Aalto University
School of Engineering
Yhd-12.3090 Sustainable Technologies Studio: Facing Local and Global Challenges P
LABORATORY REPORT
Analysis of water in ”20 de Noviembre” in Campeche, Mexico
16-21.4.2015
Contents 1 Introduction ............................................................................................................................................................. 3 2 Theory...................................................................................................................................................................... 4 3 2.1 Calcium in drinking water ................................................................................................................................ 4 2.2 Nitrate in drinking water.................................................................................................................................. 4 2.3 Ammonia in drinking water ............................................................................................................................. 4 2.4 Total Dissolved Solids in drinking water .......................................................................................................... 4 2.5 Sodium in drinking water................................................................................................................................. 4 2.6 Turbidity in drinking water .............................................................................................................................. 4 Methods and equipment ......................................................................................................................................... 5 3.1 Equipment in the field laboratory in El 20 ....................................................................................................... 5 3.1.1 Aalto’s equipment.................................................................................................................................... 5 3.1.2 Tec’s equipment....................................................................................................................................... 5 3.2 Equipment in Finland ....................................................................................................................................... 5 4 Results...................................................................................................................................................................... 6 5 Conclusions .............................................................................................................................................................. 9 6 References ............................................................................................................................................................. 10 1 Introduction
The goal of this lab report is to describe the methods and present the results of water analysis that was made
to water samples collected from a community called “20 de noviembre” or “EL 20” in the state of Campeche
in Mexico. Samples were taken from wells, rainwater collection tanks, water storage tanks and surface water
and tested in a field laboratory in the community.
Before the analysis was made, quality issues of the water were known to some extent, and the hypothesis for
the main reason for bad water quality was calcium, so it was one of the qualities tested. Apart from calcium
the water samples were also tested for pH, temperature, total dissolved solids, salinity, conductivity, nitrate,
ammonium and turbidity. 14 samples were also tested in the water laboratory in Aalto University. They were
tested for hardness, pH, total dissolved solids, salinity, conductivity, NPOC and E. Coli/Coliform bacteria.
In this report the equipment and methods we used will be presented along with World Health Organization’s
(WHO) recommendations for the amounts of some of the tested qualities in drinking water. The results from
the analysis will be presented and then some conclusions of the water quality in the community will be
drawn.
An important detail to take into consideration when interpreting the results, is that the samples were taken
during April, which is one of the driest months in the region along with May, before the rain season starts in
June.
The
last
rain
in
the
community
had
been
several
months
before.
2 Theory
2.1 Calcium in drinking water The amount of calcium in drinking water worldwide, differ depending on what the source of the water is.
According to WHO’s publication “Calcium and Magnesium in Drinking-water, Public Health Significance”
from 2009, although there are no clear lower or upper limits for recommended daily intake of calcium, there
is no clear evidence that an excess intake of calcium has a negative impact on the human health. In the
publication a greater concern is the quite common insufficient intake of calcium. (WHO, 2009)
2.2 Nitrate in drinking water The guideline value for nitrate in drinking water is 50 mg/l according to WHO’s report “Nitrate and nitrite in
drinking-water” from 2011. To infants and unborn foetuses high doses of nitrate can cause a condition called
methaemoglobinaemia, which causes disturbances in the transport of oxygen in the blood. The source of
nitrate in the ground water can be e.g. animal manure or septic tanks. (WHO, 2011)
2.3 Ammonia in drinking water Naturally occurring ammonium concentration in groundwater is from under 0,2 mg/l up to 3 mg/l. Higher
amounts than these indicate faecal pollution of the water source. Ammonium in amounts that could be
harmful to human health is not likely to be found in drinking water, so no limits have been set to ammonium
concentration in drinking water. (WHO, 2003 (1))
2.4 Total Dissolved Solids in drinking water Total dissolved solids, or TDS mainly affects the taste of the water. The effects on health depends on the
substances that form the TDS, but the upper limit of TDS, after which the taste of the water becomes
unacceptable for drinking is 1200 mg/l. (WHO, 2003(2))
2.5 Sodium in drinking water The taste threshold for sodium chloride in water is 150 mg/l. The main source of sodium chloride for
humans is food, so there is no specific limit for it in drinking water. (WHO, 2003 (3))
2.6 Turbidity in drinking water Turbidity is the measurement of the cloudiness of water. In itself it does not cause health related problems,
but when turbidity is above 5 NTU it is noticeable and affects the desirability of the water. If the water is
purified with chlorine, the turbidity should be under 5 NTU, ideally under 1 NTU, to guarantee an efficient
chlorination. (WHO, Fact sheet 2.33)
3 Methods and equipment
3.1 Equipment in the field laboratory in El 20 3.1.1 Aalto’s equipment We took with us from Finland to Mexico an in situ testing equipment, which can measure the salinity,
conductivity, total dissolved solids and temperature of a water sample. The equipment is named WTW Cond
340i and it is a small handheld meter with an attached sensor. The sensor is put into the sample, and the
results can be read from the meter’s screen immediately. The meter was calibrated in Finland, and did not
need to be calibrated during our trip.
We also took some pH-Indicator paper Dosatest from Finland to measure the pH of the samples.
3.1.2 Tec’s equipment The equipment we got to take with us from Mexico City was a kit that contained a lot of different ion
specific sensors for different measurements. The kit is called LabQuest 2, and the water qualities that we
measured with it were turbidity, conductivity, ammonium, nitrate and calcium. The sensors had to be
calibrated every time before we started measuring, and after that every few hours.
