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1.
J Vasc Surg ; 2024 Apr 22.
Article in English | MEDLINE | ID: mdl-38657701

ABSTRACT

OBJECTIVE: Vascular complications (VCs) associated with extracorporeal membrane oxygenation (ECMO) during index hospitalization are prevalent and associated with increased mortality. Few studies have evaluated late VCs following ECMO; this study aims to assess occurrence and management practices of late VCs following discharge. METHODS: A retrospective single-institution review was performed of all patients surviving initial hospitalization after being cannulated for central or peripheral veno-venous (VV) or veno-arterial (VA) ECMO between January 1, 2019, and December 31, 2020. Primary outcomes were to categorize and determine the rate of late VCs. Late VCs were defined as any cannulated vessel injury resulting from ECMO cannulation presenting after discharge from index hospitalization. Analysis was conducted by cannulated vessel and stratified by VV or VA ECMO configurations. RESULTS: A total of 229 patients were identified, of which 50.6% (n = 116) survived until discharge. Late VCs occurred in 7.8% of the surviving cohort (n = 9/116); with a median time until presentation of 150 days (interquartile range, 83-251 days). The most common late VC was infection (n = 5; 55.6%) followed by progression to limb-threatening ischemia (n = 4; 44.4%). Urgent procedures were required in 55.6% of patients (n = 5), whereas 44.4% (n = 4) were elective interventions. Interventions performed for management of late VCs included lower extremity arterial revascularization (n = 6; 66.7%), major (n = 1; 11.1%) or minor amputation (n = 1; 11.1%), and wound debridement (n = 1; 11.1%). The majority of patients presenting with late VCs had initially been cannulated for peripheral VA ECMO (n = 8; 88.9%), and one patient (11.1%) was cannulated for peripheral VV ECMO. VCs during index hospitalization were seen in 77.8% of patients (n = 7) returning with late VCs. Odds for late VCs were significantly increased in patients that had been cannulated for ECMO as part of extracorporeal cardiopulmonary resuscitation (odds ratio, 8.4; P = .016) and in cases where patients had experienced an index VC during index hospitalization (odds ratio, 19.3; P = .001). CONCLUSIONS: Late vascular complications after peripheral ECMO cannulation are not rare, particularly after arterial cannulation. Patients should be followed closely early after surviving ECMO with wound evaluation and formal assessment of perfusion with ankle-branchial indices in the cannulated limb.

2.
Ann Vasc Surg ; 99: 356-365, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37890769

ABSTRACT

Revascularization of complex pelvic vascular anatomy presents an ongoing clinical challenge when treating aortoiliac disease. As vascular surgeons continue to intervene upon increasingly complex aortoiliac pathology, the role of pelvic revascularization is important for the preservation of pelvic organ function and prevention of devastating spinal cord ischemia. In this study we describe the indications, techniques, and clinical outcomes of a novel hybrid pelvic revascularization repair that focuses on optimizing revascularization while limiting pelvic surgical dissection during the management of complex aortic pathology in patients physiologically or anatomically unsuitable for traditional pelvic revascularization techniques.


Subject(s)
Aortic Aneurysm, Abdominal , Blood Vessel Prosthesis Implantation , Endovascular Procedures , Humans , Aortic Aneurysm, Abdominal/surgery , Treatment Outcome , Pelvis/blood supply , Vascular Surgical Procedures , Aorta/surgery , Blood Vessel Prosthesis Implantation/adverse effects , Blood Vessel Prosthesis Implantation/methods , Endovascular Procedures/adverse effects , Endovascular Procedures/methods , Retrospective Studies
3.
Ann Vasc Surg ; 2024 Jun 26.
Article in English | MEDLINE | ID: mdl-38942375

