Lena Gumaelius

Comamonas denitrificans sp. nov., an efficient denitrifying bacterium isolated from activated sludge

To find a biomarker for denitrification in activated sludge, five denitrifying strains isolated from three wastewater treatment plants were studied. These strains were selected from among 1,500 isolates for their excellent denitrifying properties. They denitrify quickly and have no lag phase when switching from aerobic to anoxic conditions. All strains have the cd1-type of nitrite reductase. The strains are Gram-negative rods and they all grow as filamentous chains when cultivated in liquid solution. The strains differ in colony morphology when grown on nutrient agar. Almost full-length 16S rDNA sequences were determined and phylogenetic analysis revealed that these strains are positioned among members of the genus Comamonas in the beta-subclass of the Proteobacteria. Signature nucleotides and bootstrap percentages were also analysed to verify this position. Strains 110, 123T, 2.99g, 5.38g and P17 were < or = 96.7% similar to known strains, but > or = 99.7% similar to each other, as judged from their 16S rDNA sequences, and grouped tightly together in the phylogenetic tree. Sequence motifs in the 16S rRNA gene were also found, suggesting the monophyletic origin of these strains. Nevertheless, some strains differed from the others, for example strain 110 branches early from the other strains and 5.38g is phenotypically more inert. Therefore, it is proposed that strains 110, 123T, 2.99g and P17 are classified into a new species, Comamonas denitrificans sp. nov., while the taxonomic status of strain 5.38g will have to await the outcome of further studies. The type strain of Comamonas denitrificans is 123T (ATCC 700936T).

Comparison of inhibition assays using nitrogen removing bacteria: Application to industrial wastewater

Abstract Three pure culture assays for measurements of inhibition of the nitrogen removal process were tested and compared. The methods were performed using pure cultures of bacteria responsible for three reactions; ammonia oxidation, nitrite oxidation and nitrite reduction. The inhibition caused by 48 samples of industrial wastewater was determined and the results for the three inhibition assays were compared. The correlation coefficients were calculated to be between 0.63 and 0.73. The inhibition of the pure culture methods was also compared with results from another investigation, where the inhibition by the same wastewaters was determined by a screening method based on activated sludge. The best correlation was found with the ammonia oxidation assay. The heavy metal content was statistically analysed for relationships with inhibition using a linear model with stepwise linear regression. Although zinc was a significant inhibitor for all three methods, these responded differently in the second step, which indicate that the bacteria are not inhibited according to the same pattern. The relevance of the three pure culture assays as an inhibition test is discussed and the conclusion can be drawn that they are all needed to give a complete inhibition picture of wastewaters.

Potential biomarker for denitrification of wastewaters: Effects of process variables and cadmium toxicity

Laboratory experiments have been conducted to characterize the sensitivity of a pure-cultured denitrifying bacterium from wastewater sludge, selected by virtue of its exhibiting promising qualities as a biomarker, to wastewater process variables and potential toxic inhibition by a heavy metal, cadmium. A pure culture method offers the possibility of development of a standardized toxicity test with reproducible results that are not site specific, and enables close examination of one specific reaction without interference from other organisms in the system. Denitrification by the selected bacterium, measured in terms of nitrite reduction, is rapid, reproducible, and conforms to a linear time-concentration profile, provided a select range of process conditions is employed. The denitrification rate is a maximum at about 30°C and in a pH range of 7.5 to 8.0. The rate per unit wet mass of cells is constant for varying cell concentrations and given conditions of pH and temperature. A noncompetitive inhibition model provided a good description of the relationship between denitrification rate and the concentration of a heavy metal, cadmium. The model constant, Ki, the concentration resulting in 50% inhibition, is 12 mg/l for cadmium for the test conditions used and represents a means for assessing the relative toxicity of inhibitors. The reproducibility of the test cases studied and straightforward analysis render the bacterium and test procedures promising for development of a rapid toxicity test for wastewater in a denitrifying environment. Ongoing studies are directed toward evaluating the extent to which the test organism represents the response of a denitrifying sludge population to potentially toxic compounds.

Outreach initiatives operated by universities for increasing interest in science and technology

ABSTRACT Since the 1990s, the low number of students choosing to study science and technology in higher education has been on the societal agenda and many initiatives have been launched to promote awareness regarding career options. The initiatives particularly focus on increasing enrolment in the engineering programmes. This article describes and compares eight European initiatives that have been established and operated by universities (and in some cases through collaboration with other actors in society). Each initiative is summarised in a short essay that discusses motivation, organisation, pedagogical approach, and activities. The initiatives are characterised by comparing the driving forces behind their creation, how the initiative activities relate to the activities at the university, size based on the number of participants and cost per participant and pedagogical framework. There seem to be two main tracks for building outreach activities, one where outreach activities are based on the universitys normal activities, and one where outreach activities are designed specifically for the visiting students.

