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)

Decentralizing power generation to limit national distribution networks and cleaner production strategies for essential distribution infrastructure

Energy is only really valuable at its point of use and it therefore makes sense that the closer the point of generation is to the point of consumption, the less infrastructure is required for its distribution. This is less of a problem in largely populated areas where economies of scale make infrastructure installation more viable, or where distribution lines are only required to be relatively short due to settlements being close to each other. However, vast unpopulated countries such as Australia or even sparsely populated tracts of land such as in the world‘s deserts require a less capital and resource intensive solution to ensure the populations‘ access to power. All installations require energy, whether it be for digging holes in which to plant power poles, the production of concrete or the smelting of steel; and the less power that is used to make infrastructure to generate or distribute power, the cleaner the energy. It follows that the longer the infrastructure is made to last, the less energy is required for its maintenance and replacement. In some areas small-scale renewable energy production may be the best solution eliminating the need for large scale distribution systems. This chapter investigates, using Australia as the main example, how energy can be made cleaner by using different available renewable generation sources and materials and making those that are currently used last longer for cheaper and more energy efficient power distribution. The cost (and therefore environmental) benefits of using current distribution systems will be compared to those of small-scale renewable alternatives driven by recyclable or reusable materials and wastes. Barriers to implementation of such systems will be discussed with special reference to Australia. In essence, this chapter will discuss the choices that can be made for energy distribution and small-scale energy generation depending

Ubiquity of the water-borne pathogens, Cryptosporidium and Giardia, in KwaZulu-Natal populations

The prevalence of the diarrhoea disease caused by the water-borne pathogens Cryptosporidium and Giardia in KwaZulu-Natal, was determined from pathology laboratory data. Cryptosporidium and Giardia were found to be endemic in KwaZulu-Natal with laboratory-confirmed incidences ranging from 2.9 to 3.7% and 2.9 to 3.0% respectively of diarrhoea samples submitted for protozoan parasite analysis. Increases in the number of samples submitted for Cryptosporidium or Giardia analysis were independent of the actual incidence of either protozoan pathogen. Female and male patients tested for cryptosporidiosis had similar positive percentages while giardiasis was more prevalent in female patients. Cryptosporidium and Giardia prevalence in children under 5 years indicated that Cryptosporidium was most prevalent (39.3%) in the Giardia was most prevalent in the 3 to 4 year age group (38.5%). A low percentage of Cryptosporidium and Giardia positive cases were recorded in symptomatic (4.5% and 5.3% respectively) and asymptomatic (2.4% and 0.8% respectively) HIV patients. The incidence of Cryptosporidium and Giardia did not appear to correlate (Pearson's correlation test) with climatic factors such as rainfall, season or year, possibly indicating that water-borne transmission is not the predominant route and other factors such as personal hygiene, potable water supply, sanitation and education probably have a more significant impact. WaterSA Vol.27(1) 2001: 57-6

Molecular detection of the clostridia in an anaerobic biohydrogen fermentation system by hydrogenase mRNA-targeted reverse transcription-PCR

[[abstract]]Molecular biological approaches were developed to monitor the potential biohydrogen-producing clostridia in an anaerobic semisolid fermentation system that used brewery yeast waste as the fermentation substrate. The denaturing gradient gel electrophoresis with 16S rDNA gene-targeted polymerase chain reaction (PCR) analysis was employed to confirm the existence of clostridia in the system. Remarkably, reproducible nucleotide sequences of clostridia were obtained from different hydrogen production stages by using hydrogenase gene-targeted reverse transcription (RT)-PCR. These RNA-based information suggested that the predominant hydrogen-producing strains possess either a specific Clostridium pasteurianum-like or a specific Clostridium saccharobutylicum-like hydrogenase sequence. Comparison of the hydrogenase gene-targeted sequence profiles between PCR and RT-PCR revealed that the specific C. pasteurianum-like hydrogenase harboring bacterial strains were dominant in both mRNA and bacterial population level. On the other hand, the specific C. saccharobutylicum-like hydrogenase harboring strains expressed high level of hydrogenase mRNA but may not be dominant in population. Furthermore, quantitative real-time RT-PCR analysis showed the expression pattern of the clostridial hydrogenase mRNA and may serve as an activity index for the system