Biodesalination: an emerging technology for targeted removal of Na+and Cl−from seawater by cyanobacteria

Although desalination by membrane processes is a possible solution to the problem of freshwater supply, related cost and energy demands prohibit its use on a global scale. Hence, there is an emerging necessity for alternative, energy and cost-efficient methods for water desalination. Cyanobacteria are oxygen-producing, photosynthetic bacteria that actively grow in vast blooms both in fresh and seawater bodies. Moreover, cyanobacteria can grow with minimal nutrient requirements and under natural sunlight. Taking these observations together, a consortium of five British Universities was formed to test the principle of using cyanobacteria as ion exchangers, for the specific removal of Na+ and Cl− from seawater. This project consisted of the isolation and characterisation of candidate strains, with central focus on their potential to be osmotically and ionically adaptable. The selection panel resulted in the identification of two Euryhaline strains, one of freshwater (Synechocystis sp. Strain PCC 6803) and one of marine origin (Synechococcus sp. Strain PCC 7002) (Robert Gordon University, Aberdeen). Other work packages were as follows. Genetic manipulations potentially allowed for the expression of a light-driven, Cl−-selective pump in both strains, therefore, enhancing the bioaccumulation of specific ions within the cell (University of Glasgow). Characterisation of surface properties under different salinities (University of Sheffield), ensured that cell–liquid separation efficiency would be maximised post-treatment, as well as monitoring the secretion of mucopolysaccharides in the medium during cell growth. Work at Newcastle University is focused on the social acceptance of this scenario, together with an assessment of the potential risks through the generation and application of a Hazard Analysis and Critical Control Points plan. Finally, researchers in Imperial College (London) designed the process, from biomass production to water treatment and generation of a model photobioreactor. This multimodal approach has produced promising first results, and further optimisation is expected to result in mass scaling of this process

The effects of metallicity on {delta} Scuti star asteroseismology

In {delta} Scuti star seismology, most researchers use evolution and pulsation models assuming a solar element mixture and Z = 0.02 for preliminary determinations of stellar masses or evolutionary state from observed frequencies. Here the authors investigate the consequences of this assumption by considering the effects of metallicity changes in the models on their inferences of the internal structure of {delta} Scuti stars. They use the main-sequence {delta} Scuti star FG Vir, and the more evolved shell hydrogen burning star {delta} Scuti to illustrate their results

Case studies of data collection and decision-making for small low-income community water supply in Nepal

This project seeks to develop decision making tools to aid practitioners in Nepal to select appropriate improved water supply measures, using selected small low income communities as case studies. These include three rural communities (Bhalakhalak, Sonbarshi, Chamar Tolia) and a periurban squatter community near Kathmandu (Manohara). Household data was collected via questionnaires and site visits to assess the current practices and inform decision making. Standard water quality data was also collected to characterise water sources, several of which were deemed unsuitable for safe water supply. A decision framework, in the form of a ‘Yes/No’ decision tree, was then developed which incorporated site specific technical, demographic, and socioeconomic considerations and used literature information and local experience. It is hoped that the framework can be applied to decision making in other low income communities that face similar challenges

Evaluating the viability of establishing container-based sanitation in low-income settlements

Container-based sanitation (CBS) services operate in a number of low-income urban settlements across the globe, providing sanitation services where other on-site and off-site sanitation systems face logistical and environmental restrictions. The viability of each CBS service is influenced by a number of location specific factors. Drawing on an initial review of existing CBS services, this paper identifies and evaluates these factors in relation to establishing CBS in a new service location. By applying a weighted scoring matrix to these factors, the potential viability of CBS services has been assessed for urban informal settlements in Kathmandu Valley, Nepal. The viability of CBS services in these settlements was found to be most influenced by the current availability of basic sanitation facilities, the unfamiliarity with paying for sanitation services and the universally adopted practice of anal cleansing with water. The process and scoring matrix developed and subsequently applied in Nepal, are recommended as part of the pre-feasibility stage assessment where a CBS service is being considered as a sanitation option in new locations

Improving root cause analysis of bacteriological water quality failures at water treatment works

© 2015 Published by Elsevier Ltd. Variations in spot-sampled and continuously-monitored water quality data were assessed to determine whether they could be linked to regulatory coliform failures. Data were available from raw water to the final monitoring point at water treatment works (WTW)-B and included climate, physico-chemical and bacteriological data. These were analysed using cross-correlation and self-organising maps in MATLAB®. The results highlighted rainfall and upstream coliforms and turbidity as important factors in the coliform failures. Further examination showed that failures correlated with low turbidity and low coliform loading, but relatively high rainfall. This outcome could be used to improve bacteriological compliance at WTW-B and similar sites

The development of an onsite sanitation system based on vermifiltration: the ‘tiger toilet’

This paper describes the development of a novel onsite sanitation system based on vermifiltration, the ‘Tiger Toilet’. Initial laboratory experiments demonstrated that feed distribution was not required, a worm density of 2 kg/m2 could be used, worms preferred wetter environments, and system configuration did not affect effluent quality. Installing the first prototype in the UK proved that the process functioned when scaled, i.e., chemical oxygen demand and thermotolerant coliform reduction were found to be comparable with the laboratory results. Ten prototypes were then tested by households in rural India; all were working well after six months. The vermifilters were processing the amount of faeces entering the system on a daily basis, so faeces was not accumulating. It was estimated that they would require emptying after approximately five years, based on the depth of the vermicompost generated. With further development, it is believed that the Tiger Toilet has the potential to become a superior form of onsite sanitation, when compared with traditional onsite sanitation technologies

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

A predictive model for the formation potential of dichloroacetamide, a nitrogenous disinfection by-product formed during chlorination

Nitrogenous disinfection by-products have increasingly become a public health concern in the drinking water industry because they have been found to be more geno- and cytotoxic than most of the currently regulated disinfection by-products. Dichloroacetamide, a nitrogenous disinfection by-product which is formed during chlorination in water treatment, has increasingly received attention due to its elevated genotoxicity and cytotoxicity relative to the currently regulated disinfection by-products. In this study, a power function model with parameters of dissolved organic nitrogen, dissolved organic carbon, bromide, soluble microbial products, and aromatic proteins was developed to successfully predict dichloroacetamide formation potential. The inclusion of soluble microbial product and aromatic protein into the model significantly improved the prediction, suggesting that soluble microbial product and aromatic protein play a significant role in the formation of dichloroacetamide. Additionally, the performance of the predictive model appeared to be somewhat affected by the characteristics of raw water used to develop the model