Hi David,

Thank you so much for your information. This is quite interesting ! Let us hope we will start good research in Bangladesh that just intalled. I will try my best to bring attention to our development partners about this technology. Have already discussed with several ADB colleagues. Yes, also to CDD colleagues. I believe CDD can be a very good partner to promote this technology in the region.

Roshan

Dear Friends,

It was recently suggested that I should upload the final report from our cocopeat study that was funded by the Bill & Melinda Gates Foundation's Grand Challenges Explorations program. The paper was presented at the IWA 2012 DEWATS Conference in Nagpur, India and published by IWA in their conference proceedings. Note that you can also access the report directly from the SuSanA library at: www.susana.org/lang-en/library/library?v...eitem&type=2&id=1760

Thanks all for your interest in the cocopeat technology. We will continue to update the forum on our related activities, which in addition to S and SE Asia, are now focusing on El Salvador's tourism areas.

Cheers,

Dave Robbins

Hello Roshan,

Thanks very much for your response. I will talk with my friends at Waste Concern and see how we should proceed with the study. Thank you for the suggestion.

As for BORDA/CDD Society, I was able to meet them last year when I presented our final paper on our cocopeat study at the IWA DEWATS Conference in Nagpur, India. It was a great event, and the folks from BORDA and the CDD Society seemed interested in the cocopeat technology. Coincidentally, one of the CDD Society members just today signed up as a member of our website, Wastewater Solutions for Development (www.watsanexp.ning.com). Check it out if you haven't already. We have all of our cocopeat documents there. If you would like to see the final report that was presented, visit the site at:
watsanexp.ning.com/page/general-dewats-documents which is our documents page. The cocopeat final report is the first document listed.

On a related note, I will be talking with Elizabeth soon about rolling our webpage into Susana's site (if she will have us). It seems like the best way of sharing this information.

On another related note, we are starting the process of determining how best to commercialize the cocopeat technology in India. We have teamed up with Eram Scientific (developer of the Delight e-toilet)and tomorrow we are pitching our business plan to the US India Science and Technology Fund (wish us luck!). With all of the attention in India with cities developing their City Sanitation Plans, there really is a huge market growing in India for low cost solutions. The business plan concept we are pitching is based on inclusivity, so there is room for everyone. It includes capacity building, training and certification in the Best DEWATS Practices, and of course a modular and scalable cocopeat unit we think will have broad appeal. I would be pleased to fill you in on more of the details if you are interested in this topic.

For your last question, you are asking about the history of our cocopeat installations. I just learned that the some staffers from the Asia Development Bank took a field trip last week to visit our two systems we built in Muntinlupa City, just south of Manila. Both of those are running now for almost 18 months. These were originally slated to be decommissioned after the initial testing, but they are still being operated and maintained by the users. Those two systems are:

Putatan Elementary School - Started November, 2011 and still running strong. watsanexp.ning.com/profiles/blogs/intere...lementry-school-munt

Muntinlupa Science High School- January 2012. watsanexp.ning.com/profiles/blogs/intere...lementry-school-munt

Our other systems include:

The Institut Teknologi Bandung (ITB) in Bandung Indonesia. They built a full scale system for one of their science labs in 2011. I think it is still up and running. Here is a link to that one: watsanexp.ning.com/profiles/blogs/itb-la...t-their-bandung-indo

Greenland Subdivision, June 2008. A project of the US Navy Seabees (the construction arm of the US Navy) to provide a humanitarian project in Calbayog City, Philippines. Status is unknown (anyone know the current status?). Here is a link that describes this one: www.navy.mil/submit/display.asp?story_id=37768

Muntinlupa Public Market - The cocopeat system was installed for testing purposes only in 2007 and was decommissioned as planned after one year. The full system for the market remains (ABR/SBR) and is functioning beautifully thanks to the strong support of Jet Pabilonia, the City Environmental Officer. Here is an article on that one: watsanexp.ning.com/page/case-studies (the first case study listed is the Alabang Market Study).

And the first cocopeat system we installed, for the SOS Children's Village Cocopeat system in Calbayog City, installed in January 2007. Not sure if that one is still up and running.

So there you have it for the full scale systems. We have a number of bench scale treatability studies still running at Duke University in North Carolina and also some field trials ongoing with our friends at Can Tho University. Here is a link to their study: watsanexp.ning.com/profiles/blogs/cocope...vietnam-provinces-th

Thanks for your continued interest. If any of the links don't work, or you have trouble accessing, feel free to email me at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thanks again for your interest in this technology,

Cheers,and best regards,

Dave Robbins

Hi Dave,

Thank you so much for your additional information about the cost comparision between Constructed Wetlands and Cocapeat system. This looks quite promising. We are looking forward to see very good scientific studies at the system built in Khustia Municipality in Bangladesh. You may discuss with Waste Concern for carrying out research in this established unit.

I would also like to suggest you to establish linkage with BORDA/CDD in India who are promoting DEWATS system where constructed wetland (CW) is one of the secondary treatment unit after ABR (improved septic tank). If they replace CW with Cocopeat, cost would be reduced significantly and can be installed even in small space.

