water quality - envireau water - envireau water · •bottled mineral water –mineral water...

© Envireau Ltd 2015 © Envireau Ltd 2015

Water Quality with emphasis on inorganic chemistry

David Banks Holymoor Consultancy Ltd

© Envireau Ltd 2015

Folkefiende

I tell you-the gravest possible danger to the

public health! All the nastiness up at Mølledal,

all that stinking filth, is infecting the water in the conduit-pipes leading to

the reservoir; and the same cursed, filthy

poison oozes out on the shore too-

Henrik Ibsen: An Enemy of the People (1882)

En Folkefiende


Water quality

• The characteristics of a water, in relation to its suitability for a proposed use.

• A water may be of excellent quality for a one use, but poor quality as regards another...


Water quality

What parameters are relevant for the following uses ? • Human potable water

– drinking water regulations

• Ground source heating scheme – temperature, dissolved gases, particles, iron

• Agriculture – depends on crop; nitrate, boron, temperature?, salinity

• Laundry – hardness, colour, Fe, Mn

• Bottled mineral water – mineral water regulations, market appeal

• Industrial cooling water, boilers – hardness, salinity


Water quality parameters

• Microbiological

• Physical

• Aesthetic

• Organic chemical

• Inorganic chemical

• Radiological


Water Quality in Norway

• In around 1990, it was accepted that 100,000 to 300,000 working days were lost per year due to waterborne infection (population c. 4.3 million)

• In 1993, 25% of population received water of unsatisfactory quality

From Kuusi et al. (2003) Incidence of gastroenteritis in Norway – a population-based survey. Epidemiol. Infect. 131: 591-597


•Bacteriological non-compliance studied at 169 waterworks based on bedrock groundwater (largely untreated)

•50% had frequent or infrequent non-compliance regarding coliform bacteria

Sylvi Gaut (1999-2005) Drinking water wells in bedrock: Factors influencing microbiological quality. PhD. Department of Geology, Norwegian University of Technology and Science

DOG-NUTS


Seasonality (these diagrams from Norway) (agriculture during summer, followed by autumn rains)


Microbiology

• Microbiological – protozoa (Cryptosporidium, Giardia, amoebae) – bacteria – viruses – prions – biofilm-forming bacteria

• There are way too many potentially pathogenic species to analyse them all. We thus focus on indicator organisms... (e.g. of faecal contamination)

– e.g. faecal coliforms for pathogenic bacteria – e.g. Clostridium perfringens for protozoa (more resistant to

disinfection) – bacteriophages (e.g. coliphages) as indicators of viral

contamination


Bacteria

• Total heterotrophic plate counts (THPC) are not necessarily good indicators of microbiological water quality. It is a good indicator of disinfection efficiency.

• Faecal bacteria are a better indicator of faecal contamination or pathogenic potential

– Faecal coliforms

– Faecal streptococci

– E. coli

• E.coli

– Lives in mammalian gut.

– E.coli and similar bacteria comprise only 0.1% of gut flora.

– Are mostly harmless or even beneficial.

– Can survive for short time out of body. Transmitted by faecal-oral route.

– A very few strains can be pathogenic

E. coli. Public domain image


Protozoa: Giardia and Crytosporidium

• Ability to encyst. Periodically shed in faeces from domestic and wild and animals. Cysts or oocysts survive for prolonged periods (weeks or months)

• Cause gastrointestinal disorders. Pose a severe risk to immuno-compromised individuals.

• Rather resistant to chemical disinfection and sand filtration

• UV disinfection or membrane filtration can remove / inactivate oocysts Giardia: cyst diameter 8-12 µm. Giardia is the most common cause of

waterborne infection in the USA.

Cryptosporidium. Oocysts diameter 4-6 µm. 1993 outbreak in Milwaukee affected c. 400,000 people and cost over 96 million USD

Public domain image: CDC / Janice Carr / Stan Erlandsen Public domain image: CDC / Scale bar = 5 µm

Giardia Cryptosporidium


Biofilms on rock walls – Hvaler tunnel


Gallionella biofilm cultivated on glass slide suspended in hard rock borehole


Physical Parameters

• Temperature – ground source heat

– agriculture

• Turbidity / Suspended solids – abrasion

– aesthetics

– well design and land stability

– 2 mg/L x 50 L/s = 100 mg/s

= 8.64 kg/d = 3.2 tonnes per year

http://www.watermonitoringequip.com


Well collapse in Drammen, Norway

"geologists are going to go and look at the hole"