Hydraulic loading, stability and water quality of Nakivubo wetland, Uganda

Nakivubo wetland, which has performed tertiary water treatment for Kampala city for the past 40 years, is ecologically stressed by agricultural and infrastructural developments. Field studies were carried out to assess the hydraulic loading, pollution profile, stability and water quality of this wetland. The upper and lower Nakivubo wetland receive 4.13−7.66 × 104 and 3.50−10.32 × 104m3/day of water respectively, of which 48.3–57.9% of total hydraulic loading to the upper wetland was carried by sampling station S1. The influent water to the upper wetland had a total BOD5 and NH4-N loading ranging from 2.6−4.4 × 103kg BOD/day and 0.79−1.68 × 103kg NH4-N/day respectively. The National Water and Sewerage Corporations effluent constituted a large proportion of BOD and NH4-N loading into Nakivubo wetland. Zinc, copper and chromium were detected in trace amounts at most sampling stations. However, lead was occasionally detected at Kibira channel (station S5) at a concentration of 0.4mg/l, which is higher than the permitted Ugandan discharge limit of 0.1mg/l (NEMA 1999). The wetland showed a very high removal efficiency for BOD, ranging from 77.4%–86.3%, compared to ammonium-N which ranged from −66.1% to 33.1% indicating limitations with the nitrification process. A low self-purification for zinc, copper and chromium was also observed in the upper Nakivubo wetland, possibly due to poor plant-wastewater interaction resulting from wetland drainage. In the lower Nakivubo wetland conductivity and dissolved oxygen were generally higher in papyrus- than in Miscanthidium-vegetated zones. However, the BOD and ammonium-N loadings did not vary significantly (P = 0.217 and P = 0.359 respectively) between the two vegetated zones.

Pre-University Engineering Education

Probably we would not know about pre-university (or K-12, in USA terms) engineering education if there had not been the discussion about STEM education. STEM is the acronym for Science, Technology, Engineering and Mathematics. The term started its existence as a rather political term in the mid-2000s.

Outreach and attractiveness: a never ending story or a new approach?

Due to lack of engineers and scientists in the Western world, outreach and attractiveness have been on the societal agenda since the 1980s. During the 1980s, a new international network was established, Gender and Science and Technology (GASAT) organised around both international and European conferences (Alting, van Vonderen, and Weyers 1992; Banerjee and Mehta 1996; Granstam and Frostfeldt 1990). At that time the dominating approach was to recruit women to engineering education, which was strongly criticised by feminist researchers for not being critical towards engineering. By recruiting to engineering, it was more women and men who should adjust to existing values and thinking and not engineering that should change (Blosser 2015; Du and Kolmos 2009). The activities undertaken were at all levels in the school system – especially focused on gender issues in math and physics at the school level and making women engineers and scientists visible as role models. The funding situation was sporadic and dominated by periodic projects sponsored sometimes from institutions and sometimes national governments programmes. Characteristic of many of these initiatives were that they were initiated and driven by engaged persons and/or associations that are not part of the university organisation. Universities saw these activities as add-on activities – both in the sense of the activity itself, but also financially. This means that universities considered these outreach activities as something nice to have – especially as most of the initiatives were sponsored by government funds, or by other kind of external financing. During the 1980s science centres were established all over the world. It started out in the US where several science centres were established. Compared to the GASAT movement, these centres were mostly government sponsored and targeting young school pupils as well as adult population – although most activities addressed the school level or public. The purpose was to spread the science and technology thinking and the science centres were seen as a general education at the societal level. During the 1990s, the discourse changed from ‘recruitment’ to ‘attractiveness’ with a signal that engineering and science should reflect on own values and cultures and reach out to new student groups. Reflecting values and cultures were also included to a higher degree in order to make the programme attractive for young people (Becker 2010; Kolmos et al. 2013). During that period, several new engineering programmes were established with focus on attracting both women and men into engineering or parallel programmes were established with new pedagogy to attract new student groups. Universities also start to establish more permanent organisations responsible for outreach activities. Vetenskapens Hus in Stockholm is one of such initiatives offering technology and science classes complementary to the school curriculum. This activity has been a well-established organisation for nearly 20 years and is one of the initiatives presented later in this issue. In this special issue, we focus on the initiatives funded and run by the universities. We were keen to figure out in which way universities have developed outreach strategies? What is the effect of institutional commitment

Pre-University Engineering Education Research at a University of Technology

In recent years, the issue of students’ knowledge and interest in science and technology has attracted the attention of several international studies (e.g., PISA/OECD, ROSE, TIMMS). Findings from these studies have influenced debates about education in general and about STEM subjects in particular (Science, Technology, Engineering, and Mathematics).