Flushing Toilets with Treated Water in Oman

Subject: Re: Use of treated effluent to flush toilets in Oman
Date: Thu, 01 Oct 1998
From: Art Ludwig <Oasis Design>
To: Andrew Chell <aqua1©gto.net.om>
[responses are in the original message text]

Andrew Chell wrote:
> Dear Art,
> Been reading about greywater on your various web pages.
> We're handling a project in the Sultanate of Oman for Petroleum
> Development of Oman to recycle treated effluent and reuse it to flush
> toilets.
> Oil drilling rig camps in the desert accommodate around 200 people and
> generate typical domestic sewage strength. UAT has designed, built and
> installed a hybrid sewage treatment plant to cope with ambient
> temperatures of 55 C and sewage temperatures of 47 C. The process is
> essentially biological and by using chillers and air conditioners and
> housing the plant in an insulated road container the sewage and ambient
> temperatures are controlled to a constant 30 C. Various pretreatments and
> post treatments are also used including post treatment UV irradiation and
> chlorine dosing.

Why chill the water? I was under the impression that with higher
effluent temperatures the required contact time is less.

> Water is very scarce in the desert and the intention is to reduce potable
> water consumption by recycling the treated effluent.
> Quality of treated effluent is as per regulations for wastewater reuse
> when irrigating crops of fruit or vegetables which are likely to be eaten
> raw.
> Basic characteristics of treated effluent are as follows:
> BOD < 15 mg/l
> COD < 150 mg/l
> Suspended Solids < 15 mg/l
> pH 6 - 9
> Faecal Coliform Count < 200 per 100 ml
> Is there any reason why this treated effluent should not be piped
> through a "greywater" distribution network and used to flush toilets?

I don't see why it would be a problem. A simpler solution which may or
may not suit the situation would be dehydrating toilets.

> Can you recommend a pipe system which will be distinguishable form the
> traditional domestic type pipework?
> Your comments would be much appreciated.
> Regards,
> Andrew Chell
> Chairman & Managing Director
> Universal aqua Technologies LLC

Purple PVC is traditionally used for reclaimed water and is readily
available in the US.
If you'd like additional help, you can check out info on our consulting
service at the web site below.
Art Ludwig