Potable Use Research Articles

An evaluation of rainwater runoff quality from selected white roof membranes

While there has been research on rainwater quality and quantity from green roofs and some conventional roof systems, there does not appear to be any significant study regarding the quality of rainwater harvested from selected white membrane roof systems and subsequently treated for potable use in an urban, institutional setting. A new Leadership in Energy and Environmental Design (LEED®) Canada Gold facility on the campus of McMaster University in Hamilton, Canada offered an excellent opportunity to analyze the quality of rainwater from different roof assemblies. Field research was undertaken on the evaluation of three white roof membranes: modified bitumen finish ply, polyvinyl chloride (PVC), and thermoplastic polyolefin (TPO); and their effects on the runoff water quality were studied. An analysis of the quality of runoff was performed from each of these three membranes and compared with Ontario provincial drinking water standards. This paper provides the results of runoff quality testing on these membranes and their suitability for future institutional green building applications.

Direct potable reuse of reclaimed wastewater: it is time for a rational discussion

Water shortage arising from rapid population growth and relocation has produced an unprecedented degree of stress on regional water resources. Engineered solutions to relieve water stress are frequently based on the use of water of impaired initial quality. Chief among these impaired waters is reclaimed wastewater. For the most part, however, the breadth of both acceptable uses and use-dependent degree of treatment for reclaimed wastewater remain to be established.The chief advantages of direct potable reuse (DPR) relative to other forms of wastewater reclamation and reuse are that(i) all wastewater reclaimed for DPR can be readily used in water-stressed areas and (ii) delivery to points of use does not require a separate distribution system. The drawbacks are related to the need for highly competent, continuous on-line verification of water quality and the cost of treating all reclaimed wastewater to meet potable use requirements when only a small fraction will be used for potable purposes.We have attempted to explore those differences, providing quantitative comparisons where possible, to support selection among water reuse options in water-stressed areas.

Towards sustainable desalination

As the role of desalination in providing water is broadened, it has come under increasing scrutiny due to its perceived impact on the marine environment and its energy intensity. Desalination’s increasing popularity is due to lower cost technologies such as reverse osmosis along with the need to supply water to populations are moving towards the coast. Sustainable desalination is feasible when desalination projects are combined with demand management to ensure that the water is effectively used. There is appreciable scope to lower its energy demand through new technologies and approaches and by adopting desalination techniques wastewater can be recovered for potable and non potable use. Desalination can also play a positive role in relieving pressure on low flow rivers.

Microbial community structure of a slow sand filter schmutzdecke: a phylogenetic snapshot based on rRNA sequence analysis

Slow sand filters (SSF) are widely used to treat water for potable use. The process is dependent on the activities of complex microbial communities in the biofilm (schmutzdecke) layer. In this study, we generated a comprehensive view of three-domain microbiological complexity within a model SSF. DNA was analysed using a high-density microarray (PhyloChip) and rRNA library analysis. The Eukaryotic community was dominated by Cercozoa (Ebridd-type protists); these are likely to be involved in predation of other organisms in the schmutzdecke layer, thus proving opportunity for successional development. Ciliate protozoa, green microalgae, stramenopiles, amoeboid protozoa and fungi in the Phylum Ascomycota and the deep-branching Chytridiomycota were also detected. The Archaeal community was dominated by Euryarchaeota, and most were Halobacteriales. These organisms may contribute to filter function through removal of dissolved organic carbon, a primary treatment goal of these filters. Given that the Eukaryotic and Archaeal communities were examined using clone libraries, the expected richness of taxa present is expected to be greater than detected here and dependent on sampling effort (library size). The bacterial community was rich in taxa (21 Phyla) but was not dominated by any phylogenetic group. The successful function of SSF's relies on interactions between taxa (e.g. grazing of Cercozoa protists on bacteria), and removal of dissolved organic matter from the influent. Understanding the taxa and functions in these systems will aid in monitoring and managing SSF for optimal water quality.

