Second Response from Mr. Liaqat Hayat
Liaqat Hayat
Dear all,
I provide my response to various comments raised in email messages received and sumup as follows.
Location Description:
The site outlay is basically a row of houses from a higher ground sloping gently on a drainage path to a nearby stream under a small highway bridge location at less than a kilometer distance away approximately. A RCC pipe line has been used to convey sewerage from houses to the disposal point. Each house as a small manhole cum septic tank and this is connected to the referred street RCC pipe line. The second important aspect for consideration here is that drinking water is taken out of the ground through small borings/tube well type arrangement and hence underground water quality is an important consideration. It is for this purpose, it has been proposed to add secondary treatment after the small septic tanks to ensure that quality of effluent should be within permissible limits before its disposal to the environment. We have national emission quality standards applicable for any such disposal and to quote as example BOD parameter should not be more than 80 before disposal to the environment. This was previously 50 but has been relaxed to enable entities to start providing waste water treatment to some extent to start with. The present value of BOD parameter is around 300 and after septic tanks it is around 175. These are tentative values and are to be reconfirmed keeping actual influent samples in view from the laboratory tests but hopefully they will not be too different. May I also add here that soapy water also makes a portion of this and so far no separation arrangement for grease etc is normally made.
Various Options: (Comments of Manoj communicated vide email dated 09-07-07):
I appreciate the comments of Manoj and like to submit as follows.
(b) The reuse of this water in irrigation or to the greenery in general is very mush in my mind instead of its disposal in a natural stream. This all depends what quality of effluent I finally get out of the system. This is very much a point that needs discussion in this e-workshop. My assessment after reading available literature on constructed wetlands (CWL) reveal that it is possible and I have to study this aspect more.
(c ) The third comment is very useful to make it a sustainable project and I would request Manoj to further elaborates his point regarding generation of some revenues to the local community as well. This will atleast enable them to maintain this whole system properly to act as role model for other locations. Kindly provide me with details and results obtained for a specific community based project on this account.
Vetiver Grass/plant: (Comments of Walt communicated vide email dated 09-07-07):
I have two points in the final selection of plants for the constructed wetland plant. These should be available in natural form or can be easily grown in two to three months period. I would like plants which do not invite too many mosquitoes or insects etc as the houses are within 300 meter away approximately. I welcome the suggestion for vetiver grass but I need some more time to study this aspect in detail through my botanist friend and may have some questions toward the end after studying various alternatives. May I request Walt to assist me in my queries once I have studied various alternatives particularly if vetiver grass is to be grown specially in a nursery. I might also need seed for it. I am also not sure what sort of O&M services for this type of plant would be needed.
Design related question for comments by participants:
I have following points for which I need the experience or share lessons learnt from participants own experience in putting up or implementing a natural system for waste water treatment and disposal etc and invite comments on following aspects.
(a) How to minimize seepage into ground from wetland cell? Providing a thick polythene on earth surface and sides would be enough. Need comments on this or better alternatives
(b) Area requirement for CWL cell with BOD parameter details given earlier. I am not in a position to provide laboratory results for a sample taken at the moment but we can consider an average value of TSS, TDS and pathogen counts etc for this discussion. Presently I have no idea of nitrate, phosphorous or other nutrients in the influent that need treatment. Can I forgo them at this stage in case it do not affect the size of the CWL cell.
(c ) I can also try more than one cell with different filling materials and plants to see which cell provide the best treatment under the scenario. I like to test more than one option here as I am considering it as a pilot plant for future application as well. Can I share with your experience on this account.
What should be the depth of stone filling layer and its size? Can we use 3/4″ size crushed aggregate single size for 12″ depth to be subsequently overlaid with 2″ layer of smaller stone/sand before planting vegetation on it for the submerged vertical flow type CWL. Once functioning, how much time would be repeated to change or cleanse these two layers for say 0.5 cubic meter per person per day water requirement basis.
What should be the retention time and how to calculate it as cavities between stone pieces are not easily assessable. I need comments on this as well.
