risks and assessments of cyanotoxins in drinking water

Risks and Assessments of Cyanotoxins in Drinking

Water

Ruben Diaz Vazquez

CED 595.S30 Project Seminar

Stony Brook University

Risks and Assessments of Cyanotoxins in Drinking Water 2

Abstract

Cyanotoxins are bacteria that are harmful and can cause

potential death to living beings if contacted or ingestion of

contaminated water is taken. Some of the risks include

gastrointestinal symptoms, nausea, liver damage, neurological

symptoms and skin irritation. The issue involving these toxins

is that they have been found in drinking water and it has

prompted attention for scientists and environmentalists around

the world to take action. Drinking water treatment plants have

started to apply assessments methods like

coagulation/flocculation, oxidizing agents, activated carbon,

nanofiltration and ultrafiltration to remove cyanotoxins. Some

of these methods have not been efficient so enhancing them has

been alternative along with the development new assessment

techniques like fluorescence immunoassay and implemented

laboratory instrumentation like High Performance Liquid

Chromatography. The goal of many environmentalists and

scientists is to develop an efficient method for treatment

plants and provide the necessary information for the public

about cyanotoxins.

Keywords: cyanotoxins, drinking water, cyanobacteria, risks,

assessments


1. Introduction

In this century, the ongoing debate on environmental

awareness has become an issue. Topics such as climates change,

air pollution, renewable energy and others are discussed daily.

The search for better options is presented to improve the

situation and help younger generations embrace a better future.

Water contamination is a topic we might be familiar with due to

its importance as a resource for living beings.

Our drinking water before it reaches us for consumption

goes through a series of treatment steps that are provided from

the local water treatment plants. These steps one by one try to

remove any minerals, bacteria and natural toxins that can be

harmful to living beings if consumed. The situation with these

treatment facilities is that as efficient the steps may be,

studies have shown that they are not efficient in removing

certain bacteria and toxins. Toxins like cyanotoxins, which come

from cyanobacteria, have proven to be a problem that needs

attention and awareness to the general public.

There are different types of cyanotoxins, and each one

presents different risks depending on the type of bacteria. Some

of the risks that studies have shown include neurological,

digestive and skin rashes after consumption of drinking water.

Scientists are teaming up with water treatment facilities to


assess this growing situation and to provide solutions to

eliminate the threat of these natural toxins. Different methods

are being tested to diagnose and control this issue. The goal is

to incorporate these methods into the treatment steps of the

water treatment facilities. Some of these steps include

coagulation/flocculation, the use of fluorescence, oxidizing

agents and learning the maximum tolerable values of water.

The goal of this paper is to provide the public with the

information needed for awareness and knowledge on this

environmental issue. Removing cyanotoxins in drinking water is

the first step of many towards a future of clean water. To fully

understand the term cyanotoxins, the definition and the source

of origin must be addressed and explained in detail. After

understanding the term, we can address the risks and solutions

to this issue and spread the word to those who may not know

about it.

2. Literature Review

Westwick, Szlag, Southwell and Sinclair (2010) in their

review of cyanobacteria and cyanotoxins removal/inactivation in

drinking water focuses on how efficient the process of removing

cyanotoxins are with four different types of toxins. They

consider several factors for their argument, including the

intake and the structure of the cell. Other arguments follow on


how effective coagulation, oxidation, activated carbon, and

other known methods are in removal/inactivation of cyanotoxin in

water treatment plants. Further conclusion states the auxiliary

treatment barriers are important measures that should be

implemented for efficient removal/inactivation.

Ghernaout, Ghernaout and Saiba (2010) review on algae and

cyanotoxins focuses more directly on the treatment methods of

coagulation/flocculation. The review goes in depth of how

coagulation works and how efficient has been throughout the

years. Advance methods of coagulation are mentioned as an

improvement to the efficiency percentage in removing the

cyanotoxins. The review is an important source for information

on a treatment method that is well known and will be mostly used

throughout the years, as it has been the primary method for

water treatment plants to remove cyanotoxins.

