New user?

Revision history [back]

click to hide/show revision 1
initial version

Oil Contamination and Implications for Drinking Water

Crude oil is a complex mixture of many chemicals, each having an associated toxicity. It is the mixture of these compounds, however, that has the potential to be the most toxic. Many of the chemicals in crude oil are made up of hydrogen and carbon, but may also contain sulphur, nitrogen, heavy metals and oxygen compounds.

The composition of crude oil varies slightly by its source, but the toxic properties are consistent. Chemicals such as benzene and polycyclic aromatic hydrocarbons (PAHs) are extremely toxic components of crude oil and of high concern. These and many other chemicals in crude oil are volatile, moving from the oil into the air, where they have the potential to expose many people.

Exposure to these compounds can occur through skin contact, inhalation of contaminated air or soil and the ingestion of contaminated food and water. Different types of exposures can occur simultaneously. Exposure may result in localized symptoms (e.g., irritation of the skin following contact), but most health effects are not localized because toxic compounds can move throughout the body.

Health effects vary based on the duration of exposure and concentrations of harmful compounds in crude oil. Differences in effects may also result from location, work and personal activities, age, diet, use of protective equipment, and other factors.

The duration of exposure will determine the severity of the effects; therefore, reducing the time of exposure to chemicals found in crude oil will minimize adverse health effects.

For brief exposures at relatively high levels (known as acute exposures), crude oil may cause irritation of the skin and mucous membranes on contact. Irritant effects can range from a slight reddening of the skin to burning, swelling, pain and permanent skin damage. Commonly reported effects from acute exposure to crude oil through inhalation and ingestion include difficulty breathing, headaches, dizziness, nausea, confusion and other central nervous system (CNS) effects.

Long-term exposure at relatively low levels (known as chronic exposure) should be avoided, if at all possible, due to the possibility of serious effects including lung, liver and kidney damage, infertility, immune system suppression, disruption of hormone levels, blood disorders, gene mutations and cancer.

Susceptible populations to the toxic effects of crude oil include:

 Children are vulnerable to the toxic chemical compounds in crude oil as their brains are highly susceptible to neurotoxins, in addition, exposure to crude oil can cause abnormal growth and infertility in children.  Adverse affects can be experienced by people taking medications that reduce their detoxification ability (including aspirin) or who have nutritional deficiencies (or even concurrently drink alcohol ).  Pregnant women and the developing foetus are also at risk due to the fact that many of the chemicals in crude oil can cause skeletal deformities and incompletely formed immune and detoxification systems.

The real problem with your question is that, for completely understandable reasons, it is not possible to give an idea of the degree and nature of the contamination, i.e. higher or lower specific gravity petrochemicals/oils, and the degree (%) of contamination. Bearing in mind the natural instinct to expect drinking water to be clear, I guess the likelihood is that only non-visible lighter compounds will be present. Although I understand the conventional wisdom that disinfection is essential to reduce water related disease risks, that wisdom was not designed to apply to a petrochemical/oil & water mixture. Your comments on taste etc are noted and although they would seem to indicate low levels of contamination it is worth thinking about time of exposure.

The issue in terms of treatment is how to get both suitable disinfection and chemical treatment in a convenient manner. Here are some thoughts relating to basics.....  Crude oils are refined to separate the lighter more volatile fractions from the heavier crude oil components, for example tars etc. As even I could spot tars in a cup of water my assumption is that the lighter fractions are the problem. Boiling the water could drive off some compounds as vapour, as well as providing a degree of disinfection.  Adsorption is not easy to predict without knowing the likely chemical components but I assume that it might be possible to get petrochemicals/oils to bind to clay particles. This knowledge comes from cleaning up oil spills. This begins to get interesting when we think of physico-chemical water treatment where, essentially, the floc binds in the particles in the water. The neatness of sachet water treatment systems is that they include a large quantity of “particles” in their constituents which are matched by the sachet’s coagulant dose. Effectively, the natural load of particles in the raw water becomes insignificant by comparison and they are swept up in the floc. In the case of PUR sachets bentonite (clay) provides the particles. I wonder if there might be a benefit in terms of “petrochemical/oil” removal in your Syrian case, the PUR sachet also includes calcium hypochlorite as a disinfectant. Logistically it might simplify your support in the short term to just handing out sachets, information sheets and suitable containers. Potential difficulties should not include floating floc but there are other potential causes of this effect.  Temporary storage and subsequent media filtration can provide a degree of improvement but might be a bit contrived. It’s easier to show diagrammatically (see below):-

The strategy of just disinfecting with any hypochlorite product seems to me to be a bit risky given the very particular chemical risks that petrochemical/oil contamination can present. The potential for difficult “chloro-compounds” to be formed must be fairly high, particularly if there are periods of relatively high contamination in the raw water.

