Microbial removal rate efficiencies measured for coral sand

<p>Coral sand forms the surficial geology on many coral cay and low-lying atolls, such as are located throughout the Pacific region. Shallow groundwater hosted within such sand is the main source of freshwater for many island communities. It is critically at risk from the impacts of climate-change and anthropogenic stresses. A United Nations' Sustainable Development Goal is to improve water access and sanitation issues in such environs. Working towards that goal, we have conducted a set of laboratory column experiments to obtain some initial measures of microbial removal efficiencies for coral sand substrate from the Pacific atoll of South Tarawa, Kiribati.  </p><p>In one experiment we attempted to mimic physio-chemical conditions at the Bonriki Freshwater Reserve that supplies most of the water on South Tarawa. Three small plastic columns were packed with very poorly sorted gravelly coral sand sampled from the reserve. The effective transport of Escherichia coli J6-2 and MS2 bacteriophage through the packed columns was evaluated under saturated flow conditions.</p><p>In a second experiment we conducted infiltration tests on naturally well-sorted coral sand, sourced from Bikenibeu beach, South Tarawa. We perceive such sand has potential to be used in the construction of effluent drainage fields from septic tank systems in use on South Tarawa, where currently there are no established design criteria. The sand was packed to a depth of 400 mm in triplicate glass column apparatus. It was conditioned by dosing with septic tank effluent twice per day for 27 days (8 mm head each event). Effluent spiked with bacterial and viral indicator organisms: Escherichia coli J6-2, Enterococci faecalis and MS2 bacteriophage, as well as the viral pathogens: adenovirus, echovirus, norovirus and rotavirus was then dripped on to the columns, as a 35 mm application. Any resulting drainage from the base of the columns was collected and analysed, and the depth profile of the tracer organisms was examined in the sand columns by destructive sampling.</p><p>The very poorly sorted coral substrate from Bonriki Reserve proved very effective at attenuating Escherichia coli J6-2 under saturated flow conditions. We estimated a spatial removal rate of 0.05 ± 0.02 log<sub>10</sub> cm<sup>-1</sup> for this bacterial tracer. No removal rate could be quantified for the viral indicator. Although overall, our observations suggest the coral sand was significantly less effective at attenuating MS2 bacteriophage than it was at attenuating Escherichia coli J6-2.</p><p>In the unsaturated column experiments made on beach sand conditioned with effluent, all the microorganisms examined demonstrated >4-log removal values. Contrary to our finding from the saturated sand column experiment made with material from Bonriki Reserve, the conditioned coral beach sand filters demonstrated higher affinity for MS2 bacteriophage (also viruses) than they did Escherichia coli J6-2, or Enterococci faecalis.</p>

HIV Detection from Human Serum with Paper-Based Isotachophoretic RNA Extraction and Reverse Transcription Recombinase Polymerase Amplification

<p>The number of people living with HIV continues to increase with the current total near 38 million, of which about 26 million are receiving antiretroviral therapy. These treatment regimens are highly effective when properly managed, requiring routine viral load monitoring to assess successful viral suppression. Efforts to expand access by decentralizing HIV nucleic acid testing in low- and middle-income countries has been hampered by the cost and complexity of current tests. Sample preparation of blood samples has traditionally relied on cumbersome RNA extraction methods, and it continues to be a key bottleneck for developing low-cost POC nucleic acid tests. We present a microfluidic paper-based analytical device (µPAD) for extracting RNA and detecting HIV in serum, leveraging low-cost materials, simple buffers, and an electric field. We detect HIV virions and MS2 bacteriophage internal control in human serum using a novel lysis and RNase inactivation method, paper-based isotachophoresis (ITP) for RNA extraction, and duplexed reverse transcription recombinase polymerase amplification (RT-RPA) for nucleic acid amplification. We design a specialized ITP system to extract and concentrate RNA, while excluding harsh reagents used for lysis and RNase inactivation. We found the ITP µPAD can extract and purify 5,000 HIV RNA copies per mL of serum. We then demonstrate detection of HIV virions and MS2 bacteriophage in human serum within 45-minutes.</p>

HIV Detection from Human Serum with Paper-Based Isotachophoretic RNA Extraction and Reverse Transcription Recombinase Polymerase Amplification

<p>The number of people living with HIV continues to increase with the current total near 38 million, of which about 26 million are receiving antiretroviral therapy. These treatment regimens are highly effective when properly managed, requiring routine viral load monitoring to assess successful viral suppression. Efforts to expand access by decentralizing HIV nucleic acid testing in low- and middle-income countries has been hampered by the cost and complexity of current tests. Sample preparation of blood samples has traditionally relied on cumbersome RNA extraction methods, and it continues to be a key bottleneck for developing low-cost POC nucleic acid tests. We present a microfluidic paper-based analytical device (µPAD) for extracting RNA and detecting HIV in serum, leveraging low-cost materials, simple buffers, and an electric field. We detect HIV virions and MS2 bacteriophage internal control in human serum using a novel lysis and RNase inactivation method, paper-based isotachophoresis (ITP) for RNA extraction, and duplexed reverse transcription recombinase polymerase amplification (RT-RPA) for nucleic acid amplification. We design a specialized ITP system to extract and concentrate RNA, while excluding harsh reagents used for lysis and RNase inactivation. We found the ITP µPAD can extract and purify 5,000 HIV RNA copies per mL of serum. We then demonstrate detection of HIV virions and MS2 bacteriophage in human serum within 45-minutes.</p>

Virus removal from drinking water using modified activated carbon fibers

Activated carbon fibers revealed better performance in filtration studies towards MS2 bacteriophage removal in comparison to activated carbon powder or granules.

Effectiveness of an Ozone Disinfecting and Sanitizing Cabinet to Decontaminate a Surrogate Virus for SARS-CoV-2 on N-95 Masks

Medical demands during the COVID-19 pandemic have triggered a grave shortage of medical-grade personal protective equipment (PPE), especially, N95 respirators. N95 respirators are critical for the personal protection of medical providers and others when being exposed to individuals with infections caused by the SARS-CoV-2 coronavirus. To address the shortage of N95 respirators, innovative methods are needed to decontaminate coronaviruses from N95 respirators, allowing them to be safely reused by healthcare workers. For this research, we use a commercial ozone disinfecting cabinet to examine the efficacy of ozone-based disinfection of a conservative surrogate virus for SARS-CoV-2, the MS2 bacteriophage. Treatment of mask materials with enhanced ozone treatment resulted in 2.38-log 10 (>99%) reduction of phage from household dust masks and a range of 1.43-log 10 (96.2%) to 4-log 10 (99.99%) reductions of phage from common N95 mask materials.