PAC dosing for taste and odour removal.
WHO review of alternative disinfectants.
WHO has published a series reviewing
the state of the knowledge on the application, efficacy and toxicity of bromine, iodine and silver as drinking-water disinfectants.
Evaluation of corrosion indices
A recent paper evaluated the relevance of 10 known corrosion indices
according to their estimate of corrosion rate and iron particle release for 20 different water qualities. None of the indices properly predicted the level of risk associated with each water and corrosion and particle release were not correlated. Two novel indices were developed to predict the corrosion and particle release risks independently of each other.
Human infectious Cryptosporidium risk in drinking water supply catchments
An Australian paper reports on analysis of 962 samples
, taken during rainfall run-off conditions from 9 water supply reservoir locations, for Cryptosporidium
oocysts. 23 Cryptosporidium
species were detected, the most common being C. parvum
which was found in 23% of samples. Average infectivity of isolates was 18% with a maximum of 65.4%. The authors suggest that inclusion of measured infectivity and human pathogenicity data into a quantitative microbial risk assessment (QMRA) could reduce the source water treatment requirements by up to 2.67 log removal values.
Water fluoridation found safe and effective
Public Health England has published a report
comparing data on the health of people living in areas of England with differing concentrations of fluoride in their drinking water supply. The report concludes that water fluoridation is an effective and safe public health measure to reduce the frequency and severity of dental decay, and narrow differences in dental health between more and less deprived children and young people. It says that there is no convincing evidence of higher rates of hip fracture, Down’s syndrome, kidney stones, bladder cancer, or osteosarcoma (a cancer of the bone) due to fluoridation schemes. Although Dental fluorosis, at a level that may affect the appearance of teeth, was observed in 10% of children/young people examined in 2 fluoridated cities , there was no difference between children and young people surveyed in fluoridated and non-fluoridated cities when asked about their opinion on the appearance of their teeth.
Plastic particles in bottled water
There has been considerable media interest in the findings of a non-peer reviewed paper
, issued only as a press release and not in a recognised journal, which found traces of plastic particles in 93% of 259 bottles of packaged drinking water. The average count of plastic particles was 335/litre.
Recycled water scores best in taste test.
In a study in water stressed California
water preferences of 143 participants for one name-brand bottled water, one groundwater-sourced tap water, and one indirect potable reuse (IDR) water were assessed. (The IDR water is derived from groundwater into which reverse osmosis treated wastewater has been introduced). In blind tastings with 143 participants, the more nervous, anxious people in the study expressed the preference for IDR and bottled water, and were more negative about the more mineral-rich tap water. People more open to new experiences liked the three samples about the same
Heavy metal removal from water
A recent paper describes the development of a cheap, water stable metal–organic framework/polymer composite
, Fe-BTC/PDA, that exhibits rapid, selective removal of large quantities of heavy metals, such as Pb2+
, from real world water samples The material is further shown to be resistant to fouling when tested in high concentrations of common organic interferents, like humic acid, and is fully regenerable over many cycles. The authors suggest that this new material could become highly influential for in-home or wastewater treatment technologies, particularly in the event of an impending water crisis.
Detection of cyber attacks in water systems
Water systems are increasingly dependent on computerised systems and are therefore vulnerable to cyber attack. A competition (batadal
) was organised to compare the performance of algorithms for the detection of cyber attacks in water distribution systems. Details of the winning algorithm have been published.
Detection and prevalence of human enteric viruses in water
Anyone interested in water virology should not miss a recent Open Access paper
which comprehensively summarises recent progress on research regarding waterborne human enteric viruses. It reviews methods for concentrating and detecting viruses in water and compiles existing data on abundance and genetic diversity of viruses in water. It also discusses the use and importance of process controls in evaluating the efficiency of virus recovery and level of inhibition during the detection process.
Double disinfection, and UV-LEDs for drinking water treatment
A new study shows that a combined disinfection treatment with chlorine and UV radiation
can be highly effective in water disinfection. Chlorination followedby UV was more effective against a range of bacteriophages than either treatment alone. The same study reports that UV LEDs were effective against the same bacteriophages.
Fast-acting antidote in sight for cholera epidemics
Online fluorescence spectroscopy for the real-time evaluation of the microbial quality of drinking water.
A consortium of workers from UK water companies and academics carried out a study
which concluded that fluorescent dissolved organic matter (DOM) is strongly correlated with E. coli
and total bacterial cell counts. It is also superior to turbidity as an indicator of microbial water quality. They conclud3e that despite some limitations online fluorescent DOM sensors are a better indicator of the microbial quality of untreated drinking water than turbidity.
Direct pathogen detection in contaminated surface water
Workers in the USA studied a watershed
in which fecal coliforms have improved substantially in the watershed since its listing as a 303(d) impaired stream in 2002 and are now near United States recreational water criterion standards. Using molecular techniques they were able to detect
viruses (bocavirus, hepatitis E and A viruses, norovirus, and enterovirus G), bacteria (Campylobacter
spp., enterohemorrhagic and enterotoxigenic Escherichia coli
, uropathogenic E. coli
, Enterococcus faecalis
spp., and Vibrio
spp.), and eukaryotes (Acanthamoeba
spp., Entamoeba histolytica
, and Naegleria fowleri
. Comparison of the stream microbial ecology with that of sewage, cattle, and swine fecal samples revealed that human sources of fecal contamination dominate in the watershed.