The article “Cyanotoxin management and human health risk

mitigation in recreational waters” from Koreiviené, Anne,

Kasperoviciené and Burskyté (2014) gives out important

information on risks that cyanotoxins can cause on living

beings. Although it focuses on recreational waters, these risks

have been mentioned in other reviews if contaminated water is

ingested. The review provides a background on the types of risks

that cyanobacteria can cause such as neurotoxins, hepatotoxins,

cytotoxins, irritants and others.


Pantelic, Svircev, Simeunovic, Vidovic and Trajkovic (2013)

address in their review a recent cyanobacteria bloom in Serbia.

The review introduces characteristics of frequent cyanotoxins

and known treatment methods for the removal of them. It provides

an insight of how this issue is affecting other parts of the

world and how differently some scientists are approaching the

issue. Enhancing known treatment methods for more satisfactory

removal is the main focus of the review.

Also Kouzminov, Ruck and Wood (2007) address a risk

management in another part of the world in their article: "New

Zealand risk management approach for toxic cyanobacteria in

drinking water". They mention the impact that cyanotoxins have

had in the country and how it has changed treatment facilities

to improve their methods.

Ratnayake, Manatunge and Hapuarachchi (2012) provide in

“Dealing with algal toxins and dissolved organics in drinking

water” background information useful for readers that are not

familiar with this topic. The authors used a water supply in the

Eastern Province of Sri Lanka as a case study. The review

provides a section on background studies that provides

information on treatment methods that have been used to address

the cyanotoxins issue. The focus of the review is to provide

results of efficiency by enhancing methods that have been


implemented previously such as coagulation, oxidation and

activated carbon.

To add to their argument, Roegner, Brena, Gonzalez-Sapienza

and Puschner (2013) support the removal strategies and their

efficiency to remove cyanotoxins. Their review gives an insight

on the toxic effects and persistence that cyanotoxins have in

the water, especially microcystins, which background information

of them is provided in the following section. The review

supports strategies that others authors have mentioned and have

been already implemented in treatment plants. Their efficiencies

are discussed to provide the best option for maximum removal of

cyanotoxins in water.

Authors Triantis et al. 2010 implement laboratory systems

to monitor cyanotoxins in surface and drinking waters. Their

review examines and how effective using a High Performance

Liquid Chromatography (HPLC) can be to monitor and detect

cyanotoxins in water. The review can be categorized as

technical, but it provides information on alternative methods to

address the issue. Results show that laboratory methods can be

very efficient in monitoring and detecting cyanotoxins.

Kaushik and Balasubramanian (2013) provide methods and

approaches that are being used for detection of cyanotoxins.

They argue that current methods that used for routine are not

quite efficient in detecting all types of cyanotoxins. The


review compares between biological methods with analytical

methods to give the information of which is more efficient. The

review adds more depth on how efficiently current implemented

methods are and the importance of adding laboratory methods to

improve monitoring and detection of cyanotoxins in water.

Cheung, Liang and Lee (2012) provide more information on

problems, impact and the importance of public health on this

issue. Zamyadi et al. (2012) provide and support many other

authors in addressing cyanotoxins contamination in drinking

water plants as an environmental challenge.

3. Cyanotoxins

Cyanotoxins are natural toxins that are produced by

cyanobacteria. They are photosynthetic prokaryotes that date

back 3.5 billion years in evolution and adapt well in extreme

environment conditions (Kaushik & Balasubramanian, 2013). The

release of cyanotoxins occurs during cell life but mostly on

cell death of the algae through a passive flow process (Pantelic

et al., 2013). Westwick et al. (2010), state that over forty

cyanotoxins are toxic. Cyanobacteria develop in algae especially

the blue-green algae (Fig.1) that can be found in fresh water

ecosystems. Cyanobacteria are considered a water quality problem

around the world causing domestic animals poisoning, human

injury and deaths.