ABSTRACT

OBJECTIVES: Investigate readmission rates, diagnoses associated with readmission, and associations with mortality through 90-days post-operatively after elective endovascular thoracic and thoracoabdominal aortic repair overall and by extent of coverage. METHODS: A cohort of index elective non-traumatic endovascular thoracic and thoracoabdominal aortic cases from 2010-2018 was derived from the Vascular Implant Surveillance and Interventional Outcomes Network. Cohort readmissions within 90-days postoperative were examined both overall and by Crawford extent (CE) of aortic coverage. Postoperative mortality was examined by reason for readmission and CE. RESULTS: The cohort consisted of 2,093 patients who underwent endovascular thoracic and thoracoabdominal aortic repair (1,541 CE 0A/0B; 240 CE 1-3; 312 CE 4-5). Cumulative risk for 90-day readmission was 34.3% in CE 0A/0B repairs, 33.4% in CE4-5 repairs and 47.4% in CE 1-3 repairs. Compared to CE 0A/B, patients with CE 1-3 repairs experienced an increased risk of readmission within 90 days postoperatively after adjusting for preoperative factors (aHR 1.27(1.00,1.61) while the readmission risk for CE 4-5 repairs did not differ significantly (aHR 0.83 (0.64,1.06). Significant risk factors for 90-day readmission included COPD, dialysis dependence, limited ambulation, visceral/spinal ischemia, and in-hospital stroke. Discharge to home was protective against readmission (HR 0.65, CI 0.54-0.79). Patients with a readmission within 90-days had a 7.89-fold increase in 90-day mortality (HR 7.84; 5.17, 11.9) compared to those not readmitted. CONCLUSIONS: Increasing extent of endovascular thoracic and thoracoabdominal aortic repair was associated with higher 90-day readmission rates. Readmission for all CE was associated with near 8-fold increased risk of mortality. Risk factors associated with increased risk for readmission included pulmonary insufficiency, renal disease, and poor functional status. These findings can inform stakeholders about investment of resources to improve processes of care that both target prevention and mitigate risk of readmission after elective endovascular thoracic and thoracoabdominal aortic repair.

4.
Vascular ; : 17085381241262130, 2024 Jun 15.
Article in English | MEDLINE | ID: mdl-38877806

ABSTRACT

BACKGROUND: Veterans represent a distinct cultural group whose perceptions of illness and treatment are influenced by military culture. The study explores how prior military service shapes Veterans' assumptions and behaviors in the setting of aneurysm repair surgery. STUDY DESIGN: We conducted content and thematic analysis of a case series of 10 transcripts from telephone interviews with older (76.7 ± 4.3 years) African American and White male Veterans now residing in the Southern U.S. who underwent open or endovascular aneurysm surgery at Veterans Affairs Medical Centers or university affiliates between 2004 and2019. RESULTS: Throughout the continuum of care, Veterans described deferring to authority and not questioning provider's decisions ["I just can't make a judgment on that, because I'm not a doctor"]. Veterans valued commitment and articulated pride in keeping logistically challenging surveillance appointments [I always took them very seriously. . . If I'm scheduled for something by the doctor, I always make it."]. The routine structure of VA care aligned with Veterans military experiences, facilitating compliance with doctor's orders. However, procedural deviations in VA care were disconcerting for patients ["They haven't reached out to me in at least three years, since my surgery; I was being seen once a year and then all of a sudden, they just quit."]. While Veterans praised VA care, they exhibited sensitivity to signs of untoward treatment from clinical and support staff "…my surgeon, he never talked to me before, nor after, no anytime…I thought that maybe that wasn't right". CONCLUSIONS: Military culture embodies rank, order, and respect, and remains a source of strength and stability for Veterans in their medical care late in life. Cultural competency about how military service has shaped Veterans' expectations can enhance providers' awareness of patients' military mindsets and inform surgeons' efforts to engage Veterans in shared decision making.

5.
Community Dent Health ; 40(1): 3-8, 2023 Feb 28.
Article in English | MEDLINE | ID: mdl-36696477

ABSTRACT

Domestic violence and abuse (DVA) is a significant public health problem both globally and in the UK. Dental professionals are aptly place to detect the signs of DVA and support patients to disclose DVA. However, dental professionals may lack confidence to identify and refer patients experiencing DVA; training needs in these areas were identified in Staffordshire. Glow DVA charity and the local Dental Public Health teams worked collaboratively to develop DVA training and resources specific to the needs to the dental team; these were provided to participating dental practices in the North-Staffordshire region. Feedback from the training was positive and the training was refined to better meet the needs of the dental team.mKey challenges included obtaining dental team buy in, securing funding for the continuation of the initiative and minimising the disruption to the dental team when attending training sessions or when managing a DVA disclosure. The implementation of the training highlighted the importance of DVA champions within the third sector organisations to develop and evolve the project, within dental practices to support implementation, and within the local Dental Public Health team to facilitate dental team buy-in and sustained engagement. Future plans include developing the patient-facing resources, finding ways to formally accredit dental teams for taking part in the DVA programme, and evaluating the impact of the training programme on DVA screening, identification and referral.