Early response of the platypus to climate warming

AbstractCombining a climatic envelope modelling technique with more than two centuries (1800–2009) of distribution records has revealed the effects of a changing climate on the egg‐laying monotreme, the platypus, Ornithorhynchus anatinus. We show that the main factor associated with platypus occurrence switched from aquatic habitat availability (estimated by rainfall) to thermal tolerances (estimated by annual maximum temperature) in the 1960s. This correlates directly with the change in the annual maximum temperature anomaly from cooler to warmer conditions in southeastern Australia. Modelling of platypus habitat under emission scenarios (A1B, A2, B1 and B2) revealed large decreases (>30%) in thermally suitable habitat by 2070. This reduction, compounded by increasing demands for water for agriculture and potable use, suggests that there is real cause for concern over the future status of this species, and highlights the need for restoration of thermal refugia within the platypus’ modelled range.

Quantification of potable water savings by residential water conservation and reuse – A case study

To demonstrate the benefits of water conservation at the household level in regional Victoria in Australia, a family house “Sharland Oasis” was designed and built according to an ecologically sustainable design for improved water and energy efficiency. This study has demonstrated that the combined use of alternative water supplies together with water efficient appliances can save up to 77% of total potable water use compared to the average 1990s household water use in the same region considering the location and differing in water use approach. The use of rainwater inside the home alone saved up to 40% of potable water use. In addition to the water savings, there is a significant wastewater discharge saving achieved through the use of water conservation strategies and greywater reuse. A community survey undertaken in regional Victoria revealed that community receptivity for reusing greywater is highest for uses, such as watering gardens and flushing toilets; but it progressively decreased with increasing personal contact with greywater. Positive perception of greywater reuse needs to be encouraged through programs targeted at developing resources, skills and motivation for new water reuse practices and technologies, across a diverse range of social groups.

Salinity reduction and energy conservation in direct and indirect potable water reuse

Water scarcity combined with population growth and climate change, especially in semi-arid and arid regions like Australia, Western United States, and the Middle East, has increased the need for water conservation. Water reclamation and reuse have become an important source of water to conserve and extend water supplies. With the advancement of technologies, indirect potable water reuse (IPWR) and direct potable water reuse (DPWR) have been developed as methods for producing high-quality recycled water for potable use. In this research salinity removal and energy conservation associated with IPWR and DPWR were modeled using the system dynamics software Stella. The water/wastewater system of the Las Vegas Valley, Nevada, USA, which discharges into the Colorado River, was used as an example system augmented with reverse osmosis (RO) membranes. The results show that IPWR and DPWR reduce salinity discharge to the Colorado River. The TDS load is reduced to 0.85 and 1.02 million kg/day for DPWR and IPWR systems compared to 2.33 million kg/day by the year 2035. DPWR can also save about 50% of the energy cost of pumping water. However, one drawback with these systems is the approximately 5% loss of water in the brine of the membranes.

Microfiltration and Reverse Osmosis Membrane Replacement Understanding Operating Process Data and Autopsy Data Projection of Useful Remaining Life

Microfiltration and Reverse Osmosis Membrane Replacement Understanding Operating Process Data and Autopsy Data Projection of Useful Remaining LifeMembranes are used more and more often for the creation of process water and water for in direct potable use from wastewater. The useful life expectancy of the microfiltration (MF) and reverse osmosis (RO) membranes is projected and planed in general for 5 years, which is consistent with the manufacturers' warranties for membrane systems operating in this type of application where membranes are...Author(s)Al BazziSlavica HammondKenneth ReddMichael SarulloRoshanak AflakiDawn GuendertSourceProceedings of the Water Environment FederationSubjectSession 37: Advanced Treatment and Nutrient RemovalDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:15L.2097;1-DOI10.2175/193864711802713513Volume / Issue2011 / 15Content sourceWEFTECFirst / last page(s)2097 - 2119Copyright2011Word count190Subject keywordsAdvanced wastewater treatmentMicrofilttration (MF)Reverse Osmosis (RO)membranesuseful life expectancyuseful remaining lifereplacement