We looked at PUR and Watermaker sachets several years ago and I enclose an extract from my Edinburgh conference paper as follows:-

“Sachet Water Treatment Products

Sachet water treatment products are currently generating interest within UNICEF and the main relief agencies. PUR and Watermaker are the main products currently under consideration by Oxfam. The specific composition of the PUR sachet was described by Reller et al. (2003) as containing ferric sulphate, bentonite, sodium carbonate, chitosan, polyacrylamide, potassium permanganate and calcium hypochlorite. In an extensive, though not yet complete, investigation programme CEHE has provisionally assessed the performance of the flocculation-disinfection sachets (both Watermaker and PUR) in terms of physical, chemical, bacterial and viral improvement of test waters.

CEHE (Monge, 2007) reported that turbidity levels in samples treated with the flocculation-disinfection sachets were always <5NTU for raw water turbidities ranging from 6 to >1000 NTU. Microbiological removal levels were substantial, with treated samples constantly meeting not only the MSF indicator value (<10 cfu FC/100ml) but also the Sphere and WHO guideline value of 0cfu/100ml, even when raw water was spiked with high E.Coli concentrations. Bacterial removal was always higher than 6 log removal, achieving a maximum of 8 log. In terms of viral removal, both sachets had a minimal 8 log removal of the Phage ØX174, used as a surrogate for enteric viruses.

Both technologies showed promising results in terms of microbiological improvement, offering a means of reducing risks associated with the waterborne transmission of disease via unsafe water supplies. The main advantage of both systems is that their compact size make them readily transportable and more readily distributed in an emergency. However, there is an interesting choice to be made between the on-going sachet distribution demands in an emergency and the ability to supply a population from a centralised system where the customer comes to the tap with a container.

This high improvement in the microbiological quality of water was an indication of the effectiveness of disinfection, although free chlorine residuals were always below 0.1mg/l, presumably indicating that a significant level of combined available chlorine is providing disinfection (ironically the free chlorine residual recorded does not meet the requirements for efficient disinfection according to MSF guideline values (Monge, 2007). The main advantage for household treatment is that a combined residual is longer lasting and has a less adverse effect on the taste of the treated water.

The coagulant "residual" recorded for the sachets varied, depending on the quality of the raw water treated, with values above the WHO guideline values (0.2mg/l aluminium, 0.3mg/l iron) for low turbidity and/or when the sachet dose was increased. It is considered important to assess the potential monomer (acrylamide?) levels which could be ingested when IDP or refugee communities are using (or misusing?) the sachets under stressful field conditions in an emergency”.

Brian

Oil Contamination and Implications for Drinking Water

Crude oil is a complex mixture of many chemicals, each having an associated toxicity. It is the mixture of these compounds, however, that has the potential to be the most toxic. Many of the chemicals in crude oil are made up of hydrogen and carbon, but may also contain sulphur, nitrogen, heavy metals and oxygen compounds.

The composition of crude oil varies slightly by its source, but the toxic properties are consistent. Chemicals such as benzene and polycyclic aromatic hydrocarbons (PAHs) are extremely toxic components of crude oil and of high concern. These and many other chemicals in crude oil are volatile, moving from the oil into the air, where they have the potential to expose many people.

Exposure to these compounds can occur through skin contact, inhalation of contaminated air or soil and the ingestion of contaminated food and water. Different types of exposures can occur simultaneously. Exposure may result in localized symptoms (e.g., irritation of the skin following contact), but most health effects are not localized because toxic compounds can move throughout the body.

