Acetylation of Nata de coco (bacterial cellulose) and membrane formation

Nata de coco (NDC), a bacterial cellulose formed by Acetobacter xylinum, was utilized to fabricate a membrane via acetylation and phase inversion methods. The NDC was activated and dissolved in N,N-Dimethylacetamide (DMAc) with lithium chloride (LiCl) at varying amounts of NDC, LiCl/DMAc ratio, activation temperature, and dissolution temperature. Acetylation was done by adding acetic anhydride (in a mass ratio of 1:12 NDC-anhydride) to NDC-DMAc/LiCl solution at a dissolution temperature of 110 °C for 3 hours. The modified-NDC was recovered via precipitation in methanol. The modified-NDC was washed with deionized water then freeze-dried. Modification was verified by determining the degree of substitution (DS) using titration and FTIR analysis. It was observed that the modification could be carried out at an NDC/DMAc (w/v) ratio of 1:75 at 120 °C for 1 hour, and addition of 8% (w/v) LiCl catalyst at 110 °C for 20 minutes. The DS of the modified-NDC was observed in the range of 2.84 – 3.69, which indicates a successful modification. This was further verified by the FTIR results. Membrane fabrication was carried out using the modified-NDC via immersion-precipitation and solvent evaporation methods. A successful membrane formation was observed using solvent evaporation

Phosphorus recovery from wastewater and sludge

Wastewater and sludge are potential resource of phosphorus (P) for fertilizer production. One method of recovering phosphorus is via chemical precipitation. In the study, phosphorus was recovered from wastewater and sludge. First, hydrolysis was carried out to release the phosphorus in the sludge by the addition of 1.0M acid (sulfuric acid) or base (sodium hydroxide) solution mixed for three hours at 200 rpm. The hydrolyzed sludge was filtered, and the pH of the solution was adjusted to 9.0. Precipitation for both wastewater and hydrolyzed sludge solution was carried out using magnesium chloride hexahydrate (MgCl2•6H2O) and ammonium chloride (NH4Cl). The mixture was stirred for an hour for crystallization. Precipitates were allowed to settle for 24 hours before it was filtered and dried in an oven at 55-58oC for 24 hours. The dried sample was grinded and characterized using Fourier transform infrared spectroscopy (FTIR), x-ray fluorenscence (XRF), and scanning electron microscope with energy-dispersive x-ray spectroscopy(SEM-EDX)

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Optimization of forward osmosis system for the utilization of reverse osmosis brine

This research aimed to utilize the concentrated brine by incorporating a forward osmosis (FO) system as a post-treatment in a reverse osmosis (RO) plant. The objective of this study was to optimize the operating condition of an FO system utilizing RO brine. Water flux and reverse solute flux were measured at different draw solution (DS) concentrations. Change in the salinity of the feed and permeate flux are the two parameters that were monitored and evaluated. To further optimize the process, membrane fouling was also investigated. Fouled membrane was subjected to scanning electron microscopy and energy dispersive X-ray analyses. Seawater was used as the feed while sodium chloride was used to simulate different brine concentrations. It was observed that increasing the concentration of brine enhances permeate flux. However, increase in reverse solute flux was also observed compensating the high water flux. Fouling in the support layer of FO membrane was evident at 200 g/L DS concentration. While 100 g/L was found to be the most suitable for FO system with almost similar fouling propensity as compared to 50 and 75 g/L. With lower internal concentration polarization and optimized operating condition, FO system could be efficiently used in utilizing RO brine. © 2016 Balaban Desalination Publications. All rights reserved

Preliminary Investigation of an Installed Pilot-Scale Biological Nutrient Removal Technology (BNRT) for Sewage Treatment

Water utilities, commercial and industrial establishments are required to upgrade or install new treatment systems to comply with the revised effluent standards issued by the Department of Environment and Natural Resources – Environment Management Bureau (DENR – EMB) which now includes removal and monitoring of nutrients (nitrogen and phosphorus components). One solution is to utilize a biological nutrient removal technology (BNRT) system capable of removing nutrients from sewage. The on-going study aims to investigate the performance of the pilot-scale system in the removal of nutrients from sewage. The designed pilot-scale anaerobic-anoxic-oxic (A2O) process with a total hydraulic retention time of 8.37 hrs. was operated in an existing sewage treatment plant (STP). System modification was adapted to ensure continuous operation. Dissolved oxygen (DO) and temperature of each compartment were evaluated after 45 days of system modification. The DO of the anaerobic and oxic compartment remained within the required range, while the internal recycling flowrate and/or aeration must be adjusted to achieve a DO concentration of 0.20 – 0.50 mg/L in the anoxic compartment. The research is financially supported by the Philippine Council for Industry, Energy and Emerging Technology Research and Development of the Department of Science and Technology (PCIEERD Project No. 04176)

A decision modelling approach for selection of biological nutrient removal systems for wastewater