Soil solutions: improving water management across Sydney's public open spaces

With the support and assistance of Sydney Water Corporation (SWC), URS Australia Pty Ltd (URS) have developed an Irrigation and Landscape Efficiency Assessment methodology (ILA) to improve the management of public open space across Sydney. To date over 180 ILAs have been conducted, with a number of key management issues identified. Excessive watering from poor irrigation scheduling practises, low soil water-holding capacity (from shallow or sandy textured soils); and inappropriate location of ornamental plantings are regularly encountered. This paper explores the key issues impacting water management across Sydney's public open spaces, and highlights methods available to rectify these issues and reduce potable water use into the future.

Economic and environmental analysis of standard, high efficiency, rainwater flushed, and composting toilets

The current sanitation technology in developed countries is based on diluting human excreta with large volumes of centrally provided potable water. This approach is a poor use of water resources and is also inefficient, expensive, and energy intensive. The goal of this study was to compare the standard sanitation technology (Scenario 1) with alternative technologies that require less or no potable water use in toilets. The alternative technologies considered were high efficiency toilets flushed with potable water (Scenario 2), standard toilets flushed with rainwater (Scenario 3), high efficiency toilets flushed with rainwater (Scenario 4), and composting toilets (Scenario 5). Cost, energy, and carbon implications of these five design scenarios were studied using two existing University of Toledo buildings. The results showed that alternative systems modeled in Scenarios 2, 4, and 5 were viable options both from an investment and an environmental performance perspective. High efficiency fixtures that use potable water (Scenario 2) is often the most preferred method in high efficiency buildings due to reduced water use and associated reductions in annual water and wastewater costs. However, the cost, energy, and CO2EE analyses all showed that Scenarios 4 and 5 were preferable over Scenario 2. Cost payback periods of scenarios 2, 4 and 5 were less than 10 years; in the future, increase in water and wastewater services would further decrease the payback periods. The centralized water and wastewater services have high carbon footprints; therefore if carbon footprint reduction is a primary goal of a building complex, alternative technologies that require less potable water and generate less wastewater can largely reduce the carbon footprint. High efficiency fixtures flushed with rainwater (Scenario 4) and composting toilets (Scenario 5) required considerably less energy than direct energy demands of buildings. However, the annual carbon footprint of these technologies was comparable to the annual carbon footprint from space heating. Similarly, the carbon savings that could be achieved from Scenario 4 or 5 were comparable to a recycling program that can be implemented in buildings.

Water Reuse Relieves Drought Effects in Queensland, Australia

Many water agencies worldwide are considering high-quality reclaimed wastewater for industrial purposes to reduce demand on their potable water supplies. Because of a severe drought in Queensland, Australia, the Moreton Bay Regional Council implemented the Murrumba Downs Advanced Water Treatment Plant (AWTP) to produce up to 1.1 mgd (4,000 m3/day) of high-quality reclaimed water to replace potable water use at a local paper products manufacturing facility. In addition, AWTP treatment residuals are treated and discharged to a local river in accordance with Environmental Protection Agency statutes.

Evaluation of Renewable Energy as a Source of Power for Desalination of Remote-Oilfield Brines

Summary A hybrid system of wind, solar, and diesel generators could provide an efficient alternative for powering water-desalination projects in remote-oilfield locations in Texas, USA. Disposal of produced water from oil and gas wells is a costly procedure for production companies, but water-to-oil production ratios exceed 10:1 (by volume) at many wellsites. Much of the petroleum produced in the United States and elsewhere is found in arid regions that could benefit greatly if the produced water could be purified sufficiently for agricultural, industrial, or potable use. Our previous research identified and validated treatment options capable of recovering a high proportion of fresh water from oilfield brine. In this paper, we extend the earlier research further by examining the possibility of using renewable energy to power the units in "off-the-power-grid" situations. A macro-driven spreadsheet was created to allow for quick and easy cost comparisons of renewable energy sources for a variety of scenarios. Using this tool, wind and solar costs were compared for cities in regions throughout Texas. The renewable energy resource showing the greatest potential was wind power, with the analysis showing that in windy regions such as the Texas Panhandle, wind-generated-power costs are lower than those associated with diesel-fuel generation.

