Effect of Arsenic (III) on the Denitrification Process

A sequencing batch reactor (SBR) was operated to develop denitrifying bacteria that had a mean specific denitrification rate of 0.11 g NO₃⁻-N/gVSS/day. Another system (an anaerobic digester) was operated to generate volatile fatty acids (VFAs) with the effluent concentration being measured to be 5655 ± 876 mg/L as acetic acid. Using the denitrifying biomass developed in the SBR and VFAs generated in the digester as an external carbon source, a series of denitrification batch tests were conducted. The denitrification batch reactors were spiked with NO₃⁻- N (to get a C:N ratio of 3.0) and different arsenite concentrations to quantify the effect of arsenite on the denitrification rate. A steady deterioration in the ability of the biomass to denitrify under increasing arsenite concentrations was observed, with the mean specific denitrification rate dropping from 0.183 g NO₃⁻-N/gVSS/day at an arsenite concentration of 5 mg/L, to 0.047 g NO₃⁻-N/gVSS/day at a concentration of 25 mg/L

Encouraging creativity in design through student competitions

This paper reports on a student competition in which teams of 4 students were asked to design an egg launching and catching device capable of launching an egg an initial distance of 2 metres without breakage. The design exercise was part of a creativity module in a Systems Engineering course and the objective of the exercise was to illustrate to students how the design process involves trade-offs between sometimes potentially conflicting criteria. Thus, the designs were judged not only on the winning distance but also factored into the total score were points for weight, cost, good appearance and accuracy/repeatability. Anecdotal comments from students indicated an immense enjoyment of the design experience and a full cognisance of the objectives of the competition

Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study

The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10−8) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10−8). The top IBC association for SBP was rs2012318 (P= 6.4 × 10−6) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10−6) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexit

Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study.

The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10(-8)) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10(-8)). The top IBC association for SBP was rs2012318 (P= 6.4 × 10(-6)) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10(-6)) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)

Phosphorus removal in a waste-stabilization pond containing limestone rock filters

This study analyzed samples taken along internal transects through a small waste-stabilization pond system in New Zealand that had rock filters installed between the final maturation cells. The aim of the study was to determine the respective importance of the ponds and rock filters for phosphorus (P) removal since routine monitoring from the preceding 2 months had indicated effluent P levels below 2 g/m³ for influent levels around 9 g/m³. Despite the filters being constructed from a reactive sorbent (i.e., limestone) it was found that phosphorus removal was mainly occurring in the ponds. A solubility analysis suggested that phosphorus removal may have been due to moderate calcium hardness levels of around 60 g/m³ as Ca²⁺, while an analysis of sludge samples in the system suggested that the ratio of calcium to phosphorus in the sludge was consistent with the precipitation of phosphorus as calcium hydroxyapatite

Introducing ethics using structured controversies

This paper describes a method of introducing ethics to a second-year class of civil engineering students. The method, known as a 'structured controversy', takes the form of a workshop where the students assume the identity of stakeholders having an interest in a proposed development in an environmentally sensitive region. The instructor enhances the workshop by deliberately feeding incorrect information into a catalogue of facts that each stakeholder has at their disposal. After the workshop, the instructor draws out three ethical frameworks from which the stakeholders operate. A key component of the exercise is that the students do not know beforehand that the environmental workshop is being used to introduce ethics. When the connection is revealed, the students appreciate that much of their behaviour during the role-play was because they inadvertently adhered to an unknown ethical platform. Since it is an environmental simulation, an explicit connection can be made to the debate over 'who' to include in the moral community. In addition, a link can be drawn to the notion of sustainable development which, in this paper, is advocated as an ethical rather than a technical concep