Health effects vary based on the duration of exposure and concentrations of harmful compounds in crude oil. Differences in effects may also result from location, work and personal activities, age, diet, use of protective equipment, and other factors.

The duration of exposure will determine the severity of the effects; therefore, reducing the time of exposure to chemicals found in crude oil will minimize adverse health effects.

For brief exposures at relatively high levels (known as acute exposures), crude oil may cause irritation of the skin and mucous membranes on contact. Irritant effects can range from a slight reddening of the skin to burning, swelling, pain and permanent skin damage. Commonly reported effects from acute exposure to crude oil through inhalation and ingestion include difficulty breathing, headaches, dizziness, nausea, confusion and other central nervous system (CNS) effects.

Long-term exposure at relatively low levels (known as chronic exposure) should be avoided, if at all possible, due to the possibility of serious effects including lung, liver and kidney damage, infertility, immune system suppression, disruption of hormone levels, blood disorders, gene mutations and cancer.

Susceptible populations to the toxic effects of crude oil include:

 Children are vulnerable to the toxic chemical compounds in crude oil as their brains are highly susceptible to neurotoxins, in addition, exposure to crude oil can cause abnormal growth and infertility in children.  Adverse affects can be experienced by people taking medications that reduce their detoxification ability (including aspirin) or who have nutritional deficiencies (or even concurrently drink alcohol ).  Pregnant women and the developing foetus are also at risk due to the fact that many of the chemicals in crude oil can cause skeletal deformities and incompletely formed immune and detoxification systems.

The real problem with your question is that, for completely understandable reasons, it is not possible to give an idea of the degree and nature of the contamination, i.e. higher or lower specific gravity petrochemicals/oils, and the degree (%) of contamination. Bearing in mind the natural instinct to expect drinking water to be clear, I guess the likelihood is that only non-visible lighter compounds will be present. Although I understand the conventional wisdom that disinfection is essential to reduce water related disease risks, that wisdom was not designed to apply to a petrochemical/oil & water mixture. Your comments on taste etc are noted and although they would seem to indicate low levels of contamination it is worth thinking about time of exposure.

The issue in terms of treatment is how to get both suitable disinfection and chemical treatment in a convenient manner. Here are some thoughts relating to basics.....  Crude oils are refined to separate the lighter more volatile fractions from the heavier crude oil components, for example tars etc. As even I could spot tars in a cup of water my assumption is that the lighter fractions are the problem. Boiling the water could drive off some compounds as vapour, as well as providing a degree of disinfection.  Adsorption is not easy to predict without knowing the likely chemical components but I assume that it might be possible to get petrochemicals/oils to bind to clay particles. This knowledge comes from cleaning up oil spills. This begins to get interesting when we think of physico-chemical water treatment where, essentially, the floc binds in the particles in the water. The neatness of sachet water treatment systems is that they include a large quantity of “particles” in their constituents which are matched by the sachet’s coagulant dose. Effectively, the natural load of particles in the raw water becomes insignificant by comparison and they are swept up in the floc. In the case of PUR sachets bentonite (clay) provides the particles. I wonder if there might be a benefit in terms of “petrochemical/oil” removal in your Syrian case, the PUR sachet also includes calcium hypochlorite as a disinfectant. Logistically it might simplify your support in the short term to just handing out sachets, information sheets and suitable containers. Potential difficulties should not include floating floc but there are other potential causes of this effect.  effect.

Temporary storage and subsequent media filtration can provide a degree of improvement but might be a bit contrived. It’s easier to show diagrammatically (see below):-

Diagram

The strategy of just disinfecting with any hypochlorite product seems to me to be a bit risky given the very particular chemical risks that petrochemical/oil contamination can present. The potential for difficult “chloro-compounds” to be formed must be fairly high, particularly if there are periods of relatively high contamination in the raw water.

We looked at PUR and Watermaker sachets several years ago and I enclose an extract from my Edinburgh conference paper as follows:-

“Sachet Water Treatment Products

Sachet water treatment products are currently generating interest within UNICEF and the main relief agencies. PUR and Watermaker are the main products currently under consideration by Oxfam. The specific composition of the PUR sachet was described by Reller et al. (2003) as containing ferric sulphate, bentonite, sodium carbonate, chitosan, polyacrylamide, potassium permanganate and calcium hypochlorite. In an extensive, though not yet complete, investigation programme CEHE has provisionally assessed the performance of the flocculation-disinfection sachets (both Watermaker and PUR) in terms of physical, chemical, bacterial and viral improvement of test waters.