Migration of As, and 3H/ 3He ages, in groundwater from West Bengal: Implications for monitoring

From 2002 to 2010 inclusive we monitored concentrations of arsenic (As) and major ions (Ca, Mg, Sr, Na, K, Fe, Mn, Cl, and SO 4) in groundwater from 14 domestic wells and three piezometer nests in a shallow aquifer (<60 m depth), and 3 wells in a deep aquifer (>70 m depth), in southern West Bengal, India. In the deep aquifer, concentrations of As did not change over time despite increases in the concentration of Fe in two wells. The shallow aquifer occurs in two sedimentological settings: palaeo-channel and palaeo-interfluve. At the top of the shallow aquifer of the palaeo-channel, decreases in all constituent concentrations with time, and an 3H/ 3He age of 1.4 years, proves that the aquifer is beginning to be flushed of pollutants. In As-polluted groundwater (>50 μg/L As) tapped from deeper grey sands of the shallow, palaeo-channel, aquifer, concentrations of As were mostly stable over time, but both increases and decreases occurred with time in response to downward migration of the chemically-stratified water column. In groundwater tapped from Pleistocene brown sands, the concentration of As remained either low and stable (<2 μg/L As), or increased at rates up to 34 μg/L per year. The increases were caused by the flow of As-rich groundwater either downward into brown sand at the base of palaeo-channels, or laterally into a confined, unpolluted, palaeo-interfluvial, aquifer of brown sand that lies regionally beneath a palaeosol. Under the present pumping regime, the prognosis for As-pollution in the shallow aquifer is complex. Wells in brown sand may become polluted over timescales of as little as 2 years, whilst some wells tapping As-polluted groundwater from grey sand will become fit for potable use (<50 μg/L) within a few decades. The evidence of flushing, and of declining As in some of the groundwater from palaeo-channels, which are conduits for recharge of the confined, As-free, palaeo-interfluve aquifer, and probably also the deeper aquifer, offers hopes that the spread of As-pollution will be limited.

Evaluation of chitosan as a natural coagulant for drinking water treatment

Chitosan, a natural biopolymer, was evaluated for its ability to be used as a coagulant to treat water for potable use both in isolation and in combination with other water treatment technologies, specifically ion-exchange and activated carbon. Chitosan was found to be very effective for particle removal at doses far below those required for equivalent turbidity removal by inorganic coagulants. However in the water sources tested, chitosan was not particularly efficient for dissolved organic carbon (DOC) removal when applied as the sole treatment step. When applied as the final clarification stage of a multi-step treatment process, chitosan exhibited limited turbidity reduction due to specific flocculation requirements. This combination of treatment technologies was also unable to further reduce secondary water quality parameters, such as disinfectant demand and trihalomethane (THM) formation.

Groundwater Quality, Geochemical Processes and Groundwater Evolution in the Chateauguay River Watershed, Quebec, Canada