Subject(s)
Dental Health Services , Dentists , Domestic Violence , Public Health , Humans , Domestic Violence/prevention & control , Referral and Consultation , Dentists/psychology
6.
Sensors (Basel) ; 22(2)2022 Jan 16.
Article in English | MEDLINE | ID: mdl-35062637

ABSTRACT

Carbon nanomaterials have gained significant interest over recent years in the field of electrochemistry, and they may be limited in their use due to issues with their difficulty in dispersion. Enzymes are prime components for detecting biological molecules and enabling electrochemical interactions, but they may also enhance multiwalled carbon nanotube (MWCNT) dispersion. This study evaluated a MWCNT and diamine oxidase enzyme (DAO)-functionalised screen-printed electrode (SPE) to demonstrate improved methods of MWCNT functionalisation and dispersion. MWCNT morphology and dispersion was determined using UV-Vis spectroscopy (UV-Vis) and scanning electron microscopy (SEM). Carboxyl groups were introduced onto the MWCNT surfaces using acid etching. MWCNT functionalisation was carried out using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by DAO conjugation and glutaraldehyde (GA) crosslinking. Modified C-MWNCT/EDC-NHS/DAO/GA was drop cast onto SPEs. Modified and unmodified electrodes after MWCNT functionalisation were characterised using optical profilometry (roughness), water contact angle measurements (wettability), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) (vibrational modes and elemental composition, respectively). The results demonstrated that the addition of the DAO improved MWCNT homogenous dispersion and the solution demonstrated enhanced stability which remained over two days. Drop casting of C-MWCNT/EDC-NHS/DAO/GA onto carbon screen-printed electrodes increased the surface roughness and wettability. UV-Vis, SEM, Raman and EDX analysis determined the presence of carboxylated MWCNT variants from their non-carboxylated counterparts. Electrochemical analysis demonstrated an efficient electron transfer rate process and a diffusion-controlled redox process. The modification of such electrodes may be utilised for the development of biosensors which could be utilised to support a range of healthcare related fields.


Subject(s)
Amine Oxidase (Copper-Containing) , Biosensing Techniques , Nanotubes, Carbon , Electrochemistry , Electrodes
7.
Analyst ; 145(16): 5419-5424, 2020 Aug 21.
Article in English | MEDLINE | ID: mdl-32589168

ABSTRACT

In this communication, molecularly imprinted nanoparticles (nanoMIPs) that are produced by solid-phase synthesis are functionalised onto thermistors via dip-coating. These thermistors are soldered onto a printed-circuit board to facilitate electrical detection. Subsequently, these are inserted into a home-made thermal device that can measure the selective binding of biomolecules to the nanoMIP layer via monitoring the thermal resistance (Rth) at the solid-liquid interface. This thermal analysis technique, referred to as the Heat-Transfer Method, has previously been used for detection of proteins with MIP-based binders. While offering the advantages of low-cost and label free analysis, this method is limited by the high noise on the feedback loop and not being commercially available. These disadvantages can be overcome by the use of thermistors, which offer superior temperature sensitivity compared to thermocouples, and its electrical read-out can be easily integrated into portable devices. To our knowledge, this is the first report where MIPs are directly integrated onto thermistors for detection purposes. Measurements were conducted with an epitope of epidermal growth factor receptor (EGFR) and trypsin, where the electrical resistance was correlated to the biomolecule concentration. For both EGFR and trypsin, an enhanced signal to noise ratio for the electrical measurements was observed compared to previous analysis that was based on thermal resistance. The sensitivity of the sensors in buffered solution was in the nanomolar range, which is compatible with physiologically relevant concentrations. Upon exposure of the nanoMIP for EGFR towards pepsin no significant change in the resistance was yielded, establishing the selectivity of the developed sensor platform. Besides the enhanced sensitivity, the use of thermistors will enable miniaturisation of the device and has potential for in vivo measurements since specified electrochemical measurements are compatible with human use. To highlight the versatility of the nanoMIPs, this work should be extended to a set of biomolecules with various structures, with the possibility of extending this to an array format.


