Supervisory control of wastewater treatment plants by combining principal component analysis and fuzzy c-means clustering

In this paper a methodology for integrated multivariate monitoring and control of biological wastewater treatment plants during extreme events is presented. To monitor the process, on-line dynamic principal component analysis (PCA) is performed on the process data to extract the principal components that represent the underlying mechanisms of the process. Fuzzy c-means (FCM) clustering is used to classify the operational state. Performing clustering on scores from PCA solves computational problems as well as increases robustness due to noise attenuation. The class-membership information from FCM is used to derive adequate control set points for the local control loops. The methodology is illustrated by a simulation study of a biological wastewater treatment plant, on which disturbances of various types are imposed. The results show that the methodology can be used to determine and co-ordinate control actions in order to shift the control objective and improve the effluent quality.

DNA adducts as a biomarker of polycyclic aromatic hydrocarbon exposure in aquatic organisms: relationship to carcinogenicity

The use of DNA adduct measurement as a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs) is now well established in ecotoxicology. In particular, DNA adduct levels in aquatic organisms has been found to produce a better correlation with PAH exposure than PAH concentrations in organisms. DNA adducts levels are most commonly determined using the P-32-postlabelling assay which measures total aromatic adducts. The relationship between relative DNA adduct formation and carcinogenicity has been investigated for a number of carcinogenic and non-carcinogenic PAHs using an in vitro system. Our results demonstrate that relatively high levels of DNA adducts can be produced by some non-carcinogenic PAHs, while other non-carcinogenic compounds do not produce detectable adducts. In addition, it has been shown that all carcinogenic PAHs investigated produce DNAadducts and that a relationship exists between relative adduct formation and carcinogenic potency. An investigation of adduct levels in fish liver and crustacean hepatopancreas in Oxley Ck, Brisbane has shown that higher than expected DNA adduct levels were correlated with the presence of carcinogenic and noncarcinogenic PAHs with high relative adduct forming potential.

Promoters for pregenomic RNA of banana streak badnavirus are active for transgene expression in monocot and dicot plants

Two putative promoters from Australian banana streak badnavirus (BSV) isolates were analysed for activity in different plant species. In transient expression systems the My (2105 bp) and Cv (1322 bp) fragments were both shown to have promoter activity in a wide range of plant species including monocots (maize, barley, banana, millet, wheat, sorghum), dicots (tobacco, canola, sunflower, Nicotiana benthamiana, tipu tree), gymnosperm (Pinus radiata) and fern (Nephrolepis cordifolia). Evaluation of the My and Cv promoters in transgenic sugarcane, banana and tobacco plants demonstrated that these promoters could drive high-level expression of either the green fluorescent protein (GFP) or the beta -glucuronidase (GUS) reporter gene (uidA) in vegetative plant cells. In transgenic sugarcane plants harbouring the Cv promoter, GFP expression levels were comparable or higher (up to 1.06% of total soluble leaf protein as GFP) than those of plants containing the maize ubiquitin promoter (up to 0.34% of total soluble leaf protein). GUS activities in transgenic in vitro-grown banana plants containing the My promoter were up to seven-fold stronger in leaf tissue and up to four-fold stronger in root and corm tissue than in plants harbouring the maize ubiquitin promoter. The Cv promoter showed activities that were similar to the maize ubiquitin promoter in in vitro-grown banana plants, but was significantly reduced in larger glasshouse-grown plants. In transgenic in vitro-grown tobacco plants, the My promoter reached activities close to those of the 35S promoter of cauliflower mosaic virus (CaMV), while the Cv promoter was about half as active as the CaMV 35S promoter. The BSV promoters for pregenomic RNA represent useful tools for the high-level expression of foreign genes in transgenic monocots.

Operating space diagrams: a tool for designers of wastewater treatment plants

Recent years have seen the introduction of new and varied designs of activated sludge plants. With increasing needs for higher efficiencies and lower costs, the possibility of a plant that operates more effectively has created the need for tools that can be used to evaluate and compare designs at the design stage. One such tool is the operating space diagram. It is the aim of this paper to present this tool and demonstrate its application and relevance to design using a simple case study. In the case study, use of the operating space diagram suggested changes in design that would improve the flexibility of the process. It also was useful for designing suitable control strategies.

Molecular rates parallel diversification contrasts between carnivorous plant sister lineages

In the carnivorous plant family Lentibulariaceae, the bladderwort lineage (Utricularia and Genlisea) is substantially more species-rich and morphologically divergent than its sister lineage, the butterworts (Pinguicula). Bladderworts have a relaxed body plan that has permitted the evolution of terrestrial, epiphytic, and aquatic forms that capture prey in intricately designed suction bladders or corkscrew-shaped lobster-pot traps. In contrast, the flypaper-trapping butterworts maintain vegetative structures typical of angiosperms. We found that bladderwort genomes evolve significantly faster across seven loci (the trnL intron, the second trnL exon, the trnL-F intergenic spacer, the rps16 intron, rbcL, coxI, and 5.8S rDNA) representing all three genomic compartments. Generation time differences did not show a significant association. We relate these findings to the contested speciation rate hypothesis, which postulates a relationship between increased nucleotide substitution and increased cladogenesis. (C) 2002 The Willi Hennig Society.

A hedging point strategy - balancing effluent quality, economy and robustness in the control of wastewater treatment plants

An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds in the influent etc. Hedging is a risk minimisation tool, with the aim to "reduce one's risk of loss on a bet or speculation by compensating transactions on the other side" (The Concise Oxford Dictionary (1995)). In wastewater treatment plant operation hedging can be applied by choosing a higher level of ammonium removal to increase the amount of nitrifiers. This is a sensible way to introduce disturbance rejection ability into the multi criterion. In practice, this is done by deciding upon an internal effluent ammonium criterion. In some countries such as Germany, a separate criterion already applies to the level of ammonium in the effluent. However, in most countries the effluent criterion applies to total nitrogen only. In these cases, an internal effluent ammonium criterion should be selected in order to secure proper disturbance rejection ability.

Molecular phylogenetics of Lentibulariaceae inferred from plastid rps16 Intron and trnL-F DNA sequences: implications for character evolution and biogeography

Phylogenetic relationships among 75 species of Lentibulariaceae, representing the three recognized genera, were assessed by cladistic analysis of DNA sequences from the plastid rps16 intron and the trnL-F region. Sequence data from the two loci were analyzed both separately and in combination. Consensus trees from all analyses are congruent, and parsimony jackknife results demonstrate strong support for relationships both between and within each of the three demonstrably monophyletic genera. The genus Pinguicula is sister to a Genlisea-Utricularia clade, the phylogenetic structure within this clade closely follows Taylor's recent sectional delimitations based on morphology. Three principal clades are shown within Utricularia, with the basal sections Polypoinpholyx and Pleiochasia together forming the sister lineage of the remaining Utricularia species. Of the fundamental morphological specializations, the stoloniferous growth form apparently arose independently within Genlisea and Utricularia three times, and within Utricularia itself, perhaps more than once. The epiphytic habit has evolved independently at least three times, in Pinguicula, in Utricularia section Phyllaria, and within the two sections Orchidioides and Iperua (in the latter as bromeliad tank-epiphytes). The suspended aquatic habit may have evolved independently within sections Utricularia and Vesiculina. Biogeographic optimization on the phylogeny demonstrates patterns commonly associated with the boreotropics hypothesis and limits the spatial origin of Lentibulariaceae to temperate Eurasia or tropical America.