Pretreatment Solution for Water Recovery Systems

Chemical pretreatments are used to produce usable water by treating a water source with a chemical pretreatment that contains a hexavalent chromium and an acid to generate a treated water source, wherein the concentration of sulfate compounds in the acid is negligible, and wherein the treated water source remains substantially free of precipitates after the addition of the chemical pretreatment. Other methods include reducing the pH in urine to be distilled for potable water extraction by pretreating the urine before distillation with a pretreatment solution comprising one or more acid sources selected from a group consisting of phosphoric acid, hydrochloric acid, and nitric acid, wherein the urine remains substantially precipitate free after the addition of the pretreatment solution. Another method described comprises a process for reducing precipitation in urine to be processed for water extraction by mixing the urine with a pretreatment solution comprising hexavalent chromium compound and phosphoric acid

Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine

Two batches of nominally pretreated and augmented urine were prepared with the baseline pretreatment formulation of sulfuric acid and chromium trioxide. The urine was augmented with inorganic salts and organic compounds in order to simulate a urinary ionic concentrations representing the upper 95 percentile on orbit. Three strong mineral acids: phosphoric, hydrochloric, and nitric acid, were substituted for the sulfuric acid for comparison to the baseline sulfuric acid pretreatment formulation. Three concentrations of oxidizer in the pretreatment formulation were also tested. Pretreated urine was distilled to 85% water recovery to determine the effect of each acid and its conjugate base on the precipitation of minerals during distillation. The brines were analyzed for calcium and sulfate ion, total, volatile, and fixed suspended solids. Test results verified that substitution of phosphoric, hydrochloric, or nitric acids for sulfuric acid would prevent the precipitation of gypsum up to 85% recovery from pretreated urine representing the upper 95 percentile calcium concentration on orbit

Dimethylsilanediol (DMSD) Source Assessment and Mitigation on ISS: Estimated Contributions from Personal Hygiene Products Containing Volatile Methyl Siloxanes (VMS)

Dimethylsilanediol (DMSD) is a small organosilicon compound present in humidity condensate on the International Space Station. Aqueous DMSD originates from volatile methyl siloxane (VMS) compounds in the ISS cabin atmosphere. DMSD is not effectively removed by the WPA (Water Processor Assembly), requiring removal and replacement of both WPA Multifiltration (MF) Beds for an estimated resupply penalty of approximately 70 kg/year. Analyses indicate that WPA can handle DMSD if the concentration in the condensate can by reduced by fifty percent. Personal Hygiene Products (PHPs) used by crew are suspected to be a significant source of VMS. Source removal of VMS will be required to achieve a measurable impact to the DMSD concentration in the condensate. The inventory of total crew provisions for ISS was analyzed to identify silicon containing materials and products used for personal hygiene that emit VMS. Accounting for the wide range in mass of hygiene product applied to skin or hair, the frequency of application, the product selection, the number of crew using a given product, the range in silicon mass fraction of different products, and the potential vaporization of the product, the potential total VMS emissions from personal hygiene products for a crew of six on ISS were estimated. The total daily VMS emissions from PHPs estimate ranges from 261 to 1145 mg-Si per day, compared to total estimated VMS generation rates on ISS of 800 to 1500 mg-Si per day. The main sources of VMS were determined to be antiperspirants (173 to 696 mg-Si per day), skin lotions (63 to 248 mg-Si per day), wipes (25 to 124 mg-Si per day) and hair conditioner (0 to 69 mg-Si per day). Several siloxanes-free options are available for deodorants, wet wipes, lotions, and leave-in conditioners. These products are now being assessed for crew member use in future increments

Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems

Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper

Color Measurement and Reflectance Spectroscopy of Total Suspended Solids for Remote Sensing and Environmental Monitoring of Aquatic Ecosystems.