Simple arsenic sensor
A hand-held sensor to measure arsenic levels in water
has been developed by researchers at University College London (UCL) and Imperial College London, with funding from BBSRC. The sensor uses a modified arsenite oxidase enzyme from E.coli. The small, sensitive and accurate sensor produces an immediate measure of the arsenic level in water, at a cost of less than $1 per test. This makes it suitable for testing multiple sites in rural areas in low and middle income countries, where the problem of arsenic poisoning from contaminated drinking water is greatest, and potentially saving lives. (patent application
Efficiency programmes best strategy for water security
Combatting water shortage such as is affecting Capetown in South Africa by capital works takes a long time and cannot solve immediate crises. A recent article in Source magazine
argues that water efficiency measures can prove a more immediate solution. On the basis of cubic metres gained, water efficiency programme investments are much cleaner, cheaper, faster and fairer than building new supplies. Australia learned this lesson during its 10-year Millennium Drought. Building new dams would have cost US$1,370 per Megaliter (/Ml) of water delivered. By contrast, the same Ml could be added by plugging leaks in the network at a cost of only US$365/ Ml and the country gained additional supplies by replacing high flow plumbing fixtures for just US$454/ Ml, less than a third of the cost of developing new supply.
ATP for rapid water quality assessment
While FWR does not endorse commercial products, readers may be interested in a new test
which can indicate the microbial content of a clean water in 3 minutes. Water is filtered then any retained microbial cells are lysed and the ATP released is estimated using the luciferin/luciferase procedure. The same company offers a kit for determining coliforms and E.coli within 24 hours.
Legionella outbreak attributed to change in water supply source
A report on the Legionnaires disease out break in Flint, Michigan
attributes the outbreak to change of water supply source to the Flint River and consequent reduction in chlorine levels. The majority of the Legionalla
isolated from premises ( 16 of 18) were serogroup 6, which is not detected by the widely used urine test for legionella
Solar powered desalination
Researchers in Spain have developed a stand-alone system for desalinating and treating water through electrodialysis
. The system is directly powered by solar energy and can be applied in off-grid areas. The research group already has a pilot and demonstration plant able to generate a cubic metre of drinking water every day.
Importance of dechlorination of drinking water samples for bacteriological analysis
Results have been published of a simple laboratory and field test study which confirm the importance of sodium thiosulphate dechlorination
of bacteriological samples. All samples held without sodium thiosulfate had lower bacteria counts than comparable dechlorinated samples. In addition chlorinated water supply samples held without sodium thiosulfate had an 87.5% false negative rate.
Yorkshire Water to plant 1 million trees
Yorkshire Water has announced plans to plant 1 million trees
as part of the creation of the Northern Forest . T he Company says that planting trees in the right place will help to slow the flow of water during potential flood events, mitigate carbon emissions and boost wildlife. Although not claimed, the trees could have a beneficial effect on water quality particularly in upland reservoirs.
Novel toxicity biosensor
Workers at the University of Bath are developing a novel microbial fuel cell
capable of responding to toxicants in water. The device is fabricated by screen-printing carbon-based electrodes onto a single sheet of paper. It is membrane-less, as the paper substrate itself acts as the separator between the two electrodes. The device is fully biodegradable. The device has been evaluated using formaldehyde as the toxicant but it is expected to respond to a range of other toxicants.
Direct potable re-use
A recent review
(paper)describes long-term experience of direct potable reuse (DPR) in Windhoek, South Africa (48 years) which shows that treated domestic sewage can be safely and cost-efficiently utilized for potable reclamation (0.72 €/m3). A multiple barrier strategy is employed in order to attain the highest possible safety levels. Although most potable reuse schemes are indirect (IPR) and involve groundwater recharge or reservoir augmentation, the discharge of treated wastewater ro rivers subsequently abstracted for potable treatment has been a longstanding practice. A few other DPR schemes are in existence but invariably involve feeding the treated wastewater to conventional treatment works. DPR is likely to increase as populations increase and WHO has issued guidance for future schemes. (WHO Guidance
Priming of rapid sand filters to enhance nitrification
Danish workers have shown that nitrifying communities in new rapid sand filters could be enriched
by microbiomes from well-functioning rapid sand filters in waterworks and that the enriched nitrifying consortium could be used to inoculate fresh filters, significantly shortening the time taken for the nitrification process to start.
Low Energy Desalination
A recent letter in Environmental Science and Technology Letters
describes a novel desalination process for brackish water which has lower energy requirements than conventional techniques. The procedure does not require any regeneration stage but is not suitable for seawater higher salt sourcers such as seawater.
Impact of changing source of water supply – United Utilities, Copeland
DWI has published its assessment of an incident in Cumbria in June 2017 in which large numbers of consumers were concerned by noticeable changes in their drinking water supplies. The area affected was supplied with soft surface-derived water from Ennerdale but in 2009 its licence to abstract was reduced and it became necessary to obtain additional supply. Four boreholes were licenced to provide the additional supplies although these provided much harder water. Commissioning trials of these boreholes were commenced in May 2017. wherupon many consumers began complaining. Although supplies remained safe the Company was remiss in not informing consumers of the changing supply which resulted in widespread concern. The supply was deemed unwholesome as it breached the Taste and Odour requirements of the Regulations. DWI made several recommendations but concluded that enforcement wqs not required at this time.