A hydrogeochemical study was carried out in the Quebec portion of the Chateauguay River watershed. The objective was to characterize the chemical composition of groundwater in order to evaluate its quality and assess geochemical variations related to the geological and hydrogeological settings. Bulk groundwater samples were collected from 144 wells distributed evenly over the study area. Nine of the wells were sampled with a multi-level packer system, for a total of 22 multi-level samples. Samples were analysed for a comprehensive set of chemical inorganic parameters: dissolved major, minor and trace constituents, bacterial content, and stable (δ2H, δ13C, δ18O) and radioactive (3H, 14C) isotopes. Major dissolved constituents Ca, Mg, Na, K, Cl, SO4 and HCO3– ions represent more than 92% of total dissolved solids and their concentrations seem controlled by both hydrogeological and geological factors. Most water quality problems are related to aesthetic standards for potable water use (hardness, total dissolved solids (TDS), Fe and Mn concentrations) and TDS and Cl for irrigation use. Analyses of tritium (3H) and 14C confirm the inferred recharge zones and indicate the presence of variable water ages. Groundwater shows a wide range of compositions as indicated by 12 water types defined on the basis of major ions with a weak variation of chemical composition with depth. The predominant water type, Ca-HCO3, occurs in most geological and hydrogeological settings. Principal Component Analysis (PCA) and geochemical graphs were used to identify the major processes that exert a control over the chemical composition of the groundwater. Approximately 80% of the geochemical variation can be explained by mixing between fresh recharge water with more saline water associated with the former Champlain Sea, which invaded the aquifer. Secondary processes are related to ion exchange and the potential dissolution of minerals. A cross-section along a major flow path shows that the geochemical evolution of groundwater leads to relations between water type groups, geochemical processes, and groundwater flow conditions. The hydrogeochemical conceptual model infers that carbonate dissolution during recharge leads to one end-member, a Ca-HCO3 type water, which further evolves along its flow path due through ion exchange and mixing with remnant Champlain Sea water (Na-Cl), the other end-member.

A brief review of desalination in Australia in 2010

Recent climate changes and population growth throughout Australia have highlighted the need for more diverse and climate-independent water sources. Australia is the world's driest inhabited continent and the unpredictable climate means that the Australian population generally requires up to five times the water storage than does an equivalent population in the UK. Although 85% of its people live within 50 km of the coast, the country has only begun to consider large-scale seawater desalination within the past five years (Crisp, 2009). The total potable and industrial water consumption in Australia is around 50,000 ML/d (Hoang, 2009). In 2008, the total volume of water desalinated for potable and industrial use was about 0.6% (300 ML/d) and this is expected to increase more than seven times to 4% by 2013. A brief review of current (2010) desalination capacity in Australia follows and includes major seawater plants, brackish water and wastewater reuse.

Drinking water from alternative water sources: differences in beliefs, social norms and factors of perceived behavioural control across eight Australian locations

Australia is facing serious challenges in the management of water in various urban and regional locations. Two popular responses to these challenges are increasing supply through alternative water sources such as recycled and desalinated water. However, significant gaps exist in our knowledge of community attitudes to these alternative sources of water, particularly for potable use. This paper reports results from an Australian study of community attitudes to alternative water sources. Sixty six qualitative interviews were held at eight locations with distinctly different water situations. This paper explores all three antecedents to the behaviour of drinking recycled water and desalinated water as postulated by the Theory of Planned Behaviour: attitudes, social norms and factors of perceived behavioural control. Key results indicate that while people hold both positive and negative beliefs (mostly cost, health and environmental concerns) about water from alternative sources, nearly all of them are willing to drink it if the water crisis were to deteriorate further. People also feel they lack knowledge and state that information from scientists would influence their decision to drink recycled and desalinated water most. Friends and relatives are most influential in preventing people from drinking recycled water. The findings reported in this paper have major implications for water policy, and will be of particular interest to water engineers. The paper raises a provocative question: Is it better to avoid public consultation in introducing water from alternative sources?

Soluble, semivolatile phenol and nitrogen compounds in milk-processing wastewaters

