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From James: One thing to consider and it is a remote possibility. It is possible to get a "oily" sheen on water from natural breakdown of leaves etc in water. But I have only seen this on small patches of stagnant water in marshy environment. I assume this not the case here given the geographic location!!

This kind of sheen is relatively ease to confirm in my experience as it fractures when the surface is disturbed whereas an oil layer will distort.

one means of removing gross contaminants is to pump water from ground and not surface water. If this is possible this could be very short term option as the sand/rock should remove free product (ie.liquid hydrocarbons) but if the pollution is that bad then likely to have some dissolved hydocarbons present as well.

Seems to me the key actions are as harriet says :

1. Do not use except as extreme emergency use and then only if some form of filtration in place to remove free product. To be honest any significant free product would make it undrinkable, even trace amounts of kerosene will taint water to make it disgusting (personal experience!).

2. Get samples tested asap. Simplest test for total petroleum hydrocarbon but if possible get speciated hydrocarbon analysis.

3. Provide alternative supplies to young/old or go upstream of polluted areas.

4. Not sure where you are precisely but if you can get activated carbon (gac) supplied then this could be filter medium, worth asking around and we can look at treatment "design" but need to know flow rates required etc etc. However gac costly and probably cheaper to bowser in water in short term.

We too seeking internal advice but suspect no magic solutions.

Regards James

From John, Does the water smell? Hydrocarbons are generally detectable in minute quantities, I would have to check but less than 1 ppm of VOC's has been enough to render ground water aquifers unusable in contaminated land cases.

This might render treatment moot, as if the water smells and tastes of oil and chemicals people are unlikely to drink it? So the question I would ask is what source are people drinking from now and is it acceptable? If the water is contaminated with hydrocarbons then the the liquids will be imiscible? You could try leaving a sample to settle to see if the liquids seperate. Depending on what fractions of the oil are present you could potentially tap water from storage at different levels; from the bottom if LNAPL or from the top if DNAPL. This might work at household level, but is likely not to be feasible at process level as the flow rates required to prevent mixing would be low. For testing I would look at the Palintest photometer range, the 7100 can detect certain VOC's, BOD & COD. You most likely would need to establish the BOD:COD ratio. Over 3.5 would indicate heavy pollution. I can't check at the moment but the WHO Water Quality Guidelines chemical fact sheets are the most authoritative guide.

TOC would also be a useful measure, again in terms of ratio with TDS.

For treatment check out Josab international (pozzolonic filters) or Scan water (GAC filters). Household filtration would be a stretch I think, reasonable productivity is likely to require pressurisation.

---

From Jeff: The only easy way to get rid of hydrocarbons that I can think of is pre separation ( floating material), chemical coagulation ( Large Chain carbon) and carbon filters ( small chain C). Of course it depends on how much there is. It may be necessary to first settle water and take from below the surface, possibly also some pre-filtration may help. Actually I think that wood chip is quite good at removing hydrocarbons as a pre-filter. Often stripping is used if there is a lot of volatiles. I think though that perhaps in a river we are looking at low level pollution.

The important thing is to remove the hydrocarbons before you disinfect else will be making more carcinogenic compounds.

I am not sure about toxicity, but obviously there are a lot of different hydrocarbons from refining your own oil.

Depending on the geology, it may be possible to sink wells or boreholes close to the river which should give less contaminated water, at least for a limited period. The bad news is that household level treatment is likely to be difficult and expensive to arrange, in which case you may have to consider setting up a treatment plant or plants for the area. This could be based on a flow sheet using wells for initial filtration, coagulation and either activated carbon filtration or air stripping for removal of VOCs.

Jeff

We can provide more exact advice if you can give us more details about the pollution risk. We have sought advice from experts in the water treatment industry and this is what we have come back with so far. This is obviously a possible major issue and I guess some very clear advice would be useful. If you want us to continue investigations we should be able to get a more considered response. Best regards Toby

From James: One thing to consider and it is a remote possibility. It is possible to get a "oily" sheen on water from natural breakdown of leaves etc in water. But I have only seen this on small patches of stagnant water in marshy environment. I assume this not the case here given the geographic location!!