3.2 Equipment in Finland The equipment that was used for 14 samples that were sent to Finland, were equipment in the water
laboratory in Aalto University Otaniemi campus. Tests that were performed in Otaniemi were hardness, pH,
Total dissolved solids, salinity, conductivity, NPOC and E. Coli/Coliform bacteria. The equipment used for
the E. Coli/Coliform bacteria was the 3M Petrifilm Growth platform.
4 Results
Results from the water testing made in El 20 is presented in table 1.
Table 1. Results from water analysis in El 20.
The results from the calcium testing should not be considered to be fully accurate, since the calcium ion
specific sensor malfunctioned during the whole analysis. The concentration should not be taken literally, but
the information that can be used, is the relationship between different samples, which sample has a higher
concentration and which has a lower concentration of calcium.
A map of the village is shown in figure 1 along with how the community was divided for the samplings in
figure 2.
Figure 1. Map of El 20.
Figure 2. Division of El 20 into sectors.
There was also tests made in Finland in the water laboratory in Aalto University by Senior Laboratory
Technician Aino Peltola, and their results are presented in table 2, table 3 and table 4.
Sample communal (1) river (1) G1 (!) C1A1 (1) C1A2 (1) C1/1 C1/3 C4/1 C4/2 volume ml EDTA-­‐
consumption ml hardness mmol/l hardness ⁰dH 50 50 50 50 50 25 20 20 20 2,620 30+ 4,912 60+ 2,069 30+ 30+ 35,706 0,932 0,524 -­‐ 0,9824 -­‐ 0,4138 -­‐ -­‐ 17,853 0,466 2,94 -­‐ 5,51 -­‐ 2,32 -­‐ -­‐ 100,16 2,61 Table 2. EDTA-consumption and hardness results, made in Aalto University.
The hardness values in table 2, that are just a -, were so high that they couldn’t be measured.
Sample river (1) river (2) communal (1) communal (2) C1A/1 (1) C1A/1 (2) C1A/2 (1) C1A/2 (2) G1 (1) G1 (2) C1/1 C1/3 °C 20,9 20,6 pH 7,41 7,41 TDS. (mg/l) OFL OFL SAL. 1,8 1,8 CON. 3,23 3,22 unit mS/cm mS/cm 21,2 10,5 144 0 132,7 µS/cm 21,2 21,3 20,9 20,8 20,8 21,1 20,7 21,1 21 10,55 7,51 7,87 8,41 8,29 8,37 8,26 7,54 7,7 148 OFL OFL 143 142 316 315 OFL OFL 0 1,9 1,9 0 0 0 0 1,8 1,9 136,1 3,48 3,4 132 128,6 289 290 3,27 3,44 µS/cm mS/cm mS/cm µS/cm µS/cm µS/cm µS/cm mS/cm mS/cm C4/1 C4/2 21,3 21,5 7,22 6,6 OFL 90 1,8 0 3,2 82,4 mS/cm µS/cm Table 3. Other results from analysis made in Aalto University water laboratory.
Sample Communal River G1 (1) C1A/1 (1) C1A/2 (1) NPOC 3,225 3,632 2,192 10,21 1,965 Table 4. NPOC results, also made in the water laboratory in Aalto University.
Tests for E. Coli and coliform bacteria were also made in Aalto University’s Water laboratory. The results
were that E. Coli and/or coliform bacteria can be found in all the samples that were tested in Aalto
University, except the sample taken from the communal rainwater collection tank. The bacteria test of
sample C1/3 is shown in figure 3. The black/metallic parts are E. Coli bacteria, the red parts are coliform
bacteria.
Figure 3.Test for E. Coli and Coliform bacteria.
5 Conclusions
According to the results from the analysis, things that would require further investigation and clarifying
based on the findings and the potential health risks are the nitrate, ammonium and the E. Coli/coliform
bacteria. These all indicate that there is faecal contamination in the water, and they also pose as a risk to
human health by themselves (E. Coli/coliform bacteria and nitrate) or by making the cleaning of the water
harder (ammonium).
It could be investigated how the septic tanks in El 20 work, how the groundwater is moving and what kind
of habits people have in cleaning their wells and containers and how they treat the water before using, if at
all. Also a broader analysis of the bacteria in different water sources should be a following step.
Josefina Mena-Abraham, an expert in sanitation, promised that she will provide Aalto Lab Mexico with an
equipment to test for bacteria in situ. This is something that ALM 2016 should take into consideration.
6 References
World Health Organization, Ammonia in drinking-water. Background document for development of WHO
Guidelines
for
Drinking-water
Quality.
2003
(1).
Available:
http://www.who.int/water_sanitation_health/dwq/ammonia.pdf
World Health Organization, Calcium and magnesium in drinking-water: Public health significance. 2009.
Available: http://whqlibdoc.who.int/publications/2009/9789241563550_eng.pdf
World Health Organization, Nitrate and nitrite in drinking-water. Background document for development of
WHO
Guidelines
for
Drinking-water
Quality.
2011.
Available:
http://www.who.int/water_sanitation_health/dwq/chemicals/nitratenitrite2ndadd.pdf
World Health Organization, Sodium in drinking-water. Background document for development of WHO
Guidelines
for
Drinking-water
Quality.
2003(3).
Available:
http://www.who.int/water_sanitation_health/dwq/chemicals/sodium.pdf
World Health Organization, Total dissolved solids in drinking-water. Background document for
development of WHO Guidelines for Drinking-water Quality. 2003 (2). Available:
http://www.who.int/water_sanitation_health/dwq/chemicals/tds.pdf
World
Health
Organization,
Fact
Sheet
2.33
Turbidity
http://www.who.int/water_sanitation_health/hygiene/emergencies/fs2_33.pdf
measurement.
Available: