Evaluation of biogas yield and kinetics from the anaerobic co-digestion of cow dung and horse dung: a strategy for sustainable management of livestock manure

In this study, investigation was done to deter�mine the optimum combination of cow dung (CD) and horse dung (HD) for enhanced biogas production and plant stability. Anaerobic co-digestion of CD and HD at varying percentage combination was carried out in five (5) identical 25 L cylindrical digesters (A–E) for a retention period of 37 days, at an average ambient temperature of 33 �C. Using the Microsoft excel solver function, 2010 version,the modified Gompertz model was applied to predict the relevant kinetic variables of the digestion process. Result obtained shows that digester D with 25% CD and 75% HD produced the highest daily biogas, followed by C (50% CD and 50% HD), B (75% CD–25% HD), A (100% CD) and E (100% HD). Digester D also had maximum biogas pro�duction potential (A) of 13.8 L/gVS, maximum biogas production rate (l) of 0.69 L/gVS/day and shortest lag phase (k) of 5.20 days. Digester E with 100% HD, though had a short lag phase of 5.72 days, had the least total biogas yield of 5.1 L/gVS. The closeness of the coefficients of determination (R2) to 1 reflects a good fit, between experimental and simulated data. The study found that increase in the amount of cow dung beyond 25% led to decrease in biogas yield. It has also shown that biogas production from CD and HD is feasible and can serve as way of removing CD and HD from the environment while serving as a source of bioenergy. Further study on best ways of pre-treating the substrates for greater biogas yield is recommended

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Simulation Analysis of Benchmark Axial Velocity After Sudden Expansion using Computational Fluid Dynamics

Computational Fluid Dynamics (CFD)- ANASYS 2020R1 was used for the analysis of food and drug administration (FDA) benchmark study for biomedical flow transition. An idealized medical device is presented within this study and the CFD predictions of pressure and velocity are compared against experimental measurements of pressure and velocity. The fluid flow transition considered for Reynold numbers(s) 500, 2000, and 6500 with turbulent fluid flow models- laminar, k-omega, k-omega SST and k-epsilon based on throat Reynolds number Reth. 500, 2000 and 6500. Mesh independence K-omega SST model used at 0.0008, 0.0004 and 0.0002 element sizes showed good matched velocity of 5.9m/sec. This converged at 0.0002, which is 2% of total pressure drop. Axial velocity at centreline for Reth 500, 2000 and 6500 at line X =0, showed maximum difference of 77.4% velocity centerline at 0.08m and 19% wall pressure at -0.09m sudden expansion laminar region of Re = 500. Besides, 65.6% and 17.2% obtained at transition Re =2000, showed good agreement between CFD simulations and experimental measurements, at turbulent region Re = 6500, all models were in good agreement at 49.6% velocity centerline and 8.10% pressure drop in laminar region. Also, downstream of the simulation of Reth =6500, other models disappeared which demonstrated K-epsilon model is best at higher Reynolds region. The result revealed negligible pressure gradient at the center line of the wall pressure, and dropped at the normalization point of the experimental pressure data range of 0 to -120n/m2 and balanced at the throat Reynolds number of Reth = 500. &nbsp

Concentrations and Health Risk of Polycyclic Aromatic Hydrocarbons in Some Brands of Biscuits in the Nigerian Market

<div><p>ABSTRACT</p><p>Concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined in 40 brands of biscuits in the Nigerian market. The analyses were performed by gas chromatography-flame ionisation detection (GC-FID) after Soxhlet extraction of the sample with hexane/dichloromethane and clean-up of the extract. The concentrations of Σ16 PAHs in these biscuit samples were in the range of 35.7–645.3 μg kg⁻¹, 75.9–490.7 μg kg⁻¹, 91.5–537 μg kg⁻¹, 18.4–522.2 μg kg⁻¹, 123.5–393.8 μg kg⁻¹, 167.2–880 μg kg⁻¹, 136.5–316 μg kg⁻¹, and 135.5–241.6 μg kg⁻¹ for shortcake, digestives, cookies, shortbread, wafers, crackers, Pringles, and cabin, respectively. The concentrations of Σ8 carcinogenic PAHs in the samples ranged from not detected (nd)–323.3 μg kg⁻¹, 15.7–138 μg kg⁻¹, 9.7–312.9 μg kg⁻¹, nd–331.7 μg kg⁻¹, nd–220.9 μg kg⁻¹, nd–53.3 μg kg⁻¹, 18.4–56.6 μg kg⁻¹, and 6.6–170.8 μg kg⁻¹ for shortcake, digestives, cookies, shortbread, wafers, crackers, Pringles, and cabin, respectively. The margin of exposure (MOE), based on PAH8 as an indicator for the occurrence and effects of PAHs in food, was less than 10,000, the serious health effects value, in 30% and 8% of the brands for the child and adult scenarios, respectively.</p></div