One more question, how many units of Cocapeat treatment system are now in operation and duration of its operation. Do you have adequate research result ?

Thank you once again.

Roshan

Dear Mr. Dave,

In accordance with the response of Ms. Elizabeth, I'm attaching the publications.

Enjoy!

F H Mughal

Dear Mr. Dave,

Yes, as a matter of fact, I have some excellent publications on slow sand filtration that should keep you busy for a few weekends! I don’t know how to post them. I’m, therefore, seeking the help of Ms. Elizabeth.

Just as a passing reference, on water treatment side, in case of high raw water turbidity (> 200 ntu), there is an option of using “roughing filters,” that can take off 50-75% of raw water turbidity, depending upon the design of the roughing filters. This lessens the burden, and increases the filter runs of rapid sand filters or slow sand filters. I believe, RTI’s mandate covers water supply as well.

Ms. Elizabeth: I want to share some publications on slow sand filtrations here. How can I do it? My suggestion is that I should send them to you on your personal email address. Have a look at them and see, whether I, or for that matter the SuSanA, is not violating any copyright laws. Once cleared, you can post them on my behalf and, possibly, keep in the library, as well.

Kind regards,

F H Mughal

Dear Mr. Mughal,

Using the slow sand filtration for final effluent polishing is a great idea. I think the use of the tipping pan for our cocopeat systems, described in a previous post will help to equalize the flow, so that we won't overload the sand filter, and can keep it relatively small. I am wondering if you might have a design of a slow sand filter that you think might be applicable to these types of low-tech systems, especially those for off-grid applications where there is no electricity. I know that my new friend Srikanth, from India would also be interested in this.

Thanks again for sharing your engineering knowledge,

Cheers,

Dave Robbins
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Dear Mr. Dave,

Thank you for your nice and interesting response. I admire your patience in handling questions from India, Bangladesh and now from Pakistan!

Employing slow sand filtration (normally a rural water treatment plant) concept to the effluents of any wastewater treatment plant that produces the treated wastewater which do not meet the stringent regulatory requirements, is a cost-effective way of producing high-quality effluent. This arrangement is as good as providing a disinfection unit at the end of the wastewater treatment units. The only condition is: The system must be operated at the lower end of the slow-sand filtration system range, that is, 2 liters/square meter per minute.

Thanks again for your useful response.

Best regards,

F H Mughal

Dear Mr. M. H. Mughal;

Thank you for your response and questions. Here are my answers in the order you present them:

1. Aerobic or anaerobic process. Please refer to the discussion below that highlights the cocopeat installation from Waste Concern in Bangladesh. The cocopeat system is designed to be an aerobic treatment process by utilizing a strategy that draws atmospheric oxygen into the filter through the process of intermittent dosing. Longer term monitoring is required to verify, but my belief is that overall, this is a anoxic process, and likely oxygen transfer in the lower reaches of the filter is not very efficient. In our testing, after 9 months of use, effluent coming out of the system was quite low in DO, although removal efficiency of BOD and TSS was still quite high (85% to 95%). Interestingly, the system performed quite well at nutrient reduction, as tested by our partners at Duke University. It may be that the upper layers of the media in the filter are oxygen rich which drives the nitrification process, and anoxic in the lower reaches of the filter, which drives the denitrification process.

2. Heavy metals, inoragics and pesticides. This is a great question but I must report that we did not perform testing on these parameters. I would imagine that the cocopeat would work as well if not better at removing these constituents than a Rotating Biological Contactor or trickling filter as the mechanisms of treatment are quite similar. More research on these points is needed.

3. High or low silica content and treatment efficiency. It is a good question, but I don't know the answer. It may be the silica content in the cocopeat that is responsible for its resiliency in the wastawater environment.

4. Low DO and impacts to receiving streams. You raise two important points. The first is that adequate pretreatment is required for cocopeat systems to function properly over time. Our testing in Indonesia at the Institut Teknologi Bandung (ITB) utilized an influent source to the filter (septic tank effluent)that averaged 350 mg/l of BOD. I would imagine that this would be at the upper end. Stronger wastewater sources would require additional pretreatment. If wastewater from the source is concentrated, oversizing septic tanks (2.5 - 3.5 days detention time) might be a good idea. Otherwise, consider using ABRs which are a bit more efficient when sized properly. As for direct discharge, cocopeat effluent may require additional treatment to meet regulatory requirements. It would depend upon the nature of the receiving stream. This additional treatment might take the form of an indicator pond, or shallow impoundment which would allow surface re-aeration of the effluent while also achieving additional UV disinfection. Discharge of low DO cocopeat effluent into pristine environments is not advised. Better if the cocopeat effluent could be reused to irrigate landscape crops or agricultural crops not intended to be eaten raw. Shallow subsuface irrigation of cocopeat filter effluent I think is the key.

5. How long can the media work. Under the design provided for in these posts, the cocopeat system requires that the media be replaced every 5 years. After the first 3 months of operation, there is settling, and additional media is added to bring the level of the media back up to the original starting point. After that, as part of the routine O&M, the media surface is raked every 3 months at which time, additional media may be added to adjust for any additional minor settling.

