Tertiary nitrification of wastewater in trickling filters

This study was designed to investigate, at laboratory and pilot scale, the effects of various loading and climatic factors on the nitrification perfon-nance of four media, and to undertake a comparative assessment of the media. The media used were blast furnace slag and three random plastic media: Flocor RS, Etapak 160 and a new medium, Etapak 210. Laboratory experiments using pure cultures of Nitrosomonas europaea have determined the effect on nitrification of temperature, pH and substrate, BOD and inhibitor concentrations. Optimal values have been resolved for the temperature and pH and half- saturation constants for the substrate and inhibition are calculated for pure culture conditions. The presence of glucose and glutamic acid has been shown to have a beneficial effect on nitrification, although this observation could not be adequately explained. Pilot scale research, conducted over a two year period, has provided an accurate representation of a nitrifying trickling filter by using effluent from Cranfield STW in filters exposed to the full climadc variation. Data obtained from these filters have indicated the superior performance of the blast furnace slag media due mostly to its ability to maintain a large active bacterial Population without excessive accumulation. Results have been used to support or challenge previous publications, and to generate a set of desion curves. Conclusions from this research have been used in the design of a full scale nitrifying trickling filter which has been constructed at Cranfield STW, early data from which are presented

Thermodynamic bounds on ultrasensitivity in covalent switching

Switch-like motifs are among the basic building blocks of biochemical networks. A common motif that can serve as an ultrasensitive switch consists of two enzymes acting antagonistically on a substrate, one making and the other removing a covalent modification. To work as a switch, such covalent modification cycles must be held out of thermodynamic equilibrium by continuous expenditure of energy. Here, we exploit the linear framework for timescale separation to establish tight bounds on the performance of any covalent-modification switch, in terms of the chemical potential difference driving the cycle. The bounds apply to arbitrary enzyme mechanisms, not just Michaelis-Menten, with arbitrary rate constants, and thereby reflect fundamental physical constraints on covalent switching.Comment: 29 pages, 6 figure

Rotating biological contactors for wastewater treatment - A review

Rotating biological contactors (RBCs) for wastewater treatment began in the 1970s. Removal of organic matter has been targeted within organic loading rates of up to 120 g m−2 d−1 with an optimum at around 15 g m−2 d−1 for combined BOD and ammonia removal. Full nitrification is achievable under appropriate process conditions with oxidation rates of up to 6 g m−2 d−1 reported for municipal wastewater. The RBC process has been adapted for denitrification with reported removal rates of up to 14 g m−2 d−1 with nitrogen rich wastewaters. Different media types can be used to improve organic/nitrogen loading rates through selecting for different bacterial groups. The RBC has been applied with only limited success for enhanced biological phosphorus removal and attained up to 70% total phosphorus removal. Compared to other biofilm processes, RBCs had 35% lower energy costs than trickling filters but higher demand than wetland systems. However, the land footprint for the same treatment is lower than these alternatives. The RBC process has been used for removal of priority pollutants such as pharmaceuticals and personal care products. The RBC system has been shown to eliminate 99% of faecal coliforms and the majority of other wastewater pathogens. Novel RBC reactors include systems for energy generation such as algae, methane production and microbial fuel cells for direct current generation. Issues such as scale up remain challenging for the future application of RBC technology and topics such as phosphorus removal and denitrification still require further research. High volumetric removal rate, solids retention, low footprint, hydraulic residence times are characteristics of RBCs. The RBC is therefore an ideal candidate for hybrid processes for upgrading works maximising efficiency of existing infrastructure and minimising energy consumption for nutrient removal. This review will provide a link between disciplines and discuss recent developments in RBC research and comparison of recent process designs are provided (Section 2). The microbial features of the RBC biofilm are highlighted (Section 3) and topics such as biological nitrogen removal and priority pollutant remediation are discussed (Sections 4 and 5). Developments in kinetics and modelling are highlighted (Section 6) and future research themes are mentioned

Microbial extracellular enzyme activity affects performance in a full-scale modified activated sludge process