Water color and water quality are related in complex and poorly understood ways. Suspended particulates, such as phytoplankton, bacteria, and soil particles, contribute significantly to the color and quality of natural water bodies by absorbing and scattering sunlight. There is currently no standard method to measure the color and optical properties of total suspended solids (TSS). Remote sensing algorithms estimate TSS concentrations from observed values of reflectance. There are spectral differences in TSS over time and space. A convenient, inexpensive, and quick method is developed and evaluated to quantify optical differences between different TSS. The technique links the traditional TSS laboratory method to the Hapke radiative transfer theory of closely packed particles. The Hapke bidirectional reflectance model is modified to incorporate the measured dry mass of TSS on the filter paper. The measured reflectances of a series of different TSS layer thicknesses (mass per filter area) enables calculation of the absorption and scattering properties of TSS particles. The specific extinction, absorption and scattering coefficients are calculated to classify TSS. The observed relationship between reflectance and TSS mass loading rate is modeled. Model parameters are determined by nonlinear least squares. The parameters, expressed as functions of wavelength (390 to 700 nm), permit optical classification and comparison of TSS from different locations and times. The extinction, absorption, and scattering efficiencies, the volume single-scattering albedo (w) and the effective single-particle absorption-thickness (espat) are also calculated with the model. This is the first time these parameters have been measured for TSS. Reflectance spectra may also be converted to CIE XYZ tristimulus values or Munsell colors. The method is evaluated using eutrophic lake TSS, Mississippi River TSS, wastewater bacteria, and algae (Chladymonas reinhardtii). A remote sensing model is presented based on the Hapke model parameters. The method enables quantification of the packaging effect of algae. The technique is easily incorporated into any TSS analysis and has applications in sediment tracing and nonpoint source pollution, laboratory methods to measure TSS pigments (chlorophyll), remote sensing, and water quality monitoring

Preventing Precipitation in the ISS Urine Processor

The ISS Urine Processor Assembly (UPA) was initially designed to achieve 85% recovery of water from pretreated urine on ISS. Pretreated urine is comprised of crew urine treated with flush water, an oxidant (chromium trioxide), and an inorganic acid (sulfuric acid) to control microbial growth and inhibit precipitation. Unfortunately, initial operation of the UPA on ISS resulted in the precipitation of calcium sulfate at 85% recovery. This occurred because the calcium concentration in the crew urine was elevated in microgravity due to bone loss. The higher calcium concentration precipitated with sulfate from the pretreatment acid, resulting in a failure of the UPA due to the accumulation of solids in the Distillation Assembly. Since this failure, the UPA has been limited to a reduced recovery of water from urine to prevent calcium sulfate from reaching the solubility limit. NASA personnel have worked to identify a solution that would allow the UPA to return to a nominal recovery rate of 85%. This effort has culminated with the development of a pretreatment based on phosphoric acid instead of sulfuric acid. By eliminating the sulfate associated with the pretreatment, the brine can be concentrated to a much higher concentration before calcium sulfate reach the solubility limit. This paper summarizes the development of this pretreatment and the testing performed to verify its implementation on ISS

Estimating relative risk of within-lake aquatic plant invasion using combined measures of recreational boater movement and habitat suitability

Effective monitoring, prevention and impact mitigation of nonindigenous aquatic species relies upon the ability to predict dispersal pathways and receiving habitats with the greatest risk of establishment. To examine mechanisms affecting species establishment within a large lake, we combined observations of recreational boater movements with empirical measurements of habitat suitability represented by nearshore wave energy to assess the relative risk of Eurasian watermilfoil (Myriophyllum spicatum) establishment. The model was evaluated using information from a 17 year (1995–2012) sequence of M. spicatum presence and absence monitoring. M. spicatum presence was not specifically correlated with recreational boater movements; however its establishment appears to be limited by wave action in Lake Tahoe. Of the sites in the “High” establishment risk category (n = 37), 54% had current or historical infestations, which included 8 of the 10 sites with the highest relative risk. Of the 11 sites in the “Medium” establishment risk category, 5 had current or historical M. spicatum populations. Most (76%) of the sites in the “Low” establishment risk category were observed in locations with higher wave action. Four sites that received zero boater visits from infested locations were occupied by M. spicatum. This suggests that the boater survey either represents incomplete coverage of boater movement, or other processes, such as the movement of propagules by surface currents or introductions from external sources are important to the establishment of this species. This study showed the combination of habitat specific and dispersal data in a relative risk framework can potentially reduce uncertainty in estimates of invasion risk