CEHE (Monge, 2007) reported that turbidity levels in samples treated with the flocculation-disinfection sachets were always <5NTU for raw water turbidities ranging from 6 to >1000 NTU. Microbiological removal levels were substantial, with treated samples constantly meeting not only the MSF indicator value (<10 cfu FC/100ml) but also the Sphere and WHO guideline value of 0cfu/100ml, even when raw water was spiked with high E.Coli concentrations. Bacterial removal was always higher than 6 log removal, achieving a maximum of 8 log. In terms of viral removal, both sachets had a minimal 8 log removal of the Phage ØX174, used as a surrogate for enteric viruses.

Both technologies showed promising results in terms of microbiological improvement, offering a means of reducing risks associated with the waterborne transmission of disease via unsafe water supplies. The main advantage of both systems is that their compact size make them readily transportable and more readily distributed in an emergency. However, there is an interesting choice to be made between the on-going sachet distribution demands in an emergency and the ability to supply a population from a centralised system where the customer comes to the tap with a container.

This high improvement in the microbiological quality of water was an indication of the effectiveness of disinfection, although free chlorine residuals were always below 0.1mg/l, presumably indicating that a significant level of combined available chlorine is providing disinfection (ironically the free chlorine residual recorded does not meet the requirements for efficient disinfection according to MSF guideline values (Monge, 2007). The main advantage for household treatment is that a combined residual is longer lasting and has a less adverse effect on the taste of the treated water.

The coagulant "residual" recorded for the sachets varied, depending on the quality of the raw water treated, with values above the WHO guideline values (0.2mg/l aluminium, 0.3mg/l iron) for low turbidity and/or when the sachet dose was increased. It is considered important to assess the potential monomer (acrylamide?) levels which could be ingested when IDP or refugee communities are using (or misusing?) the sachets under stressful field conditions in an emergency”.

Brian

Oil Contamination and Implications for Drinking Water

Crude oil is a complex mixture of many chemicals, each having an associated toxicity. It is the mixture of these compounds, however, that has the potential to be the most toxic. Many of the chemicals in crude oil are made up of hydrogen and carbon, but may also contain sulphur, nitrogen, heavy metals and oxygen compounds.

The composition of crude oil varies slightly by its source, but the toxic properties are consistent. Chemicals such as benzene and polycyclic aromatic hydrocarbons (PAHs) are extremely toxic components of crude oil and of high concern. These and many other chemicals in crude oil are volatile, moving from the oil into the air, where they have the potential to expose many people.

Exposure to these compounds can occur through skin contact, inhalation of contaminated air or soil and the ingestion of contaminated food and water. Different types of exposures can occur simultaneously. Exposure may result in localized symptoms (e.g., irritation of the skin following contact), but most health effects are not localized because toxic compounds can move throughout the body.

Health effects vary based on the duration of exposure and concentrations of harmful compounds in crude oil. Differences in effects may also result from location, work and personal activities, age, diet, use of protective equipment, and other factors.

The duration of exposure will determine the severity of the effects; therefore, reducing the time of exposure to chemicals found in crude oil will minimize adverse health effects.

For brief exposures at relatively high levels (known as acute exposures), crude oil may cause irritation of the skin and mucous membranes on contact. Irritant effects can range from a slight reddening of the skin to burning, swelling, pain and permanent skin damage. Commonly reported effects from acute exposure to crude oil through inhalation and ingestion include difficulty breathing, headaches, dizziness, nausea, confusion and other central nervous system (CNS) effects.

Long-term exposure at relatively low levels (known as chronic exposure) should be avoided, if at all possible, due to the possibility of serious effects including lung, liver and kidney damage, infertility, immune system suppression, disruption of hormone levels, blood disorders, gene mutations and cancer.