Fig. 1 Blue-green algae in the waters of Quingdao. Image taken from http://www.nysun.com/foreign/chinas-olympic-sailing-venue-beset-by-algae-bloom/80768/

Harmful algal blooms are formed mostly when an event of

large growth of algae occurs. This event occurs because of an

unstable environment. The accelerated eutrophication, which by

definition means the addition of phosphates and nitrogen of

freshwaters and human activity are the main causes for the

development of harmful algae blooms. Human activities such as

farming practices, usage of detergents and sewage runoff have

increased the nutrient levels in water reservoirs causing this

event to increase over the years (Pantelic et al., 2013). Over

50% of these algae blooms are considered toxins and they are

affecting lakes, reservoirs, rivers, streams, etc. It prompts

action in drinking water treatment plants to remove these toxins

from the water to avoid any related injuries.

To manage this ongoing situation treatment plants around

the world must know about the different species of cyanotoxins.


There are four species that are the most dangerous for living

beings. These are microcystins, saxitoxins, anatoxin-a and

cylindrospermopsin. Identifying their physical, chemical

properties, their patterns, and nature of growth is the key to

effective treatment.

3.a. Microcystins

Microcystins are the most frequent and studied cyanotoxins.

They originate from several cyanobacteria: Microcystins,

Anabaena, Planktothrix, Nostoc and Anabaenopsis. Microcystins

can persist inadequate levels of phosphorus and nitrogen in the

water. According to the Environmental Protection Agency (EPA),

2007, they can persist on temperatures of 5 to 30 degrees

Celsius and a pH in the range 6 to 9 (water has a pH of 7, which

is neutral in the pH scale). Most of these blooms occur during

late summer and early fall because of the higher temperatures in

the water. These cyanotoxins are nonvolatile, stable in sunlight

and hydrophilic (attracted to water).

The US EPA has added microcystins to the US EPA Contaminant

List III (Westwick et. al, 2010). The World Health Organization

(WHO) has established a drinking water guideline of one

microgram per liter for this cyanotoxin.

3.b. Saxitoxins

Saxitoxins are cyanotoxins that are associated with "red

tides". These "red tides" are a group of dinoflagellates that


can be found on algae blooms on the water. The name comes from

the red color these blooms have and gives out the illusion that

the water is completely red. These cyanotoxins release a strong

poison that is harmful mostly to shellfish. Humans that consume

these contaminated shellfish will be at risk of getting poisoned

as well. Countries around the world have established guidelines

for their drinking water to control this toxin, for example,

Australia has a guideline of three micrograms per liter for

their drinking water standard (Westwick et. al, 2010).

3.c. Anatoxin-a

Anatoxin-a is a common cyanotoxin and a very potent

neurotoxin. It poses a hazard to humans and animals if contacted

or ingestion of contaminated water is taken. The WHO does not

have a guideline in drinking waters for anatoxin-a but

scientists and environmentalists are recommending a guideline

concentration of one microgram per liter (Fawell et. al, 1999).

3.d. Cylindrospermopsin

The first discovery of cylindrospermopsin came from a case

of poisoning on a water reservoir in Australia. Considered one

of the most dangerous cyanotoxins, the EPA and WHO are currently

evaluating data that has been collected around the world to

determine a guideline for drinking water for this cyanotoxin. On

natural waters, this cyanotoxin is soluble. Human exposure


occurs by drinking water, doing recreational sports and food

consumption due to its high bioaccumulation in water systems.

Microcystins, Anatoxin-a, Saxitoxins and Cylindrospermopsin

are the most common and dangerous of cyanotoxins. The EPA has

included these and other cyanotoxins in their Contaminant

Candidate List (CCL). Also cylindrospermopsin, microcystins and

anatoxin-a are identified in the target list of toxins that pose

a health risk to water sources for drinking utilities in the

United States (Ratnayake et. al, 2012). Knowing the background

of these cyanotoxins is only the beginning of a bigger issue.

The next step is addressing the risks that these cyanotoxins

have towards living beings.