The Lancet Global Health Commission on Global Eye Health: vision beyond 2020

Eye health and vision have widespread and profound implications for many aspects of life, health, sustainable development, and the economy. Yet nowadays, many people, families, and populations continue to suffer the consequences of poor access to high-quality, affordable eye care, leading to vision impairment and blindness. In 2020, an estimated 596 million people had distance vision impairment worldwide, of whom 43 million were blind. Another 510 million people had uncorrected near vision impairment, simply because of not having reading spectacles. A large proportion of those affected (90%), live in low-income and middle-income countries (LMICs). However, encouragingly, more than 90% of people with vision impairment have a preventable or treatable cause with existing highly cost-effective interventions. Eye conditions affect all stages of life, with young children and older people being particularly affected. Crucially, women, rural populations, and ethnic minority groups are more likely to have vision impairment, and this pervasive inequality needs to be addressed. By 2050, population ageing, growth, and urbanisation might lead to an estimated 895 million people with distance vision impairment, of whom 61 million will be blind. Action to prioritise eye health is needed now. This Commission defines eye health as maximised vision, ocular health, and functional ability, thereby contributing to overall health and wellbeing, social inclusion, and quality of life. Eye health is essential to achieve many of the Sustainable Development Goals (SDGs). Poor eye health and impaired vision have a negative effect on quality of life and restrict equitable access to and achievement in education and the workplace. Vision loss has substantial financial implications for affected individuals, families, and communities. Although high-quality data for global economic estimates are scarce, particularly for LMICs, conservative assessments based on the latest prevalence figures for 2020 suggest that annual global productivity loss from vision impairment is approximately US$410·7 billion purchasing power parity. Vision impairment reduces mobility, affects mental wellbeing, exacerbates risk of dementia, increases likelihood of falls and road traffic crashes, increases the need for social care, and ultimately leads to higher mortality rates. By contrast, vision facilitates many daily life activities, enables better educational outcomes, and increases work productivity, reducing inequality. An increasing amount of evidence shows the potential for vision to advance the SDGs, by contributing towards poverty reduction, zero hunger, good health and wellbeing, quality education, gender equality, and decent work. Eye health is a global public priority, transforming lives in both poor and wealthy communities. Therefore, eye health needs to be reframed as a development as well as a health issue and given greater prominence within the global development and health agendas. Vision loss has many causes that require promotional, preventive, treatment, and rehabilitative interventions. Cataract, uncorrected refractive error, glaucoma, age-related macular degeneration, and diabetic retinopathy are responsible for most global vision impairment. Research has identified treatments to reduce or eliminate blindness from all these conditions; the priority is to deliver treatments where they are most needed. Proven eye care interventions, such as cataract surgery and spectacle provision, are among the most cost-effective in all of health care. Greater financial investment is needed so that millions of people living with unnecessary vision impairment and blindness can benefit from these interventions. Lessons from the past three decades give hope that this challenge can be met. Between 1990 and 2020, the age-standardised global prevalence of blindness fell by 28·5%. Since the 1990s, prevalence of major infectious causes of blindness—onchocerciasis and trachoma—have declined substantially. Hope remains that by 2030, the transmission of onchocerciasis will be interrupted, and trachoma will be eliminated as a public health problem in every country worldwide. However, the ageing population has led to a higher crude prevalence of age-related causes of blindness, and thus an increased total number of people with blindness in some regions. Despite this progress, business as usual will not keep pace with the demographic trends of an ageing global population or address the inequities that persist in each country. New threats to eye health are emerging, including the worldwide increase in diabetic retinopathy, high myopia, retinopathy of prematurity, and chronic eye diseases of ageing such as glaucoma and age-related macular degeneration. With the projected increase in such conditions and their associated vision loss over the coming decades, urgent action is needed to develop innovative treatments and deliver services at a greater