Physical Parameters

• Electrical conductivity – indicator of salinity

– corrosivity

• Redox potential – may be an indicator of other “problem parameters” (iron, H2S, taste)

– may be an indicator of corrosivity

– “master variable” controls solubility of many other species (e.g. Fe, Mn, Ra, Ba, U)

• pH – may be an indicator of corrosivity

– “master variable” controls solubility of many other species (e.g. Al, Fe, Mn, Ca, CO2)


Note that, for many field parameters, it’s really important to analyse on site

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7

pH Field

pH

Lab

0

1

2

3

0 1 2 3

Alkalinity (meq/l) Field

Alk

alin

ity (

meq

/l)

Lab

Data from Sheephouse Wood mine water discharge, South Yorkshire

pH and alkalinity decrease on storage due to oxidation and hydrolysis of iron

4Fe2+ + 10H2O +O2 ↔ 4Fe(OH)3 + 8H+


Throughflow cell

• To ensure minimal contact with the atmosphere, pumped water is often directed through a sealed cell, containing electrodes….

From “Water Wells and Boreholes” by Misstear, Banks and Clark (2006)


Field “laboratories”


Aesthetic parameters

• Odour – e.g. rotten egg smell caused by H2S

• Colour – may indicate surface water influence (humic acids)

– may be related to iron / manganese

• Dissolved gases

• Taste


There’s nothing more irritating than negotiating with a village elder for access to his well....arranging a tank truck....calculating the amount of chlorine to add to the tanker....


...installing a nice shiny PVC bladder tank....


...and looking forward to distributing water to waiting refugees...

Photos by Dave Banks, Chad, 2004


Inorganic Water

Chemistry

We’ve heard some scare stories from Norway in the 1990s.

BUT

A recent survey (Banks et al. 2015, Flem et al. 2015) found that, for inorganic chemical quality of public European tap water

•for most parameters a 99% (or better) degree of compliance was achieved. •1% non-compliance in EU member states for arsenic (1.6% when samples from non-EU states are also considered) •0.6% non-compliance in EU member states for sodium (1.0%) •0.2% 1% non-compliance in EU member states for uranium

Banks, D., Birke, M., Flem, B. & Reimann, C. (2015). Inorganic chemical quality of European tap-water: 1. distribution of parameters and regulatory compliance. Applied Geochemistry, 59, 200-210. doi: 10.1016/j.apgeochem.2014.10.016 (first published online 31 October 2014) Flem, B., Reimann, C., Birke, M., Banks, D., Filzmoser, P. & Frengstad, B. (2015). Inorganic chemical quality of European tap-water: 2. Geographical distribution. Applied Geochemistry, 59, 211–224. doi: 10.1016/j.apgeochem.2015.01.016

http://dx.doi.org/10.1016/j.apgeochem.2014.10.016



A Lot of Processes Conspire to Determine the Chemical Fingerprint of a Water Sample

Rainfall

Water-mineral reaction in unsaturated zone

Interaction with soil and vegetation

Water-mineral reaction in saturated zone

Mixing with deep groundwater near borehole

Water treatment Use

Contamination (bacteria, NO3

-)


Rainfall chemistry

H and O isotopes Nitrate, sulphate Oxygen Sodium and Chloride

•Concentrations of marine salts increase with proximity to the coast.


Soil zone and vegetation: evapoconcentration and CO2 generation

Rainfall

Cl = 4 mg/L

1 L

Evapotranspiration 60%

Cl = 0 mg/L

0.6 L

Recharge

0.4 L

Cl = 4 mg

Cl = 10 mg/L

Soil

and a lot of CO2


Water-rock interaction

Acid-base reactions (reactions using up CO2)

CaCO3 + CO2 + H2O Ca2+ + 2HCO3-

Calcite + carbon dioxide + water = dissolved cations + alkalinity

2NaAlSi3O8 + 2CO2 + 3H2O 2Na+ + 2HCO3- + Al2Si2O5(OH)4 + 4SiO2

Feldspar + carbon dioxide + water = dissolved cations + alkalinity + silica + clay

Redox reactions (reactions using up O2)

Oxidation of organic matter

CH2O + O2 CO2 + H2O HCO3- + H+

Oxidation of pyrite

2FeS2 + 2H2O + 7O2 2Fe2+ + 4SO42- + 4H+


Contamination and mixing

Contamination -nitrate from agriculture / land use -nitrate / bacteria from latrines / septic tanks -industrial chemicals

Shallow groundwater: oxic, Ca-HCO3, nitrate, vulnerable to pollution

Deep groundwater: anoxic, saline (Na-Cl or Na-HCO3), no nitrate, H2S, methane, iron, manganese

Sea water intrusion

Na-Cl-SO4

Sea

Mixing & reaction

Run-in of surface water via well-head


Typical natural water composition

Net result – Consumption of O2 and CO2

– Increase in pH, alkalinity

– Release of base cations (Ca2+, Mg2+, Na+, K+)

– Mixing with Cl- and SO4=

from deep brines or marine salts

Thus, the major ions in most groundwaters are dominated by

Cations

Ca2+

Mg2+

Na+ K+

HCO3-

Cl-

SO42-

NO3-

Anions

Ca2+

Mg2+


Presentation of hydrochemical data Pie diagrams

If good ion balance, the cations and anions should form 180° of the pie each…

Borehole 2

Na+

K+

Ca++Mg++

SO4=

NO3-

Cl-

F-

Alkalinity


Major Ion Chemistry is also important for practical purposes

Iron normally exists in water in its

reduced ferrous (Fe2+) form

on contact with oxygen, it oxidises to its insoluble ferric (Fe3+) form

which then reacts with water to produce ‘ochre’ flocs / precipitate

Fe3+ + 3H2O = Fe(OH)3 + 3H+

Note that bacterial biofilms may be involved

in some iron clogging problems

Fe2+ Fe3+ O2

=

http://www.filtersfast.com/forums/whole-house-water-filter-systems/863-whole-house-iron-filter.html

http://www.h2oequipment.com/water-problems/iron-bacteria/



Manganese normally exists in water in its

reduced Mn2+ form

on contact with oxygen, it oxidises to its insoluble black dioxide

Mn2+ MnO2 O2

=



Alkalinity

is the sum of alkaline species in water

[ ]

it describes the buffering capacity of the water (to withstand acidification)

At high pH and Ca2+ can contribute to calcite scale formation

Hardness is the sum of calcium and

magnesium in water (meq/L)

calcium and magnesium react with stearates in soap and prevent it from scumming

can also contribute to scaling

Ca2+ Mg2+ HCO3-

CO3=

OH-

Ca2+ + HCO3- + OH- = CaCO3 + H2O



i.e. determining whether the water will cause scaling or corrosion:

Langelier Saturation Index (LSI) and Ryznar Saturation Index (RSI) are calculated using Ca, HCO3, pH and temperature and predict tendency for calcium scaling

Larson-Scold Corrosion Index (LSCI) is calculated using Cl-, SO4= and alkalinity

and predicts tendency for corrosion of mild steel

Abesser et al. (2014) Mapping suitability for open-loop ground source heat pump systems; a screening tool for England and Wales, UK. Quarterly Journal of Engineering Geology and Hydrogeology 47:373-380


Water Treatment

• Did you know that most of UK’s water is dosed with phosphate to suppress plumbosolvency?

• No, neither did I !

Flem, B., Reimann, C., Birke, M., Banks, D., Filzmoser, P. & Frengstad, B. (2015). Inorganic chemical quality of European tap-water: 2. Geographical distribution. Applied Geochemistry, 59, 211–224. doi: 10.1016/j.apgeochem.2015.01.016



A hydrochemical fingerprint

=


...and, of course, water chemistry is important for health

A study in 1996-98 of Norwegian (mostly) private hard-rock boreholes

– 13.9% exceed the recommended action level for radon (500 Bq/L in Norway at that time)

– 16.1% exceed the drinking water norm for fluoride (1.5 mg/L)

– Considering pH, sodium, radon and fluoride together, 29.9% of all wells violate drinking water maximum concentrations for one or more of these parameters.

– 12% exceeded the WHO provisional guideline level of 30 µg/L for uranium

Banks, D., Frengstad, B., Midtgård, Aa.K., Krog, J.R. & Strand, T. 1998. The Chemistry of Norwegian Groundwaters: I. The Distribution of Radon, Major and Minor Elements in 1604 Crystalline Bedrock Groundwaters. The Science of the Total Environment, 222, 71-91. 2000 Frengstad, B., Midtgård Skrede, Aa., K., Banks, D., Krog, J.R. & Siewers, U. 2000. The chemistry of Norwegian groundwaters. III. The distribution of trace elements in 476 crystalline bedrock groundwaters, as analysed by ICP-MS techniques. The Science of the Total Environment, 246, 21-40.