4. Risks of Cyanotoxins

Many risks have been linked to cyanotoxins in the past

years. There are different ways a living being can be exposed to

cyanotoxins. That is through consumption of fish or aquatic

organisms that could have been exposed to cyanotoxins, ingestion

of contaminated water and through recreational water sports

where the skin can be exposed to contaminated water. Exposure to

these toxins can trigger chronic toxicity on organisms that can

cause illness or death. The cyanotoxins are categorized in three

toxic groups, which are hepatotoxins, neurotoxins and

dermatoxins. It is important to have knowledge of all the


possible risks that these toxins can cause to be able to create

awareness and safety measures. Each one of the toxins can cause

a series risks that can have a hazardous effect on living

beings.

Microcystins are categorized under the toxic group of

hepatotoxins1. This cyanotoxin has been associated to cause liver

damage and in some cases it has caused liver cancer in

laboratory studies on animals. Reports on toxin effects

involving liver damage on humans have been minimal so far

(Ghernaout, Ghernaout & Saiba, 2010). Other risks that

microcystins can cause are gastrointestinal illness, severe

headache, pneumonia and myalgia (muscle pain). These symptoms

have been reported to occur after 4 to 24 hours of contact with

water.

Cylindrospermopsin is also a toxin that is categorized as

hepatotoxins. Symptoms that can occur after several days of

exposure are anorexia, nausea, headache, constipation, abdominal

pain, liver inflammation, fever and asthma. Continuous low-level

exposure can cause liver cancer (Koreiviené et al., 2014).

The risks associated with saxitoxins are categorized under

neurotoxins2. Symptoms can start to occur between 2 to 12 hours

1 Toxics that can cause damage or destruction to the liver. The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. 2 Poisonous complex that acts on the nervous system. ("Neurotoxin." Merriam-‐Webster.com. Merriam-‐Webster, n.d. Web. 18 Sept. 2014. http://www.merriam-‐webster.com/dictionary/neurotoxin)


and can cause death. According to Cheung, Liang and Lee (2012),

effects on toxicity include tingling, numbness, drowsiness,

burning, difficulty to speak, paralysis, which can all lead to

death. Saxitoxins are considered to be one of the most dangerous

cyanotoxins to date. A long-term effect is unknown to this day.

Anatoxin-a is also a neurotoxin where symptoms can occur

faster than saxitoxins. The time of occurrence for symptoms to

appear is 15 to 20 minutes after exposure. Anatoxin-a shows

symptoms that are similar to saxitoxins; only that anatoxin-a

can cause a long-term affect, such as cardiac arrhythmia that

could eventually lead to death.

Human exposure due to these risks has been well documented

throughout the years. In 1960, Buffalo Pound Lake had a case of

microcystins blooms that led to numerous deaths of cows and dogs

(Roegner et al., 2013). The year 1989, two army recruits fell

into the lake and swallowed water that contained cyanobacterial

blooms that led to them developing acute pneumonia and

gastrointestinal symptoms (Roegner et al., 2013). One documented

case that caused attention toward awareness of cyanotoxins in

drinking water was in 1996, when over a 100 patients developed

liver failure when they received water from a reservoir that was

contaminated. This happened in Caruaru, Brazil in a hemodialysis

center (Carmichael et al., 2001).


Many more cases have been documented throughout the history

of science and health. These cases are the ones that have helped

raised the necessary precautions and awareness to study these

risks and to find proper ways to assess them. The efficiency of

these assessments is the daily goal of every scientist and

environmentalist. Also, great skills of management techniques

must be implemented to make these assessments efficient at

removing these harmful toxins. Water treatment plants have

developed numerous assessment techniques and procedures to

remove cyanotoxins and provide cleaner drinking water for

humans.