Susceptible populations to the toxic effects of crude oil include:

 Children are vulnerable to the toxic chemical compounds in crude oil as their brains are highly susceptible to neurotoxins, in addition, exposure to crude oil can cause abnormal growth and infertility in children.  Adverse affects can be experienced by people taking medications that reduce their detoxification ability (including aspirin) or who have nutritional deficiencies (or even concurrently drink alcohol ).  Pregnant women and the developing foetus are also at risk due to the fact that many of the chemicals in crude oil can cause skeletal deformities and incompletely formed immune and detoxification systems.

The real problem with your question is that, for completely understandable reasons, it is not possible to give an idea of the degree and nature of the contamination, i.e. higher or lower specific gravity petrochemicals/oils, and the degree (%) of contamination. Bearing in mind the natural instinct to expect drinking water to be clear, I guess the likelihood is that only non-visible lighter compounds will be present. Although I understand the conventional wisdom that disinfection is essential to reduce water related disease risks, that wisdom was not designed to apply to a petrochemical/oil & water mixture. Your comments on taste etc are noted and although they would seem to indicate low levels of contamination it is worth thinking about time of exposure.

The issue in terms of treatment is how to get both suitable disinfection and chemical treatment in a convenient manner. Here are some thoughts relating to basics.....  Crude oils are refined to separate the lighter more volatile fractions from the heavier crude oil components, for example tars etc. As even I could spot tars in a cup of water my assumption is that the lighter fractions are the problem. Boiling the water could drive off some compounds as vapour, as well as providing a degree of disinfection.  Adsorption is not easy to predict without knowing the likely chemical components but I assume that it might be possible to get petrochemicals/oils to bind to clay particles. This knowledge comes from cleaning up oil spills. This begins to get interesting when we think of physico-chemical water treatment where, essentially, the floc binds in the particles in the water. The neatness of sachet water treatment systems is that they include a large quantity of “particles” in their constituents which are matched by the sachet’s coagulant dose. Effectively, the natural load of particles in the raw water becomes insignificant by comparison and they are swept up in the floc. In the case of PUR sachets bentonite (clay) provides the particles. I wonder if there might be a benefit in terms of “petrochemical/oil” removal in your Syrian case, the PUR sachet also includes calcium hypochlorite as a disinfectant. Logistically it might simplify your support in the short term to just handing out sachets, information sheets and suitable containers. Potential difficulties should not include floating floc but there are other potential causes of this effect.

Temporary storage and subsequent media filtration can provide a degree of improvement but might be a bit contrived. It’s easier to show diagrammatically (see below):-

Diagramdiagram

The strategy of just disinfecting with any hypochlorite product seems to me to be a bit risky given the very particular chemical risks that petrochemical/oil contamination can present. The potential for difficult “chloro-compounds” to be formed must be fairly high, particularly if there are periods of relatively high contamination in the raw water.

We looked at PUR and Watermaker sachets several years ago and I enclose an extract from my Edinburgh conference paper as follows:-

“Sachet Water Treatment Products

Sachet water treatment products are currently generating interest within UNICEF and the main relief agencies. PUR and Watermaker are the main products currently under consideration by Oxfam. The specific composition of the PUR sachet was described by Reller et al. (2003) as containing ferric sulphate, bentonite, sodium carbonate, chitosan, polyacrylamide, potassium permanganate and calcium hypochlorite. In an extensive, though not yet complete, investigation programme CEHE has provisionally assessed the performance of the flocculation-disinfection sachets (both Watermaker and PUR) in terms of physical, chemical, bacterial and viral improvement of test waters.

CEHE (Monge, 2007) reported that turbidity levels in samples treated with the flocculation-disinfection sachets were always <5NTU for raw water turbidities ranging from 6 to >1000 NTU. Microbiological removal levels were substantial, with treated samples constantly meeting not only the MSF indicator value (<10 cfu FC/100ml) but also the Sphere and WHO guideline value of 0cfu/100ml, even when raw water was spiked with high E.Coli concentrations. Bacterial removal was always higher than 6 log removal, achieving a maximum of 8 log. In terms of viral removal, both sachets had a minimal 8 log removal of the Phage ØX174, used as a surrogate for enteric viruses.