6. Insects. We did not experience any mosquito or insect breeding. The systems we installed were all open at the top to maximize oxygen transfer. Heavy rain didn't seem to affect the system, although we did experience a problem during a typhoon in Manila where the existing septic tank was flooded. The cocopeat filter system may be covered, but if that is the case, a dedicated vent stack open at the top and discharging at roof level would be required. Filter flies and or odors might be a problem if systems are covered without adequate ventilation.

7. Concentrated waste from septic tanks. Please see the answer under #4 above. You are right. If the waste is too concentrated, and adequate pretreatment is not possible, the cocopeat system will not function properly. Providing adequate primary treatment (and pre treatment for commercial sources) is required.

8. The cocopeat specs. We used raw (dried) cocopeat for our systems. This was the dust that remained after the fibers were initially removed. It still contained some larger particles and fibers. We estimated that the fibers and larger particles contributed about 30% of the total volume. This is the material that was readily available and required little processing. Here is an image of the cocopeat we used in Vietnam that is representative of all of our testing.




Thanks again for your comments and questions.

Best regards,

Dave Robbins
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Dear Roshan,

Thank you for your message. Yes, we have been working with Waste Concern indirectly through their subcontracted engineer, Md. Nazmul Hasan, of Edeltech Engineering in Dhaka. He was the engineer that designed the cocopeat components for Waste Concern's project you are referring to. Hasan helped us with the development of the

tipping pan (see attached photo). The image shows the prototype which provides a non electric method of achieving intermittent dosing. As you can see in the image, the silver tube represents the effluent pipe from the septic tank or ABR. It first fills up one side of the tipping pan (blue structure) and when the weight of the effluent is sufficient, it dumps the effluent into one side of the filter, which is divided in half. Then the pan starts to fill the other side and when the weight is sufficient, it dumps the effluent to the other side. Intermittent dosing is important as it helps to entrain atmospheric oxygen into the media. As the effluent trickles through the media, empty pore spaces in the media fill with air, which helps achieve aerobic conditions within the filter.

Now, that being said, our initial research indicates that treated effluent from the filter is still rather low in dissolved oxygen, indicating that oxygen transfer is not efficient. Agreed that more research into this mechanism is warranted.




As for the cost issues, the image here shows a comparison between a hypothetical wastewater source of 10 cubic meters per day (Philippine pricing). The cocopeat system is about 75% of the cost of a wetlands system, but more significant I think is the time it takes to set up the system, which is much quicker with the cocopeat. Also notice the overall size of the system. The cocopeat filter takes up less than half of the space compared to the wetlands, which may be significant in urban or peri urban areas where space is constrained.

Since you asked about costs, here is the data from the Waste Concern system you reference (figures from Hasan received March 28)



Also of interest is the DO levels. Note that here it seems like the filter is efficiently transferring DO to the effluent. It will be interesting to see if this continues over time.

Thanks Roshan for your interest in this project. Next time you are in Dhaka, please plan to visit my friend Hasan. He is a great promoter of sustainable sanitation in Bangladesh.

Cheers,

Dave Robbins
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Dear Mr. Dave,

I’m joining the discussions rather late. I may have missed some initial points. Please excuse my omissions.

I have few minor questions:

1. It is an aerobic or anaerobic process;
2. Can the system remove heavy metals, pesticides, iron, and other inorganic and organic compounds (now common in wastewaters in developing countries – DCs);
3. Does high or low silica content in the cocopeat impacts its filtering properties;
4. As I understand, the system is to be used as a secondary treatment unit. Effluent from septic tanks or ARBs is low in DO (dissolved oxygen). If there is no aeration in cocopeat system, the final effluent will be low in DO, causing oxygen sag in the receiving streams. In DCs, due to relatively high ambient temperatures, the solubility of oxygen in receiving streams is low. This may cause anaerobic conditions in the receiving streams;
5. How long can the media work, before they need replacement or recharging;
6. How can the breeding of insects and mosquitoes be controlled; and what needs to be done in case of heavy rainfall;
7. Wastewaters in DCs are, typically, concentrated (BOD> 400 mg/l) and acidic (pH < 6.5), due to low volume of water available. Septic tanks, therefore (since their performance is not monitored) do not work properly, biologically. That means all the load would pass through and come to the cocopeat system. Will the system be able to handle that?
8. Has the specs of cocopeat been developed.

Thank you,

Kind regards,

F H Mughal (Mr.)
Karachi, Pakistan

Hi Dave,

You gave very good response about Cocopeat treatment mechanism. Thanks ! Do you have any cost comparison data between constructed wetland and cocopeat treatment ? Last month I visited a cocopeat treatment unit for treatment of effluent from fecal sludge drying bed in Khustia, Bangladesh. It was nicely designed by the Waste Concern and just started its operation. Were you also engaged for its design? We may need very good research plan to see its treatment efficiency. Please let me know if you are also working with Waste Concern in Bangladesh.

Best,

Roshan

Roshan Raj Shrestha, Ph.D. Program Officer | Global Development Water, Sanitation and Hygiene

Bill & Melinda Gates Foundation www.gatesfoundation.org/