5. Assessments of Cyanotoxins in Drinking Water

The assessment of cyanotoxins has become an important

environmental issue that if not attended may cause many problems

regarding public health and safety. Drinking Water Treatment

Plants (DWTP) have developed certain steps or techniques to

manage this ongoing issue. Among the steps that have been

currently applied include coagulation/flocculation, oxidation,

the use of activated carbon filters, nanofiltration,

ultrafiltration and other assessments that are being created to

improve efficiency. Besides these steps, DWTP must have a team

of well-trained managers to recognize these issues and help with

the efficient removal of cyanotoxins before it reaches human or


animal consumption. Recent studies have shown that current steps

in DWTP are not as efficient, and alternatives are being

implemented like, for example, enhancing coagulation and using

stronger oxidizing agents. A brief explanation of each step will

be provided ahead with an analysis of which is more efficient

and economically viable for treatment plants.

5.a. Coagulation/flocculation

The treatment method of coagulation/flocculation is the

most common and frequent assessment that has been used for the

removal of cyanotoxins in drinking water. Its use has been

effective to eliminate the turbidity and organic matter that can

be found in water. Drinking water treatment plants use this

method as their primary step. Coagulation/flocculation has not

been an efficient method at removing cyanotoxins due to the

increasing number algae blooms in past years. Scientists and

treatment managers seek alternatives to improve this method.

Enhancing the process and coagulation/flocculation has

shown significant improvement for treatment plants. An

enhancement technique that has proven to be efficient is

powdered activated carbon 3 (PAC) (Ghernaout, Ghernaout & Saiba,

2010). Using this technique along with coagulation/flocculation

has a positive removal effect on cyanotoxins in drinking water.

3 PAC is used by water treatment plants on either a full-‐time basis or as needed for taste and odor control or removal of organic chemicals. Source: http://iaspub.epa.gov


The only problem with PAC as an enhancing coagulation technique

is that physical perturbations can cause cells to break and

increase the amount of cyanotoxins in the water.

In fact, other studies have shown that PAC does not remove

cyanotoxins entirely (Zamyadi et al., 2012). The alternative to

PAC is Dissolved Air Flotation (DAF); this technique has proven

to remove consistently cyanotoxins. It is a cheap enhancing

method and treatment plants are using it more frequently in

recent years.

5.b. Oxidation

The use of oxidants helps to reduce taste and odor in

water. It is added at the intake to stimulate coagulation and

any disinfection by-products that could have been formed during

previous steps. The most common oxidants used in treatment

plants are ozonation, ultraviolet light, chlorination and

permanganate. The use of ozonation and ultraviolet among the

most common are the least used due to their high cost. Both have

proven to be very efficient at removing cyanotoxins except for

saxitoxins, which to this day insufficient data cannot validate

their effectiveness (Cheung, Liang & Lee, 2013). Another issue

regarding ozonation is that it can cause cell lysis, which

results in the release more of toxins into the water.

Chlorination as an oxidizing agent has played an important

role throughout years for treatment plants. It is the primary


oxidizing agent used in the treatment of drinking water. The

negative side to chlorination is that the high dosage of this

oxidizing agent can cause disinfection by-products and odor to

the water. This can cause problems if water is consumed, and it

can increase toxins release due to cell lysis. Scientists have

concluded that if chlorination is kept in low dosage (a pH <8.0)

it can be useful for the removal of cyanotoxins (Westwick et

al., 2010).

The use of permanganate as an oxidizing agent works as an

alternative for chlorination. Permanganate does not depend on

the pH and does not leave residuals of taste like chlorination

does. This oxidizing agent works well with

coagulation/flocculation steps because it controls biological

growth. Permanganate is efficient at removing cyanotoxins like

microcystins and anatoxin-a, but it is not efficient removing

saxitoxins and cylindrospermopsin, which both are neurotoxins

and can cause serious risks if contaminated drinking water is

consumed.

There is an oxidizing agent that is gaining a reputation

for being effective against three out of the four most common

cyanotoxins known as the hydroxyl radical. The hydroxyl radical

is the neutral from of a hydroxide ion, and it has proved in

recent studies that it can help in the removal of cyanotoxins

like microcystins, anatoxin-a and saxitoxins. The only


disadvantage of this oxidizing agent is that its effectiveness

works at pH 3, which is not good for drinking water treatment

because the acidity of water is too high for an effective

removal (Westwick et al., 2010). This oxidizing agent needs more

time to expand research for other cyanotoxins like

cylindrospermopsin.