Subject(s)
Molecular Imprinting , Nanoparticles , Humans , Peptides , Polymers , Solid-Phase Synthesis Techniques
8.
Respir Res ; 20(1): 157, 2019 Jul 16.
Article in English | MEDLINE | ID: mdl-31311604

ABSTRACT

BACKGROUND: The purpose of this study was to use CT scanning with computational fluid dynamics to evaluate the mechanisms by which Bronchial Thermoplasty (BT) improves asthmatic symptoms. METHODS: The study was conducted in a university teaching hospital, experienced in performing BT. Imaging studies were performed before, and after, BT of the left lung, and prior to treatment of the right lung, which therefore acted as a control. On each occasion, two high-resolution CT scans were performed, one at full inspiration (TLC) and the other at Functional Residual Capacity (FRC). The study protocol was offered to 10 patients, all of whom met the definition of severe asthma, despite high dose inhaled corticosteroids and dual long acting bronchodilators. RESULTS: Significant increases in airway luminal volume were observed on the treated side, compared with control, at both full inspiration (by 27%) and at FRC (by 17%). The ratio of distal airway volume to lung volume significantly increased on the treated side. The change in airway volume with inspiration from FRC increased by 48% on the treated side compared to 5% in the control lung, suggesting treatment increased airway distensibility. No effect was observed on airway wall thickness, nor air trapping. There was a trend towards correlation between the improvement in airway volume at TLC and improvement in symptoms. CONCLUSION: This study demonstrates that BT increases the luminal airway volume on the treated side compared to the control lung. We suggest that this is an important link between the airway smooth muscle atrophy demonstrated pathologically, and the improvement in symptoms observed clinically.


Subject(s)
Asthma/diagnostic imaging , Asthma/therapy , Bronchial Thermoplasty/methods , Lung/diagnostic imaging , Lung/physiology , Tidal Volume/physiology , Aged , Female , Humans , Male , Middle Aged , Respiratory Mechanics/physiology , Tomography, X-Ray Computed/methods
9.
Pediatr Cardiol ; 40(2): 437-444, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30302505

ABSTRACT

Neonatal cardiac transplantation for hypoplastic left heart syndrome (HLHS) is associated with excellent long-term survival compared to older recipients. However, heart transplantation for neonates is greatly limited by the critical shortage of donor hearts, and by the associated mortality of the long pre-transplant waiting period. This led to the development of staged surgical palliation as the first-line surgical therapy for HLHS. Recent advances in genetic engineering and xenotransplantation have provided the potential to replicate the excellent results of neonatal cardiac allotransplantation while eliminating wait-list-associated mortality through genetically modified pig-to-human neonatal cardiac xenotransplantation. The elimination of the major pig antigens in addition to the immature B-cell response in neonates allows for the potential to induce B-cell tolerance. Additionally, the relatively mature neonatal T-cell response could be reduced by thymectomy at the time of operation combined with donor-specific pig thymus transplantation to "reprogram" the host's T-cells to recognize the xenograft as host tissue. In light of the recent significantly increased graft survival of genetically-engineered pig-to-baboon cardiac xenotransplantation, we propose that now is the time to consider devoting research to advance the potential clinical application of cardiac xenotransplantation as a treatment option for patients with HLHS. Employing cardiac xenotransplantation could revolutionize therapy for complex congenital heart defects and open a new chapter in the field of pediatric cardiac transplantation.


Subject(s)
Genetic Engineering/methods , Graft Survival/immunology , Heart Transplantation/methods , Hypoplastic Left Heart Syndrome/surgery , Transplantation, Heterologous/methods , Animals , Graft Rejection , Heterografts/immunology , Heterografts/transplantation , Humans , Immune Tolerance/immunology , Infant, Newborn , Papio , Swine
10.
Analyst ; 143(9): 2002-2007, 2018 Apr 30.
Article in English | MEDLINE | ID: mdl-29671423

ABSTRACT

In this communication, we present the first developed Molecularly Imprinted Polymers (MIPs) for the specific detection of a New Psychoactive Substance (NPS); namely, methoxphenidine (MXP) and its regioisomers. Selectivity of the MIP towards MXP is studied by analysing mixtures and an acquired street sample with High Performance Liquid Chromatography coupled to UV detection. The study demonstrates that the engineered polymers selectively extract MXP from heterogeneous samples, which makes for a very powerful diagnostic tool that can detect traces of MXP in complicated NPS samples.