This kind of sheen is relatively ease to confirm in my experience as it fractures when the surface is disturbed whereas an oil layer will distort.

one means of removing gross contaminants is to pump water from ground and not surface water. If this is possible this could be very short term option as the sand/rock should remove free product (ie.liquid hydrocarbons) but if the pollution is that bad then likely to have some dissolved hydocarbons present as well.

Seems to me the key actions are as harriet says :

1. Do not use except as extreme emergency use and then only if some form of filtration in place to remove free product. To be honest any significant free product would make it undrinkable, even trace amounts of kerosene will taint water to make it disgusting (personal experience!).

2. Get samples tested asap. Simplest test for total petroleum hydrocarbon but if possible get speciated hydrocarbon analysis.

3. Provide alternative supplies to young/old or go upstream of polluted areas.

4. Not sure where you are precisely but if you can get activated carbon (gac) supplied then this could be filter medium, worth asking around and we can look at treatment "design" but need to know flow rates required etc etc. However gac costly and probably cheaper to bowser in water in short term.

We too seeking internal advice but suspect no magic solutions.

Regards James

From John, Does the water smell? Hydrocarbons are generally detectable in minute quantities, I would have to check but less than 1 ppm of VOC's has been enough to render ground water aquifers unusable in contaminated land cases.

This might render treatment moot, as if the water smells and tastes of oil and chemicals people are unlikely to drink it? So the question I would ask is what source are people drinking from now and is it acceptable? If the water is contaminated with hydrocarbons then the the liquids will be imiscible? You could try leaving a sample to settle to see if the liquids seperate. Depending on what fractions of the oil are present you could potentially tap water from storage at different levels; from the bottom if LNAPL or from the top if DNAPL. This might work at household level, but is likely not to be feasible at process level as the flow rates required to prevent mixing would be low. For testing I would look at the Palintest photometer range, the 7100 can detect certain VOC's, BOD & COD. You most likely would need to establish the BOD:COD ratio. Over 3.5 would indicate heavy pollution. I can't check at the moment but the WHO Water Quality Guidelines chemical fact sheets are the most authoritative guide.

TOC would also be a useful measure, again in terms of ratio with TDS.

For treatment check out Josab international (pozzolonic filters) or Scan water (GAC filters). Household filtration would be a stretch I think, reasonable productivity is likely to require pressurisation.

---

From Jeff: The only easy way to get rid of hydrocarbons that I can think of is pre separation ( floating material), chemical coagulation ( Large Chain carbon) and carbon filters ( small chain C). Of course it depends on how much there is. It may be necessary to first settle water and take from below the surface, possibly also some pre-filtration may help. Actually I think that wood chip is quite good at removing hydrocarbons as a pre-filter. Often stripping is used if there is a lot of volatiles. I think though that perhaps in a river we are looking at low level pollution.

The important thing is to remove the hydrocarbons before you disinfect else will be making more carcinogenic compounds.

I am not sure about toxicity, but obviously there are a lot of different hydrocarbons from refining your own oil.

Depending on the geology, it may be possible to sink wells or boreholes close to the river which should give less contaminated water, at least for a limited period. The bad news is that household level treatment is likely to be difficult and expensive to arrange, in which case you may have to consider setting up a treatment plant or plants for the area. This could be based on a flow sheet using wells for initial filtration, coagulation and either activated carbon filtration or air stripping for removal of VOCs.

Jeff

We can provide more exact advice if you can give us more details about the pollution risk. We have sought advice from experts in the water treatment industry and this is what we have come back with so far. This is obviously a possible major issue and I guess some very clear advice would be useful. If you want us to continue investigations we should be able to get a more considered response. Best regards Toby