With best wishes to every one and hope to hear from you soon to continue this discussion. I shall welcome hand made small sketches as well to clarify points being discussed. Please note that I have not yet seen a functioning wetland.
Liaqat Hayat
Jacky Foo
original message contains an image.
click on source to view image
--------Forwarded message--------
Location Description
Submitted by Jacky Foo on Wed, 11/07/2007 - 18:03.
Dear Liaqat Hayat
thanks for the description of the location.
>The site outlay is basically a row of houses.....
>A RCC pipe line has been used to convey sewerage from
> houses to the disposal point.
Is the RCC pipe still in working order ?
I presume the RCC pipe serves other communities where drainage pipes
join along the way to the stream. If the RCC pipe is working, then the
baffled septic tank system should allow you to discharge the effluent
into the RCC pipe. THis means that you dont need the CWL.
IF...... you cannot use the RCC pipe any more and you must develop an
onsite system, then I would suggest a single underground collection
tank for the effluent from the houses and followed by an open tank
system that serves as the CWL.
Each house already have their own septic tank. Essentially you just
need to have a central collection point for collecting effluents from
all the houses. I dont think you need an underground baffled septic
tank system. This will save you some money.
Secondly, the community gets its drinking water from a borehole. A mud
plaster will leak and may risk contaminating the ground water (unless
you have geological scan of the ground below).
So you can use your savings on a series of open shallow tanks as your
CWL. However you have 4 months of cold weather in a year and this
could be a problem on the cleaning efficiency.
An open tank system may allow you to generate some income from the
sales of ornamental plants which can partially pay the salary of a
worker. Also you may consider integrating the use of nutrient rich
effluent in a plant nursery.
-----
Jacky Foo
http://www.iobbnet.org
Liaqat Hayat
I need to clarify one point here before we discuss this issue further. The small manholes of individual houses are connected to the RCC pipe line running in front of the houses in the street and disposes off the sewerage water thus collected into nearby natural stream. The collection tank with baffled walls is one option to collect all this water of the houses to divert and distribute it to CWL as per hand written sketch as attachement. Now I feel we should have simple tank without baffled walls and divert the collected sewerage of individual houses into the CWL and from there dispose it off to the stream which is about 200 meters away. This is a community efforts and RCC pipe line belongs to these 10 or so houses.
Jacky Foo
click on source to view image
Submitted by Jacky Foo on Thu, 12/07/2007 - 07:33.
Dear Liaqat
thanks for the useful additional information and the sketch of the area.
As you can see, with more information and details, the ideas for opportunities also changes.
e.g. earlier I thought the stream was "at less than a kilometer distance away" ( http://www.iobbnet.org/drupal/node/view/970/3271#comment-3271).
The new information provided says that the CWL will be located 200 meters from the stream.
Q: who owns the strip of land between the houses and the river ?
I am thinking ......Q: why not have the CWL parallel to the stream ?
This way you may not even need a new septic tank ----- the RCC empties effluent directly into the CWL - canal or pond system). You dont need pumps and it is just a gravitational flow system.
If you put the CWL in the middle of the 1 km strip, there may be building construction in the future and you will have to move the CWL.
I made a proposal in 2004 for cleaning stream water for bathing purposes but there was not follow-up by the partner until a week ago since 2 students were interested to visit Nairobi and to do a project there.
In the same manner, a project (with some funding) could be developed at your site.
Is the housing area organised as a NGO ?
Liaqat:
are you operating as a company or via a research institution ?
regards
jacky
Liaqat Hayat
To Jacky Foo
Thanks for your prompt response and like to respond as follows on various points mentioned there
(a) I like your idea having CWL parallel to the stream in the form of pond. I will however visit the area today and reconfirm this. I shall feed some more information to you on the subject as well. I also feel that we can turn into a project with some money from the community and some from other funding etc probably you can be some idea on this as well.
(b) The land is owned by the community and it was one of the owner of the houses who is coordinating with me on the subject when he was told that present arrangement can contaminate the underground water.