5.c. Activated Carbon

Activated carbon is by far the most effective assessment

for removal of cyanotoxins that can exist; it has a 99% removal

of cyanotoxins in drinking water. One can find activated carbon

in home purification filters due to their high percentage of

removal. For activated carbon, there are two types that are used

in treatment plants: (1) Powdered Active Carbon (PAC), which was

discussed as an enhancing agent for the coagulation/flocculation

process and (2) Granular Activated Carbon (GAC) (Westwick et al,

2010). GAC is mostly used to reduce organic matter, taste and

odor from the source water.

The effectiveness of activated carbon filters mostly

depends on the size of the pore within the filters. Those with

large pores have more capacity to absorb cyanotoxins. The best-

activated carbons that are steam activated; coconut based and

coal based. GAC has shown to have an efficient removal rate for

saxitoxins and microcystins but have shown low removal for

cylindrospermopsin.


Although activated carbon may be the best at assessing

cyanotoxins it also has its disadvantages. These are that

filters saturate over time and the cost can make it a challenge

for communities that are resource-limited (Roegner et al.,

2013). An alternative would be to utilize both types of

activated carbon, PAC and GAC for an effective removal of all

types of cyanotoxins that could be found in drinking water. When

compared with other assessment methods, activated carbon is

still the most efficient at removing cyanotoxins from drinking

water.

5.d. Ultrafiltration & Nanofiltration

Nano and ultrafiltration are emerging assessment methods

that drinking water treatment plants (DWTP) are trying to

implement as a cost-effective alternative. This filtration

process works by utilizing pressure filtration through small

pores to eliminate any bacteria that a typical assessment or

step cannot remove (Roegner et al., 2013). Many DWTP are trying

to make this assessment as their top step because with the

correct pressure and flow, the step does not provoke any type of

break on cyanotoxins. Breaks can cause an increase of toxins and

bloom.

When it comes to a comparison of both filtration methods,

research has shown that nanofiltration is more effective at

capturing or removing organic material and bacteria. According


to Costa & Norberta de Pinho (2006), nanofiltration has a better

quality treatment for water. This was determined by a series of

experiments that were based for comparison between the two

filtration methods, using a series of pressures and fluxes in

the system helped determine which filtration method is more

effective.

5.e. Other assessments for removal of cyanotoxins

The topic of efficient removal of cyanotoxins has been in

the past years growing due to many environmental factors.

Environmentalists and scientists have been developing other

assessments techniques to support or even replace those that

already exist. Besides these recent assessments, scientists are

suggesting that water treatment managers must have certain

skills to help monitor the bloom of cyanotoxins in drinking

water. Many of these skills use an alternate supply source of

water and adjust the intake of water in the treatment facility.

One recent technique that water treatment managers in

Europe are using is monitoring water using maximum tolerable

values of the toxin in raw water (untreated water). This method

has proven to be effective because it has helped to recognize

any critical phase of the cyanotoxin bloom in water and to

enhance any existing removal step that may exist in the facility

(Schmidt et al, 2008). The knowledge of maximum tolerable values


has helped treatment facilities in Europe reduce cyanotoxin

contamination in their drinking water.

Another method that has been developed involves using a

fluorescence immunoassay 4 . This technique helps to detect and

diagnose any potential risk of cyanotoxins in drinking water.

When fluorescence immunoassay is compared to other conventional

methods, it shows improvements in removing cyanotoxins from

drinking water. According to Yu, Jang, Hee Kim, Kim and S. Kim

(2011), “This technique fills the strong need for a rapid

analytical tool and it can be a critical component in

environmental management” (p.7810).

Other analytical tools have been implemented in recent

years that include the use of laboratory systems. This involves

using instrumentation such as High Performance Liquid

Chromatography (HPLC), protein-based assays and enzyme assays.

These tools have been tested and have shown effective removal of

cyanotoxins in drinking water. The authors state that these

systems can be useful for large scale monitoring of cyanotoxins

in drinking water treatment plants (Triantis, Tsimeli, Kaloudis,

Thanassoulias, Lytras & Hiskia, 2010).

