Thank you.
0.25 g of seed powder can be measued with a senstive balance. For practical purpose it is approximately 2 pinches.
Using slightly more than this amount is not very critical. The excess powder that does not take part in the clearing process
will remain in the filtered water. It will not affect the water quality, except a slight increase in turbidity. Use of very tightly woven cloth
(e.g.muslin, if available) can further reduce turbidity. Filter paper is found to reduce turbidity by about 35% compared to cloth.
All the best.

Thank you. The article is quite interesting. It is an example of the use of Indigenous Technology (IK). More work is needed
for grey water reuse / treatment.

Dear Dr Varkey,

In Table 1, some parameters have increased after 4 hours of operation.

Sulfate has increased from 1 to 4 mg/L; chloride from 4 to 6; potassium from 1 to 5.4; sodium 18.64 to 26.87; and more importantly, copper itself has increased from 0 to 0.24 mg/L. Can you please clarify?

Attached is a WHO publication on copper in drinking water.

Regards,
F H Mughal

Thank you for the comments.
My idea of a comparing those parameters in raw water and treated water was to test how far they change after treatment and to find out if the treated water has any of the parameters outside the accepted guidelines for drinking water quality. This was to test the efficacy of the technique to see if it could be recommended for use.(needs more tests for confirmation). After comparing the two, there is increase in some elements after treatment. It is not surprising because moringa seeds contain these elements and after mixing with raw water they can leach into it and can be carried over to treated water during decanting. Increase in copper is not from copper wire or pot used in disinfection. Please see attached file for a list of nutrients in moringas seeds. (This is from literature; I did not do a nutrient analysis of the seeds. They might differ in samples grown in different countries). However they are all within accepted limits for drinking water and therefore I don’t think it should be a concern. Moreover as seen attached file, the daily intake limits of these elements seems to be much higher than what one would get by consuming the treated water.
Trace elements (including copper) are needed in small quantities for proper body function which is obtained from foods. If they are available in the treated water, will it not supplement them by consumption? Just a thought; I am not an authority to say so! A nutritional analysis of the water might be useful.

Thank you for your enlightened reply.

How to know when to replace the seeds. In poor household settings, labs are not available to test the water quality. They go by the thumb rule, say, for example, replace the seeds once a month at 5 liters/day flow rate, or its equivalent (roughly).

Regards,
F H Mughal

Thank you.
Once seed powder is used up, it should be thrown away along with the residual and replaced with fresh ones because during coagulation the seed particles (more specifically the proteins, MOCP) attract dirt from raw water (an electrostatic phenomenon), get clogged and settle down. It cannot be re-sued. At the rate of 0.25 g /L, 5 L raw water needs 1.25 g powder. 1 kg powder costs about $ 1.00 or less (in most countries) which is enough for 800 L water. Very cost effective. Copper can be reused several times. Only needs occasional cleaning which can easily be done using lemon juice mixed with a small amount of salt. Everything can be done in a rural household except quality test which should be done in a laboratory, once in a while by, say, the local water authority.
Regards,
Dr. Varkey

Thank you for your response.

Turbidity in canals here is high (500-800 ntu). From Table 1, it appears, you have studies waters with 200 ntu turbidity.
What changes would you suggest for highly turbid waters (500-800 ntu)?

Regards,
F H Mughal

Thank you.
If turbidity is high only after rain it can first be reduced by allowing water to stand for some time for natural sedimentaion to occur.
It can then be decanted and use smiliar amount of moriga powder for further clarity. If turbidity is always high, more seed powder
(say 0.3 - 0.35 g/L) may reduce it to desired levels. I think 500 - 800 NTU is not normal in river waters.
Regards,
Varkey

Phuleli Canal in Hyderabad has high turbidity. As you rightly say, it goes further high during rains. In addition, there is significant soil erosion.
High turbidity of Phuleli is recorded is recorded in papers.

Natural sedimentation will take a long time. Further, if the turbidity is colloidal in nature, it won't settle.

Would you recommend roughing filters? See this link:

www.ircwash.org/sites/default/files/Wegelin-1996-Surface.pdf

Regards,
F H Mughal

Roughing filters are good enough for waste water management and as a pre-treatment procedure for potable water.
Regards,
Dr Varkey

Roughing filters are not used for wastewater management. The name of the publication is:

Surface Water Treatment by Roughing Filters

Regards,
F H Mughal

Thank you for the information.
I am curious to know the problem in Phuleli. Is canal the only source of water for the community?
Regards,
Dr. varkey