The rate-limiting step of wastewater treatment is the breakdown of polymers by extracellular enzyme activity (EEA). The efficacy of EEA on biomass from full scale conventional activated sludge (AS) and modified AS with bench scale and full scale rotating biofilm reactors (RBR) was compared. The maximum amino-peptidase EEA was 394 ± 34 μmolL−1 min−1 for the bench RBR which was 11.7 and 4.5 times greater than maximum α-glucosidase and phosphatase EEA in these reactors. At full scale the RBR gave ~4.6, 13.5 and 6.3 times the EEA for amino-peptidase, α-glucosidase and phosphatase (based on enzyme Vmax) compared to the highest EEA in conventional AS biomass. Controlled overloading of the bench RBRs revealed that EEA increased with OLR up to 190 g tCOD m−2d−1 and further increases in OLR reduced the EEA. Pretreatment of wastewater by EEA in the RBR was linked to better performance of the modified activated sludge process. Maintaining high EEA of biofilms is critical for the design of high OLR wastewater treatment systems

Exercise interveNtion outdoor proJect in the cOmmunitY for older people - The ENJOY Senior Exercise Park project translation research protocol

Background: Creating inclusive and accessible outdoor environments that provide and encourage opportunities for older adults to engage in physical activity and social interaction is important for healthy ageing. The Senior Exercise Park is outdoor exercise equipment designed specifically for use by older people that provides physical and social benefits for older people in the community, and has the potential to be used widely as a sustainable mode of physical activity. The aim of this study is to implement and evaluate the effects of sustained engagement through the use of a community-based novel outdoor physical activity program (purpose-built exercise park) for older people on physical, mental and social health and physical activity outcomes (the ENJOY project). Methods: This is a prospective pre-post design study with 12 months follow up. Adults aged ≥60 years will be recruited from the general community from the suburbs close to the Senior Exercise Parks locations in Melbourne. Participants will undergo a 12 week structured supervised physical activity program using the outdoor Senior Exercise Park equipment followed by 6 months unstructured physical activity program. Participants will be assessed at baseline, 3, 9, and 12 months. The following outcomes will be assessed: physical activity, physical function, psychosocial and mental health outcomes, falls risk and falls occurrence, participants' feedback and satisfaction, and health care resource use. Discussion: The ENJOY trial is designed to operate in a community setting with local government engagement to maximise the usage of the exercise park and provide an outdoor space for older people to be physically active. This project will evaluate the effectiveness and sustainability of the outdoor exercise park on a range of health outcomes and its long-term usability in the community. Trial registration: This trial is prospectively registered with the Australian New Zealand Clinical Trials Registry. Trial registration number ACTRN12618001727235 registered 18th of October 2018

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Biosolids recycling impact on biofilm extracellular enzyme activity and performance of hybrid rotating biological reactors

Biological processes for wastewater treatment is limited by extracellular enzyme activity (EEA) of the biofilm on polymeric substrates. The efficiency of biodegradation / biosorption mechanisms causing EEA and organic load removal in biofilms remains unknown. Our hypothesis was that the limiting step of biological process can be overcome by biostimulation and/or bioaugmentation of the return sludge in hybrid biofilm reactors, which leads to competition between suspended and attached bacteria and lower effective substrate to microrganism ratio. Therefore, we considered more active biosolids to perform best at enhancing reactor removal rate. To test this, the efficacy of recycling distinct bio-solids types considered to have different bacterial activity such as final effluent (FE), humus solids (HS) and recycle activated sludge (RAS) on performance improvements of rotating biofilm reactors (RBRs). These bio-solids were investigated under high organic loading rates (OLR) and solids loading rates (SLR) using pilot scale reactors receiving real municipal wastewaters. Controlled overloading of RBRs revealed that EEA improved with increasing OLR/SLR. High SLR (>3.3 kg Total Suspended Solids m−2 d−1) delayed and decreased the reduction of organic and inorganic removal rates in the biological processes which commonly occurs under high OLRs. This effect was more pronounced in the highest activity solids (RAS > HS > FE) suggesting the activity and function of bio-solids was critical to improve performance of RBRs. High OLR and SLR induced efficient denitrification and organics removal within the biofilm reactor at residence times of <5 min. Recycling active solids permitted EEA despite overloading which was critical to the performance of the RBRs