Both technologies showed promising results in terms of microbiological improvement, offering a means of reducing risks associated with the waterborne transmission of disease via unsafe water supplies. The main advantage of both systems is that their compact size make them readily transportable and more readily distributed in an emergency. However, there is an interesting choice to be made between the on-going sachet distribution demands in an emergency and the ability to supply a population from a centralised system where the customer comes to the tap with a container.

This high improvement in the microbiological quality of water was an indication of the effectiveness of disinfection, although free chlorine residuals were always below 0.1mg/l, presumably indicating that a significant level of combined available chlorine is providing disinfection (ironically the free chlorine residual recorded does not meet the requirements for efficient disinfection according to MSF guideline values (Monge, 2007). The main advantage for household treatment is that a combined residual is longer lasting and has a less adverse effect on the taste of the treated water.

The coagulant "residual" recorded for the sachets varied, depending on the quality of the raw water treated, with values above the WHO guideline values (0.2mg/l aluminium, 0.3mg/l iron) for low turbidity and/or when the sachet dose was increased. It is considered important to assess the potential monomer (acrylamide?) levels which could be ingested when IDP or refugee communities are using (or misusing?) the sachets under stressful field conditions in an emergency”.

Brian

Oil Contamination and Implications for Drinking Water

Crude oil is a complex mixture of many chemicals, each having an associated toxicity. It is the mixture of these compounds, however, that has the potential to be the most toxic. Many of the chemicals in crude oil are made up of hydrogen and carbon, but may also contain sulphur, nitrogen, heavy metals and oxygen compounds.

The composition of crude oil varies slightly by its source, but the toxic properties are consistent. Chemicals such as benzene and polycyclic aromatic hydrocarbons (PAHs) are extremely toxic components of crude oil and of high concern. These and many other chemicals in crude oil are volatile, moving from the oil into the air, where they have the potential to expose many people.

Exposure to these compounds can occur through skin contact, inhalation of contaminated air or soil and the ingestion of contaminated food and water. Different types of exposures can occur simultaneously. Exposure may result in localized symptoms (e.g., irritation of the skin following contact), but most health effects are not localized because toxic compounds can move throughout the body.

Health effects vary based on the duration of exposure and concentrations of harmful compounds in crude oil. Differences in effects may also result from location, work and personal activities, age, diet, use of protective equipment, and other factors.

The duration of exposure will determine the severity of the effects; therefore, reducing the time of exposure to chemicals found in crude oil will minimize adverse health effects.

For brief exposures at relatively high levels (known as acute exposures), crude oil may cause irritation of the skin and mucous membranes on contact. Irritant effects can range from a slight reddening of the skin to burning, swelling, pain and permanent skin damage. Commonly reported effects from acute exposure to crude oil through inhalation and ingestion include difficulty breathing, headaches, dizziness, nausea, confusion and other central nervous system (CNS) effects.

Long-term exposure at relatively low levels (known as chronic exposure) should be avoided, if at all possible, due to the possibility of serious effects including lung, liver and kidney damage, infertility, immune system suppression, disruption of hormone levels, blood disorders, gene mutations and cancer.

Susceptible populations to the toxic effects of crude oil include:

 Children are vulnerable to the toxic chemical compounds in crude oil as their brains are highly susceptible to neurotoxins, in addition, exposure to crude oil can cause abnormal growth and infertility in children.  Adverse affects can be experienced by people taking medications that reduce their detoxification ability (including aspirin) or who have nutritional deficiencies (or even concurrently drink alcohol ).  Pregnant women and the developing foetus are also at risk due to the fact that many of the chemicals in crude oil can cause skeletal deformities and incompletely formed immune and detoxification systems.

The real problem with your question is that, for completely understandable reasons, it is not possible to give an idea of the degree and nature of the contamination, i.e. higher or lower specific gravity petrochemicals/oils, and the degree (%) of contamination. Bearing in mind the natural instinct to expect drinking water to be clear, I guess the likelihood is that only non-visible lighter compounds will be present. Although I understand the conventional wisdom that disinfection is essential to reduce water related disease risks, that wisdom was not designed to apply to a petrochemical/oil & water mixture. Your comments on taste etc are noted and although they would seem to indicate low levels of contamination it is worth thinking about time of exposure.