Water quality of Bomadi Creek in the Niger Delta of Nigeria: assessment of some physicochemical properties, metal concentrations, and water quality index

Abstract In this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and Mn), and the overall water quality from Bomadi Creek in the Niger Delta of Nigeria were assessed over two seasons. Water samples were collected from designated areas along the course of the river and were prepared for analysis by standard procedures. The ranges of the mean values for some water quality indicators were found to be as follows: pH: 7.40–8.17, turbidity (NTU): 20.5–42.3, total dissolved solids (mg L−1): 27.5–44.7, total suspended solids (mg L−1): 34.1–61.7, dissolved oxygen (mg L−1): 3.07–6.53, biochemical oxygen demand (mg L−1): 0.13–2.77, total hardness (mg L−1): 28.3–60.0, and nitrate (mg L−1): 0.37–0.92. Only the turbidity values exceeded the permissible limit of 5 NTU. The concentration ranges (mg L−1) for the six metal ions determined were: Pb: 0.01–0.02, Cd: 0.01–0.03, Zn: 0.1–0.3, Cu: 0.03–0.07, Fe: 0.6–0.9, and Mn: 0.01–0.05. There were no significant variations in many of the locations between the wet and dry seasons. The comprehensive pollution index values indicated severe pollution of the Creek, with Cd, Fe, and turbidity, identified as the major contributors to the deteriorated water quality. The sources of high loads of Cd, Fe, and turbidity in this river system include discharges from oil production activities, speed boats, illegal bunkering, and domestic waste dumps. Principal component and cluster analysis were used to establish relationships between the various parameters and sites. The risk assessment indicated adverse non-carcinogenic and carcinogenic risks arising from human consumption of the water. The risk is higher for children than adults. Therefore, the Bomadi water is considered unsuitable for drinking and other domestic purposes, and remediation is required

Effects of Flooding on the Sources, Spatiotemporal Characteristics and Human Health Risks of Polycyclic Aromatic Hydrocarbons in Floodplain Soils of the Lower Parts of the River Niger, Nigeria

<p>The concentrations of the 16 US EPA polycyclic aromatic hydrocarbons (PAHs) were determined in the floodplain soils of the lower parts of the River Niger, Nigeria in 2013 and 2014 after recent flood waters had receded completely into the river channels. The aim of the research was to provide data on the spatiotemporal changes in the contamination levels, compositional patterns, sources and human health risks linked with exposure to PAHs in these soils through non-dietary ingestion, inhalation and dermal contact pathways. The PAHs in the soil samples were extracted by ultrasonication with hexane/dichloromethane, followed by clean-up on a silica gel/alumina column, and gas chromatography-mass spectrometry was used for their separation, detection and quantification. The concentrations of the 16 PAHs varied from 812 to 10,700 µg kg⁻¹ in 2013 after an extreme flooding event, and from 12.2 to 2630 µg kg⁻¹ in 2014 after a natural flooding event. The benzo[a]pyrene (B<i>a</i>P) potency factors and incremental life cancer risks (ILCR) were used to evaluate the risks of human exposure to PAHs in these soils. The average total ILCR values obtained for 2014 (a year after the extreme flooding) indicated that there was a probability of 443 children and 308 adults in a population of one million equally exposed individuals at risk of developing cancer or cancer-related illnesses in their lifetime as opposed to 6450 children and 4480 adults in 2013 immediately after the extreme flooding event. This study has shown that flooding events can cause significant variations in pollutant concentrations of floodplain soils that markedly alter human health risks.</p