Countries around the world are also implementing their risk

management assessment based on how gravely their situation might

4 Sensitive technique that can be used in the measurement of many compounds, including drugs, hormones, and proteins; in the identification of antibodies; and in the quantification of antigens such as viral particles and, potentially, bacteria. (http://www.ncbi.nlm.nih.gov/pubmed/6365732)


be, as for the case of a New Zealand river in 2002 and 2003. The

Waikato River in 2002/03 suffered a massive cyanobacteria bloom

causing a large release of cyanotoxins in their drinking water.

The New Zealand Ministry of Health implemented strong regulatory

guidelines to control the situation. The guidelines included a

multi-barrier and process-control management that was

complemented by monitoring program (Kouzminov, Ruck & Wood,

2007). A multi-barrier and process-control is an integrated

system of procedures that prevent or reduce the contamination of

drinking water from source to reduce risks to public health.

This risk management proved efficient, and it is an approach

that other countries that experience cyanotoxins issues in

drinking water should consider implementing.

Many more assessment methods are being developed each day

to address these cyanotoxins in drinking water. A new filtration

method has been studied recently that uses a hollow fiber

microfiltration process, which has shown removal rates higher

than 98% for a large number of cyanotoxins (Sorlini, Gialdini &

Collivignarelli, 2012).

Another assessment method involves using pigmentation of

cyanotoxins to function as an indicator on cyanotoxins in

drinking water. This particular method can help reduce time and

eliminate expensive measurements but more research has to be

done because studies show that if treatment plants use oxidizing


agents the pigment detection would not be effective (Schmidt,

Petzoldt, Bornman, Imhof & Moldaenke, 2009).

6. Conclusion

Cyanotoxins can be controlled at an early stage if

environmental factors such as eutrophication and water

contamination can be reduced. Many types of cyanotoxins exist;

the four most common are to be assessed as soon as they show up

in monitoring systems. Water ecosystems that are contaminated

with cyanotoxins must be avoided at all cost to avoid any

potential and fatal risks.

Ingesting water that contains cyanotoxins can cause

numerous risks to living organisms. These risks include

gastrointestinal symptoms, liver damage that can lead to liver

cancer, neurological symptoms and skin irritation. Due to these

risks, drinking water treatment plants have developed different

assessments to their system to remove cyanotoxins from drinking

water. These include the most common like

coagulation/flocculation, utilizing oxidizing agents, activated

carbon filters, nanofiltration and ultrafiltration. Other

assessments are being developed to improve efficiency or replace

other methods that eliminate cyanotoxins from drinking water.

Coagulation/flocculation is one of the most common

assessments because it has an effective rate of removal of


cyanotoxins. The increasing of algae blooms has brought problems

for this method and enhancing it has proven to be effective. The

only disadvantage to this is that high perturbations can cause

cyanobacteria to break and release toxins to the water. Others

assessments that exist have shown an efficiency in removing

cyanotoxins from drinking water. Oxidizing agents like chlorine,

permanganate and ultraviolet light help at removing cyanotoxins

but they are too expensive to use, and high dosage can cause

cell lysis.

The assessment that should be recommended to use most is

activated carbon. Applying both Powdered Activated Carbon (PAC)

and Granular Activated Carbon (GAC) with an intensive monitoring

of their filters to avoid saturation over time can be very

effective at removing cyanotoxins from drinking water. If a pre-

chlorination and nanofiltration step is added in low dosage, the

rate removal could improve.

Drinking water treatment plants must develop better

monitoring systems and improve their assessments methods for an

effective removal of cyanotoxins. Treatment managers must

develop skills to address this issue before it gets worse, and

scientists must continue research to develop a more effective

method that could remove all four of the most common cyanotoxin

at once. It is a matter of public awareness; decreasing

contamination in water systems and drinking water treatment


plants applying assessments can help reduce the risks that

cyanotoxins can cause to all living organisms.


References

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