MCPA degradation by nitrate reducing bacteria

Introduction MCPA (2-methyl-4-chlorophenoxyacetic acid) is a selective, post-emergence herbicide frequently used to control broad leaf weeds in New Zealand (Costa et al., 2013). In 2013, approximately NZ $7.5 million was invested to import MCPA from around the world (Statistics New Zealand, 2013). Unfortunately however, pollution of aqueous environments is caused by the discharge of MCPA originating from manufacturing plants, transportation and storage sites and/or accidental spills. Some notable studies have shown that denitrifying microorganisms can acclimatize to industrial-strength concentrations of pesticides (e.g. 2,4-D) in a SBR regime (He and Wareham, 2009); however, there does not seem to be any studies that specifically focus on the ability of denitrifying microorganisms to degrade MCPA in an SBR. As such, the major aim of this work was to investigate the potential of MCPA biodegradation by activated sludge microorganisms under anoxic conditions. The research was divided into three phases; namely, Phase I (a proof-of-concept phase); Phase II (an initial “limit” exploration phase) and Phase III (effect of HRT phase). Materials and Methods A 20 L SBR bioreactor was constructed and inoculated with 10 L of activated sludge from a local wastewater treatment plant in Christchurch, New Zealand. To maintain a constant COD, a synthetic wastewater using acetate was prepared having approximately the same characteristics as municipal wastewater (i.e. 300 - 350 mg/L of COD). The target COD: NO3-N ratio of 3.0 to 3.4 was achieved with NaNO3 injected twice per cycle to provide an electron acceptor (NO3-N). A long SRT of 40 – 60 days allowed for slow-growing biomass under anoxic conditions while a 24- hr HRT was initially selected. Filling, mixing/reacting, settling and decanting functions were controlled via a programmable controller. During Phase I, 20 mg/L of DMCPA (MCPA in the form of dimethylamine salt) was fed to the biomass; however once complete MCPA degradation was observed the herbicide concentration was increased to 50 mg/L (Phase II). A solid phase micro extraction (SPME) technique was used to extract the pesticide from wastewater samples, with herbicide analysis performed on a gas chromatograph HP 6890 series, equipped with a Ni-63 electron capture detector. Results and Discussion Baseline data collected prior to feeding MCPA into the bioreactor showed that TSS and VSS values stabilized at 4000 ± 400 mg/L and 2800 ± 300 mg/L respectively, with track studies revealing more than 98 % removal of the COD and NO3-N within the first five hours’ time period. Phase I: MCPA acclimatization period (proof of “degradation” concept): As indicated, in Phase I, 20 mg/L of MCPA (in salt form) was continuously fed to the SBR with 25 days passing before MCPA removal was observed. Three track studies (Fig. 1a) revealed that MCPA conversion (from salt to acid form) and degradation occurred simultaneously. That is, the rising peak indicates the rate of acid formation was larger than its removal rate (in the first half of the cycle) while acid biodegradation was dominant in the second half of the cycle. More than 98 % removal of MCPA was achieved within 90 days. Phase II: Effect of increased concentration of herbicide (“limit phase”): The amount of DMCPA was increased to 50 mg/L and after steady effluent COD concentrations were obtained, track studies were conducted to observe the new MCPA formation and degradation pattern (Fig. 1b). Results indicate the microorganisms took much longer (i.e. 8-9 h) to convert 50 mg/L of MCPA salt to acid, with eventually incomplete biodegradation occurring. Phase III: Effect of HRT on removal of herbicide: Because incomplete removal of MCPA occurred in a 12 h cycle, the biodegradation response was investigated during a 48 h HRT (i.e. a 24 h cycle). Track studies revealed that 48 h HRT was sufficient to degrade 98 % of the concentration of 50 mg/L of MCPA. Nitrate removal: More than 98 % of the nitrate was removed in the first five hours of the cycle. In order to maintain the bioreactor in anoxic conditions, a second dose of nitrate was injected into the SBR after five hours of reaction time but in this particular instance only 50% of the nitrate was removed. Different levels of MCPA had no effect on denitrification activity. Conclusion Results show that an anoxic SBR can be designed to remove approximately 50 mg/L of MCPA in the presence of acetate while simultaneously removing nitrate