The issue in terms of treatment is how to get both suitable disinfection and chemical treatment in a convenient manner. Here are some thoughts relating to basics.....  Crude oils are refined to separate the lighter more volatile fractions from the heavier crude oil components, for example tars etc. As even I could spot tars in a cup of water my assumption is that the lighter fractions are the problem. Boiling the water could drive off some compounds as vapour, as well as providing a degree of disinfection.  Adsorption is not easy to predict without knowing the likely chemical components but I assume that it might be possible to get petrochemicals/oils to bind to clay particles. This knowledge comes from cleaning up oil spills. This begins to get interesting when we think of physico-chemical water treatment where, essentially, the floc binds in the particles in the water. The neatness of sachet water treatment systems is that they include a large quantity of “particles” in their constituents which are matched by the sachet’s coagulant dose. Effectively, the natural load of particles in the raw water becomes insignificant by comparison and they are swept up in the floc. In the case of PUR sachets bentonite (clay) provides the particles. I wonder if there might be a benefit in terms of “petrochemical/oil” removal in your Syrian case, the PUR sachet also includes calcium hypochlorite as a disinfectant. Logistically it might simplify your support in the short term to just handing out sachets, information sheets and suitable containers. Potential difficulties should not include floating floc but there are other potential causes of this effect.

Temporary storage and subsequent media filtration can provide a degree of improvement but might be a bit contrived. It’s easier to show diagrammatically (see below):-

diagramdiagram

The strategy of just disinfecting with any hypochlorite product seems to me to be a bit risky given the very particular chemical risks that petrochemical/oil contamination can present. The potential for difficult “chloro-compounds” to be formed must be fairly high, particularly if there are periods of relatively high contamination in the raw water.

We looked at PUR and Watermaker sachets several years ago and I enclose an extract from my Edinburgh conference paper as follows:-

“Sachet Water Treatment Products

Sachet water treatment products are currently generating interest within UNICEF and the main relief agencies. PUR and Watermaker are the main products currently under consideration by Oxfam. The specific composition of the PUR sachet was described by Reller et al. (2003) as containing ferric sulphate, bentonite, sodium carbonate, chitosan, polyacrylamide, potassium permanganate and calcium hypochlorite. In an extensive, though not yet complete, investigation programme CEHE has provisionally assessed the performance of the flocculation-disinfection sachets (both Watermaker and PUR) in terms of physical, chemical, bacterial and viral improvement of test waters.

CEHE (Monge, 2007) reported that turbidity levels in samples treated with the flocculation-disinfection sachets were always <5NTU for raw water turbidities ranging from 6 to >1000 NTU. Microbiological removal levels were substantial, with treated samples constantly meeting not only the MSF indicator value (<10 cfu FC/100ml) but also the Sphere and WHO guideline value of 0cfu/100ml, even when raw water was spiked with high E.Coli concentrations. Bacterial removal was always higher than 6 log removal, achieving a maximum of 8 log. In terms of viral removal, both sachets had a minimal 8 log removal of the Phage ØX174, used as a surrogate for enteric viruses.

Both technologies showed promising results in terms of microbiological improvement, offering a means of reducing risks associated with the waterborne transmission of disease via unsafe water supplies. The main advantage of both systems is that their compact size make them readily transportable and more readily distributed in an emergency. However, there is an interesting choice to be made between the on-going sachet distribution demands in an emergency and the ability to supply a population from a centralised system where the customer comes to the tap with a container.

This high improvement in the microbiological quality of water was an indication of the effectiveness of disinfection, although free chlorine residuals were always below 0.1mg/l, presumably indicating that a significant level of combined available chlorine is providing disinfection (ironically the free chlorine residual recorded does not meet the requirements for efficient disinfection according to MSF guideline values (Monge, 2007). The main advantage for household treatment is that a combined residual is longer lasting and has a less adverse effect on the taste of the treated water.

The coagulant "residual" recorded for the sachets varied, depending on the quality of the raw water treated, with values above the WHO guideline values (0.2mg/l aluminium, 0.3mg/l iron) for low turbidity and/or when the sachet dose was increased. It is considered important to assess the potential monomer (acrylamide?) levels which could be ingested when IDP or refugee communities are using (or misusing?) the sachets under stressful field conditions in an emergency”.

Brian