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Archer Salazar posted an update 6 months, 1 week ago
This research paper concentrates on the removal of heavy metal from wastewater which was produced from an electroplating industry. Here, the Dissolved Air Flotation (DAF) treatment process is carried out to remove toxic metals such as chromium, cadmium, nickel, lead, and copper using Sodium Dodecyl Sulfate (SDS) as a collector. The best-optimized conditions for the maximum removal of all the metal ions about 97.39% was achieved at pH 8, contact time of 60 min, surfactant dosage of 0.2 g, and the pressure of 137.89 kPa. At optimized conditions, the treated water consists of 2.71 mg/L of chromium, 1.13 mg/L of cadmium, 10.24 mg/L of nickel, 0.06 mg/L of lead, and 1.14 mg/L of copper. The used surfactant SDS was found as an environmentally friendly compound as prescribed by the Environmental Protection Agency. It is inferred that the flotation kinetics that manifests the rate of recovery and time for all the metal ions follow first-order kinetics. Further, the removal rate constant (k) increases with decreasing the initial metal ion concentration. Overall, the result of this work propounds that the DAF process plays as a promising technique to eliminate noxious pollutants from the wastewater.Resource recovery and reuse from domestic wastewater has become an important subject for the current development of sanitation technologies and infrastructures. Different technologies are available and combined into sanitation concepts, with different performances. This study provides a methodological approach to evaluate the sustainability of these sanitation concepts with focus on resource recovery and reuse. St. Eustatius, a small tropical island in the Caribbean, was used as a case study for the evaluation. Three source separation-community-on-site and two combined sewerage island-scale concepts were selected and compared in terms of environmental (net energy use, nutrient recovery/reuse, BOD/COD, pathogens, and GHG emission, land use), economic (CAPEX and OPEX), social cultural (acceptance, required competences and education), and technological (flexibility/adaptability, reliability/continuity of service) indicators. The best performing concept, is the application of Upflow Anaerobic Sludge Bed (UASB) and Trickling Filter (TF) at island level for combined domestic wastewater treatment with subsequent reuse in agriculture. Its overall average normalised score across the four categories (i.e., average of average per category) is about 15% (0.85) higher than the values of the remaining systems and with a score of 0.73 (conventional activated sludge – centralised level), 0.77 (UASB-septic tank (ST)), 0.76 (UASB-TF – community level), and 0.75 (ST – household level). Dactolisib The higher score of the UASB-TF at community level is mainly due to much better performance in the environmental and economic categories. In conclusion, the case study provides a methodological approach that can support urban planning and decision-making in selecting more sustainable sanitation concepts, allowing resource recovery and reuse in small island context or in other contexts.The present study was conducted to statistically optimize the biosurfactant production yield of Pseudomonas sp. F5 using raw orange peel extract (Central composite design (CCD) design; Surface tension (ST) reduction = 32.41 dyne/cm; biosurfactant yield = ~2.4 g/L). The extracted biosurfactant was characterized as a glycolipid having predominant mono-rhamnolipids than di-rhamnolipids with a critical micelle concentration (CMC) of 40 mg/L. The potential of strain F5 for good biosurfactant yield during Pb2+ stress and the inherent mechanism for simultaneous biosorption of Pb2+ was also investigated. During concomitant submerged fermentation from 100 to 500 mg/L of Pb2+ showed enhancement in adsorption capacity from 99.44 to 267.86 mg/g respectively having 60.33 ± 2.87 of emulsification index (E24%) measured at 100 mg/L Pb2+ corresponding to maximum biosurfactant production during metal stress. The bacterium showed a high Pb2+ MIC (minimum inhibitory concentration) of 2200 mg/L and efficiently biosorbed Pb2+ ions at pH 7 and a dosage of 0.05 g under varying initial metal ion concentration and contact time. The exothermic biosorption (chemisorption) mechanism was found to be fitted well with Langmuir (R2 = 0.9859) and Pseudo second-order kinetic model (R2 = 0.9975; 200 mg/L) having a maximum adsorption capacity of 294.12 mg/g. These findings indicated the excellent potential of biosurfactant producing strain F5 in the removal of Pb2+ ions from aqueous system and management of agrowastes as suitable carbon substrate.Accurately predicting nitrogen (N) outputs in manure, urine and faeces from beef cattle is crucial for the realistic assessment of the environmental footprint of beef production and the development of sustainable N mitigation strategies. This study aimed to develop and validate equations for N outputs in manure, urine and faeces for animals under diets with contrasting crude protein (CP) concentrations. Measurements from individual animals (n = 570), including bodyweight, feed intake and chemical composition, and N outputs were (i) analysed as a merged database and also (ii) split into three sub-sets, according to diet CP concentration (low CP, 84-143 g/kg dry matter, n = 190; medium CP, 144-162 g/kg dry matter, n = 190; high CP, 163-217 g/kg dry matter, n = 190). Prediction equations were developed and validated using residual maximum likelihood analysis and mean prediction error (MPE), respectively. In low CP diets the lowest MPE for N outputs in manure, urine and faeces was 0.244, 0.594 and 0.263, respectidiction accuracy when feed intake or dietary CP concentration are not known. However, in beef cattle fed medium or high CP concentration diets, using equations that have been developed from animals fed similar CP concentration diets, substantially improves the prediction accuracy of N outputs in manure, urine and faeces in most cases.As a waste valorisation option, agro-industrial residues (rice husk, apple pomace, whisky draff, soy fiber, rice fiber, wheat straw, beer draff, orange peel and potato peel) were tested as feasible substrates for fungal conidia production. Solid-state fermentation tests were conducted at laboratory scale (100 g) with Beauveria bassiana or Trichoderma harzianum which conidia are reported to have biopesticide properties. Conidia concentrations with all substrates were at least two orders of magnitude above inoculum except for both fibers, thus demonstrating the possibilities of the proposed waste recovery option. Highest productions were at least 1 × 109 conidia g-1 dry matter for Beauveria bassiana using rice husk or potato peel and higher than 5 × 109 conidia g-1 dry matter for Trichoderma harzianum using beer draff, potato peel or orange pomace. Principal component analysis has been used to understand which parameters affect the most fungal conidia production for an easier evaluation of other similar wastes, being air-filled porosity and initial pH for Beauveria bassiana and cumulative oxygen consumption, initial moisture and total sugar content for Trichoderma harzianum.