How to Design Wastewater Systems for Local Conditions in Developing Countries

  • kevintayler
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Re: How to Design Wastewater Systems for Local Conditions in Developing Countries

Dear All

As requested by Mughal, I am trying to add the Punjab wastewater report as an attachment. I hope that it works - it is almost 2Mb and I am not sure whether there is a limit.

In answer to Christoph, I think that the UASB plants in India varied in capacity from about 5000m3/d up to 25000m3/d and above. I have another report which should provide details but will have to look for it.

A couple of points, first -responding to Pawan's point on the effluent quality of the Indian UASBs. The UASBs were followed by 'polishing' ponds that were meant to provide secondary treatment but they only had a bout 1 day's retention and only reduced perhaps 25 - 30% of the polluting load. UASBs are what I would refer to as enhanced primary treatment - they remove more BOD and SS than a conventional sedimentation tank but nowhere near the amount required to meet generally accepted effluent standards. This was a big flaw in the design and it would have been better to have provided proper secondary treatment.

With regard to Mughal's point about failure to provide maintenance for WSPs in Sindh - I saw the same thing a few years ago in Sukkur, Larkana and other North Sindh towns. Also, I designed a system for Kohat in the north that was built but never commissioned. I think that Mughal's point about the difficulties of getting staff to maintain ponds that require fairly simple maintenance is an important one. There is a good report by the Indian Central Pollution Control Board that examines the operation of a large number of plants throughout India. I looked at the findings to see whether there was any correlation between simplicity of process and successful operation, focusing particularly on WSPs. The result supports Mughal's point - hardly any of the WSPs were operating satisfactorily. I think that that report is available on the internet.

Kevin Tayler
Independent water and sanitation consultant
Horsham
UK

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  • christoph
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Re: How to Design Wastewater Systems for Local Conditions in Developing Countries

Dear All,
based on the data from Kevin I did a quick calc about the mentioned combination UASB and WSP in India which has a black effluent.
No wonder the effluent is black. please see this table



The actual load for the WSP is 4 !! times higher than the recommended load. Therefore the lagoon must by anaerobic, therefore presenting strong odour and black effluent. This seems not to be a problem of the technology but yes of dimensioning.
And I choose the values totally in favor a low load of the WSP.

Pawan and Kevin, could you check if my data are more or less correctly assumed?

Regards

Christoph
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  • kevintayler
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Re: How to Design Wastewater Systems for Local Conditions in Developing Countries

A quick follow-up on Christoph's email. His basic calculations confirm the point about the pond being overloaded - there is no way that a facultative pond could work with such a short retention time. The sewage strength was probably slightly lower than assumed by his 54gm BOD per capita per day (for some reason Indian wastewater is very weak). However, this does not alter the main conclusions.

I have found a couple of pieces of information that may be interesting and am sending them as attachments. One provides a list of WWTPs constructed under the Yamuna Action Plan with design capacities. The second is one of the Japanese university reports that I mentioned. I do have some other relevant reports and will try to sort out the best ones

Kevin Tayler
Independent water and sanitation consultant
Horsham
UK

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  • F H Mughal
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Re: How to Design Wastewater Systems for Local Conditions in Developing Countries

Dear Kevin,

That is a very interesting and useful report. It is sad that Punjab government did not take any action. It is, in fact, a guidance manual, specific to our local conditions. Because of some similarities, the report would be useful for friends in India, as well. I see, you have been to Sukkur, Larkana and other northern Sindh towns.

Where can I find the report of Indian Central Pollution Control Board, you have referred to?

Regards,

F H Mughal

F H Mughal (Mr.)
Karachi, Pakistan
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