11.
J Public Health (Oxf) ; 40(3): e375-e387, 2018 09 01.
Article in English | MEDLINE | ID: mdl-29253218

ABSTRACT

Background: Psychological therapies are increasingly delivered in community care settings. In existing literature, patient, disorder and service variables are known to have a significant impact on the recovery outcomes for patients undergoing psychological treatment in secondary care. The aim of this review is to establish which predictors have a significant impact on recovery from common mental health disorders in community settings. Methods: A systematic review of the literature was conducted according to PRISMA guidelines to identify variables with a predictive power on psychological therapy outcomes. We searched databases using key words and MeSH terms and a strict scoring system and bias check were used. Results: A total of 486 unique references were identified from the search. Overall, 19 papers met the inclusion criteria. These reported on a total of 34 778 patients from five countries in various community care settings. Predictive factors identified and found to be significant were initial severity and comorbid depression (11/19 studies), which negatively impacted outcome in all studies. Conclusions: We identified key predictors for recovery in a community settings from five countries. The evidence currently available for this setting is limited, so this review serves as a starting point to highlight key factors that warrant further investigation.


Subject(s)
Community Mental Health Services , Mental Disorders/therapy , Psychotherapy , Humans , Treatment Outcome
12.
Anaesthesia ; 73(2): 195-204, 2018 Feb.
Article in English | MEDLINE | ID: mdl-29150856

ABSTRACT

Our aim was to prospectively determine the predictive capabilities of SEPSIS-1 and SEPSIS-3 definitions in the emergency departments and general wards. Patients with National Early Warning Score (NEWS) of 3 or above and suspected or proven infection were enrolled over a 24-h period in 13 Welsh hospitals. The primary outcome measure was mortality within 30 days. Out of the 5422 patients screened, 431 fulfilled inclusion criteria and 380 (88%) were recruited. Using the SEPSIS-1 definition, 212 patients had sepsis. When using the SEPSIS-3 definitions with Sequential Organ Failure Assessment (SOFA) score ≥ 2, there were 272 septic patients, whereas with quickSOFA score ≥ 2, 50 patients were identified. For the prediction of primary outcome, SEPSIS-1 criteria had a sensitivity (95%CI) of 65% (54-75%) and specificity of 47% (41-53%); SEPSIS-3 criteria had a sensitivity of 86% (76-92%) and specificity of 32% (27-38%). SEPSIS-3 and SEPSIS-1 definitions were associated with a hazard ratio (95%CI) 2.7 (1.5-5.6) and 1.6 (1.3-2.5), respectively. Scoring system discrimination evaluated by receiver operating characteristic curves was highest for Sequential Organ Failure Assessment score (0.69 (95%CI 0.63-0.76)), followed by NEWS (0.58 (0.51-0.66)) (p < 0.001). Systemic inflammatory response syndrome criteria (0.55 (0.49-0.61)) and quickSOFA score (0.56 (0.49-0.64)) could not predict outcome. The SEPSIS-3 definition identified patients with the highest risk. Sequential Organ Failure Assessment score and NEWS were better predictors of poor outcome. The Sequential Organ Failure Assessment score appeared to be the best tool for identifying patients with high risk of death and sepsis-induced organ dysfunction.


Subject(s)
Organ Dysfunction Scores , Sepsis , Terminology as Topic , Adolescent , Adult , Aged , Aged, 80 and over , Cross Infection/mortality , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Multiple Organ Failure/etiology , Multiple Organ Failure/mortality , Predictive Value of Tests , Prevalence , Prognosis , Prospective Studies , ROC Curve , Sensitivity and Specificity , Sepsis/mortality , Treatment Outcome , Young Adult
13.
J Mol Recognit ; 30(1)2017 01.
Article in English | MEDLINE | ID: mdl-27611483

