microbial aggregates and protruding filaments in eight different wastewater treatment plants, for a combined period of 2 years. The monitoring of the activated sludge contents allowed for the detection of bulking events proving that the developed image analysis methodology is adequate for a continuous examination of the morphological changes in microbial aggregates and subsequent estimation of the sludge volume index. In fact, the obtained results proved that the developed image analysis methodology is a feasible method for the continuous monitoring of activated sludge systems and identification of disturbances.Empresa de Águas, Efluentes e Resíduos de Braga, Portugal - EM (AGERE)Fundação para a Ciência e a Tecnologia (FCT

Quantitative image analysis for the characterization of microbial aggregates in biological wastewater treatment : a review

Quantitative image analysis techniques have gained an undeniable role in several fields of research during the last decade. In the field of biological wastewater treatment (WWT) processes, several computer applications have been developed for monitoring microbial entities, either as individual cells or in different types of aggregates. New descriptors have been defined that are more reliable, objective, and useful than the subjective and time-consuming parameters classically used to monitor biological WWT processes. Examples of this application include the objective prediction of filamentous bulking, known to be one of the most problematic phenomena occurring in activated sludge technology. It also demonstrated its usefulness in classifying protozoa and metazoa populations. In high-rate anaerobic processes, based on granular sludge, aggregation times and fragmentation phenomena could be detected during critical events, e.g., toxic and organic overloads. Currently, the major efforts and needs are in the development of quantitative image analysis techniques focusing on its application coupled with stained samples, either by classical or fluorescent-based techniques. The use of quantitative morphological parameters in process control and online applications is also being investigated. This work reviews the major advances of quantitative image analysis applied to biological WWT processes.The authors acknowledge the financial support to the project PTDC/EBB-EBI/103147/2008 and the grant SFRH/BPD/48962/2008 provided by Fundacao para a Ciencia e Tecnologia (Portugal)

TDI based automotive seating: Solutions for enhancing foam durability

Improving the comfort and durability properties of automotive seating is an increasingly important issue within the global automotive seating industry. The technology for enhancing the comfort properties of polyurethane foams is one of the major needs of seating foam manufacturers and seat producers, whose focus is both foam density reduction and overall weight reduction of car seats. Shell Chemicals has therefore embarked on a fundamental program, focusing on the foam formulation-durability relation of TDI-based foam grades. The study consists of a thorough investigation of the influence of independent formulation variables such as raw materials composition, water level and ancillary chemicals levels on foam processing and durability performance. A statistics driven experimental approach (central composite and full factorial designs) helped to increase the predictive power of the outcome, concerning overall mechanical foam properties and comfort performance in particular