(c) I am working as individual consultant with highway construction authority and is advising them on Contract administration and Procurement of works/services related matters. CWL is my focus of attention as hobby to provide some suitable matter of waste water treatment and recycling for the villages in Pakistan. It is a solo effort and I do it on my own whatever time I find. I like to, however, complete this project as pilot plant in next 4-5 months. I would need some more assistance in design as well as good hints for construction as well as you are all giving me your comments at this planning stage.
(d) Can we extend the scope of this work by incorporating rain harvesting measures as well?
Best Regards,
Liaqat Hayat.
Jacky Foo
----forwarded message-----
Liaqat wrote:
>(b) The land is owned by the community and it was one
>of the owner of the houses who is coordinating with me
>on the subject when he was told that present arrangement
>can contaminate the underground water.
The contribution of pollution to a stream (depending on the water flow rate) from 11 m3 per day of effluent from septic tanks (my guess) is probably also insignificant. There is usually a die-off and dilution factor by the time it goes down-stream to e.g. 500 meters. There has been studies on die-off of microorganizms for direct discharge of even a much more polluting wastewater e.g. from a slaughterhouse in Nigeria. At 400 m downstream, the fecal coliforms and BOD was the same as up-stream before the point of discharge.
Pollution will be significant if all the residential houses along the stream does the same and discharge effluent from their septic tanks into the stream.
regards
jacky
Jacky Foo
---------- Forwarded message ----------
From: Grimshaw Richard <dickgr...@vetiver.org>
Date: 15-Jul-2007 06:08
Subject: Re: Second Response from Mr. Liaqat Hayat
To: Jacky Foo <jack...@gmail.com>
Please post the following for me:
"I could write a lot about the Vetiver System, but will keep my
comments to the minimum.
First in Pakistan and north India Vetiver grass (Vetiveria
zizanioides) is known locally as Khus Khus. It is a well known grass.
Vetiver grass from south India is used in most tropical and semi
tropical countries for soil and water conservation, slope
stabilization and pollution control. Cultivars of the south Indian
variety is preferred, and most of the research world wide has been
carried out on the south Indian type vetiver.
There is a project in Punjab State, India where Vetiver will be used
to clean up the pollution of a "holy" river. Vetiver grass hedgerows
will be planted along 200km of river bank to act as a buffer, thus
preventing sediment and other pollutants from entering the river. In
addition vetiver constructed wetlands and small individual vetiver
beds will be created to deal with effluent from community sewage
outlets and for the clean up of effluent from individual sceptic
tanks. Vetiver will also be used to stabilize village trash dumps in
order to reduce leachate flows from thise heaps
You can find out more about this from M.P.Singh
email:earth...@oceanofdrops.com
Most of the research on vetiver for pollution control has been
carried out in Australia (Queensland, China, and Thailand. All the
results conclude that Vetiver grass can remove oner 90% of nitrates
and phosphates and most of the BODs. Effluent having been thus
treated meets general EPA standards to be returned to the river. I
point you to two papers:
THE USE OF VETIVER GRASS FOR SEWERAGE TREATMENT http://
www.vetiver.org/AUS_ekeshire01.pdf
MONTO VETIVER GRASS EFFECTIVENESS IN TREATING SEWAGE EFFLUENT
http://www.vetiver.org/AUS-Beelarong.pdf
There is a huge amount of information on the Vetiver Network Site at:
http://www.vetiver.org
All the information is in the public domain
I see one person has been asked what economic purposes can vetiver be
used for. There are many including its use as a forage,mulch, thatch,
fuel,mattrass filler, medicinal purposes and as a plant sold to
engineering construction sites when used for slope stabilization and
other non agricultural purposes.
Vetiver grass is propagated by clump division and NOT by seed.
For those of you who want a quick look at the Vetivers System visit
http://picasaweb.google.com/VetiverClients where there are 20 mini
power points describing Vetiver's many uses
Dick Grimshaw