ABSTRACT

In recent years, there has been a tremendous increase in the papers published on synthetic recognition elements. Molecularly imprinted polymers (MIPs), also referred to as "man-made mimics" of antibodies, are able to rebind their template molecules with high affinity. Advantages compared with those of natural receptors include their excellent thermal and chemical stability, low cost, and ease of the production process. However, their use in commercial biosensors is limited owing to the difficulty to incorporate MIPs into suitable sensing platforms and traditional detection techniques, such as chromatography, that require bulky and sophisticated equipment. In this review, we evaluate the potential to use MIPs combined with thermal read-out for the detection of low-weight organic molecules. We discuss thermal methods to study MIP-template complexation and to determine neurotransmitters concentrations. In particular, we highlight the heat-transfer method, a recent technique that is straightforward and low cost and requires minimal instrumentation. Until now, sample preparation involves a 2-step process, making it time-consuming, and measuring biological samples is difficult owing to the noise in the signal. Different sample preparation methods are discussed, and it will be demonstrated how this affects the thermal response. An outlook is given in novel methods that can simplify and speed up sample preparation. Finally, we show a novel thermal technique, which is based on the analysis of transport of thermal waves rather than evaluating the fixed heat-transfer resistance. Through applying the concept of thermal waves, signal-noise ratio is significantly increased, which results in lower detection limits and has potential for the study of biological samples.


Subject(s)
Molecular Imprinting/methods , Polymers/chemical synthesis , Limit of Detection , Molecular Weight , Polymers/chemistry , Thermodynamics
14.
Psychol Med ; 45(8): 1613-27, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25425086

ABSTRACT

BACKGROUND: Negative symptoms are a core component of schizophrenia which can severely impact quality of life and functional outcomes. These symptoms are understood to be highly stable but this has not been tested in a meta-analysis, despite the wealth of longitudinal data available. METHOD: A systematic review of the literature was conducted, with eligible studies pooled into a random-effects meta-analysis. Planned meta-regressions were conducted to evaluate the impact of factors known to induce secondary negative symptoms, in addition to other possible sources of heterogeneity. RESULTS: The main analysis included 89 samples from 41 studies, totalling 5944 participants. Negative symptoms were found to significantly reduce in all treatment interventions, including in placebo and treatment as usual conditions, with a medium effect size (ES) present across all study conditions (ES = 0.66, 95% confidence interval 0.56-0.77, I(2) = 94.0%). In a multivariate meta-regression, only the type of scale used was found to significantly influence negative symptom change. No difference in outcome was found between studies that excluded patients with a high level of positive or depressive symptoms, compared to those that did not. CONCLUSIONS: Negative symptoms were found to reduce in almost all schizophrenia outpatient samples. A reduction was found across all conditions, with effect sizes ranging from small to large depending upon the condition type. These findings challenge the convention that negative symptoms are highly stable and suggest that they may improve to a greater extent than what has previously been assumed.


Subject(s)
Schizophrenia/diagnosis , Schizophrenic Psychology , Humans , Internationality , Longitudinal Studies , Psychiatric Status Rating Scales
15.
Anaesthesia ; 73(7): 913-914, 2018 07.
Article in English | MEDLINE | ID: mdl-29889994
16.
Water Sci Technol ; 67(5): 1105-12, 2013.
Article in English | MEDLINE | ID: mdl-23416604

ABSTRACT

An intermittent discharge waste stabilisation pond system was trialled for treatment of a seasonal wastewater load from a campsite. The system showed rapid acclimatisation to incoming load, with chlorophyll-a exceeding 700 mg l(-1) within 2 weeks and filtered and unfiltered effluent biochemical oxygen demand below 20 and 30 mg l(-1) respectively. Good performance continued for some weeks, after which photosynthetic oxygenation capacity in the first pond was seriously impaired by a shock loading believed to include fatty material. Inflow to the system was suspended and a surface film was broken up, after which the pond recovered within an 8-day period. Laboratory experiments indicated that interventions such as artificial aeration and dilution with effluent had no beneficial effect although mixing may have increased the rate of recovery.


Subject(s)
Ponds , Seasons , Waste Disposal, Fluid/methods , Biological Oxygen Demand Analysis , Chlorophyll/analysis , Chlorophyll A , Hydrogen-Ion Concentration , Oxygen/analysis , Photosynthesis , United Kingdom
17.
Water Sci Technol ; 66(12): 2737-44, 2012.
Article in English | MEDLINE | ID: mdl-23109593