Potable water is an essential and major input in processing our food supplies, and the continued growth in food manufacturing is placing increased pressure on this limited resource. Recycling and reuse of factory wastewater can lessen potable water use but requires a detailed understanding of wastewater properties. This study uses solid-phase extraction techniques with gas chromatography-mass spectrometry analysis to investigate trace-level semivolatile organic species in various waste and reference waters associated with the Burra Foods milk-processing plant located in Southeastern Australia. Our focus was on contaminants containing phenolic and heterocyclic nitrogen functional groups, which, because of their toxicity and persistence, may limit options for water recycling and reuse. Effluent from the wastewater treatment plant of the factory showed both the highest soluble carbon burden (47 mg/kg) and concentrations of target compounds. The target species found in these effluents included methyl phenol (13 mg/kg), hydroxy indole (9.8 mg/kg), synthetic tolyltriazoles (5.1 mg/kg) and alkyl phenol ethoxylates (0.2 mg/kg). Given the environmental stability of the tolyltriazoles, they may act as chemical markers where these effluents are used for purposes such as irrigation. Milk evaporator condensate waters, in contrast to the effluent, contained very few target species, with only low levels of pyrrolidine and piperidine derivatives such as ethylglutarimide (450 μg/L) detected. Although there were fewer target microcontaminants overall in the potable and creek reference waters, these samples had characteristic profiles. The potable water analysis revealed hydroxy cineole (2.1 μg/L) and the creek analysis revealed dichlorohydroxyacetophenone (0.3 μg/L), which were not detected in other waters. The compounds found in the wastewaters are likely to have been derived from milk or synthetic chemicals used in factory operations. The presence of nitrogen compounds in all the different milk-processing waters suggest their likely source was milk, probably milk phosphoproteins subjected to thermal, chemical, or microbial degradation. Our benign results for the condensates suggest it may be possible to substitute condensate for potable water with minimal pretreatment, both within the plant and in other applications, such as irrigation of recreation turf.

Performance of ultrafiltration plants in France

The demand for high quality municipal potable water is booming all over the world, especially in France where there is an additional requirement for virus reduction that can be satisfied with the use of ultrafiltration (UF) membranes. Many of these advanced treatment plants have been awarded, and are using capillary UF membrane technology, such as the HYDRAcap UF membrane as part of the treatment process. Plant output from these installations ranges from 1000 m 3 /d to 150,000 m 3 /d and they treat different types of feed waters (mainly surface water and ground water), typically high turbidity values. Capillary UF is usually used as a final treatment step to successfully remove viruses, bacteria and the finest particles. The removal rating depends upon the pore size of the active layer of the membrane; for example HYDRAcap UF, has approximately 0.02 μm pore size. This paper will present the current and future trends regarding the use of UF in treatment plants in France. In particular, detailed design and commissioning data for two different plants will be presented. One site is a medium-scale operating plant for potable water use. The high quality of feed water enables the system to run at high fluxes, as we have also demonstrated at many other sites. Secondly, a small scale plant will be described; this plant can also run at high fluxes, but is subject to high concentrations of iron in feed water, which requires frequent cleanings at low pH. In both cases, UF performance data, including flux, transmembrane pressure, backflush trends and fiber integrity will be presented in order to have a clear picture of the potential of the plant.

Desalination: Supplementing Freshwater Supplies Approaches and Challenges

A broad definition of desalination includes the treatment of all impaired waters; waters contaminated by salts, metals, radionuclides, biologic organisms, organic chemicals, fertilizers, pesticides, and a number of other substances that must be removed prior to water being suitable for potable use. The U.S. Department of Interior, Bureau of Reclamation along with the Sandia National Laboratories has created the Desalination and Water Purification Technology Roadmap to meet future water demand in the United States (Sandia National Laboratories 2003). The U.S. Bureau of Reclamation has published a desalting handbook for planners (U.S. Bureau of Reclamation 2003). Future desalination technologies are expected to treat a variety of impure waters such as urban runoff, wastewater treatment plant discharge, and saline water for possible reuse or underground storage. For the purposes of this report, the definition of desalination is limited to removing salts from brackish water and seawater to produce potable water. The amount of salt in water is usually described by the concentration of total dissolved solids (TDS) in the water. TDS refers to the sum of all minerals, metals, cations, and anions dissolved in water. Water that contains significant amounts of dissolved salts is called saline water, and is expressed as the amount (by weight) of TDS in water in mg/L. More than seventy elements are dissolved in seawater, but only six elements make up greater than 99 percent (by weight). These major elements occur as electrically charged ions. Table 1 shows the approximate composition of typical seawater by weight and concentration. Seawater is a solution of salts of nearly constant composition. Table 1. Composition of Seawater