Mesh rotating reactors for biofilm pre-treatment of wastewaters – Influence of media type on microbial activity, viability and performance

The impact of using different plastic mesh in rotating biofilm reactors (RBRs) on the treatment performance, biofilm activity and viability under varying organic loading rates (OLRs) was investigated. Laboratory-scale RBRs treating real wastewater were operated under OLR loading conditions typical of pre-treatment processes. A fully-crossed, three-factorial design series of experiments was undertaken with low and high surface area mesh made from polyvinyl chloride (PVC) and polypropylene (PP) operated at low, medium, high and very high OLR. The maximum volumetric removal rate of 2.4 kg sCOD m3 d−1 occurred at the high OLR, for low surface area mesh, irrespective of plastic used. The highest OLR at which nitrification could be attained was 35 g sCOD m−2 d−1. The biofilm growth decreased under medium compared to low OLR on all mesh. This coincided with a ∼2 fold decrease in the microbial viability. Higher surface area mesh was important for high nitrification rates at medium OLR (p < 0.05). In contrast the low surface area PVC and PP mesh was best at very high OLR (160 g sCOD m−2 d−1 or ∼320 g BOD5 m−2 d−1) for bulk organics removal (p < 0.05). Therefore, lower surface area mesh is recommended for wastewater pre-treatments at high OLR, whilst high surface area mesh was best for elevated nitrification rates at medium OLR. The microbial activity and viability had a strong positive correlation with OLR (R2 = 0.92, p < 0.001 and 0.81, p < 0.001 respectively). The microbial activity and viability also positively correlated (R2 = 0.4, p < 0.05 and 0.29, p < 0.01 respectively) to the sCOD removal performance but not the ammonia removal in mesh RBRs. This confirms the importance of maintaining biofilm activity and viability for bulk organics removal in biofilm processes in wastewater treatment

Allosteric conformational ensembles have unlimited capacity for integrating information

Integration of binding information by macromolecular entities is fundamental to cellular functionality. Recent work has shown that such integration cannot be explained by pairwise cooperativities, in which binding is modulated by binding at another site. Higher-order cooperativities (HOCs), in which binding is collectively modulated by multiple other binding events, appear to be necessary but an appropriate mechanism has been lacking. We show here that HOCs arise through allostery, in which effective cooperativity emerges indirectly from an ensemble of dynamically interchanging conformations. Conformational ensembles play important roles in many cellular processes but their integrative capabilities remain poorly understood. We show that sufficiently complex ensembles can implement any form of information integration achievable without energy expenditure, including all patterns of HOCs. Our results provide a rigorous biophysical foundation for analysing the integration of binding information through allostery. We discuss the implications for eukaryotic gene regulation, where complex conformational dynamics accompanies widespread information integration

Research priorities for child and adolescent physical activity and sedentary behaviours : an international perspective using a twin-panel Delphi procedure

BACKGROUND: The quantity and quality of studies in child and adolescent physical activity and sedentary behaviour have rapidly increased, but research directions are often pursued in a reactive and uncoordinated manner. AIM:To arrive at an international consensus on research priorities in the area of child and adolescent physical activity and sedentary behaviour. METHODS:Two independent panels, each consisting of 12 experts, undertook three rounds of a Delphi methodology. The Delphi methodology required experts to anonymously answer questions put forward by the researchers with feedback provided between each round. RESULTS:The primary outcome of the study was a ranked set of 29 research priorities that aimed to be applicable for the next 10years. The top three ranked priorities were: developing effective and sustainable interventions to increase children's physical activity long-term; policy and/or environmental change and their influence on children's physical activity and sedentary behaviour; and prospective, longitudinal studies of the independent effects of physical activity and sedentary behaviour on health. CONCLUSIONS:These research priorities can help to guide decisions on future research directions