This paper proposes a decision model built on a hierarchical network for optimal selection of biological nutrient removal systems (BNR) in wastewater treatment plants. BNR is an important component of a sustainable wastewater management wherein resource recovery from wastewater becomes an integral part of the municipal wastewater treatment plants (WTP). However, selection of the most appropriate technology or systems requires a multiple criteria analysis. This study focuses on the following criteria namely 1) Economic aspect; 2) Technical aspect; 3) Environmental Aspect; and 4) Space Requirement. The following alternatives were then evaluated: 1) 3 Stage Pho-redox (A2O); 2) 5 Stage Bardenpho (5BP); 3) University of Cape Town (UCT); 4) Virginia Initiative Plant; 5) Sequencing Batch Reactor (SBR); 6) Membrane Bioreactor (MBR). A fuzzy ANP approach with Monte Carlo simulation was used to derive the overall priorities of these alternatives. This decision modelling approach addresses the uncertainty and complexity involved in the selection of appropriate BNR in Metro Manila’s WTP

A decision modelling approach for selection of biological nutrient removal systems for wastewater

This paper proposes a decision model built on a hierarchical network for optimal selection of biological nutrient removal systems (BNR) in wastewater treatment plants. BNR is an important component of a sustainable wastewater management wherein resource recovery from wastewater becomes an integral part of the municipal wastewater treatment plants (WTP). However, selection of the most appropriate technology or systems requires a multiple criteria analysis. This study focuses on the following criteria namely 1) Economic aspect; 2) Technical aspect; 3) Environmental Aspect; and 4) Space Requirement. The following alternatives were then evaluated: 1) 3 Stage Pho-redox (A2O); 2) 5 Stage Bardenpho (5BP); 3) University of Cape Town (UCT); 4) Virginia Initiative Plant; 5) Sequencing Batch Reactor (SBR); 6) Membrane Bioreactor (MBR). A fuzzy ANP approach with Monte Carlo simulation was used to derive the overall priorities of these alternatives. This decision modelling approach addresses the uncertainty and complexity involved in the selection of appropriate BNR in Metro Manila\u27s WTP. © The Authors, published by EDP Sciences, 2018

Sustainable Desalination by 3:1 Reduced Graphene Oxide/Titanium Dioxide Nanotubes (rGO/TiONTs) Composite via Capacitive Deionization at Different Sodium Chloride Concentrations

The capability of novel 3:1 reduced graphene oxide/titanium dioxide nanotubes (rGO/TiONTs) composite to desalinate using capacitive deionization (CDI) employing highly concentrated NaCl solutions was tested in this study. Parameters such as material wettability, electrosorption capacity, charge efficiency, energy consumption, and charge-discharge retention were tested at different NaCl initial concentrations—100 ppm, 2000 ppm, 15,000 ppm, and 30,000 ppm. The rGO/TiONTs composite showed good material wettability before and after CDI runs with its contact angles equal to 52.11° and 56.07°, respectively. Its two-hour electrosorption capacity during CDI at 30,000 ppm NaCl influent increased 1.34-fold compared to 100 ppm initial NaCl influent with energy consumption constant at 1.11 kWh per kg with NaCl removed. However, the percentage discharge (concentration-independent) at zero-voltage ranged from 4.9–7.27% only after 30 min of desorption. Repeated charge/discharge at different amperes showed that the slowest charging rate of 0.1 A·g−1 had the highest charging time retention at 60% after 100 cycles. Increased concentration likewise increases charging time retention. With this consistent performance of a CDI system utilizing rGO/TiONTs composite, even at 30,000 ppm and 100 cycles, it can be a sustainable alternative desalination technology, especially if a low charging current with reverse voltage discharge is set for a longer operation

Evaluation of bacterial cellulose-sodium alginate forward osmosis membrane for water recovery

Water resources are very important to sustain life. However, these resources have been subjected to stress due to population growth, economic and industrial growth, pollution and climate change. With these, the recovery of water from sources such as wastewater, dirty water, floodwater and seawater is a sustainable alternative. The potential of recovering water from these sources could be done by utilizing forward osmosis, a membrane process that exploits the natural osmotic pressure gradient between solutions which requires low energy operation. This study evaluated the potential of forward osmosis (FO) composite membranes fabricated from bacterial cellulose (BC) and modified with sodium alginate. The membranes were evaluated for water flux and salt rejection. The effect of alginate concentrations and impregnation temperatures were evaluated using 0.6 M sodium chloride solution as feed and 2 M glucose solution as the draw solution. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Contact Angle Meter (CAM). The use of sodium alginate in BC membrane showed a thicker membrane (38.3 μm to 67.6 μm), denser structure (shown in the SEM images), and more hydrophilic (contact angle ranges from 28.39° to 32.97°) compared to the pristine BC membrane (thickness = 12.8 μm and contact angle = 66.13°). Furthermore, the alginate modification lowered the water flux of the BC membrane from 9.283 L/m2-h (LMH) to value ranging from 2.314 to 4.797 LMH but the improvement in salt rejection was prominent (up to 98.57%). © 2018 Penerbit UTM Press. All rights reserved