Evaluation of activated sludge treatment and settleability in remediation of edible oil effluent

Wastewater discharged from the edible oil industry contains a very concentrated amalgamation of organic and inorganic materials making it a problematic effluent to treat. The aim of this study was to evaluate the activated sludge treatment of edible oil effluent from a sunflower oil processing company in KwaZulu-Natal. A 28 ℓ laboratory-scale modified Ludzack-Ettinger (MLE) activated sludge process was used to treat refinery effluent from the industry. Pre-flocculation of the effluent was necessary to remove the bulk of the fats, oils and greases (FOG) prior to treatment. Routine analyses of chemical oxygen demand (COD), total nitrogen (N), total phosphorus (TP), total suspended solids (TSS), dilute sludge volume index (DSVI) and FOG were conducted in conjunction with microscopic analyses of floc structure, filamentous bacteria and protozoa. An average COD removal of 81% was obtained for the flocculated effluent, at a 15 d sludge age and 24 h hydraulic retention time. However, significantly high TSS values were observed in the treated effluent as a result of sludge-oil aggregation, pin-point floc formation and high numbers of freeswimming bacteria. Microscopic analysis confirmed an absence of filamentous bacteria resulting in poor floc formation, subject to shearing. Periods of soybean oil effluent addition, however, resulted in sludge bulking with DSVI measurements as high as 770 mℓ /g. Fluctuating protozoan populations were also correlated to fluctuating TSS values and were found to be negatively impacted by uncontrolled pre-flocculation. Water SA Vol.29(3) 2003: 245-25

An Expressed Sequence Tag collection from the male antennae of the Noctuid moth Spodoptera littoralis: a resource for olfactory and pheromone detection research

<p>Abstract</p> <p>Background</p> <p>Nocturnal insects such as moths are ideal models to study the molecular bases of olfaction that they use, among examples, for the detection of mating partners and host plants. Knowing how an odour generates a neuronal signal in insect antennae is crucial for understanding the physiological bases of olfaction, and also could lead to the identification of original targets for the development of olfactory-based control strategies against herbivorous moth pests. Here, we describe an Expressed Sequence Tag (EST) project to characterize the antennal transcriptome of the noctuid pest model, <it>Spodoptera littoralis</it>, and to identify candidate genes involved in odour/pheromone detection.</p> <p>Results</p> <p>By targeting cDNAs from male antennae, we biased gene discovery towards genes potentially involved in male olfaction, including pheromone reception. A total of 20760 ESTs were obtained from a normalized library and were assembled in 9033 unigenes. 6530 were annotated based on BLAST analyses and gene prediction software identified 6738 ORFs. The unigenes were compared to the <it>Bombyx mori </it>proteome and to ESTs derived from Lepidoptera transcriptome projects. We identified a large number of candidate genes involved in odour and pheromone detection and turnover, including 31 candidate chemosensory receptor genes, but also genes potentially involved in olfactory modulation.</p> <p>Conclusions</p> <p>Our project has generated a large collection of antennal transcripts from a Lepidoptera. The normalization process, allowing enrichment in low abundant genes, proved to be particularly relevant to identify chemosensory receptors in a species for which no genomic data are available. Our results also suggest that olfactory modulation can take place at the level of the antennae itself. These EST resources will be invaluable for exploring the mechanisms of olfaction and pheromone detection in <it>S. littoralis</it>, and for ultimately identifying original targets to fight against moth herbivorous pests.</p

Isolation and cultivation of filamentous bacteria implicated in activated sludge bulking

Filamentous bacteria have long been associated with activated sludge bulking and foaming and are known to be the main cause of this problem. Chemical control methods such as chlorination and the use of hydrogen peroxide have been, and still are, used to cure bulking and foaming but are only effective as interim measures. More detailed understanding of the physiology and biochemistry of filamentous bacteria is still required for effective long-term control of bulking and foaming. Isolation and cultivation of filamentous bacteria in pure culture have shown promise as methods to gaining better understanding of bulking and foaming. The aim of this project was, therefore, to assess different techniques for effective isolation and cultivation of filamentous bacteria in pure culture. Activated sludge samples from Durban and surrounding areas were screened microscopically to identify constituent filamentous bacterial populations. Samples with varieties of different filamentous bacteria were subjected to various floc break-up procedures (nonidet surfactant treatment, sonication and cellulase hydrolysis) in conjunction with physical separation (centrifugation) to separate filamentous bacteria from floc-forming bacteria. Both treated and untreated samples were serially diluted and plated onto a variety of different solid media, whereafter discrete bacterial colonies were isolated and screened microscopically for filamentous morphology. Cellulase hydrolysis proved unsuccessful for filament isolation while direct inoculation, nonidet pretreatment and sonication resulted in the isolation of five different filaments, one via sonication and two each via the other methods. The filaments were provisionally identified as Sphaerotilus natans, Microthrix parvicella, Type 1863, Type 0092 and Haliscomenobacter hydrossis. WaterSA Vol.29(4) 2003: 405-41

Online Learning in Higher Education: Exploring Advantages and Disadvantages for Engagement

As the popularity of online education continues to rise, many colleges and universities are interested in how to best deliver course content for online learners. This study explores the ways in which taking courses through an online medium impacts student engagement, utilizing data from the National Survey of Student Engagement. Data was analyzed using a series of ordinary least squares regression models, also controlling for relevant student and institutional characteristics. The results indicated numerous significant relationships between taking online courses and student engagement for both first-year students and seniors. Those students taking greater numbers of online courses were more likely to engage in quantitative reasoning. However, they were less likely to engage in collaborative learning, student-faculty interactions, and discussions with diverse others, compared to their more traditional classroom counterparts. The students with greater numbers of online courses also reported less exposure to effective teaching practices and lower quality of interactions. The relationship between these engagement indicators and the percentage of classes taken online suggests that an online environment might benefit certain types of engagement, but may also be somewhat of a deterrent to others. Institutions should consider these findings when designing online course content, and encourage faculty to contemplate ways of encouraging student engagement across a variety of delivery types