ABSTRACT

Wheat straw is a major potential source of waste biomass for renewable energy production, but its high salt content causes problems in combustion. The salts can be removed by washing, but this process also removes a proportion of the organic material which could potentially be recovered by anaerobic digestion of the washwater leachate. This approach would maximise the overall energy yield in an integrated process in which washwater could be recycled after further desalting. Leachate from cold water washing with a chemical oxygen demand (COD) of 1.2 g l⁻¹ was fed to mesophilic upflow anaerobic sludge blanket (UASB) digesters at a loading rate of 1 g COD l⁻¹ day⁻¹ to determine the energy yield and any detrimental effects of the leached salts on the process. The specific methane production was 0.29 l CH4 g⁻¹ COD(added), corresponding to a COD removal rate of 84%. Light metal cations in the leachate, especially potassium, were found to accumulate in the digesters and appeared to have a synergistic effect up to a concentration of ∼6.5 mg K g⁻¹ wet weight of the granular sludge, but further accumulation caused inhibition of methanogenesis. It was shown that gas production in the inhibited digesters could be restored within 12 days by switching the feed to a synthetic sewage, which washed the accumulated K out of the digesters.


Subject(s)
Biofuels/analysis , Bioreactors , Rheology , Sewage/chemistry , Triticum/chemistry , Waste Products/analysis , Water Pollutants, Chemical/isolation & purification , Acclimatization , Anaerobiosis , Biological Oxygen Demand Analysis , Cations/analysis , Metals/analysis , Microscopy, Electron, Scanning , Potassium/analysis , Spectrometry, X-Ray Emission
18.
Water Sci Technol ; 66(11): 2336-42, 2012.
Article in English | MEDLINE | ID: mdl-23032762

ABSTRACT

Co-digestion of cattle slurry and maize has been shown to have benefits for both, improving the biogas yield of the slurry and stability of digestion of the maize. The effect of increasing the total loading rate from 3 to 6 g VS l(-1) day(-1) on the co-digestion of cattle slurry and maize, mixed at equal volatile solids volumes, was investigated in laboratory-scale continuously stirred digesters. These were compared with similar digesters evaluating the increase of 1.5 to 3 g VS l(-1) day(-1) loading rates of slurry and maize digested separately. Compared with mono-digestion of the substrates, where the digestion of maize failed at loading rates greater than 2.5 g VS l(-1) day(-1), the co-digestion of cattle slurry and maize was feasible at all the loading rates tested with an increase in the volumetric methane yield occurring with loading rate. Even at the lowest rate of loading, the addition of equal amounts of volatile solids of maize to slurry leads to an increase in volumetric methane yield of 219%.


Subject(s)
Biofuels , Bioreactors , Manure , Zea mays , Animals , Cattle
19.
Water Sci Technol ; 66(9): 1893-9, 2012.
Article in English | MEDLINE | ID: mdl-22925861

ABSTRACT

This research examined the use of a single facultative pond for treatment of an intermittent discharge from a UK campsite. The system was monitored over an 11-month period to determine the optimum time for discharge in terms of quality standards. The results showed that based on organic strength, discharge was possible in winter between November and March but February was the optimum to meet nutrient and suspended solids requirements. The pond showed rapid acclimatisation to the influent wastewater, with biochemical oxygen demand removal rates during the filling period of around 60 kg ha(-1) day(-1) and removal efficiencies of ∼95% after maturation. The system proved simple to operate. A major design factor is the requirement for storage of net incoming precipitation, which may provide dilution of residual pollutants but requires additional system capacity.


Subject(s)
Waste Disposal, Fluid/methods , Biological Oxygen Demand Analysis , Ponds
20.
Water Sci Technol ; 66(9): 1864-70, 2012.
Article in English | MEDLINE | ID: mdl-22925857

ABSTRACT

As organic farming prohibits the use of synthetic fertilisers, animal slurries and manures must be used. Digestate offers an alternative to these and this study reports on three experiments conducted to determine its usability in terms of: (1) the effect on earthworm populations, (2) its fertilising effects on Italian Ryegrass and wild Creeping Thistle, and (3) the suppression effects digestate has on weed emergence. The results for digestate application to field plots were intermediate between slurry and no treatment for earthworm attraction and wild thistle suppression. In glasshouse trials it led to increased ryegrass growth compared with undigested slurry. Analysis showed that the digestate had improved nitrogen availability, leading to increased plant growth, but a reduced organic matter content compared with the slurry, leading to a positive though less beneficial impact on the earthworms. Digestate therefore provides a suitable fertiliser for organic farming. This suitability could be improved by drying or separation to increase the OM content making its properties closer to those of slurry whilst still retaining the higher content of plant available nitrogen.


Subject(s)
Organic Agriculture/methods , Animals , Fertilizers , Lolium , Manure , Oligochaeta
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