Fluoride

• Typical drinking water limit = 1.5 mg/l

• Excessive consumption can lead to dental or skeletal fluorosis in humans or cattle

• Sources: fluorite, apatite, some aluminosilicates (amphiboles)

• Characteristic of granites, gneisses and other metamorphic rocks, tuffs/volcanics (but not only these).

• Also found in many lithologies under low Ca, high pH conditions. May be concentrated by evaporative processes

Treatment: •Change of usage habits: avoid F-rich water for young children, avoid supplements •Low tech: Adsorption onto laterite-based ceramics, fish bone-ash •Small scale: Reverse osmosis, anion exchange •Large scale: co-precipitation with alumina / Nalgonda method


Uranium

Not as rare (or as toxic) as you might think!


Uranium

•Very soluble under oxidising conditions. •In Scandinavia, can get high concentrations especially in granites and acidic metamorphic rocks •Over 20 mg/L have been reported in groundwater from Finland •Elsewhere, can occur in a variety of lithologies •Is susceptible to evapotranspiration •Can be derived from apatite (amongst other sources) and apatite derived fertilisers may be a source of U

Frengstad, B.S. & Banks, D. (2014). Uranium distribution in groundwater from fractured crystalline aquifers in Norway. In: Sharp, J.M. (ed.) “Fractured Rock Hydrogeology”, International Association of Hydrogeologists Selected Papers, 20, 257-276. CRC Press/ Taylor & Francis, London. ISBN 9781138001596. doi: 10.1201/b17016-17.

N=476 Norway

http://dx.doi.org/10.1201/b17016-17

http://dx.doi.org/10.1201/b17016-17

http://dx.doi.org/10.1201/b17016-17


Uranium

•Very long half-life, so not very radioactive •Eventually degrades radioactively to radium and thence uranium •Chemotoxicity probably exceeds radiotoxicity

– No drinking water limit in EU – 20 µg/l in Canada – 30 µg/l in USA (USEPA) – 30 µg/l = WHO provisional

guideline – 10 µg/L in Germany

(Umweltbundesamt) – 15µg/L in Sweden

Livsmedelsverket (recommended)


Mo

dif

ied

fro

m U

.S. G

eolo

gic

al

Surv

ey

The uranium-238 decay series

Radon gas 3.8 days half-life

Radon progeny: solid and short-lived polonium, bismuth, and lead isotopes

Radium-226

Uranium


Radon (222Rn)

Part of Uranium-238 decay series

A radioactive gas which is moderately soluble in cold water (222 mL per L at 20°C)

A noble gas essentially non-reactive

A dense gas - 9.73 kg/m3 at STP (air = 1.217 kg/m3)

Decays by -particle emission with a half-life of 3.8 days

The leading cause of lung cancer next to smoking

Radon is found in rocks rich in radium.

Because radium behaves very differently (chemically) from uranium...

...there is not necessarily a very close correlation between uranium and radon in rocks


For the treatment of: Gout

Rheumatism Arthritis

Nephritis Arterio-sclerosis

Diabetes etc etc


Those were the days, my friend….

“All the next day the family is provided with two gallons of real, healthful radioactive water . . . nature's way to health….”

“Vita Radium suppositories. Recommended for sexually weak men. Also splendid for piles and rectal sores”

“Die Zellen werden mit neuer Lebensenergie geladen, die Bakterien in ihrer zerstörenden Wirksamkeit gehemmt.”

“mmm…chocolate”


Radon

•Norwegian domestic water limit = 500 Bq/l

•De-gasses inside the home via showers, washing machines etc.


Concentr

ation

Perc

entile

Rn Bq/L %

Radon in Norwegian crystalline bedrock groundwater: n=1326

Maximum recorded value 32,000

Bq/l in Iddefjord granite in an area

covered with thick marine clay


Radon Guidelines

COUNCIL DIRECTIVE 2013/51/EURATOM:

• The long-lived decay products of radon are included in the evaluation of Total Indicative Dose as defined in the Drinking Water Directive (Council Directive 98/83/EC) (0.1 mSv/year)


DWI Recommendation


Hazard Maps . Report 24/3/15


Radon: Water Treatment

•Relatively simple: – aeration

– plus storage to allow daughters to decay

– filtration (activated carbon / RO) to remove residual daughters

– Better ventilation in home

– Wear a gas mask in the shower

http://www.awqinc.com/clearadon_works.html


Thanks for your attention

Thanks to: Bjørn Frengstad as co-author in a recent Geological Society talk on radon (from which some slides are taken) and the Sedatives® (new album soon to be available through several semi-reputable outlets)

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