scale than previously achieved. Good eye health at the community and national level has been marginalised as a luxury available to only wealthy or urban areas. Eye health needs to be urgently brought into the mainstream of national health and development policy, planning, financing, and action. The challenge is to develop and deliver comprehensive eye health services (promotion, prevention, treatment, rehabilitation) that address the full range of eye conditions within the context of universal health coverage. Accessing services should not bring the risk of falling into poverty and services should be of high quality, as envisaged by the WHO framework for health-care quality: effective, safe, people-centred, timely, equitable, integrated, and efficient. To this framework we add the need for services to be environmentally sustainable. Universal health coverage is not universal without eye care. Multiple obstacles need to be overcome to achieve universal coverage for eye health. Important issues include complex barriers to availability and access to quality services, cost, major shortages and maldistribution of well-trained personnel, and lack of suitable, well maintained equipment and consumables. These issues are particularly widespread in LMICs, but also occur in underserved communities in high-income countries. Strong partnerships need to be formed with natural allies working in areas affected by eye health, such as non-communicable diseases, neglected tropical diseases, healthy ageing, children's services, education, disability, and rehabilitation. The eye health sector has traditionally focused on treatment and rehabilitation, and underused health promotion and prevention strategies to lessen the impact of eye disease and reduce inequality. Solving these problems will depend on solutions established from high quality evidence that can guide more effective implementation at scale. Evidence-based approaches will need to address existing deficiencies in the supply and demand. Strategic investments in discovery research, harnessing new findings from diverse fields, and implementation research to guide effective scale up are needed globally. Encouragingly, developments in telemedicine, mobile health, artificial intelligence, and distance learning could potentially enable eye care professionals to deliver higher quality care that is more plentiful, equitable, and cost-effective. This Commission did a Grand Challenges in Global Eye Health prioritisation exercise to highlight key areas for concerted research and action. This exercise has identified a broad set of challenges spanning the fields of epidemiology, health systems, diagnostics, therapeutics, and implementation. The most compelling of these issues, picked from among 3400 suggestions proposed by 336 people from 118 countries, can help to frame the future research agenda for global eye health. In this Commission, we harness lessons learned from over two decades, present the growing evidence for the life-transforming impact of eye care, and provide a thorough understanding of rapid developments in the field. This report was created through a broad consultation involving experts within and outside the eye care sector to help inform governments and other stakeholders about the path forward for eye health beyond 2020, to further the SDGs (including universal health coverage), and work towards a world without avoidable vision loss. The next few years are a crucial time for the global eye health community and its partners in health care, government, and other sectors to consider the successes and challenges encountered in the past two decades, and at the same time to chart a way forward for the upcoming decades. Moving forward requires building on the strong foundation laid by WHO and partners in VISION 2020 with renewed impetus to ultimately deliver high quality universal eye health care for all

Impact of wastewater fouling on contact angle

Capillary dependent systems are highly influenced by surface fouling and may degrade as material surface properties change. In anticipation of a spacecraft microgravity fluids management system exposed to highly variable wetting conditions, the impact of urine wastewater fouling on capillary contact angle was examined. The results indicate that, in general, surface fouling can decrease the contact angle when crystalline structures or biofilms form. Small crystalline growth on the order of 10 µm can lower advancing contact angles θadv by approximately 30˚, while biofilm growth can lower it by approximately 15˚. Vacuum drying of fouled surfaces increased θadv by about 8˚, and defects greater in height than 5% of the capillary length increased θadv by approximately 30˚. These trends may indicate that promotion of wastewater fouling may improve the performance of capillary dependent fluids management systems. These results may also influence terrestrial technologies, including medical catheters and sustainable wastewater treatment systems exposed to wastewater fouling